Crop rotation
In the main regions of potato growing, 7-9-field crop rotations are usually adopted , which differ depending on the specialization of the economy and soil and climatic conditions. Potato saturation of these crop rotations: for 7-field is – 14-29%, 8-field – 12-25%, 9-field – 11-22% of the crop area, that is, in each crop rotation there are 1-2 fields occupied potatoes.
In potato farms, 5-field crop rotations are also common, in which a powerful arable horizon for potatoes is created faster as a result of more frequent deep plowing. In short crop rotations, potatoes use fertilizer more efficiently; facilitating weed control.
The best predecessors for potatoes are winter cereals after organic and mineral fertilizers have been applied under them, annual leguminous crops, for example, peas, vetch, lentils, beans.
In field and fodder crop rotations of the Non-Chernozem zone, it is placed along the layer or turnover of the layer of perennial grasses, winter crops, legumes, annual grass mixtures and flax, on sandy soils – after lupine.
In the Central Black Earth zone, the North Caucasus, the Volga region, Ukraine and Central Asia, the best predecessors are considered to be winter crops, corn, annual grasses, sugar beet, millet. In areas of sufficient moisture, winter crops grow along occupied annual legume pairs, corn for silage, and leguminous crops.
In the Far East, potatoes can be placed after soybeans.
In Eastern Siberia and Kazakhstan, potatoes are grown after grain and legume-cereal mixtures, in the Urals and the Far East – after grain and leguminous crops.
In the western and central regions of Russia, potatoes are grown after winter crops, going through lupine fallow, winter crops for green fodder with stubble oversowing of perennial lupine, fodder lupine for seeds or silage.
On drained peatlands, it is placed along a layer or turnover of a layer of perennial grasses, in this case the fields are less clogged, and groundwater occurs 1-1.2 m from the soil surface.
In arid steppe conditions, potatoes can be placed in floodplains and estuaries.
In vegetable crop rotations, potatoes are placed after vegetables, with the exception of the nightshade family. In specialized potato crop rotations, saturation can reach 35-50%, in which it is placed after annual grasses, clover of the 1st use. In some cases, re-sowing is allowed two years in a row on the same site. High saturation of crop rotations is possible under the condition of a high culture of agricultural technology and a good phytosanitary condition of the soil.
Potatoes are one of the few agricultural crops that, with good tillage and fertilizer application, give good yields when re-sown. Under unfavorable cultivation conditions, the decrease in yield during re-sowing reaches 30%. When sowing late potatoes after early, it is advisable to introduce intermediate crops. The recommended period for the return of potatoes to their original place is 3-5 years.
Potatoes can be cultivated as a fallow crop; early varieties are used for these purposes. To obtain a high yield in a busy fallow and subsequent winter crop, it is necessary to apply organic and mineral fertilizers. Harvesting in the fallow field is carried out no later than 12-15 days before sowing winter crops.
In crop rotation, it is important to ensure a deficit-free balance of organic matter. This is achieved by introducing perennial grasses into the crop rotation and applying at least 15-20 t/ha of organic fertilizers.
The potato itself serves as a good precursor for other crops, most notably early spring cereals, leguminous, corn, oilseeds, and fiber crops.
Fertilizer
Potatoes are responsive to soil fertilization. The yield increase with the joint application of organic and mineral fertilizers reaches 50%. When determining the need for nutrients, they are guided by soil characteristics, the chemical composition of fertilizers, their availability to plants and potato varieties.
Organic fertilizers
Organic fertilizers increase the starchyness of tubers and their size.
In all regions of potato growing, organic fertilizers are usually applied under potatoes in spring. However, this creates difficulties and tension in carrying out field work when planting potatoes, often leading to delays in planting dates and soil compaction. As a result, yield losses exceed the effect of fertilization. Therefore, for planting potatoes in optimal agrotechnical terms, it is necessary to make the most of the autumn time for fertilizing, especially in the southern regions, where, due to lack of moisture, manure introduced in spring decomposes very slowly and its efficiency decreases.
Part of organic fertilizers can be applied under the previous crop – winter grains of group I. Practical results show that when organic fertilizers are applied under the predecessor, only mineral fertilizers can be applied under potatoes. At the same time, the decrease in the collection of potatoes is compensated by an increase in the yield of winter crops.
When growing early potatoes, organic fertilizers are applied only in autumn for autumn processing in order to be able to plant germinated tubers in the early stages.
Manure
The effectiveness of the use of manure for potatoes varies depending on the soil-climatic zone.
For most regions, the optimal rate of manure application is 20-40 t/ha, but it also responds well to higher rates. In the Non-Chernozem zone, record yields are achieved with the introduction of 40-60 t/ha of manure.
In the north and northeast of Russia, on cold soils, increased rates are applied – 60 t/ha, on poorly cultivated soils – 80 t/ha.
On chernozem soils, manure rates for potatoes of more than 20-39 t/ha do not give a significant increase in yield, while on soddy-podzolic soils, an increase in yield is not observed at doses of more than 100-120 t/ha.
The average increase in the yield of potato tubers from the introduction of each ton of manure is highly dependent on soil and climatic conditions. On light sandy soils of the central regions of the Non-Chernozem Zone, the average yield increase from each ton of manure at a rate of 20-40 t/ha is 0.3-0.4 t/ha, in the western regions – 0.4-0.5 t/ha (Potato Research Institute). On loamy, clayey and gray forest soils of the Nonchernozem zone, at an application rate of 40 t/ha, each ton of manure gives an average increase of 0.2 t/ha.
For potatoes, semi-rotted manure is better, which is obtained 4-8 months after storage. The introduction of fresh manure leads to an intensification of microbiological activity in the soil, which is associated with a significant uptake of ammonia nitrogen from both the manure itself and the soil. This results in a lack of nitrogen.
The effectiveness of manure increases when it is mixed with phosphate rock at the rate of 20-30 kg per 1 ton of manure.
Under conditions of excessive moisture, high doses of manure over 50 t/ha in combination with nitrogen fertilizers can lead to a powerful development of the above-ground mass to the detriment of the yield and quality of tubers, their maturation occurs later.
Potatoes also respond well to the aftereffect of manure applied under the predecessor.
Green manure
On soddy-podzolic loamy and sandy loamy soils of the Non-Chernozem Zone, in addition to manure, peat and other organic fertilizers, green manure is of great importance. For these purposes, plants of the legume family are used, for example, lupine, seradella. Due to the ability to fix nitrogen , they accumulate nitrogen in the soil. When the green mass of green manure is plowed up, the soil is also enriched with phosphorus, potassium, calcium and other nutrients absorbed by the powerful root system of green manure from the deep layers of the soil.
In new areas and depleted lands, to increase their fertility , green manure is sown immediately before planting potatoes. Lupine, sown in spring, by autumn creates a green mass, the amount of which in favorable years is up to 50 t/ha.
Seradella is used primarily as a subsowing crop. It is sown in early spring under winter crops or sown simultaneously with spring crops (oats, barley). Under cover plants, it grows slowly at the beginning of its development, but after harvesting cereals, it quickly creates a large green mass.
It has been established that the greater the potato yield, the more green mass is plowed into the soil.
Potatoes also respond to poisonous green manure (perennial lupine, clover, seradella). In the case of an aftertaste fertilizer, the main crop of the crop is harvested and taken out of the field, and the growing aftermath is plowed.
The combined use of green manure and mineral fertilizers increases the yield by up to 30%.
Other organic fertilizers
Other organic fertilizers can be used for potatoes, for example, peat in the form of peat-dung, peat-liquid, peat-fecal or peat-plant composts. For the preparation of these composts, meadow lowland peat of a high degree of decomposition is used.
To increase efficiency, peat composting is carried out with mineral fertilizers. Peat-mineral-ammonia fertilizers are often used for potatoes, which are prepared by mixing peat with ammonia water at the rate of 20-30 l/t of peat with the simultaneous addition of phosphate, potash and other fertilizers.
Mineral fertilizers
Application rates
The application of only organic fertilizers for potatoes cannot fully satisfy the need for nutrients in potatoes, since after their application, time is needed for mineralization and the release of nutrients available to plants. For this reason, mineral fertilizers must be applied to obtain high yields.
