Growing Potatoes

Organic Fertilizers

Organic fertilizers increase the starch content and size of tubers.

In all potato-growing regions, organic fertilizers are usually applied under potatoes in spring. However, this creates difficulties and pressure during field work at potato planting, often leads to delayed planting dates and soil compaction. As a result, yield losses exceed the effect of fertilizer application. Therefore, to plant potatoes at optimal agronomic dates, it is necessary to make maximum use of autumn time for fertilizer application, especially in southern regions, where, due to lack of moisture, manure applied in spring decomposes very slowly and its efficiency decreases.

Part of the organic fertilizers can be applied under the preceding crop — winter cereals of group I. Practical results show that when organic fertilizers are applied under the predecessor, only mineral fertilizers can be applied under potatoes. In this case, the reduction in potato harvest is compensated by an increase in the yield of winter crops.

When growing early potatoes, organic fertilizers are applied only in autumn under fall plowing, so that it is possible to plant sprouted tubers early.

Mineral Fertilizers

Micronutrient Fertilizers

On peat-bog soils, copper micronutrient fertilizers are applied. For this, they are applied in an amount of 5-6 kg of copper sulfate during planting locally together with 100-150 kg of superphosphate.

On sod-podzolic soils, boron, zinc and molybdenum micronutrient fertilizers are applied under potatoes. The boron application rate is 1.5-2 kg/ha a.i.

Treatment of micronutrient fertilizers can be carried out for planting tubers with a 0.05% solution of boron, zinc, copper and molybdenum. Yield increases by 12-15%.

Liming

Soils with acidity less than pH 4.5 are subject to liming. Liming is desirable under preceding crops; otherwise it is carried out under potatoes in autumn under fall plowing or in winter on snow; the rates of lime fertilizers are reduced to 0.25-0.5 of hydrolytic acidity. Excess lime under potatoes can cause scab development.

Primary Tillage

Primary tillage after cereals and grain legumes includes soil discing and deep fall plowing. Discing is performed with disk stubble cultivators to a depth of 5-8 cm immediately after harvesting the predecessor. Delay in carrying out this operation leads to moisture loss and reduced effectiveness. In semi-arid and arid regions, the importance of discing increases.

After 2-3 weeks after discing, plowing is carried out to the depth of the arable layer for sod-podzolic soils with simultaneous loosening of the subsoil horizon, or 30-35 cm for chernozems. When tilling soil for potatoes, it is possible to carry out deepening of the arable layer by 2-3 cm.

Fields after non-stubble predecessors and in the northeast of Russia with a short post-harvest period can be plowed immediately without discing after harvesting. However, on sod-podzolic loamy soil after fall plowing, especially if it is carried out early, the soil becomes compacted and overgrown with weeds. In this case, the field is cultivated or disced (stubble-cultivated), which helps destroy weeds and loosen the soil for accumulation of precipitation during autumn-winter.

When planting potatoes after perennial grass sod, it is cut with disk implements in two directions, followed by plowing with a plough 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 early fall plowing of the soil is difficult, they are limited only to discing; plowing is left for a more favorable time.

In the Central Chernozem zone, on fields free of weeds, it is possible, along with moldboard tillage in autumn, to carry out non-moldboard loosening of the soil.

In regions subject to wind erosion, deep non-moldboard tillage is used. It is more advisable to apply organic fertilizers here under the preceding crop.

Pre-planting Tillage

Pre-planting soil tillage in spring should ensure preservation of moisture accumulated during autumn-winter in the soil, creation of a finely cloddy loose arable layer with a leveled surface, and weed control.

In the Non-Chernozem zone, the plot is harrowed or cultivated. Then, on slaking heavy soils, as well as when applying organic fertilizers in spring, plowing is carried out to 17-20 cm. On light-textured sandy soils, as well as in dry years, instead of plowing, cultivation is carried out to a depth of 12-15 cm (if organic fertilizers were applied in autumn) or re-plowed to 16-18 cm.

In the zone of excessive moisture in the northwest and north of Russia, in spring fields are re-plowed to a depth of 18-20 cm with moldboard ploughs with skimmers and subsoilers.

