Effect Of Different Nitrogen Application On Soil Fertility Of Spring Wheat Mulitiple Cropping Forage

To study the effect of compound forage grass on soil fertility under different nitrogen application treatments with sorghum bicolor,Zea mays and Avena sativaare as test material,using the split zone design,the main area contains different species of forage grass A,sorghum bicolor(A1),Zea mays(A2),Avena sativa(A3),The secondary zone are different nitrogen applications(N1:0kg·hm-2,N2:180 kg·hm-2,N3:225 kg·hm-2,N4:270 kg·hm-2),Through the determination of plant growth status,soil physical and chemical traits,and enzyme activity during forage growth,the comprehensive influence of three kinds of grass and different nitrogen application.1.Appropriate reduction of nitrogen fertilizer application is conducive to the improvement of forage yield.The yield of the three herbage reached the highest when the nitrogen application level is 225kg-hm’2,with the highest sorghum yield at the same nitrogen level.The yield of A1N3 treatment was the highest in all treatments.2.Appropriate reduction of nitrogen fertilizer is conducive to improving soil capacity weight.Under different nitrogen application levels,A1 treatment is higher than A2 and A3 treatments.The highest water content under N2 in different N ranges,A2 is higher than A1 and A3,and A2N2 is more water than A1N2 and A3N2.Moderate reduction of nitrogen fertilizer improves the soil conductivity,A1,A2 treatments are the highest under N2 and N3 treatments,respectively,nitrogen application has no significant effect on Avena sativa conductivity;the three forage grass conductivity is not significantly different.Multiple cropping improved soil pH,nitrogen application and forage species had insignificant effects on soil pH.All the soil organic matter increased first and then decreased;under the same nitrogen application level,Sorghum was greater than Zea mays and Avena sativa,A1N2 treatment was significantly greater than A2N3,A3N4 treatment.Moderate nitrogen reduction increases the alkali nitrogen content of sorghum and Zea mays,with highest N4 level.Under different nitrogen levels,A3 treatment is higher than A1 and A2 treatment,and A3N4 treatment is greater than A1N3 and A2N3.Regular influence of nitrogen application on soil quick potassium content;at the same nitrogen level,A1 was higher than A2 and A3,and A1N2 was higher than A2N3 and A3N1.With the increase of nitrogen application,the content of soil whole phosphorus increased first and then decreased sorghum and Avena sativa with N3,Zea mays with N2,A1 treatment was greater than A2 and A3,and all treatments with A1N3 and higher than A2N2 and A3N3.Nitrogen application is beneficial to improve the soil rapid phosphorus content;A1 treatment is greater than A2 and A3 at the same nitrogen level,and A1N2 treatment is the highest in all treatments.3.Soil sucrase activity of Sorghum and Zea mays was highest with N2 and Avena sativa with N3.When nitrogen application was 0-270 kg·hm-2,A1 treatment was significantly higher than A2 and A3 treatments.With the increase of nitrogen application,the catalase activity of A1,A2 treatments gradually decreased,A3 treatment first decreased and then decreased,the highest under N3 treatment;under different nitrogen levels,A3 treatment is higher than A1,A2 treatments,the highest under A3N3 treatment.With the increase of nitrogen application,soil alkaline phosphatase activity increased under Al,A2 and A3.At the same nitrogen level,A3 was greater than A1 and A2,A3N2 than A1N2 and A2N3.The change coincides with the activity of alkaline phosphatase.With the same amount of nitrogen,the urease activity treated with A1 was higher than A2 and A3,and the soil urease activity treated under A1N2 is higher than A2N2 and A3N3.4.Comparing the bacterial genetic diversity index of grass and wheat roots,the sparsity curve and Shannon-Wiener curve found that the bacterial diversity of grass roots was significantly higher than that of wheat.Under different nitrogen levels,the bacterial diversity of Sorghum increased and decreased with the increase of nitrogen application,Zea mays and Avena sativa were increasing,and the nitrogen level had no significant effect on the bacterial diversity.Under the same nitrogen level,the bacterial diversity of the three grasses is greater in Sorghum than Zea mays and Avena sativa.The level of bacterial diversity treated with sorghum N2 were higher than Zea mays and Avena sativa N4.5.Comprehensive evaluation of different nitrogen treatment of compound grass by principal component analysis and membership function analysis shows that A1N4>A1N2>A2N2>A2N2>A2N3>A2N3>A2N1>A3N3>A3N2>A3N1>A1N1>A3N4.It shows that treatments A1N4,A1N2 and A2N2 have a strong effect on soil fertility improvement,while A3N4 has the worst effect on soil fertility improvement.