Почвоведение и агрохимия
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Почвоведение и агрохимия, №4, 2020 The rest of the table 1 0,153 0,130 3,08 0,68 0,88 0,69 1 6,4 4 0,6 5,81 13 Post- melior- period (2016) 0,153 0,130 3,08 0,68 0,88 0,69 1 6,4 4 0,6 5,81 13 As can be seen from table 1, the level of soil fertility in the dynamics of 2016 has improved slightly, the growth to the origi- nal was only 13%, which is only due to the return of part of the biomass, i.e. the total fertility of the soil is low. The increase in humus content due to increasing the productivity of agricultural crops is not significant, i.e. the expanded reproduction of humus reserves, and as a result, the growth of soil fertility without the use of fertilizers is limited [10]. As shown by numerous studies, in the arid zone, the main role in the for- mation of soil fertility belongs to mobile nutrition elements (NPK) ~40%, the PH of the soil solution ~33%, and the humus content ~27 %. In the Russian Federation, the corresponding Method for calculating the soil fertility index is used to assess soil fertility (the order of the Ministry of agri- culture of the Russian Federation dated January 11, 2013) № 5. According to this method, the assess- ment of soil fertility is carried out on the basis of specific indicators of its fertility status, as the average value of the sum of the ratios of the actual four agrochemical indicators to their optimal values.When calculating using this method, the follow- ing agrochemical parameters are taken into account:soil acidity (pH, units); humus content (%); content of mobile forms of phosphorus (P 2 O 5 mg/kg of soil); content of exchange potassium (K 2 O mg/kg of soil). The acidity index for alkaline soils is calculated as the ratio of the optimal value of the indicator to the actual, for acidic soils - the actual to the optimal [11]. The fertility index for a specific type of soil is calculated for alkaline soils using the formula (4), for acidic soils using the formula (5): where: - soil fertility index for each soil type; (humus), (pH), (P 2 O 5 ), (K 2 O) - agro- chemical indicators; f - actual values of agrochemical indi- cators; opt-optimal values of agrochemical indicators; - for alkaline soils; - for acidic soils. The integral indicator of soil fertility is calculated using the formula: , (6) where K 1 the indicator of soil fertility; K pp1 , K pp2 ,…. K ppn - fertility index for each type of soil; S 1, S 2,…. S n - sown area of agricultural crops occupied by each type of soil, ha; S j - total sown area of agricultural crops, ha. Due to the fact that in our case, esti- mated the fertility of the reclaimed saline soils, we recommended to additionally in- (H2O) pH (KCl) pH |