In the zone of insufficient moisture, in the forest-steppe and steppe zones, depending on weather conditions in spring, 1-2 loosenings are performed with a cultivator or ploughs without moldboards to a depth of 16-18 cm with simultaneous harrowing.

An effective method of pre-planting tillage can be re-plowing of fall plowing with ploughs without moldboards, but with installed skimmers to a depth of 12-14 cm, which incorporate fertilizers applied in spring. The shares and standards of the plough bodies allow deep loosening of the soil, while applied fertilizers are incorporated to a shallower depth, which promotes their decomposition, especially in years of excessive moisture (NIIKH).

In spring, deep non-moldboard tillage to 25-27 cm can be used, followed by discing or milling.

In Poland and Germany, pre-planting soil tillage in spring is carried out using rotary ploughs. When treated with rotary ploughs, the soil layer coming off the plough body with shortened moldboards is crushed by looseners standing behind the moldboards. The advantage of this method is more thorough mixing of organic and mineral fertilizers with the soil and good crumbling in one pass of the implement.

In Belarus, when using rotary ploughs for soil tillage under potatoes, the yield increase was 10-12% compared with conventional moldboard tillage, harrowing or cultivation (N. A. Dorozhkin, 1976).

Spring milling shows good results.

In some areas, pre-planting ridge cutting may be effective, replacing cultivation with tiered hillers. On sandy loam soils, this operation can replace spring re-plowing of fall plowing.

A promising method of preparing soil for potato planting can be autumn ridge cutting, which allows earlier planting in spring.

Tillage Depth

Potatoes are very sensitive to plowing depth. Deep plowing allows increasing the thickness of the soil layer in which tubers develop and ensures subsequent good hilling. Shallow plowing complicates hilling, and poorly performed plowing leads to the formation of small tubers and their placement at the very surface of the soil.

For example, on sandy loam soils, the potato yield in crop rotation without deepening the arable layer and without fertilizer application was 10.6 t/ha, whereas with deepening to 30 cm — 12.7 t/ha (NIIKH, MSAA named after K. A. Timiryazev). On cohesive medium loamy soils, the yield of a mid-early potato variety when plowing fallow to 20-22 cm was 23.0 t/ha; with deepening of the subsoil layer by 15 cm — 24.8 t/ha. Moreover, the effect of deep plowing on potato yield is noted over several years. Deep plowing helps increase starch content in tubers.

According to research by the NIIKH Department of Agronomy, the arable layer of loamy soils ripens gradually: the upper layer 12-16 cm deep is ready for tillage 5-7 days earlier than the lower one at a depth of up to 28-30 cm. Therefore, on sod-podzolic medium loamy soil, it is more effective to till the soil for potatoes in two periods. When the upper soil layer reaches physical ripeness, discing or fall plowing is carried out using share stubble 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.

Features of Tillage of Peat-Bog Floodplain Soils

On peat-bog soils, which are common in the central and southern potato-growing regions of Russia, immediately after harvesting the preceding crop, discing is carried out with disk stubble cultivators to a depth of 6-10 cm, then fall plowing is carried out using bog ploughs to 30-35 cm. After 2-3 weeks after plowing, if weather conditions permit, autumn discing of the fall plowing is performed, which destroys sprouted weeds and levels the soil surface, promoting its uniform thawing in spring.

In spring, bog soils and cultivated peatlands are disced 1-2 times after the soil thaws to 10-15 cm. Before planting, repeated discing with harrowing and rolling with water-filled rollers are carried out.

Tillage of floodplains is determined by the location of the plot and the speed of floodwater flow. Usually, soils of the central and near-terrace floodplain are not at risk of arable layer washout, so their tillage begins with fall plowing to 27-30 cm. In spring, cultivation or re-plowing of fall plowing to 18-20 cm with simultaneous harrowing is done.

On floodplain lands of the Central Chernozem zone, Middle Volga region and arid regions of the south and southeast of Russia, instead of spring re-plowing of fall plowing, non-moldboard tillage is carried out.