In the northern, northwestern, northeastern and western regions of Russia, increased doses are used, in the southern and southeastern regions – reduced ones.
The recommended application rates of mineral fertilizers should be adjusted taking into account the planned harvest, applied fertilizers, and soil conditions.
Table. Approximate application rates of mineral fertilizers for potatoes for the main application, calculated for a planned yield of 20-25 t/ha, kg/ha a.s.
| Sod-podzolic sandy loam | ||||||
| Sod-podzolic loamy | ||||||
| Gray forest | ||||||
| Chernozem leached | ||||||
| Chernozem typical weakly leached | ||||||
| Peat | ||||||
| Floodplain | ||||||
Doses of fertilizers to obtain the planned harvest are calculated not by removal, but by periods of maximum nutrient consumption. To do this, you need to have information:
- consumption of nutrients per 1 ton of crop, taking into account the periods of maximum consumption by a particular variety;
- the content of the main nutrients in mobile forms in the soil and organic fertilizers;
- coefficients of use by potato plants of the main nutrients from the soil and applied fertilizers.
The optimal dose of nitrogen fertilizers when applied before planting for early and medium early varieties is 90 kg/ha for heavy soils in terms of granulometric composition, and 110-120 kg/ha for medium and light loamy and sandy loamy soils. For late and mid-late varieties on heavy loamy soils – 60 kg/ha, on medium and light loamy and sandy loamy soils – 90 kg/ha (All-Russian Institute of Fertilizers and Agrosoil Science, Potato Research Institute).
Terms of application
In the zone of sufficient moisture, phosphorus and potash fertilizers are applied in autumn for autumn cultivation, nitrogen and part of phosphorus – in the spring for plowing.
In the zone of insufficient moisture, all mineral fertilizers are applied to the main fertilizer, which are plowed into the soil in autumn.
Application methods
When introducing into the main fertilizer not the full rate, it is recommended to feed the potatoes after the appearance of full shoots before the first inter-row treatment. Top dressing is carried out with nitrogen fertilizers at the rate of 20-30 kg/ha of a.s. or organic – 5-10 t/ha of slurry (diluted 4-5 times with water), or 0.4-0.6 t/ha of bird droppings (diluted 8-10 times with water).
Top dressing with nitrogen fertilizers is necessary on sandy and sandy loamy soils in years with a large amount of precipitation and during irrigation, since nitrogen deficiency on plants is manifested due to leaching.
On soddy-podzolic, gray forest soils and podzolized chernozems, it is recommended to apply ammonium nitrate 15-20 kg/ha and granulated superphosphate 10-20 kg/ha P2O5 into nests or furrows during planting. Also for these purposes, you can use nitrophoska, diammonium nitrophoska, nitroammophoska, chlorine-free nitrophoska.
On chernozem soils of the forest-steppe and steppe zones, top dressing is ineffective. In areas of sufficient moisture in the Non-Chernozem zone, early feeding with N30P30 gave an increase in yield up to 12%.
Chlorine-containing potash fertilizers are applied only in autumn, so that chlorine is washed out of the root layer of the soil during the autumn-winter period, thereby reducing the negative effect of chlorine on potatoes.
When growing table and seed potatoes, it is recommended to use non-chlorine forms of potash fertilizers , for example, potassium sulfate or kalimag. If chlorine-containing fertilizers cannot be avoided, then it is better to use highly concentrated forms, such as potassium chloride, in which less chlorine is applied per unit of potassium.
When making a full dose of mineral fertilizer, the ratio of N, P and K is taken into account, which should shift towards an increase in phosphorus and potassium (Korshunov, 1983). With a planned yield of more than 40 t/ra and the use of higher doses of fertilizers (more than 120 kg/ha a.s.), the ratio N : P : K should be 1 : 1.5-2 : 1.35-1.8.
If at a rate of 120 kg/ha a.i. nitrogen, phosphorus and potassium are applied in the same amounts, the effectiveness of fertilizers is sharply reduced, the growing season is lengthened, the tubers by the time of harvesting are physiologically immature, with a fragile skin, which leads to severe damage during harvesting, poor storage, and when cooked they turn black with poor taste (Korshunov, 1983).
The introduction of granular nitrogen-phosphorus and complex fertilizers with a tape into the furrow during planting increases the efficiency of fertilizers by 2 times compared to the broadcast method of application.
Magnesium fertilizer and microfertilizers
On light soils, it is recommended to additionally apply magnesium fertilizer, which helps to increase the yield and starch content of tubers. On average, the application rate for magnesium fertilizer is 40-50 kg/ha, for dolomite flour (15-18% MgO) – 250-300 kg/ha.
On peat-bog soils, copper microfertilizers are applied. To do this, they are introduced in the amount of 5-6 kg of copper sulphate when planting locally, together with 100-150 kg of superphosphate.
On soddy-podzolic soils, boric, zinc, and molybdenum microfertilizers are applied under potatoes. Boron application rate is 1.5-2 kg/ha a.s.
Processing with microfertilizers can be carried out for planting tubers with a 0.05% solution of boron, zinc, copper and molybdenum. The yield increases by 12-15%.
Liming
Soils with acidity less than pH 4.5 are subject to liming. Liming is preferably carried out under the previous crops, otherwise it is carried out under potatoes in the fall for autumn processing or in winter under snow, while the doses of lime fertilizers are reduced to 0.25-0.5 hydrolytic acidity. Excess lime under potatoes can cause scab development.
Tillage
The main task of soil cultivation for potatoes is the creation of a deep, loose, well-aerated and sufficiently moistened arable layer. Also, the treatment should ensure the cleansing of areas from weeds, pests, pathogens and the incorporation of fertilizers.
Soil preparation includes the main, or autumn, and pre-planting treatments.
Basic processing
The main processing after grain and leguminous crops includes soil peeling and deep autumn plowing. Peeling is carried out with disc cultivators to a depth of 5-8 cm after harvesting the predecessor. The delay in carrying out this technique leads to loss of moisture and a decrease in its effectiveness. In semi-arid and arid regions, the importance of peeling increases.
2-3 weeks after peeling, plowing is carried out to the depth of the arable layer for sod-podzolic soils with simultaneous loosening of the sub-arable horizon or 30-35 cm for chernozems. When cultivating the soil for potatoes, it is possible to carry out a reception by deepening the arable layer by 2-3 cm.
Fields after non-stubble predecessors and in the north-east of Russia with a short post-harvest period can be plowed immediately without peeling after harvest. However, on soddy-podzolic loamy soil after autumn plowing, especially if it is carried out early, the soil is compacted and overgrown with weeds . In this case, the field is cultivated or disked (husked), which contributes to the destruction of weeds, loosening the soil for the accumulation of precipitation for the autumn-winter period.
When planting potatoes after a layer of perennial grasses, they are cut with disk tools in two directions, followed by plowing with a plow with a skimmer.
Plowing of light sandy soils can be replaced by autumn tillage to a depth of 14-16 cm.
In dry summer-autumn periods, when it is difficult to carry out early autumn plowing of the soil, they are limited only to disking, plowing is left for a more favorable time.
In the Central Black Earth zone, on fields clean of weeds, it is possible, along with moldboard tillage, to carry out non-moldboard loosening of the soil in the fall.
In regions prone to wind erosion, deep non-moldboard processing is used. Organic fertilizers here are more expedient to apply under the previous crop.
Pre-sowing treatment
Pre-sowing tillage in spring should ensure the preservation of moisture accumulated in the soil during the autumn-winter period, the creation of a finely crumbled loose arable layer from a leveled surface and weed control.
In the Non-Chernozem zone, the plot is harrowed or cultivated. Then, on floating heavy soils, as well as when organic fertilizers are applied in spring, plowing is carried out to 17–20 cm. organic fertilizers) or plowed up by 16-18 cm.
In the zone of excessive moisture in the north-west and north of Russia, in spring, the fields are plowed to a depth of 18-20 cm with moldboard plows with skimmers and subsoilers.
In the zone of insufficient moisture, in the forest-steppe and steppe zones, depending on weather conditions, 1-2 loosenings are performed in the spring with a cultivator or plows without mouldboards to a depth of 16-18 cm with simultaneous harrowing.
