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A field experiment was conducted at an agro-ecological station (53 ° 33‘58.75 “N and 102 ° 35‘23.90” E) of the Siberian Institute of Plant Physiology and Biochemistry on gray forest medium loam soil. Winter rye (family 6) and winter triticale (No. 430-6002) were sown in 4 terms with a 10-day interval (10, 20, 30 August and 10 September) in three replications. The results of the two-year studies show that the winter crops included in the experiment had a higher (higher than 5 t/ha) and more stable yield between the years with the planting dates held on August 20, 30 and September 10 for rye and August 30 and September 10 for triticale. Earlier sowing time contributed to intensive tillering, strong growth, which led to the plant death and lower yields.

Changes in carbon balance during short-term green manure of a fallow in the conditions of the forest-steppe zone of the Baikal region are studied on the basis of the results of three-year field experiments. It was revealed that the introduction of green mass of oilseed radish (Raphanus sativus var. Oleifera Metzg) into gray forest soil at the end of the summer period significantly activates the processes of mineralization. The total CO2 emission from the soil surface in the variants with green manure increases by 1.3–1.6 times as compared with pure fallow. Compensation of gaseous carbon losses due to newly introduced organic matter is possible only at high yields of oilseed radish (3-5 tons of dry matter per ha) and hydrothermal conditions unfavourable for its mineralization. Under favourable conditions for the mineralization of fresh organic matter, a negative carbon balance is formed, but its value remains less deficient than in the variants of pure fallow. The data obtained allow us to recommend this technique of agriculture to reduce the share of net sources of carbon dioxide in the carbon balance.

The cold-resistant soybean cultivar of the northern ecotype Sayana was selected from the hybrid combination F4 L-2577 × Aldana according to the traits of cold and frost resistance and a reduced reaction for a length of a day. Additionally, the degree of cold resistance of this cultivar was evaluated by the cryosedimentation method. The cultivar Sayana belongs to a very early group of ripeness, which matures in 98 days at the latitude of Krasnodar (45°). In the competitive variety test in 2018–2020 its yield amounted to 1.19–2.10 t per ha. During the agroecological testing of the cultivar Sayana in Irkutsk region at a latitude of 53°, the duration of its vegetative period was 126–133 days with the average yield of 2.95 t per ha, which exceeded the standard cultivar Sibiryachka by 0.43 t per ha. The plant height of the cultivar Sayana at the latitude of Krasnodar was 77–88 cm, in the Irkutsk region at latitudes of 53°, it increased to 105–147 cm. The new soybean cultivar of the northern ecotype Sayana is highly resistant to low temperatures of air and soil during the seedling phase, and has increased productivity in long-day conditions of deficient heat supply and cold stress. This allows it to be cultivated as a main crop in the Central Chernozem, Northern Caucasian, Middle Volga, Lower Volga, Ural, West Siberian and East Siberian regions of the Russian Federation.