Light sandy loam soils of floodplains located in places with strong floodwater flow are plowed only in spring to 20-25 cm as these plots are freed from water.

On heavy loamy floodplain soils, mole drainage is carried out simultaneously with plowing. The effectiveness of the operation on the plot persists for 2-3 years.

Preparing Tubers for Planting

Healthy, undamaged, well-formed tubers typical of the given variety are suitable for planting. For seed purposes, tubers are selected from the most productive plots, grown on peat soils or floodplains, tubers of summer plantings or early harvests.

Preparation of 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 sprouted or wilted tubers, they can be treated with growth stimulants.

Before planting, seed tubers that are no longer in a state of dormancy should be removed from low-temperature storage and placed for several days at a temperature of 10-13 °C. The transition from low to high temperatures promotes better sprout emergence after planting.

Planting Dates

Potatoes are planted when the soil temperature at a depth of 8-10 cm is 6-8 °C; in southern regions — up to 5-6 °C, but the preferred soil temperature is above 15 °C. For emergence at a temperature of 12 °C, 30-35 days may be required. At a temperature from 22 to 30 °C, seedlings emerge from seeds within 10 days. Earlier planting leads to damage of sprouts by rhizoctoniosis, the optimal temperature for development of the causative agent of which is 4-5 °C. Under production conditions, planting usually begins after sowing cereal crops and is completed within 8-10 days.

Delay in planting at optimal dates by 10-20 days leads to a yield decrease of 10-20%, and starch content in tubers — by 2-4%.

Sowing dates on light sandy and sandy loam soils, as well as on uplands and southern slopes, are somewhat earlier than on heavy loams.

Early-ripening, mid-early and mid-ripening varieties in occupied fallow are planted first, then seed potatoes are planted. Food potatoes are planted last.

According to data from the Institute of Experimental Meteorology, isolines of the optimal planting date:

• April 20-30 passes through Vilnius — Minsk (south) — Tula — Penza (south);
• May 1-10 passes through Riga (north) — Pskov — Tver — Ivanovo — Cheboksary — Ufa (south) — Chelyabinsk — Kurgan;
• May 10-20 passes through St. Petersburg — Omsk — Novosibirsk (north);
• May 20-30 passes north of the previous isoline;
• June 1-15 passes through the north of Arkhangelsk and Murmansk regions, Karelia and the Komi Republic.

Planting Density

The potato planting density at which maximum yield is achieved varies and depends on the quality of planting material, variety, agronomic practices, cultivation purposes, and soil-climatic conditions. The higher the soil fertility 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 feeding areas, haulm overgrows, the growing season lengthens and tubers do not ripen. Conversely, on light sandy soils, dense plantings do not give an effect, since plants experience moisture deficiency.

For the Non-Chernozem zone, the optimal planting density is:

• for northern and northwestern regions 50-55 thousand plants/ha;
• for central and southern regions — 45-55 thousand plants/ha, and on sandy and sandy loam soils — 45 thousand/ha, on loamy — 50-55 thousand/ha.

In the steppe zone, the recommended planting density is 30-40 thousand plants/ha.

On irrigated lands, density is increased to 60 thousand plants/ha. For example, in the steppe part of Voronezh region, potato yield at planting density 40.8 thousand/ha was 28 t/ha; at density 55.6 thousand/ha — 35 t/ha.

For seed potato plantings — 60-70 thousand/ha to obtain a larger number of seed tubers.

Density is increased for early-ripening varieties with compact plants and upright haulm, as well as when using small tubers for planting.

Planting Depth and Methods

The planting depth of whole or cut potato tubers depends on soil type, climatic conditions and variety and generally varies from 5 to 15 cm. It is important to ensure sufficient soil cover and avoid drying out, greening, sunburn and other damage to developing tubers.

In the Non-Chernozem zone, ridge planting is usually used to a depth of 8-12 cm; on peat bogs — 10-12 cm; on floodplain lands — 8-10 cm. The ridge method allows the row surface to warm up better, is less compacted by precipitation, weed seeds germinate faster, which facilitates further weed control; the ridge surface allows soil loosening without compacting the rows by 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, semi-ridge planting with an oval row shape is used. With this method, tubers are incorporated to a depth of 12-14 cm relative to the tuber surface. The semi-ridge surface of rows with an oval shape is obtained by installing curved harrows after the covering disks of the unit.