An effective method of pre-sowing treatment can be the plowing of plowing with plows without mouldboards, but with installed skimmers to a depth of 12-14 cm, which close up the fertilizers applied in the spring. Shares and tines of the plow bodies allow deep loosening of the soil, and applied fertilizers are planted to a shallower depth, which contributes to their decomposition, especially in years of excessive moisture (NIIKH).
In spring, deep non-moldboard tillage of 25-27 cm can be used, followed by disking or milling.
In Poland and Germany, pre-sowing tillage in the spring is carried out with the help of plows. When processing with plow cutters, the soil layer descending from the plow body with shortened mouldboards is crushed by rippers standing behind the mouldboards. The advantage of this method is a more thorough mixing of organic and mineral fertilizers with the soil and its good crumbling in one pass of the tool.
In Belarus, when using plows for tillage for potatoes, the increase in yield was 10-12% compared with conventional moldboard processing, harrowing or cultivation (N.A. Dorozhkin, 1976).
Spring milling shows good results.
In some areas, there may be effective preplant ridge cutting that replaces cultivation with longline hillers. On sandy soils, this technique can replace the spring plowing of fallow.
A promising way to prepare the soil for planting potatoes can be the autumn cutting of ridges, which allows you to start planting earlier in the spring.
Tillage depth
Potatoes are very sensitive to the depth of plowing. Deep plowing allows you to increase the thickness of the soil layer in which tubers develop and ensure subsequent good hilling. Shallow plowing makes hilling difficult, and poorly executed leads to the formation of small tubers and their placement at the very surface of the soil.
For example, on sandy loamy soils, the potato yield in crop rotation without deepening the arable layer and without applying fertilizers was 10.6 t/ha, while with a deepening of up to 30 cm – 12.7 t/ha (Potato Research Institute, All-Russian Institute of Fertilizers and Agrosoil Science). On bound medium loamy soils, the yield of a medium-early potato variety when plowing a fallow by 20-22 cm was 23.0 t/ha, with a deepening of the subarable layer by 15 cm – 24.8 t/ha. At the same time, the effect of deep plowing on potato yields has been observed for several years. Deep plowing increases the starch content in tubers.
According to research by the department of agricultural engineering of the Potato Research Institute, the arable layer of loamy soils ripens gradually: the upper layer 12–16 cm deep is ready for processing 5–7 days earlier than the lower one at a depth of up to 28–30 cm. potatoes in two terms. When the physical ripeness of the topsoil is reached, disking or ploughing of the fallow land is carried out using share cultivators to a depth of 12-16 cm, then 3-4 days before planting potatoes – deep non-moldboard tillage to a depth of 28-30 cm.
Peculiarities of processing peat-bog floodplain soils
On peat-bog soils, which are common in the central and southern regions of potato growing in Russia, after harvesting the previous crop, plowing is carried out with disc cultivators to a depth of 6-10 cm, then ploughing is carried out using swamp plows at 30-35 cm. 3 weeks after plowing, if weather conditions allow, autumn plowing is performed, with the help of which germinated weeds are destroyed and the soil surface is leveled, which contributes to its uniform thawing in the spring.
In spring, marsh soils and cultivated peatlands are disked 1-2 times after thawing the soil by 10-15 cm. Before planting, repeated disking with harrowing and rolling with water-filled rollers is carried out.
Soil cultivation on floodplains is determined by the location of the site and the speed of the flood waters. Usually, the soils of the central and near-terrace floodplain are not at risk of washing off the arable layer, so their cultivation begins with autumn plowing at 27-30 cm.
On the floodplain lands of the Central Black Earth zone, the Middle Volga region and arid regions of the south and southeast of Russia, instead of spring plowing, plowing is carried out without a moldboard.
Light sandy loamy soils of floodplains located in places with a strong flow of flood waters are plowed only in spring by 20-25 cm as these areas are freed from water.
On heavy loamy floodplain soils, mole is carried out simultaneously with plowing. The effectiveness of the reception on the site is maintained for 2-3 years.
Planting
Preparing tubers for planting
Suitable for planting are healthy, intact, formed potato tubers typical of this variety. For seed purposes, tubers are selected from the most productive areas grown on peat soils or floodplains, tubers from summer plantings or early harvests.
Preparing potato tubers for planting includes:
- separation into fractions by size and weight;
- removal of diseased and damaged tubers;
- sprouting or wilting.
To increase the productivity of germinated or dried tubers, they can be treated with growth stimulants.
Before planting, seed tubers that are no longer dormant should be removed from low temperature storage and placed for a few days at 10-13°C. Going from low temperatures to high temperatures promotes the best emergence of seedlings after planting.
Faction division
Sorting by fractions is done in the fall before laying for storage or in early spring before the appearance of sprouts. The tubers are divided into a fine fraction up to 50 g, an average seed fraction 50-80 g and a large fraction over 80 g. If necessary, a small fraction of tubers from healthy plants can be further sorted into seed tubers weighing 30-50 g.
Large tubers weighing more than 80 g also serve as good seed material. When planted, they give the highest yields, but economically significantly higher consumption of seed material is not always justified.
For mechanized planting, leveled tubers of a fraction of 50-80 g are suitable. The use of tubers of different sizes for planting is not allowed, as this leads to sparseness, uneven germination and crop shortages.
Drying
When warm days with positive temperatures arrive, light drying of seed tubers begins during the night. Drying is carried out in relatively warm and bright rooms, where they are spread in a thin layer 10-15 cm thick. They are kept until the seedlings appear. In case of frosts, the tubers are covered with film or straw for the night or on cool days.
Drying causes a loss of 10-15% of moisture in tubers, which stimulates enzymatic processes, provides partial greening, and leads to early uniform shoots. Dried tubers are better suited for mechanized planting because the eyeballs are just beginning to awaken, but sprouts have not yet appeared.
Germination
Sprouting accelerates emergence of seedlings, promotes rapid plant development and yield formation. This method is especially important when growing potatoes for early bunting, when cultivating highly productive seed material with early harvesting terms and with a short vegetation period (haulm does not have time to die off) in cultivation for food purposes. On average, this method gives a yield increase of 2.5-3 t/ha.
Sprouting is carried out 25-30 days at 12-15 ° C in a light ventilated room. According to other recommendations, germination is carried out in the light at 20-25°C (Rubatzky). Under the influence of light, the sprouts become short, thick and green, and as a rule, they are not injured and do not interfere with planting.
The duration of germination can be adjusted to the conditions and cultivar. Sprouting can be carried out in unlit warm rooms, the duration is reduced to 15-17 days, so that the length of the sprouts was no more than 15-20 mm. Sprout potatoes in boxes of 10-12 kg tubers or in free greenhouse pits.
Sprouting in the northern and north-eastern regions of Russia, where short summer and early autumn frosts are typical, is a mandatory technique of agrotechnics. Under these conditions, it lengthens the frost-free period. In this case, the yield increase reaches 7-13.5 t/ha (State Agricultural Experimental Station of the Komi Republic).
In the south and southeast of Russia, sprouting accelerates tuber formation and shortens the growing season, thus allowing for an earlier harvest before the onset of high summer temperatures. The efficiency of germination here is the higher the less degenerate the seed. Severely degenerate potatoes usually do not yield an increase in yield from germination.
Under the conditions of high humidity in the western and north-western regions of Russia, potatoes are severely affected by phytophthorae in autumn. Sprouting allows you to start harvesting before the period of mass spread of this disease.
In the Non-Black Soil Zone, this method can be complemented by powdering tubers with ashes at a rate of 5 kg/t and treatment with 0.01% solutions of boric acid or copper sulfate at a rate of 15-18 liters of solution per 1 ton of tubers.
Tuber cutting
Whole tubers are preferred because they produce more stems compared to the equivalent weight of a cut seed tuber. Whole seed tubers are easier to handle and the spread of cutting-related diseases is reduced. However, when planting material is scarce in the potato industry, cutting tubers is resorted to. During mechanized planting, tubers that are cut are used mixed with uncut tubers at a ratio of not more than 1 : 3, because otherwise the specified planting density will not be achieved.
