Effects of coupling control of straw and nitrogen fertilizer on comprehensive effect of soil fertility in salinized soil
To study the characteristics of soil water and salt migration in saline soil treated with straw and nitrogen fertilizer in the Hetao Irrigation district,the comprehensive effect of soil fertility improvement under this treatment mode was clarified.Through a field experiment,three straw returning amounts were set:no straw returning(C0),4 500 kg·hm-2(C1),and 9 000 kg·hm-2(C2);and three kinds of fertilization levels were specified:no nitrogen application(N0),traditional nitrogen application amount reduced by 30%,210 kg·hm-2(N1),and 300 kg·hm-2(N2).The results showed that after irrigation,the straw interlayer formed a"water storage layer"and a"salt isolation layer".The straw interlayer and upper layer significantly increased soil water storage capacity by 22.19%and the desalination rate by 18.20%compared to that of non-straw returning.Additionally,the soil under the straw showed varying degrees of salt accumulation.The soil salinity in the topsoil consistently decreased as the amount of straw returning increased,with the C2 treatment showing the most effective desalination.Straw decomposition exhibited an exponential decay pattern,with a rapid initial decomposition rate within the first 60 days,followed by a gradual slowdown in the subsequent 90 days.The amount of straw returned and the rate of nitrogen application significantly impacted straw decomposition.The straw decomposition rate in the C2N2 treatment was 67.02%,which was 29.57%higher than that in the C2N0 treatment.Nitrogen fertilizer application boosts organic matter decomposition and nutrient release from straw.A single application of nitrogen fertilizer decreased soil organic matter and nutrients,whereas adding straw significantly reduced soil inorganic nitrogen levels.The interaction of straw returning and nitrogen fertilizer significantly affected maize yield.The maize yield in the C2 treatment initially increased but then decreased as the nitrogen application rate increased.Excessive nitrogen inhibits straw decomposition and reduces nutrient accumulation in soil,thereby affecting crop growth.The C2N1 treatment achieved the highest yield at 16 985 kg·hm-2,9.47%higher than the local conventional fertilization C0N2 treatment.A comprehensive evaluation regression model was established using the entropy method,which considered soil structure,water and salt transport,nutrient release,and crop yield.The results indicate that combining maize straw return with 9 000 kg·hm-2 and 210 kg·hm-2 of nitrogen fertilizer is the most effective model.
straw turnoverN fertilization ratestraw decompositionsoil water and salt dynamicsmaizeyield
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