In the zone of insufficient moisture, for example, in the steppe part of Western and Eastern Siberia, the south and southeast of Russia, as well as in years with dry spring, and in some regions of the Non-Chernozem zone where agronomic practices are aimed at moisture conservation (on sandy and sandy loam soils), flat planting is carried out with incorporation of tubers to a depth of 8-10 cm.

Larger tubers are incorporated deeper than small ones.

The influence of physiological maturity of planting material on subsequent growth of stems and tubers can be partly compensated by the distance between plants and the length of the growth period. When using old planting material, the distance between plants can be increased to compensate for the expected large number of tubers. With proper management, equivalent yields can be obtained using seeds of different physiological ages.

In the northern and northwestern regions, for example, in Arkhangelsk, Vologda, Murmansk, Leningrad and Novgorod regions and the Komi Republic, planting is carried out in pre-cut beds. The technology of the method is that after the first pass of the tractor, a straight line is marked; after the second and subsequent passes, the tractor wheel goes along the cut furrow; during planting, the coulters of the potato planter go along the center of the bed, the soil is moved to the side, and the coverer following behind again forms ridges. The use of this method in Kaluga and Moscow regions increases potato yield by 12-17% compared with ordinary ridge planting; the productivity of planting units increases by 10-15%. The effectiveness is achieved due to the higher (by 2-4 °C) temperature in already cut ridges, as a result of which emergence appears 4-6 days earlier (Zamotaev, 1975).

For planting potatoes, potato planters SN-4B-1, SN-4B-2, KSM-6 can be used, which are intended for row planting with row spacings of 60 and 70 cm and in-row distance between tubers of 20-40 cm.

The row spacing for early and mid-early potato varieties is recommended to be up to 75 cm; for late varieties — up to 85 cm.

NIIKH proposed a two-row planting scheme (60+80)/2 x 20-40 cm. For this scheme, in the SN-4B planter, the coulters are shifted in pairs by 5 cm: the outer ones inward of the planter, the middle ones from the center toward the outer ones, so that an 80 cm row spacing runs along the center of the planter. The butt row spacings are also 80 cm. So that during harvesting the combine wheel goes along the wide row spacing, the left half-axle with hub is lengthened using an extension.

Planting with 90 cm row spacing while maintaining the same planting density also gives good results. The yield increase reaches 5-20%, under irrigation — up to 25%. The method helps create better air-light conditions for plant growth, weed control, and facilitates mechanized care of plantings and harvesting.

For planting sprouted potato tubers, the SAYA-4 planter is used.

In some cases, planting units consisting of two SN-4B planters are used.

On small areas in the northern, northwestern and northeastern regions, the two-row planter KSKN-2 can be used.

The average productivity of SN-4B planters is 0.5-0.7 ha/h at a planting rate of 2.5 to 3.5 t/ha.

Herbicides

On heavily weed-infested plots, treatment is carried out 3-4 days before potato emergence; subsequent harrowings are not performed.

The consumption rate of herbicides: prometryn — 2-2.5 kg/ha a.i., 2M-4X — 0.8-1 kg/ha a.i., topogard — 1-2 kg/ha a.i., sitrin — 2-3 kg/ha a.i. The consumption rate of preparation solutions is 250-400 l/ha for ground spraying, 80-100 l/ha for aerial spraying.

Pre-emergence herbicides: Sangli, Glyphos, Kosmik, Roundup, Tornado, Khvastoks Extra, Herbitoks-L, Stomp, Prometrin, Gezagard, Fusilade Forte, Racer, Targa Super, Target Super.

Special post-emergence herbicides: Pantera, Zenkor, Zontran, Agritoks, Titus.

Pests

Among the most dangerous potato pests in Russia are the Colorado potato beetle and wireworms; potato and stem nematodes are also dangerous.

The plant protection system against pests provides for preventive and eradication measures. The first are aimed at suppressing the spread of pests; the second — at destroying pests already spreading on plants by treatment with insecticides.