The cutting of the tubers may be done on the day of planting or the day before, but usually the cut tubers should be placed in warm (15-21°C) and high humidity conditions for a few days in order to allow the cuts to heal and to be corked, protecting the tubers in the soil from rotting and disease. The process of cork layer formation (suberization) is faster at warm temperatures. You can also use fungicides to protect the cuttings from rotting.
The cut pieces should be approximately equal in number of eyes and size and should have at least one eye, preferably two or three.
Pieces of cut seed tubers should be block-shaped and weigh between 40 and 60 g. The size of the seed tuber affects the stem size of the plant and its viability. Large seed tubers produce large stems that grow faster and produce more leaf area and high yields, although this advantage decreases when tubers weigh more than 60 g. Roots develop from the base of the stems rather than from the tissues of the seed tuber.
Depending on the scale of the operation, the cutting of seed tubers is done manually or with automated equipment. To avoid the spread of diseases during cutting, it is important to use disease free tubers and to follow sanitary regulations.
Planting dates
Potatoes are planted when the soil temperature at a depth of 8-10 cm is 6-8 ° C, in southern areas – up to 5-6 ° C, but the preferred soil temperature is above 15°C. It may take 30-35 days for seedlings to emerge at 12°C. At 22 to 30°C, seedlings emerge from seed within 10 days. Earlier planting leads to rhizoctoniosis damage, the optimum temperature for the development of the pathogen is 4-5°C. In production conditions, planting is usually started after sowing of grain crops and completed within 8-10 days.
Delay in planting at the optimal time by 10-20 days leads to a decrease in yield by 10-20%, starch content in tubers – by 2-4%.
Sowing dates on light sandy and sandy loamy soils, as well as on uplands and southern slopes, are somewhat earlier than on heavy loams.
Early ripe, mid-early and mid-season varieties are planted first in a busy fallow, then they start planting seed potatoes. Potatoes for food purposes are planted last.
According to the Institute of Experimental Meteorology, the isolines of the optimal landing time are:
- April 20-30 passes Vilnius – Minsk (to the south) – Tula – Penza (to the south);
- May 1-10 passes Riga (to the north) – Pskov – Tver – Ivanovo – Cheboksary – Ufa (to the south) – Chelyabinsk – Kurgan;
- May 10-20 St. Petersburg – Omsk – Novosibirsk (to the north);
- May 20-30 passes north of the previous isoline;
- June 1-15 passes through the north of the Arkhangelsk and Murmansk regions, Karelia and the Komi Republic.
Planting density
Potato planting density, at which the maximum yield is achieved, is different and depends on the quality of planting material, variety, agricultural technology, cultivation goals, soil and climatic conditions. The higher the fertility of the soil and the more favorable the conditions for growth and development, the denser the plants can be planted.
On cultivated loamy soils of the Non-Chernozem Zone, with large areas of nutrition, tops grow, vegetation lengthens, and tubers do not ripen. On the contrary, on light sandy soils, thickened plantings do not work, as the plants are deficient in moisture.
For the Non-Chernozem zone, the optimal planting density is:
- for the northern and northwestern regions 50-55 thousand bushes/ha;
- for the central and southern regions – 45-55 thousand bushes / ha, and on sandy and sandy soils – 45 thousand/ha, on loamy soils – 50-55 thousand/ha.
In the steppe zone, the recommended planting density is 30-40 thousand bushes per hectare.
On irrigated lands, the density is increased to 60 thousand bushes/ha. For example, in the steppe part of the Voronezh region, the potato yield at a planting density of 40.8 thousand/ha was 28 t/ha, at a density of 55.6 thousand/ha – 35 t/ha.
For planting seed potatoes – 60-70 thousand/ha to obtain more seed tubers.
The density is increased for early ripe varieties with compact bushes and upright tops, as well as when using small tubers for planting.
Depth and planting methods
The planting depth of whole or cut potato tubers depends on soil type, climate conditions and cultivar and generally varies from 5 to 15 cm. It is important to ensure adequate soil cover and avoid drying out, greening, sunburn and other damage to developing tubers.
In the Non-Black Soil Zone, the ridge planting method is usually used at a depth of 8-12 cm, in peatlands – 10-12 cm, in floodplains – 8-10 cm. Ridge method allows the surface of the rows to warm up better, less compacted by atmospheric precipitation, weeds germination is faster, which facilitates further control of them, ridge surface allows you to loosen the soil without compacting the rows with tractor wheels. When planting in well warmed ridges, the planting depth can be reduced to 3-4 cm.
In areas where soil moisture strongly depends on weather conditions, the half-crow method of planting with oval row shape is used. In this method of planting the tubers is carried out at a depth of 12-14 cm relative to the surface of the tuber. The semicollared surface of rows with an oval shape is obtained by the installation of bent rayboronok after the planting discs of the unit.
In the zone of insufficient moisture, such as the steppe of Western and Eastern Siberia, the south and south-east of Russia, as well as in years with dry spring, and some areas of the Nonchernozem zone, where agricultural practices aimed at conservation of moisture (on sandy and sandy loam soils), smooth planting with tubers embedded in a depth of 8-10 cm.
Larger tubers are planted deeper than small ones.
The influence of the physiological maturity of the planting material on the subsequent growth of stems and tubers can be compensated to some extent by the distance between the plants and the duration of the growth period. If old planting material is used, plant spacing can be increased to compensate for the large number of tubers expected. With proper management, equivalent yields can be obtained using seeds of different physiological ages.
In the northern and northwestern regions, for example, in the Arkhangelsk, Vologda, Murmansk, Leningrad and Novgorod regions and the Komi Republic, planting is carried out in pre-cut ridges. The technology of the method lies in the fact that after the first pass of the tractor a straight line is hung, after the second and subsequent passes the tractor wheel goes along the cut furrow; when planting, the coulters of the potato planter go along the center of the ridge, while the soil moves apart to the side of the soil, and the following harrow again forms ridges. The use of this method in the Kaluga and Moscow regions increases the yield of potatoes by 12-17% compared to conventional ridge planting, the productivity of planting units increases by 10-15%. Efficiency is achieved due to the higher (by 2-4 °C) temperature in the already cut ridges,
For planting potatoes, potato planters СН-4Б-1, СН-4Б-2, КСМ-6 can be used, which are designed for an ordinary planting method with row spacing of 60 and 70 cm and a distance in a row between tubers of 20-40 cm.
The row spacing for early and mid-early varieties of potatoes is recommended to be up to 75 cm, for late varieties – up to 85 cm.
Potato Research Institute proposed a two-line planting scheme (60+80)/2 x 20-40 cm. In the center of the planter there was a row spacing of 80 cm. Butt row spacings are also obtained by 80 cm. In order for the harvester wheel to run along a wide row spacing, the left axle shaft with the hub is extended using an extension.
Also, planting with row spacing of 90 cm gives good results while maintaining the same planting density. The increase in yield reaches 5-20%, with irrigation – up to 25%. The method contributes to the creation of better air-light conditions for plant growth, weed control, facilitates mechanized planting care and harvesting.
For planting germinated potato tubers, the САЯ-4 planter is used.
In some cases, planting units are used, consisting of two planters СН-4Б.
On small areas in the northern, northwestern and northeastern regions, a two-row planter КСКН-2 can be used.
The average productivity of СН-4Б planters is 0.5-0.7 ha/h at a planting rate of 2.5 to 3.5 t/ha.
Crop care
Timely and high-quality care for planting potatoes helps to increase yields by 20%. The soil at the time of harvesting in such fields remains quite loose, which facilitates the work of potato harvesters, reduces losses and mechanical damage to tubers.
Before the emergence of seedlings after planting, harrowing is carried out with simultaneous inter-row loosening of the soil, for which КОН-2,8ПМ is used, on six-row plantings and pre-cut ridges – КРН-4,2Г. Pre-emergence tillage prevents soil compaction, contributes to the accumulation of plant-available forms of nutrients and serves as an agrotechnical method of weed control. Harrowing is carried out 6-8 days after planting. On smooth crops, it is carried out with mesh harrows or harrows with shortened teeth.
In the Non-Chernozem zone, 2-3 harrowings may be required, the latter is carried out on seedlings, for which light harrows are used.
