Modeling the effect of mineral fertilizers on maize silage biomass formation under saline soil conditions in southern Kazakhstan

The article presents the results of field studies assessing the effects of mineral fertilizer rates and ratios on maize silage yield under different levels of soil salinity in southern Kazakhstan. The research was conducted on light sierozem soils of the Otyrar district, Turkestan region, under two salinity backgrounds (0.13 and 0.59% total soluble salts). The study object was the maize hybrid Gladius F1 (FAO 700). Fertilizer rates were tested within the ranges of N0–150, P0–120, and K0–90 kg/ha. Biometric traits, silage biomass yield, and economic efficiency of fertilizer application were evaluated. It was established that on slightly saline soils, mineral fertilization significantly increased maize silage yield up to 84.5–90.7 t/ha, which was 41.4–56.5% higher than the unfertilized control. Under increased salinity, productivity decreased by more than twofold, and the efficiency of high nitrogen rates declined due to intensified salt stress. A highly reliable model (R²=0,993; F=586,94; p<0,001) was obtained using multivariate regression analysis, confirming the dominant negative effect of soil salinity and the nonlinear response of maize to fertilization. Economic assessment showed that on slightly saline soils, the optimal fertilizer rates were N100–150P80K30–60, providing profitability to 270-300%, whereas under medium saline conditions, moderate rates of N50P80K30–60 were more economically justified. The results confirm the need for a differentiated and adaptive fertilization strategy for silage maize depending on soil salinity levels.

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