Potato tuberworm, preparations for spraying during the growing season: Splender, Atom, Decis Extra, Bi-58 New, Danadim, Kemidim, Rogor S, Di-68, Nugor, Prorogor, Tagor, Zolon, Fort, Arrivo, Inta-Vir. During storage — Lepidocid SK-M (immersion of tubers in 1% solution before storage).

Colorado potato beetle, preparations for spraying during the growing season: Bikol, Fitoverm, Afarin, Fastak, Altalf, Tsunami, Alpha Tsipi, Alfas, Rotalaz, Faskord, Caesar, Piket, Mospilan, Bankol, Kinmiks, Buldok, Vanteks 60, Decis, Decis Extra, Fury, Taran, Tarzan, Kofidor, Imidzh, Marshal, Match, Karate, Lambda-S, Altyn, Karate Zeon, Gladiator, Kungfu, Karagr, Operkot, Actellik, Mavrik, Aktara, Regent, Zolon, Fort, Dursban, Pirineks, Chlorpyrifos, Derazgan, Sainer, Tsipi Plus, Almetrin, Tsiraks, Sherpa, Tsitkor, Tsipi, Sharpey, Tsiperon, Vega, Inta-Vir, Sumi-Alpha, Sempai.

Potato ladybird, preparations for spraying plants during the growing season: Fitoverm, Mospilan, Splender, Atom, Fury, Taran, Tarzan, Almetrin, Tsiraks, Sherpa, Tsitkor, Tsipi, Sharpey, Tsiperon, Vega, Inta-Vir.

Wireworms, preparations for application to soil at planting — Bazudin, Pochin. For treatment of plants during the growing season — Aktara.

Aphids, preparations for treating plants: Bi-58 New, Nugor.

Main potato pests:

• Macrosteles quadrilineatus (English: Aster leafhopper);
• Circulifer tenellus (English: Beet leafhopper);
• Leptinotarsa decemlineata (English: Colorado potato beetle);
• Ostrinia nubilalis (English: European corn borer);
• Epitrix spp. (English: Flea beetles);
• Myzus persicae (English: Green peach aphid);
• Empoasca spp. (English: Leaf hopper);
• Macrosiphum euphorbiae (English: Potato aphid);
• Phthorimaea operculella (English: Potato tuberworm);
• Tetranychus urticae (English: Two-spotted spider mite);
• Limonius spp. (English: Wireworms).

Nematodes:

• Globodera spp. (English: Cyst);
• Globodera rostochiensis (English: Golden);
• Meloidogyne spp. (English: Root knot);
• Pratylenchus spp. (English: Root lesion);
• Trichodorus spp. and Paratrichodorus spp. (English: Stubby root).

Diseases

Main page: Potato diseases

Harvest Dates

The potato crop is harvested 90-160 days after planting, but this period can vary depending on variety, production region and market conditions. High yields are usually achieved when using late-ripening varieties and a long growing period. Sometimes it is necessary to harvest before leaves wither or frost occurs, and tubers do not have time to fully develop.

Signs of potato maturation are drying of haulm, formation of a dense peeling (in some varieties) skin on tubers, drying of stolons, tubers separate easily from them. However, sometimes yellowing and death of haulm may be a consequence of disease damage; in northern regions — early frosts.

Moderately moist soil and soil temperature above 20 °C during harvest help reduce the frequency of bruising compared with harvesting at low temperatures and dry soil.

Depending on the variety and purpose of tubers, harvesting is carried out in summer for early varieties for food purposes, no later than 2 weeks before sowing winter crops in the case of occupied fallow.

In the Non-Chernozem zone, mid-ripening and late-ripening varieties are usually rarely harvested after natural completion of the growing season. Their harvest begins earlier due to the likelihood of plant damage by frost, late blight, or due to the onset of autumn bad weather and persistent frosts. According to long-term observations, harvesting in the central regions of the Non-Chernozem zone is recommended to be completed by October 1; in northern regions — by September 25 or even 20.

