Response Mechanism Of Soil Nitrogen And Maize Root Characteristics To Controlled Release Nitrogen Fertilizer In Dryland

In order to investigate the impact of urea/controlled release nitrogen fertilizer on the soil of dryland maize spring activity,plant growth and nitrogen accumulation.Using 'Xianyu 698' as the test material,two kinds of nitrogen fertilizers(common urea,controlled release nitrogen)were studied in five fertilizer allocation modes(T1:no fertilizer application,T2:common urea base application N 150 kg·hm-2 At the jointing stage,75 kg-hm-2,T3:ordinary urea based application N 75 kg·hm-2 controlled release nitrogen based application N 75 kg·hm-2 at the jointing stage 75 kg·hm-2,T4:Controlled-release nitrogen application N 150 kg·hm-2 ordinary urea based application 75 kg·hm-2,T5:controlled release nitrogen based application N 225 kg·hm-2)on the soil moisture of the mulched spring maize growth period,The effects of different nitrogen content changes,soil enzyme activities,maize growth and development indicators,nitrogen accumulation and yield of various organs.The aim is to find a better fertilizer distribution method and provide theoretical basis and technical support for maize planting in this area.The results are as follows:1.Urea/controlled release nitrogen fertilizer combined application increased soil water use efficiency,soil enzyme activity and nitrogen content.The water use efficiency of T3 increased by 4.19%and 3.59%compared with T2 and T5,and T4 increased by 5.42%and 4.81%compared with T2 and T5.In the 0-80 cm soil layer,the ammonium nitrogen of T3,T4 and T5 increased by 10.79%,11.34%and 5.6%,respectively,compared with T2.The nitrate nitrogen of T3,T4 and T5 increased by 78.26%,94.35%and 95.20%,respectively,compared with T1.The inorganic nitrogen of T3,T4 and T5 increased by 59.54%,67.34%and 70.14%,respectively,compared with T1.The soil urease activities T3,T4 and T5 increased by 6.52%,4.28%and 1.77%,respectively,compared with T2.2.Urea/controlled release nitrogen fertilizer significantly increased the leaf area index and root activity of maize and improved other root indicators.During the whole growth period of maize,the leaf area index of T3 was 10.28%and 14.42%higher than that of T2 and T5,respectively,and T4 was 11.16%and 15.33%higher than T2 and T5.The root vigor of T3 was 4.22%and 15.41%higher than that of T2 and T5,respectively.The root activity of T4 was 2.84%and 13.89%higher than that of T2 and T5.The DRWD of T3 was 4.05%and 24.07%higher than T2 and T5,respectively,and T4 was 2.12%and 21.76%higher than T2 and T5,respectively.The root surface areas of T3 and T4 were 4.35%and 9.08%higher than T2,respectively.The root length density of T3 and T4 increased by 13.55%and 35.83%respectively compared with T2.The root bulk density of T2 was 12.86%and 5.71%higher than that of T3 and T4,respectively.3.Urea/controlled release nitrogen fertilizer significantly increased the accumulation of dry matter in maize plants and promoted the absorption,operation and distribution of nitrogen.The nitrogen uptake and accumulation of T3 and T4 were 24.30%and 5.55%higher than those of T2,respectively,and were more obvious in the operation of leaves and ears.Urea/controlled release nitrogen fertilizer promotes the ability of nitrogen to absorb,accumulate and transport,and maintains its high nitrogen use efficiency while increasing maize yield.The agronomic utilization rate of nitrogen fertilizer of T3 was 125.84%and 99.67%higher than that of T2 and T5,respectively,and T4 was 131.46%and 104.64%higher than T2 and T5,respectively.The nitrogen partial productivity of T3 was 4.16%and 3.59%higher than that of T2 and T5,respectively,and T4 was 5.34%and 4.76%higher than T2 and T5,respectively.The physiological utilization rate of nitrogen fertilizer of T3 was 58.96%and 56.72%higher than that of T2 and T5S respectively,and T4 was 44.78%and 42.74%higher than T2 and T5,respectively.The nitrogen fertilizer utilization rates of T3 and T4 were 10.04%and 8.82%higher than those of T2,respectively.4.In the two-year test,it is guaranteed that the application of pure nitrogen is 225 kg·hm-2.The yield and economic benefits of T4(urea/controlled release nitrogen fertilizer mixed with one-time base application in a ratio of 1/3:2/3)were 8.15%and 8.24%higher than the local conventional model(T2).