Weed seeds usually do not have time to sprout by this time, so loosening the soil, especially in dry sunny weather, contributes to the destruction of up to 80% of weeds. The second harrowing on smooth crops can be carried out until the seedlings reach a height of no more than 12 cm. Harrowing is effective until weeds take root. On ridge plantings, pre-emergence inter-row loosening with harrowing is more effective.
If, during cultivation with harrowing, part of the tubers is at the top, then the cultivator is equipped with dump paws, rotary rippers or hillers. Paws-dumpers cut weeds on the slopes of the ridges, add 3-5 cm of soil per row, and the harrow following them destroys the crust, destroys weeds and dumps part of the soil poured onto the ridges back to the bottom of the furrow, forming a loose layer that retains moisture. Rotary rippers also loosen the soil and kill emerging weeds.
On heavy loamy soils, it is effective to use the ФПУ-4,2 milling cultivator with disk hilling bodies, which are well loosened by the row spacing, and the disks, installed at an angle of 20-30 ° to the direction of movement, add loose soil to the bases of the bushes and fall asleep weeds.
6-7 days after the first cultivation, by the time of re-germination of weeds, the treatment is repeated. The third cultivation is done already by shoots at a plant height of 5-6 cm. It is not recommended to do cultivation with simultaneous harrowing when shoots appear, since young plants break off easily at this time.
In the steppe zone, the first processing of row spacing is done to a depth of 14-16 cm after emergence. The next 2-3 cultivations are carried out depending on the weediness and compaction of the soil.
During the growing season, at least 2-3 row-spacing treatments are usually carried out. They improve the air regime of soils, thereby contributing to the action of fertilizers and the intensity of tuberization.
The most intensive care for planting potatoes occurs at the beginning of the growing season, when mechanical damage to the tops and roots is not as significant as in late treatments. Treatments improve the water-air regime in the area where roots, stolons and tubers are located.
In the south and southeast of the European part of Russia, in the steppe zone of Western and Eastern Siberia, planting care includes inter-row loosening; in the Central Black Earth zone, the Volga region – loosening and hilling; in the north and northwest, on loamy and peaty soils of the Non-Chernozem Zone and the Far East – hilling.
Hilling at a young age of plants with sufficient moisture supply stimulates the formation of additional stolons and tubers. Hilling at a later date is ineffective, and the increase in yield in this case is achieved only by increasing the size of the tubers from improving the water-air and nutritional regimes. Hilling is carried out at a plant height of 15-20 cm to a depth of 4-6 cm, the second – before flowering or 10-15 days after the first.
In areas of sufficient moisture, hilling is done to a depth of 6-8 cm with a plant height of 15-18 cm. The hilling depth is increased on wet and heavy soils, as well as with shallow planting of tubers. The efficiency of hilling increases with increasing soil moisture, since at a moisture content of more than 80% of the lowest moisture capacity, tuberization stops, and after 3-5 days, the formed tubers may rot. Whereas hilling and loosening in these conditions prevents waterlogging.
On wet and compacted soils, the first treatments are carried out to a depth of 14-16 cm. In case of poor soil development, hilling is combined with loosening the bottom of the furrow. To do this, one lancet paw is installed behind each hiller. With a lack of soil moisture, loosening is performed by 8-10 cm for the first time and by 6-8 cm in the second.
Hilling is 1.5 times more effective in weed control than loosening alone (Dorozhkin, 1976). However, in years with dry summers in the central regions of Russia and in arid conditions of the steppe zone, hilling is not carried out, as this leads to even greater drying and overheating of the soil. In these cases, cultivators are equipped with lancet paws, chisel-shaped paws are installed in the side holders of the cultivator sections.
3-4 days before harvesting potatoes on heavy soils, pre-harvest loosening can be useful.
Physiological disturbances
Low-temperature conditions during development cause tuber injury; too high temperatures cause tissue damage called internal thermal necrosis.
Other tuber defects are as follows:
- hollow core, caused by low temperatures during tuber initiation and/or excessive rapid enlargement, often provoked by high temperatures during development;
- black heart caused by a lack of oxygen due to waterlogging or inadequate ventilation in the storage facilities;
- black spot, tissue darkening resulting from enzymatic oxidation of phenolic compounds, initiated or resulting from impact trauma or bruising from pressure on susceptible tissue, usually at the end of the stem;
- irregular growth (tuberosity) resulting from moisture stress;
- enlarged lenticels caused by excessive soil moisture;
- greening resulting from exposure to light.
Plant protection
Potato is a crop that is highly susceptible to diseases and pests. The total world crop losses from pests and diseases reach 32% of the actual gross harvest, or 129 million tons.
Often treatments against diseases and pests can be combined, increasing the cost-effectiveness of the intake, for example, simultaneous treatment against phytophthora and the Colorado potato beetle.
Herbicides
In heavily weedy areas, processing is carried out 3-4 days before the emergence of potato seedlings, while subsequent harrowing is not performed.
Pests
Among the most dangerous potato pests in Russia are the Colorado potato beetle and wireworm, as well as potato and stem nematodes.
The system of measures to protect plants from pests provides for preventive and extermination measures. The first are aimed at suppressing the spread of pests, the second – at the destruction already when pests spread on plants using insecticide treatment.
Main potato pests:
- Macrosteles quadrilineatus (Aster leafhopper);
- Circulifer tenellus (Beet leafhopper);
- Leptinotarsa decemlineata (Colorado potato beetle);
- Ostrinia nubilalis (European corn borer);
- Epitrix spp. (Flea beetles);
- Myzus persicae (Green peach aphid);
- Empoasca spp. (Leaf hopper);
- Macrosiphum euphorbiae (Potato aphid);
- Phthorimaea operculella (Potato tuberworm);
- Tetranychus urticae (two-spotted spider mite);
- Limonius spp. (wireworms).
Nematodes:
- Globodera spp. (Cyst);
- Globodera rostochiensis (Golden);
- Meloidogyne spp. (Root knot);
- Pratylenchus spp. (root lesion);
- Trichodorus and Paratrichodorus spp. (Stubby root).
Diseases
The high content of carbohydrates in the tops and tubers of potatoes serve as a breeding ground for numerous microorganisms that cause various plant diseases. Diseases can affect potatoes during the growing season and during storage. In some cases, the scale of the spread of diseases can negate all the most advanced cultivation practices.
The causative agents of potato diseases can be fungal, bacterial, viral and mycoplasmal in nature.
Common fungal diseases of potatoes include late blight, potato cancer, rhizoctoniosis and common scab.
To improve the phytosanitary condition of the soil and cleanse it of pathogens, potatoes should be placed after winter rye, corn, turnover of perennial grasses, alkaloid lupine. The introduction of organic and mineral (with an excess of potassium) fertilizers increases the resistance of plants to pathogens.
Usually the source of the spread of pathogens are diseased tubers. Therefore, an effective method of struggle is phytopathological cleaning of seed plots and breeding nurseries, the exclusion of diseased tubers from the seed material.
Often, infection of tubers with late blight, as well as other diseases, occurs during harvesting when the tubers come into contact with the affected tops. Therefore, pre-harvest mowing or destruction of haulm is of preventive importance.
Phytophthora infestans
Late blight is one of the most harmful and common fungal diseases of potatoes. It causes the greatest damage in areas with heavy precipitation in the second half of summer. The regions with the greatest severity of this disease include the northwestern and mountainous regions, the Far East, as well as the Baltic countries and Belarus (All-Union Institute of Plant Protection). In the central regions of the Non-Chernozem zone, it occurs on average once every two years, not always to a large extent, but the losses from it are 10-12%, in some years up to 30%.
Against late blight, the introduction of copper sulfate into the soil in the amount of 4 kg/ha is effective.
Potato wart
Potato cancer was first discovered in the USSR in 1936 in Ukraine, subsequently spreading to the western, southwestern, northwestern and central regions of the country. The disease leads to large crop losses, sometimes its complete destruction.
Cancer affects potatoes during the growing season, but is only detected during harvesting, since the disease does not affect the development of potatoes, but affects tubers and stolons, while the roots remain healthy.
Rhizoctonia
Rhizoctonia is common in all areas of potato growing. The disease is most damaging in regions with cold, long springs. For the development of the rhizoctoniosis fungus, soil with a high content of humus and high humidity is favorable.