Harvesting is carried out in a short time: within 10-12 days in northern regions, 15-20 days — in the central belt and south. Green haulm is removed 1-3 days (in seed plantings 10-14 days) before harvest using UBD-ZA or KIR-1.5B machines. Haulm diseased with late blight is mowed 7-10 days before harvest and removed from the field.

Good healthy haulm, with permissible residual pesticide content, is suitable for silaging.

Harvest Methods

Potatoes can be harvested by continuous, separate or combined methods.

Continuous harvesting is carried out on large areas or closely located fields, with an area of at least 30-50 ha. The method is used on light and medium soils with moisture of 12-25%. Potatoes are harvested by combines, from which tubers are unloaded into transport vehicles, transported to sorting stations, where potatoes are additionally cleaned and separated into fractions. The large fraction intended for food purposes is sent to the retail network or for permanent storage; the small fraction is used for feed purposes; the medium seed fraction goes to storage.

Separate harvesting is used on medium and heavy soils. In the potato field, first potato harvesters-windrowers UKV-2 dig two rows of potatoes per pass, separate tubers from soil, haulm residues and impurities, and place them in a windrow.

Under good weather conditions, tubers and soil in the windrow dry quickly. Depending on yield, tubers from another two or four neighboring windrows can be collected into one windrow. Then potatoes are picked up according to the same scheme as with the continuous method. In this case, using the KKU-2A combine, in one pass it picks up tubers laid in the windrow. Picking up already dug and cleaned tubers from soil and impurities allows accelerating the work of combines.

The combined method involves harvesting with the UKV-2 machine, which lays tubers in the inter-row space of two adjacent undug rows. On the next pass, if the yield is low, potatoes from two other adjacent rows can be added to this windrow. After that, the pick-up combine digs the undug rows, while simultaneously picking up the tubers laid between them. As with separate harvesting, in one pass the combine harvests potatoes from four or six rows.

Movement of the UKV-2 windrower and KKU-2A pick-up combine is carried out in a field-sectional way. The number of rows in the field section should be a multiple of the number of rows harvested in one pass by the pick-up combine.

The combined method of potato harvesting allows reducing labor costs by 25-50% compared with direct combining and increasing combine productivity by 1.5-2 times.

For harvesting, methods using diggers of the KTN-2B type and tractor ploughs can also be used. After digging, potatoes are then harvested manually. The method is very labor-intensive, but tuber damage is significantly less.

Haulm can interfere with mechanized harvesting, so the aboveground part is mowed a week or two before harvest. Removal of haulm promotes strengthening of the periderm of immature tubers, which increases their resistance to possible damage during harvest.

With any harvesting method, to reduce losses after machine passes, the field is harrowed and remaining tubers are picked up. It is also recommended after the first harrowing to re-plow the plot or cultivate it, harrow again and carry out a second picking of remaining tubers.

If for some reason it is not possible to immediately remove all potatoes from the fields, they are covered with straw or soil.

Physiological Periods

During long-term storage, tubers pass through three physiological periods: maturation, dormancy and bud awakening.

During the tuber maturation period, which occurs in the first 20-45 days, intensive respiration and moisture evaporation are noted.

During the winter dormancy period, which lasts from one to several months, the eyes remain dormant and do not sprout; the release of heat and moisture by tubers is insignificant.

Bud awakening is the beginning of the active vegetation process and is a continuation of tuber development, the dormancy period of which has ended. Weight losses in this period increase proportionally to the degree of sprouting.

Storage Conditions

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 one. During long-term storage of potatoes intended for food purposes, the temperature in bulk should be lower than during 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 somewhat higher temperatures (10-16 °C), since starch at low temperatures is converted into reducing sugars. The presence of reducing sugars increases the tendency for tissue darkening when potatoes are processed by frying or dehydration. At warm temperatures, reducing sugars are converted back into starch. At a high ratio of starch to reducing sugars, tissue discoloration is minimized or prevented. To prolong storage time and thereby ensure continuous potato supply, most producers usually provide low-temperature storage. To correct the situation with 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 consumed immediately and thus are reconditioned under warm temperatures during marketing. Potatoes with a high content of reducing sugars generally have a somewhat sweet taste. There is a significant difference among varieties in their ability to accumulate sugars. Therefore, variety selection is of great importance for producing processed potato products of acceptable quality.

