Effects of nitrogen addition on soil phosphorus components and plant phosphorus distribution in topsoil of spring wheat in the Loess Plateau
Taking spring wheat in dry farmland as the research object,four nitrogen addition gradients of 0(control),75,115,190 kg·hm-2 were set up in spring wheat of dry farmland.The inorganic phosphorus and or-ganophosphate components in 0～20 cm topsoil were determined by Gu Yichu-Jiang Baifan method and Bowman-Cole method for two consecutive years.The effects of nitrogen addition on soil phosphorus content and plant organ phosphorus content and the key factors driving soil phosphorus transformation were analyzed.Nitrogen addition for two consecutive years(2019-2020)increased the biological availability of soil phosphorus,increased the proportion of soil inorganic phosphorus to total phosphorus 1.02％～4.93％in 2019,1.31％～4.92％in 2020,and decreased the proportion of soil organic phosphorus to total phosphorus:0.74％～4.92％(in 2019),2.50％～4.92％(in 2020),compared with the control treatment.The N115 treatment significantly(P＜0.05)reduced the slow and difficult to absorb and utilize phosphorus sources,among them,inorganic phosphorus components in 2019 and 2020 were Ca8-P(8.55％,19.53％),Al-P(9.26％,12.88％),Fe-P(10.34％,39.21％),Ca10-P(2.87％,16.27％).The contents of MROP in 2019 and 2020(18.18％,16.53％)and MLOP(23.29％,14.59％)were sig-nificantly reduced.Nitrogen addition significantly increased soil organic carbon by 2.85％to 5.54％in 2019 and 8.54％to 15.35％in 2020,but significantly decreased soil pH by 0.47％to 0.83％and 1.85％to 2.42％.With the increase of nitrogen application,grain yield and aboveground biomass increased first and then decreased,the range was 1 890.26～1 961.91,1 886.19～2 263.42 kg·hm-2(2019),4 726.41～5 905.79,5 283.62～5 755.19 kg·hm-2(2020),which were the smallest in NO treatment and the largest in N115 treatment.The available phosphorus was positively correlated with inorganic phosphorus Ca2-P(P＜0.01),positively correlated with organophosphorus MLOP(P＜0.05),and negatively correlated with inorganic phosphorus O-P(P＜0.05).The application of nitrogen fertilizer for two consecutive years in the topsoil of spring wheat in the Loess Plateau might mainly through increasing the effectiveness of alkaline phosphatase and microbial biomass carbon,nitrogen,and phosphorus,thereby reducing the slow and difficulty level to absorb and utilize phosphorus sources in the soil;inorganic phos-phorus Al-P,Fe-P,Ca8-P and Ca10-P,promoting the mineralization of organophosphorus MLOP and MROP,and then improving conversion of soil available phosphorus.
万方数据
维普