Common scab
Common scab is a common disease of potato tubers of a fungal nature, which is especially pronounced on soils that are light in granulometric composition. The losses from this disease are difficult to estimate, since the yield does not decrease, but the marketable value of the tubers decreases, and the seed quality of the tubers deteriorates.
To combat common scab, it is recommended to use acidic forms of fertilizers, for example, ammonium sulphate and superphosphate, which are applied to the rows during planting in the amount of 100-150 kg/ha. On the contrary, fresh manure and lime in increased application rates increase the susceptibility of tubers to scab.
Ring rot
Ring rot leads to premature wilting and death of the tops and rotting of tubers in the field and during storage. The loss of tubers from this disease by the time of harvesting can reach 11-44.5%. Ring rot is common in the northern and middle strip of the European part of Russia and Siberia.
Blackleg
The black leg is common in all countries where potatoes are cultivated. In Russia, this disease occurs in the middle and northern zones of the European part, in Siberia and the Far East. As a rule, the proportion of diseased plants is 1-10%, however, in rainy years, this proportion can increase significantly.
In conditions of insufficient soil moisture and elevated temperatures, the development of the disease stops, and the harvested tubers may not have external signs of damage. However, tubers with a latent form of infection during storage begin to rot and infect other healthy tubers, which leads to large losses.
Wet, or bacterial, rot
Wet, or bacterial, rot is common in all potato-growing countries. Losses from the disease can reach 10-15%.
Bacteria penetrate tubers through places damaged by insects, when damaged by phytophthora, scab, when they are in waterlogged soil, etc. Tubers with a whole skin are practically not affected by wet rot.
If the storage regime is violated, for example, high humidity or temperature, the development of the disease passes very quickly. Rotting tubers completely decompose within 1-2 weeks. Under normal potato storage conditions (low temperatures and good ventilation), bacterial rot develops slowly, rarely spreading to healthy tubers.
Macrosporiosis
For the treatment of plants during the growing season against macrosporiosis, Ditan M-45, Pencozeb, Mancozeb, Profit, Acrobat MC, Kuproskat, Borodoskaya mixture, Abiga-Peak are used.
Alternariosis
For the treatment of plants during the growing season against alternariosis, Acrobat MC, Yunomil MC, Metaxil, Ridomil Gold, Sectin Phenomenon, Kuprikol, Copper oxychloride, Ordan, Tsikhom, Thanos, Shirlan, Folpan are used.
For processing seed potato tubers before storage – Maxim.
Viral diseases
Viral diseases are common in all potato-growing countries. They become the main reason preventing the spread of crop planting in areas of warm and hot climates.
Tuber yield losses due to viral diseases in the world are difficult to estimate, since in most cases there is no standard for comparison (healthy plantings), but they are assumed to be large.
It has been established that diseases such as stolbur and witch’s broom, which were previously classified as viral, are caused by microorganisms of the mycoplasma group. Also, from the group of viral diseases, viroid diseases were isolated, that is, the pathogens of which are stable RNA without a protein coat. Among the viroids are a common disease in Russia – gothic, or fusiform tubers.
Signs of viral diseases: twisting and wrinkling of leaves, mottling (mosaic), small tubers.
Irrigation
Irrigation of planting potatoes significantly increases productivity. In arid regions, irrigation is one of the most important ways to control plant growth and development. In the middle lane, with uneven precipitation, this crop is also responsive to irrigation.
Soil cultivation when cultivating potatoes during irrigation should include soil deepening, the formation of a plow pan is not allowed. On sloping lands, planting rows are placed across the slope or at an angle.
Under irrigation conditions, the method of planting potatoes is ridge or semi-ridge to a depth of 6-8 cm.
When irrigated, the application rates of organic and mineral fertilizers are increased, while the effectiveness of the fertilizers themselves also increases. Irrigation in combination with top dressing is of the greatest importance before the formation of tubers.
The number of vegetation irrigations, according to experimental production data, is recommended:
- for arid regions of the south-east of Russia – 3-5;
- in the steppe zone – 2-5;
- in the south of Ukraine and in Moldova – 4-6;
- in the Central Black Earth zone – 2-3;
- in Central Asia and Transcaucasia – up to 8-10.
The irrigation rate is from 500 to 800 m 3 /ha and is adjusted depending on the region of cultivation, weather and soil conditions. Irrigation rates should be set based on the need to provide optimal soil moisture, which is equal to 70-80% of field capacity.
Before watering with the help of sprinkling, it is recommended to slot the row spacing to a depth of 20 cm (Northern Research Institute of Hydraulic Engineering and Land Reclamation). This technique promotes the absorption of moisture, reduces surface runoff and prevents the appearance of soaks. This technique increases the yield of tubers by 30-40%, compared with irrigated areas without slotting (D.B. Tsipris, 1969).
After each watering, inter-row loosening is carried out with a slight hilling. On heavy soils, it is useful to loosen before watering. Watering is stopped after most of the tubers have matured, otherwise watering can cause the formation of new and early-set tubers, as well as delayed maturation.
In dry years, irrigation helps to reduce the infestation of tubers with scab and rhizoctonia.
Harvest
Harvesting time
Potatoes are harvested 90-160 days after planting, but this may vary depending on the variety, production area and marketing conditions. High yields are usually achieved with late maturing varieties and a long growing season. Sometimes it is necessary to harvest before leaf wilt or frost occurs and the tubers have not had time to fully develop.
Signs of ripening potatoes are the drying of the tops, the formation of a dense flaky (in some varieties) peel on the tubers, the drying of the stolons, the tubers are easily separated from them. However, sometimes yellowing and dying off of the tops can be the result of disease damage, in the northern regions – early frosts.
Depending on the variety and purpose of the tubers, harvesting is carried out in the summer for early varieties of food purposes, no later than 2 weeks before sowing winter crops in case of a busy fallow.
In the Non-Chernozem zone, mid-ripening and late-ripening varieties are usually rarely harvested after the natural end of the growing season. Their harvesting begins earlier due to the likelihood of damage to plants by frost, late blight, or due to the onset of autumn bad weather and persistent frosts. According to long-term observations, cleaning in the central regions of the Non-Chernozem Zone is recommended to be completed before October 1, in the northern regions – before September 25 or even 20.
Harvesting is carried out in a short time: within 10-12 days in the northern regions, 15-20 days – in the central strip and the south. Green tops are removed 1-3 days before harvesting (in seed crops 10-14 days) before harvesting by УБД-ЗА or КИР-1,5Б machines. Tops sick with late blight are mowed 7-10 days before harvesting and removed from the field.
Good healthy haulm, with an acceptable content of residual pesticides, is suitable for ensiling.
Harvesting methods
Potatoes can be harvested by in-line, separate or combined methods.
In-line harvesting is carried out on large areas or closely spaced fields, with an area of at least 30-50 hectares. The method is used on light and medium soils with a moisture content of 12-25%. Potatoes are harvested by combines, from which the tubers are unloaded into vehicles, transported to sorting points, where the potatoes are further cleaned and divided into fractions. The large fraction intended for food purposes is sent to the distribution network or for permanent storage, the fine fraction is used for feed purposes, the medium seed fraction goes to storage.
Separate cleaning is used on medium and heavy soils. On a potato field, first, using potato harvesters-swathers УКВ-2, they dig two rows of potatoes in one pass, separate the tubers from the ground, the remains of tops and impurities, and lay them in a swath.
Under good weather conditions, the tubers and soil in the swath dry out quickly. Depending on the yield, tubers can be collected in one roll from two or four adjacent rolls. Then the potatoes are selected according to the same scheme as the in-line method. In this case, with the help of the ККУ-2А combine, it picks up the tubers laid in the swath in one pass. A selection of tubers already dug up and cleaned of soil and impurities allows you to speed up the work of combines.
The combined method involves harvesting with a УКВ-2 machine, which places the tubers in the aisle of two adjacent undigged rows. On the next pass, if the yield is low, potatoes from two other adjacent rows can be harvested into this swath. After that, the pick-up harvester digs out the unharvested rows at the same time picks up the tubers laid between them. Just like with the separate harvesting method, in one pass the combine harvests potatoes from four or six rows.
The movement of the УКВ-2 swather and the ККУ-2А combine-picker is carried out by a driven method. The number of rows in a paddock must be a multiple of the number of rows harvested in one pass by the pick-up combine.