Tubers intended for long-term storage are preferably harvested at optimal dates. Before storage, they are sorted and graded. It is not recommended to store tubers with signs of bacterial or fungal diseases, with mechanical damage and torn skin for long-term storage, as they store poorly, start growing earlier, and worsen storage conditions for healthy tubers. Frozen potatoes are unsuitable for storage.

Handling and transportation of potatoes intended for storage are minimized. Loading and unloading operations and transportation should minimize mechanical damage. The free-fall height of tubers during loading or unloading should be no more than 30 cm.

For transporting tubers, containers, boxes, baskets, bags, etc. are better suited. Potatoes from combines can be reloaded directly into containers installed on transport vehicles. Then they are reloaded with forklifts or other lifting equipment. The container method of transporting and storing potatoes reduces the proportion of damaged and diseased tubers, helps preserve the sowing qualities of seed potatoes and increase yield, and saves storage space (containers can be placed in 4-5 tiers).

Potatoes store well in bins of specialized stores using active ventilation. The loading height of tubers is 2.5-4 m.

In stores intended for seed potatoes, a room for sprouting tubers is provided. Large stores designed for 1000 and 2000 t should be equipped with refrigeration units for part of the bins. Conveyors can be used for loading and unloading potatoes from the store.

Ordinary stores are dried and disinfected before filling with potatoes. Microclimate conditions are regulated by heating equipment and ventilation.

Potatoes can be stored in clamps or trenches. The place for arranging clamps should be located on elevated ground, dry and with a slight slope. The ends of the clamps are oriented in the direction of prevailing winter winds. At the base of the trench, a recess is made 20-30 cm deep, 2 m wide and 15-20 m long for ventilation. Groundwater depth — no more than 1.3-1.5 m. The recess is connected to vertical pipes. Tubers for storage are filled in pyramids up to 1 m high, covered with a layer of straw and soil. For the middle zone, the cover thickness is 60 cm; in the northeast and Siberia — up to 1.5 m. To regulate the temperature inside the bulk, additional soil or manure covering is used, and the snow cover thickness is increased.

For storing potatoes, clamps with supply-exhaust or active ventilation and trenches can be used. Active ventilation involves forcing air with a fan through the main ventilation channel. Fresh air enters through grilles into the potato mass, dries and cools the tubers. Air removal occurs through exhaust pipes. Shield clamps can be used; their advantage is that through existing hatches one can enter empty compartments for sorting or selling potatoes.

With all storage methods using active ventilation, several regimes are used. Immediately after placing tubers for storage, for rapid healing of mechanical damage and removal of excess moisture from the potato mass, a temperature of 15-16 °C is set for 3-4 weeks (healing period). When storing healthy tubers, the temperature can be maintained at about 18 °C (Gusev, 1975). Relative air humidity during the healing period is 90-95%. The healing process is completed within 8-10 days.

The second period — the cooling period — lasts 22-40 days. During this period, the air temperature in the potato mass is gradually reduced to 2-4 °C. The rate of temperature decrease depends on the quality of stored tubers. With a small proportion of damaged tubers, the temperature is reduced by 0.5 °C per day; with a large proportion — by 1 °C per day.

The third, main storage period. In the potato store or clamp, a temperature of 2-4 °C and air humidity of (85) 90-95% is maintained (NIIKH, Rubatzky). High temperature shortens storage life due to increased respiration. However, relative humidity is also important, since about 90% of weight loss occurs from moisture loss and about 10% from respiration. Light is excluded to avoid chlorophyll development, which leads to greening of tubers and the associated formation of toxic and bitter-tasting glycoalkaloids.

Depending on the duration of the storage period, the temperature regime does not always fully control tuber sprouting. Therefore, to further minimize sprouting, chemical treatment can be applied. Maleic hydrazide is sprayed on leaves 2-3 weeks after full flowering or when most tubers reach a size of 3-4 cm. Application of 1000-6000 ppm effectively suppresses sprouting. Chloroisopropyl-TV-tetrachlorocarbamate (CIPC) can be applied by dipping or aerosol treatment of tubers after harvest and after wound healing. Inhibitors should not be applied to tubers intended for use as planting material.

