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Seeded fallow

Seeded (busy, occupied) fallow is a fallow field sown in the spring with a crop and released early. After harvesting the crop, soils are cultivated according to the fallow type and the field is prepared for sowing winter or spring crops. The seeded fallow plays the most important role in increasing grain and fodder production, especially in areas with sufficient moisture.

Crops can be sown in seeded fallows, such as bovine-oat, pea-oat, pea-barley or other mixtures of annual crops, as well as some perennial grasses for hay, green fodder or silage, corn and early potatoes. Such crops are called annual grasses and are harvested for fodder in the phase of budding – the beginning of flowering of the legume component. 

The fallow time in the seeded fallow is much shorter than in the bare fallow. They are widespread in zones with sufficient moisture: Non-chernozem and forest-steppe zones, as well as in zones with sufficient moisture in the North Caucasus, Siberia, Central Black Earth zone. In these regions, cultivation of crops intended for fallow (fallow crops), with sufficient moisture does not lead to a decrease in yields of winter cereals sown after fallow, which allows for obtaining additional amounts of green fodder for livestock, hay, silage, potatoes under proper farming techniques.

As a rule, seeded fallows are sown on weed-free fields with sufficient fertilizers. This increases the productivity of the use of arable land and the yield of agricultural products as compared with crop rotations with bare fallows.

Fallow crops must mature early and suppress the growth of weeds. Fallow crops are mainly represented by legume crops.

Types of seeded fallows

Continuous fallow is a seeded fallow in which the fallow crop is a continuous crop, i.e. annual and perennial grasses, cereals, legumes and their mixtures.

Row seeded fallow is a seeded fallow in which the fallow crop is early mature row crops such as early potatoes, in the southern regions – corn, sunflowers for green fodder or silage, etc.

Due to the fact that crops are planted with row spacing of 45-60-70 cm in row seeded fallow, it allows, unlike continuous fallow, summer tillage, which reduces the number of weeds, preserves moisture, maintains favorable air and nutrient regimes of soils.

Sideral fallow is a seeded fallow in which the fallow crop is a siderat (green fertilizer). Most often this role is played by leguminous crops such as clover, lupine, seradella.

Plowing green mass of green manure enriches the soil with organic matter, which during decomposition improves its agrophysical, agrochemical and biological indicators of fertility. Sideral fallows are often used in the zone of sufficient moisture on poor organic matter and light sandy soils. They are also used on heavy clay soils, which contributes to structuring and creation of better friability and water permeability.

Half-fallow is a fallow field left after harvesting cereals, leguminous and some other crops, which is repeatedly tilled by the type of fallow. As a rule, fallowing lasts 2-3 months. Half-fallow is more often used in the steppe regions of European Russia.

Non-fallow predecessors are crops in the rotation with a late harvesting period that do not have a fallow period.

Peculiarities of the use of seeded fallows

In contrast to bare fallows, which are mainly used in conditions of insufficient moisture, seeded fallows are characteristic of conditions of sufficient moisture or irrigation, as well as higher cropping culture (use of fertilizers, modern technologies of soil treatment and plant protection). Winter crops are placed after seeded fallow, which in the Non-Chernozem zone give 5-15% lower yields than after bare fallow, however, due to the products obtained from the fallow crop, the efficiency is generally higher. This is especially noted if legumes, which accumulate nitrogen in the soil, and siderates are used as a fallow crop. For example, in Nizhny Novgorod region winter wheat yield by sideral (lupine) fallow was 0.4 t/ha, or 11% more than by black fallow, by vetch-oat seeded fallow – by 0.46 t/ha, or 12%.

Vetch-oat seeded fallow is often used in the Non-Black Soil Zone, where its efficiency in terms of effect on potatoes and other row crops is comparable to that of bare fallow.

Potato seeded fallow by its effect on the yield of winter crops, as well as on the productivity of the section of the rotation with row crops is comparable with vetch-oat seeded fallow. However, in comparison with bare fallow, the productivity of the section is higher by 23-30%.

In more moisture-deficient conditions, for example, in the Central Black Earth zone, winter wheat yields are 15-20% higher with bare fallow than with vetch-oat fallow. However, even in this case, the efficiency of the section due to the production of fallow crops is higher.

In areas of sufficient moisture in the North Caucasus, seeded fallows of leguminous perennial grasses – clover and sainfoin – allow to obtain the same yields of winter wheat as after bare fallow.

On sandy and sandy loam soils, sideral fallows play an important role. For example, in the Nizhny Novgorod region, lupine sideral fallow reduced weed infestation, improved soil structure, and increased winter rye yields up to 3.91 t/ha. The efficiency of black fallow without manure application in these conditions was 3.56 t/ha, and with the application of 50 t/ha of manure – 4.13 t/ha.

In Priob’ye and Altai, the cultivation of spring wheat after sideral (clovergrass) fallow yielded 2.59 t/ha, after bare fallow – 2.90 t/ha.


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