The combined method of harvesting potatoes allows to reduce labor costs by 25-50% compared to the method of direct combining and increase the productivity of combines by 1.5-2 times.
Also, for harvesting, methods using КТН-2Б type diggers and tractor plows can be used. Potatoes after digging are then harvested by hand. The method is very laborious, but the damage to tubers is much less.
The haulm can interfere with mechanized harvesting, so the above-ground part should be mowed a week or two before harvesting. The removal of the haulm strengthens the periderm of immature tubers, which increases their resistance to possible damage during harvesting.
In all methods of harvesting, the field is harrowed and the remaining tubers are picked up to reduce losses after the machine passes. After the first harrowing, it is also recommended to plough or cultivate the field, harrow a second time, and pick up the remaining tubers.
If for some reason it is not possible to remove all potatoes from the fields at once, they are covered with straw or earth.
Post-processing
Dug potatoes destined for seed or food purposes for better winter storage and less damage are recommended to be sorted two weeks after harvesting.
After harvesting, potatoes, especially those intended for storage, should be kept at 15-20°C and high relative humidity for 10 or more days to enhance periderm formation and healing of harvest wounds. Wound healing – the formation of a cork-like layer of cells under damaged tissues – occurs rapidly at 20°C and helps limit disease contamination and moisture loss. After curing, the temperature is reduced; the amount of reduction depends on the expected duration of storage and intended use.
Storage
Potatoes achieve their best culinary and technological quality at the time of harvest. Storage prolongs availability and thereby facilitates orderly marketing, distribution and use. Although storage can extend the usefulness of harvested potatoes, their quality decreases in proportion to the length of storage. However, in well constructed and managed storage facilities, tubers of some varieties can be stored in marketable condition for more than 10 months.
At an average water content of 75% potato tubers spoil easily, so storage conditions, especially temperature, humidity and air composition, play an important role in preserving the crop. Unfavorable storage conditions lead not only to losses, but also to changes in the chemical composition and physiological state of tubers.
Physiological periods
During long-term storage, tubers go through three physiological periods: ripening, dormancy and awakening of the kidneys.
During the period of ripening of tubers, which takes place during the first 20-45 days, intensive respiration and evaporation of moisture are noted.
During the period of winter dormancy, which lasts from one to several months, the buds of the eyes remain dormant and do not germinate, the release of heat and moisture by the tubers is insignificant.
Awakening of the kidneys is the beginning of the active process of vegetation and is a continuation of the development of the tuber, the dormant period of which has ended. Weight loss during this period proportionally increases the degree of germination.
Storage conditions
The storage temperature depends on the purpose of the tubers. tubers intended for processing should be stored at a higher temperature, seed and food tubers at a lower temperature. For long-term storage of potatoes intended for food purposes, the temperature should be lower in bulk than for short-term storage.
Table potatoes are usually stored at high relative humidity and a temperature of about 4°C. For processing, they are also stored at high relative humidity, but at slightly higher temperatures (10-16°C) because the starch is converted into reducing sugars at low temperatures. The presence of reducing sugars increases the tendency to darken tissues when potatoes are processed by frying or dehydrating. At warm temperatures, reducing sugars are converted to starch. When the ratio of starch to reducing sugars is high, tissue discoloration is minimized or prevented. In order to prolong storage time and thereby ensure a continuous supply of potatoes, most growers usually provide low temperature storage. To remedy the conversion of starch to reducing sugar, potatoes can be “reconditioned” before processing. Reconditioning involves removing potatoes from low-temperature storage and placing them for several days or more at 18-21°C and 85-90% relative humidity to accelerate conversion. Most often, potatoes removed from low temperature storage are not immediately consumed and thus recovered under the influence of warm temperatures during the sales period. Potatoes high in reducing sugars tend to have a slightly sweet taste. There is considerable variation between varieties in their ability to store sugars. The choice of variety is therefore of great importance for the production of processed potato products of acceptable quality.
Tubers intended for long-term storage tend to be harvested at the optimum time. Before they are stored, they are sorted and sorted. It is not recommended to put tubers with signs of bacterial or fungal diseases, with mechanical damage and peeled skin for long storage, as they are poorly stored, start to grow earlier, worsen storage conditions for healthy tubers. Frozen potatoes are not suitable for storage.
Transshipment, transportation of potatoes intended for storage is kept to a minimum. Handling and transportation should minimize mechanical damage. The free height of tubers during loading or unloading should be no more than 30 cm.
Containers, boxes, baskets, bags, etc. are better suited for transporting tubers. Potatoes from harvesters can be reloaded directly into containers mounted on vehicles. Then by forklifts or other lifting means are reloaded. The containerized way of transporting and storing potatoes reduces the share of damaged and diseased tubers, helps to preserve the sowing qualities of seed potatoes and increase the yield, saving storage space (containers can be placed in 4-5 tiers).
Potatoes are well stored in the bins of specialized storage facilities with active ventilation. The height of tubers loading is 2.5-4 m.
In storages designed for seed potatoes, a room is provided for the germination of tubers. Large storage facilities designed for 1000 and 2000 tons must be equipped with refrigerating units for a part of the bins. Transporters can be used to load and unload potatoes from the stores.
Conventional storages are dried and disinfected before the potatoes are loaded. The heating and ventilation systems regulate the microclimate.
Potatoes can be stored in mounds or trenches. The place for the pile should be elevated, dry and with a slight slope. The ends of the bunks are placed in the direction of prevailing in the winter winds. At the bottom of the trench there is a 20-30 cm deep, 2 m wide and 15-20 m long hole for ventilation. The depth of ground water is not more than 1,3-1,5 m. The excavation is connected with vertical pipes. Tubers for storage are covered with pyramids up to 1 m in height, covered with a layer of straw and soil. For the middle belt, the thickness of the shelter is 60 cm, in the north-east and in Siberia – up to 1.5 m. To regulate the temperature inside the embankment, additional covering with soil or manure is used, and the thickness of snow cover is increased.
To store potatoes, pits with induced-exhaust or active ventilation and trenches can be used. Active ventilation involves a fan blowing air through the main ventilation duct. Fresh air flows through the grilles into the potato mass, drying and cooling the tubers. The air is evacuated through the exhaust pipes. Shielded bollards can be used, the advantage of which is that the empty compartments can be accessed through the available hatches in order to re-assemble or sell the potatoes.
In all methods of storage with active ventilation several regimes are used. Immediately after the laying of tubers in storage for rapid healing of mechanical damage and the removal of excess moisture from the mass of potatoes for 3-4 weeks (healing period) set the temperature at 15-16 ° C. When laying healthy tubers, the temperature can be maintained at about 18°C (Gusev, 1975). The relative humidity during the healing period is 90-95%. The healing process is completed within 8-10 days.
The second period is a cooling period of 22-40 days. During this period the temperature in the potato mass is gradually reduced to 2-4 ° C. The rate at which the temperature is lowered depends on the quality of the tubers laid. If the share of damaged tubers is small, the temperature is reduced by 0.5°C per day, and if the share of damaged tubers is high, the temperature is reduced by 1°C per day.
The third, main storage period. In a potato storehouse or a bunker, maintain a temperature of 2-4°C and humidity (85) 90-95% (NIICH, Rubatzky). High temperature shortens the storage period because of increased respiration. However, relative humidity is also important because about 90% of the weight loss is due to moisture loss and about 10% is due to respiration. Light is excluded to avoid the development of chlorophyll, which causes the tubers to turn green and the associated formation of toxic and bitter-tasting glycoalkaloids.
Depending on the length of the storage period, the temperature regime does not always fully control tuber germination. Therefore, to further minimize germination, a chemical treatment can be applied. Maleic hydrazide is sprayed on the leaves 2-3 weeks after full bloom or when most of the tubers have reached 3-4 cm in size. Applications of 1000-6000 ppm are effective in suppressing germination. Chloroisopropyl-TV-tetrachlorocarbamate (CIPC) can be applied as a dip or aerosol treatment to tubers after harvest and after damage has healed. Inhibitors should not be used on tubers intended for use as planting material.