Storage Facilities

Many types of storage facilities are used; ideal are those that provide precise control of temperature and humidity. Some of them are highly automated and can also provide controlled atmosphere (CA) management. Others are very simple, for example, field storage <i>in situ*, field clamps, placement in moist sand and various types of pits, cellars and aboveground or underground covered structures that rely on environmental temperature management. Even simple stores, if well designed and insulated, can provide satisfactory storage conditions. Stores should be clean and, if necessary, disinfected to minimize diseases. Diseased and damaged potatoes should be excluded, and direct contact with moisture should be avoided to limit the spread of rot. If tubers are to be washed, this is usually delayed until removal from storage.

In many modern stores, potatoes are placed in bulk in large piles or bins. Too large piles can impede ventilation and cause crushing of tubers at the bottom. To improve ventilation and remove accumulated moisture, wooden slatted floors or ventilation channels are usually used. Some stores use large boxes on pallets, which improve ventilation, reduce damage and greatly facilitate loading and unloading with forklifts.

Ventilation Technique

With active ventilation, 50-70 m³/h of air with relative humidity of at least 75% is provided per 1 t of tubers. Ventilation technique depends on the storage period and condition of potato tubers.

During the healing period, cooling is carried out only if the temperature in the bulk rises above the value established for this period. At this time, recirculating (internal) air is used for ventilation. Ventilation is carried out 5-6 times a day for 30 minutes; the interval between ventilations is 3.5-4 h. After loading wet potatoes, they are dried — the bulk is ventilated from several hours to 2 days during daytime with dry warm air until droplet-liquid moisture on the tuber surface is removed. After that, ventilation is carried out in the regime characteristic of the healing period.

During the temperature reduction period, ventilation is carried out more intensively: in cold times of day — with outside air with exhaust shafts open, achieving a temperature decrease rate in the bulk of 0.5-1 °C per day.

At negative outside air temperatures, it is mixed with internal air; the mixture should have a temperature not lower than 0.5 °C. When stored potatoes are of different quality, ventilation is carried out separately. Parts of the bulk, section or bin with a low temperature are temporarily disconnected from the ventilation unit using gates or air supply to them is regulated. The most intensive ventilation is established for places with high temperature, preventing the danger of potato heating.

After reaching the variety-specific temperature in the bulk, ventilation is carried out periodically to maintain the specified storage conditions. For this, depending on weather conditions, tubers are ventilated only with outside air or its mixture with internal air of the store. In the latter case, internal air is supplied first, then cold outside air is introduced into the flow through control valves of the supply shaft. On very cold days, only internal air is used for ventilation.

With the onset of spring, a reserve of cold is created in the bulk, reducing its temperature to 1.5-2.0 °C. This reserve is replenished by ventilation during night and morning hours. When the outside air temperature at this time is higher than the bulk temperature, ventilation is carried out only with store air.

When storing seed tubers, varietal characteristics of potatoes are taken into account. For example, when the storage temperature of tubers of the varieties Priekulsky early, Severnaya Roza, Falensky is reduced to 1.5-2.0 °C, the technological properties of tubers improve, and seed productivity increases. Whereas for the varieties Lorkh, Lyubimets, Stolovy 19, yield increases when tubers are stored at 4-5 °C (NIIKH, BelNIIKPO).

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 warm period without sprouting.

10-14 days before planting or sale, it is recommended to increase the air temperature during ventilation to 15-20 °C in order to enhance growth processes in seed potatoes or for partial conversion of sugar into starch in food potatoes.

The above potato storage technology has proven itself in production practice of potato growing: the proportion of losses and tubers that have produced sprouts is very small.

Storage Diseases

Except for early sprouting, most storage diseases are caused by rough physical handling starting from harvest and unfavorable conditions existing in the store. Diseases are usually associated with previous infection of tubers before storage, although insufficient disinfection of the store can also be a cause.