Agrohimiâ

In a two-factor long-term field experiment in the vetch-oatmeal–winter wheat–barley crop rotation, the effect of fertilizer and liming systems on changes in the content of mobile (according to Kirsanov) and lightly mobile (according to Scofield) phosphorus and potassium in sod-podzolic light loamy soil was studied. The effect of various fertilizer systems was studied: organic (cattle manure), mineral and 2 organomineral fertilizer systems on a limed background and without liming. According to the effect on crop yields, fertilizer systems were arranged in the following ascending order: organic ≥ mineral ≥ organomineral (half doses) > organomineral (full doses). In the 2nd rotation, the aftereffect of liming at a dose of 1.0 А_g at an initial pH_KCl value of 5.1–5.2 units was statistically insignificant. The use of an organomineral fertilizer system (manure at a dose of 50 t/ha + N150P120K225) made it possible to increase the productivity of the crop rotation link to 3.84–4.07 t feeding units (f.u.)/ha, which was 1.57–1.75 t f.u./ha more than in the control without fertilizers. At the same time, the content of mobile phosphorus (capacity factor) increased by 13%, the degree of mobility (intensity factor) increased by 2.6 times compared with the control. The content of mobile potassium increased by 65%, the degree of its mobility increased by 2.0 times. The difference utilization rate was 18–21% P₂O₅ and 41–46% K₂O. The specific phosphorus removal was 9.5–9.9, potassium – 32–33 kg f.u./t and did not depend on the level of soil acidity. The phosphorus balance had a positive average correlation (r = 0.58) with the change in the content of readily available phosphorus determined by the Scofield method. The potassium balance had an average strength correlation (r = 0.46) with a change in the content of mobile potassium determined by the Kirsanov method. We believe that in agrochemical practice, these methods should be used together, mutually complementing each other, most fully characterizing the mobility and availability of phosphorus and potassium in the soil for plants.

In the field experiment, the effect of binary sideral mixtures with soybeans on the volume mass, structural coefficient and degree of aggregation of arable and sub-arable horizons of typical heavy loamy chernozem was studied. It is shown that mixing crops in sideral agricultural communities in most cases led to an increase in the yield of subsequent grain crops and an improvement in the studied agrophysical properties. A decrease in bulk weight, an increase in the coefficient of structurality and the degree of aggregation in both the arable and sub-arable horizons were in most cases more effective under mixed agricultural communities compared to the corresponding horizons under variants with clean crops. The most significant was the improvement of agrophysical properties in the soils under the agricultural communities of soybeans + corn and soybeans + sunflower. The ability of mixed sideral agricultural societies to effectively reduce the bulk mass of soils makes it possible to reduce it on over-compacted soils, thereby improving their quality.

The effect of iron chelates and its ultrafine particles (UFPs) on the growth and biochemical parameters of Triticum aestivum L. plants was compared. As an example of the effect of chelates, iron glycinate was chosen, with the help of which UFPs were obtained by interacting with quercetin. The relevance of the study was the development of new types of fertilizers based on UFPs metals, characterized by higher bioavailability, which will reduce their application rates to 6.25 · 10^–4 mg/l of the finished solution. UFPs of iron were obtained by the method of “green” synthesis. The confirmation of their sizes was carried out by the method of dynamic light scattering. The positive effect of UFPs on the length and biomass of shoots and wheat roots was shown, which increased these indicators relative to the control by 29, 45 and 81%, respectively. The use of quercetin as a separate supplement improved these indicators by 37% relative to the control. The possibility of using iron UFPs obtained by the method of “green” synthesis to increase stress resistance of plants is substantiated.

The effect of treating rice seeds (Oryza sativa japonica) of the Koshihikari variety, spring barley (Hordeum vulgare L.) of the Moskovsky 86 variety and winter wheat (Triticum aestivum L.) of the Nemchinovskaya 85 variety with a new biostimulator (BS) on the germination and development of seedlings was studied. The biostimulator was obtained at the All-Russian Research Institute of Phytopathology using the developed technology of liquid-phase catalytic oxidation of starch-containing raw materials. The biostimulator (concentrate with a molecular weight ≥ 30 kDa) contains a complex of phytohormones of cytokinic and gibberellic nature, free amino acids, and hydroxycinnamic acids. Soaking rice seeds in BS solution at concentrations of 10^–4, 10^–5, and 10^–6 ml/l stimulated their germination and increased root length by 2.6–2.7 times. A more intensive accumulation of seedling biomass (43% more than in the control) was observed when using BS at a concentration of 10^–6 ml/l. After treating the surface of spring barley seeds with a biostimulator at a concentration of 10^–6 ml/l, an increase in germination energy, laboratory germination, length of the main germinal root, and the wet mass of roots and seedlings were noted. The trends towards changes in the morphophysiological parameters of the development of winter wheat seedlings largely coincided with the results for barley. The highest rates were observed when using BS at a concentration of 10^–6 ml/l. The data obtained indicated the positive effect of the new biostimulator on the germination of seeds of various grain crops.

In a 14-year 10-variant laboratory experiment on columns, the migration mobility of magnesium, which remains annually in dolomite-reclaimed sod-podzolic soil after harvesting, was studied. A “pool” of magnesium compounds capable of migration has been identified during the years of “average long-term”, “excessive” and “insufficient” moisture levels. It was found that an increase in the volume of drained moisture contributed to an increase in unproductive magnesium losses. The higher the dose of dolomite and the smaller the particle size, the greater the eluvial loss of magnesium. The bulk of the migration-capable magnesium was removed from the soil at the initial stage of washing. During the entire study period, migration losses of magnesium after pea harvesting exceeded losses after mustard cultivation. A ranking of various experimental options was carried out according to the scale of magnesium losses. It is shown that over 14 years of observations, the maximum loss of magnesium as a result of migration was typical for the variant produced by dolomite flour, calculated from the full dose of hydrolytic acidity (Ah). Magnesium losses from soil reclaimed by dolomite particles 5–7 and 7–10 mm in size in doses equal to 1, 3 and 5 Ah were lower. Empirical dependences have been developed describing the loss of magnesium from the soil produced by dolomite in a wide range of doses. The graphs of the models for each of the variants with different levels of moisture availability were almost parallel, they were located on top of each other depending on the degree of moisture. This indicated that the mechanisms of magnesium migration, regardless of the degree of soil moisture, were of a similar nature. The degree of moisture affected only the total migration volumes of the element.

The influence of deficiency and excess of essential microelements (Cu, Zn, Mn, Fe, B, Co, Mo) on humans, farm animals and crops, factors influencing their distribution in the soil–plant system were considered. It has been shown that liming of acidic soils has a significant and long-term impact on the microelement composition of plants and can lead to their deficiency in food products and animal feed. This soil fertility enhancement technique affects the elemental status of humans and farm animals and should be considered as an additional health risk factor. It has been shown that the decrease in the yield of many crop plants when full doses of lime are applied can be largely associated with a lack of mobile microelement compounds in the soil. It has been substantiated that in order to control the element composition of cultivated plants, the doses of lime ameliorants should maintain the soil acidity at levels that ensure optimal contents of mobile compounds of vital microelements. The deficiency of microelements (Cu, Zn, B, Co, Mn) in limed soils can be compensated by using micronutrient fertilizers.