Vaults
Many types of storage facilities are in use; those that provide precise temperature and humidity control are ideal. Some are highly automated and can also provide controlled atmosphere (CA) control. Others are very simple, such as in situ field storage, field clamps, placement in wet sand, and various types of pits, cellars, and above-ground or underground covered structures that rely on ambient temperature control. Even simple storage facilities, if well designed and insulated, can provide satisfactory storage conditions. Storage facilities should be clean and, if necessary, disinfected to minimize disease. Sick and damaged potatoes should be excluded, and direct contact with moisture should be avoided to limit the spread of rot. If tubers must be washed, this is usually delayed until removal from storage.
In many modern bulk storage facilities, potatoes are stacked in large piles or compartments. Piles that are too large can interfere with ventilation and cause the tubers to crush at the bottom. Wooden slatted floors or ventilation ducts are usually used to improve ventilation and drain accumulated moisture. Some storage facilities use large boxes on pallets to improve ventilation, reduce damage, and make loading and unloading with forklifts much easier.
Ventilation technique
With active ventilation, 50-70 m3/h of air with a relative humidity of at least 75% is provided for 1 ton of tubers. The ventilation technique depends on the storage period and the condition of the potato tubers.
During the treatment period, cooling is carried out only if the temperature in the embankment rises above the value set for this period. At this time, recirculated (internal) air is used for ventilation. Ventilation is carried out 5–6 times a day for 30 minutes, the interval between ventilation is 3.5–4 hours. on the surface of the tubers will not be removed. After that, ventilation is carried out in a mode characteristic of the treatment period.
During the period of temperature decrease, ventilation is carried out more intensively: in the cold season – with outside air with open exhaust shafts, achieving a rate of temperature decrease in the embankment of 0.5-1 °C per day.
At negative temperatures of the outside air, it is mixed with internal air, the mixture must have a temperature of at least 0.5 °C. With different quality of planted potatoes, ventilation is carried out separately. Parts of the mound of a bulk section or bins with a low temperature are temporarily disconnected from the ventilation unit with the help of gates or the air supply to them is regulated. The most intensive ventilation is set for places with high temperatures, preventing the danger of warming the potatoes.
After reaching the varietal temperature in the embankment, ventilation is carried out periodically to maintain the specified storage conditions. To do this, depending on the weather conditions, the tubers are ventilated only with outside air or its mixture with the internal air of the storage. In the latter case, the internal air is supplied first, then cold external air is introduced into the flow by means of the control valves of the supply shaft. On very cold days, only indoor air is used for ventilation.
When spring comes, a cold reserve is provided in the embankment, reducing the temperature in it to 1.5-2.0 °C. This reserve is replenished with ventilation at night and in the morning. When the outside air temperature at this time is higher than the temperature of the embankment, ventilation is carried out only with the storage air.
When storing seed tubers, varietal characteristics of potatoes are taken into account. For example, with a decrease in the storage temperature of tubers of varieties Priekulsky early, Northern rose, Falensky to 1.5-2.0 °C, the technological properties of tubers improve, and seed productivity increases. Whereas, for varieties Lorkh, Lyubimets, Stolovy 19, the yield increases when tubers are stored at a temperature of 4-5 °C (Potato Research Institute, BelNIIKPO).
Table. Storage modes of potato varieties in winter (BelNIIKPO, Potato Research Institute)
| Priekulsky early, Falensky | It is possible to lower the temperature up to 1 °С | |
| Berlichingen | It is possible to reduce the temperature to 1 °C and increase to 3 °C | |
| Northern rose | - | |
| Ogonyok, Temp, Loshitsky | - | |
| Smena | - | |
| Lorch, Stolovy 19, Druzhny | Temperature drop down to 3°C possible | |
| Lyubimets, Petrovsky | - | |
| Peredovik | It is possible to reduce the temperature to 1-3 °C |
In spring, the storage temperature of potatoes intended for seed and food purposes, of all varieties, is reduced to 1.5-2 °C, thereby extending the storage period by 3-4 weeks of the warm period without germination.
10-14 days before planting or selling tubers, it is recommended to increase the air temperature during ventilation to 15-20 °C in order to enhance growth processes in seed potatoes or to partially convert sugar into starch in food potatoes.
The given potato storage technology has proven itself in the production practice of potato growing: the share of losses and tubers that sprout is very small.
Storage diseases
With the exception of early germination, most storage diseases are caused by rough physical handling from the time of harvest and unfavorable storage conditions. Diseases are usually related to a previous infection of the tubers before storage, although inadequate disinfection of the storage facility may also be the cause.
Dutch cultivation technology
The Dutch technology of growing potatoes is used in the countries of Western Europe, which began to be used in the Non-Chernozem zone.
The Dutch technology provides for a high supply of potato plants with nutrients. Areas with an organic matter content in the soil of at least 2.0-2.5% are allotted for potatoes . Organic fertilizers are applied under the predecessor or under autumn cultivation at the rate of 70-100 t/ha. Mineral fertilizers are applied in a broadcast manner, followed by shallow incorporation. The recommended application rates are nitrogen 100-180 kg/ha, phosphorus – 120-200 kg/ha, potassium – 150-200 kg/ha a.s. Of great importance is the uniform distribution of organic and mineral fertilizers.
In crop rotation, the optimal predecessors are winter crops. Return to the original place is allowed no earlier than 3-4 years.
The main tillage provides for early autumn plowing and subsequent autumn cultivation. Plowing is carried out using reversible plows of the Lemken company without dump ridges and breakup furrows.
According to the recommendations of some firms, spring plowing of fallows to cover moisture is not done in order to more quickly dry the topsoil. Preplant tillage is done by milling cultivators of the “Dominator” type with vertical rotation of the knives. This unit combines milling to a depth of 12-14 cm, leveling and rolling the soil.
For planting take seed tubers of high reproduction, 100% varietal purity and germination, 30-60 mm in size. Particular attention is paid to the germination of tubers. The length of the sprouts when planting should be 2-5 mm. Seed tubers are treated against fungal and bacterial diseases.
Planting is carried out using 4-row machines, for example, “Structure” or “Kramer”, the row spacing is 75 cm. The planting rate depends on the variety, purpose of cultivation and the size of planting tubers, varies from 40 to 100 thousand tubers per 1 ha, or 2.7-6.7 t/ha. The depth of planting in the ridges is 4-6 cm. The closing disks of the planters form ridges 8-10 cm high and 30-35 cm wide at the base. Inter-row treatment is carried out 14-18 days after planting, when most of the weed seeds germinate , and the tuber sprouts reach the surface of the ridge.
The care unit is a milling cultivator with a ridge former, for example, “Rumstad” or “Amak”. Milling soil between rows with the help of a ridge former is formed into a trapezoidal ridge 23-25 cm high, 75 cm wide at the base, 15-17 cm at the top, the cross-sectional area of the ridge is 950-1000 cm 2 . After ridge formation, the rest of the inter-row processing is not done.
To combat weeds, the herbicide zenkor is used: before emergence on light soils at a dose of 0.5-0.75 kg/ha, on medium soils – 0.75-1.0 kg/ha, on seedlings – 0.5-0 .75 kg/ha. After potato plants reach a height of more than 10 cm, the drug is not recommended for use.
In the fight against late blight, 5-6 treatments are done. Highly effective pesticides are used to control the Colorado potato beetle.
10 days before harvesting, the tops are removed chemically (desiccation) or mechanically, or a combination of them. Potato tubers are harvested with Amak or ККУ-2А, КПК-3 combines.
Sources
V.V. Kolomeychenko. Horticulture/Textbook. – Moscow: Agrobiznesentr, 2007. – 600 с. ISBN 978-5-902792-11-6.
Horticulture/P.P. Vavilov, V.V. Gritsenko. Vavilov. ed. by P.P. Vavilov, V.S. Kuznetsov et al. – M.: Agropromizdat, 1986. – 512 p.: ill. – (Textbook and Tutorials for Higher Education Institutions).
Fundamentals of Technology of Agricultural Production. Farming and plant growing. Under the editorship of Niklyaev V.S. – Moscow: “Bylina”, 2000. – 555 с.
World vegetables: principles, production, and nutritive values / Vincent E. Rubatzky and Mas Yamaguchi. — 2nd ed. 1997.