To establish the optimal balance in «income-costs» during irrigation of agricultural crops, an algorithm has been developed for determining a techno-economically substantiated irrigation rate that ensures maximum profit, taking into account the cost of irrigation and the cost of crop increases from irrigation. A techno-economically sound irrigation regime allows planning and conducting irrigation at a rate that gives the maximum economic effect.

Studies to substantiate the effectiveness of fertilizing irrigation with livestock runoff have been conducted in various regions of the Russian Federation, the Baltic States, and foreign countries. In the Republic of Belarus, scientists of the Belarusian State Agricultural Academy, the Institute of Land Reclamation and Meadow Management of the National Academy of Sciences of Belarus, the Institute of Soil Science and Agrochemistry of the National Academy of Sciences of Belarus, and some branch institutes of the National Academy of Sciences have been working on this problem in different years. At the same time, despite more than 20 years of experience in irrigation with livestock runoff, the applied recycling technology requires further improvement. That is why the justification of the modes of technology for the use of livestock runoff in irrigation fields in the conditions of technological pollution of land is an urgent scientific problem, and the development of new environmentally friendly technological solutions is of great practical importance.

The results of research on the formation of surface and drainage runoff dynamics on land reclamation systems with low water permeability soils are presented. Critical periods of formation of surface and drainage drain modules are given, their determining factors are disclosed. There is a cyclical operation of drainage systems with mainly atmospheric water supply and the duration of drainage work in different years of water content. The distribution of drainage runoff by year periods is given and the average annual duration of surface runoff is indicated. The influence of the drainage system area on the volume and drainage drain module is illustrated. When designing drain headers, it is proposed to summarize the drainage and surface runoff modules.

The article presents the results of a study devoted to the typification of soils of agricultural lands in the region of Belarusian Polessie according to the degree of their vulnerability (predisposition) to droughts. For this, an assessment was made of the moisture content of these soils during the period of climate warming (1989–2018), and the dynamics of their moisture reserves during the growing season (April – October) was revealed. Using the example of agricultural land use in the Kalinkovichi and Pinsk administrative districts, we show the spatial difference and soil fertility in terms of their vulnerability to droughts, which requires the use of differentiated measures to adapt them to mitigate the consequences of climate change.

The deficit of water balance for vegetables and fodder crops has significantly increased on the territory of Belarus in recent decades. Maintaining a sufficiently high level of soil fertility and increasing the efficiency of agriculture in such conditions requires additional moisture. The performed economic calculations showed that irrigation of vegetables in open ground and forage crops (for example, Japanese millet) in the Republic of Belarus is a profitable reclamation measure.

On average, over the years of use of the Lathyrus sylvestris L. seed crop, the number of stems per plant on the peat soil of the southern zone of Belarus varied more (V = 14 %) than on the mineral soil of the central zone (V = 4.7 %). The number of seeds in the pods and, accordingly, the weight of seeds from one plant was maximum when harvesting crops with a proportion of brown pods of 60 %, both on the peat soil of the southern zone and on the mineral soil of the central zone. The optimal harvest time is Lathyrus sylvestris L. on seeds is the phase of plant development, in which about 60 % of the beans of the upper tier of branches acquire a brown color. The seed yield in this phase was 7.4 c/ha on the sod-gley soil in the central zone on average for 3 years, and 4.5 c/ha on the peat soil of the southern zone. When harvesting seeds in the later phase (70 % of brown pods), their yield decreased due to shedding.

The article presents the results of research on the impact on the yield of red clover of different sowing dates and seed seeding rates, as well as the doses of nitrogen fertilizers applied under the cover crop, its seeding rates and harvesting times. It was found that the preservation of clover plants during the growing season is more affected by earlier harvesting of the cover crop. An increase in the dose of nitrogen fertilizers and the seeding rate of barley also leads to a decrease in the safety of clover. The highest yield of green mass is formed during the spring non-crop sowing period. When sowing under the cover crop, the highest productivity was provided by options with the maximum rate of sowing clover and harvesting barley in milk-wax ripeness with the introduction of nitrogen fertilizers N₆₀.

The article considers the photosynthetic activity of plants by the phases of development during the application of nitrogen fertilizers and during the aftereffect of mowing periods in the second year of plant life, as well as the effect of photosynthetic activity of plants on seed yield. The positive effect of increased doses of nitrogen fertilizers, as well as the earlier mowing periods on the photosynthetic activity of plants, is noted. A strong relationship between photosynthetic activity and seed yield during the application of nitrogen fertilizers has been established.

An urgent problem in many countries is the development of new forms of fertilizers and growth regulators, which, in comparison with the use of simple fertilizers, provide a balanced ratio of nutrients for the crop, increase economic efficiency by reducing the cost of application. The article presents data on the effect of microfertilizers and growth biostimulants on the photosynthetic activity of seed crops of hybrid clover. The use of the studied preparations for foliar treatment of hybrid clover on average for 2018–2020 it increased the leaf surface area and photosynthetic potential by 1.7–39.7 %, and the net photosynthetic productivity by 8.7–50 %.

The manuscript presents an analysis of the longterm experience of agroforestry scientific and practical developments in the main areas, identifies the main problems and identifies the prospects for further artificial afforestation in Russia in the southern regions. Based on the published data, a number of main reasons have been formed that determine the decrease in the functions of protective forest plantations in the regions; a set of forest reclamation measures aimed at increasing their viability and efficiency in extreme forest conditions has been proposed. Integrated reforestation activities include improving the range of trees and shrubs used for afforestation in arid conditions.