Почвоведение и агрохимия
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Почвоведение и агрохимия, №4, 2020 clude in the above formulas (5,6) ratio of valid values of salinity to its real rate (in%) (in this case we give a formula for the stud- ied type of alkaline soils), i.e.: Calculations of the dynamics of the soil fertility level using our corrected for- mula (7) are presented in the following table №2. As shown by analytical calcula- tions (table 2), if the initial (natural) level of soil fertility before reclamation (1985) was not satisfactory, then after capital washing of saline soils and application of mineral fertilizers (in addition, P 2 O 5 - 270 kg/ha was added before sowing), the level of fertility in relation to the original in- creased by 19%, and amounted to only 33% (1986) of the optimal level, i.e. it be- came satisfactory. After three years of culti- vation of alfalfa on washed soils (1989), the level of fertility decreased sharply and reached the optimal level of -2 %, due to seasonal salinization of the soil and remov- al of nutrients by the crop, i.e. it became unsatisfactory. In postmilitary period (2016) had a slight increase in the level of fertility, levels of fertility to the source in- creased by 19% and amounted to 35% of the optimal level (the level match in 1986, after major flushing), i.e., is satisfactory, which is due only to the accumulation of plant residues in soil (table 2). Thus, it can be stated that during the post-melioration period, there was a simple reproduction of fertility, which is due to the extensive na- ture of agricultural production) [12]. The ecological significance of re- claimed land is determined by the formula: where K (after) , K (before) coefficients of the ecological significance of the land be- fore and after land reclamation; (C+g) before , (c+g) after - the sum of sur- face runoff and water exchange with ground water before and after land recla- mation, mm; U before and U after - crop yields before and after the reclamation of land, kg/ha. Taking into account the fact that the studied landscape was used as a low- productive pasture before reclamation (K before =0.3), then after capital washing of saline soils, introduction of the optimal reclamation mode of irrigation of washed soils, the agrolandscape can be used for high-performance fodder crop rotations. The calculated coefficient of environmental significance can be K after =1.2 i.e. an in- crease of 4 times. To assess the environmental sustain- ability of reclaimed agro-landscapes (agro- cenoses) is used the coefficient of ecologi- cal stability of the natural environment, which is determined depending on pat- terns of usage and relative ecological im- portance of different agricultural land sub- ject to geological and morphological condi- tions of the terrain: where K ust is the coefficient of eco- logical stability of the agricultural land- scape, in fractions of one; F 1 -area of biotic and abiotic ele- ments, %; K 1 -coefficient that characterizes the ecological significance of individual biotic and abiotic elements (0.19 for pastures and hayfields); K 2 -coefficient of geological and mor- phological stability of the terrain [K 2 = 0.7 for unstable terrain (Sands, slopes, land- slides) and K 2 = 1.0 for stable terrain]; F - the total area of the array. The significant levels of environmen- tal sustainability of the agricultural land- scape used in the assessment practice be- fore and after the complex of reclamation measures of the systems are shown in the following table №3. |