Effects Of Different Fertilization Level On N And P Losses On Sloping Farmland Of Purple Soil

Through monitoring the runoff in plots,the soil erosion characteristics and N and P losses was studied under CK(T0),combined application of manure and fertilizer(T1),chemical fertilizer(T2),chemical fertilizer with increasing fertilizition(T3),and contour plowing with chemical fertilizer(T4) with "Winter Wheat-Summer Maize" on the sloping farmland of purple soil.lt is designed to reduce fertilizer loss from the runoff and provide good information.for the environmental issues.The main conclusions are as follows:(1)Effects of fertilization level and rainfall on runoff were quite remarkable, second rainfall sediment loss was linearly related to rainfall on different fertilization levels.The relation between sediment loss and runoff was power function relation in the unit area when fertilizition increasing,while was logarithmic function in other fertilization levels.In addition,for changes in slope length,cross-slope tillage affected slope runoff,resulting in less energy function fitting effective.(2)Effects of fertilization level and rainfall on nitrogen and phosphorus concentration in runoff were quite remarkable.The varying trend of nitrogen and phosphorus concentration loss in runoff was consistent with the varying trend of rainfall on different fertilization levels. With increasing of rainfall it increased,and nitrogen and phosphorus concentration fluctuation range were different on different fertilization levels; Combing of application of manure and fertilizer,nitrogen and soluble phosphorus concentration in runoff were stabler;Maximum concentrations of nitrogen and phosphorus in runoff was consistent with occurrence of heavy rain on different fertilization levels,while additional fertilizer and other agricultural activities had influence on the maximum phosphorus concentration.(3)The relationship between nitrogen and phosphorus rainfall loss and rainfall amount was not obvious on different fertilizer levels,furthermore, total nitrogen,soluble phosphorus cumulative loss and rainfall cumulative loss were linearly related,and nitrate nitrogen,ammonia nitrogen, total phosphorus accumulated loss and accumulation runoff were logarithmic function correlated;In the relationship between the amount of nitrogen loss and runoff,total nitrogen,nitrate nitrogen and ammonia nitrogen loss with runoff meet the functional relationship y=1/(ax2+bx+c,a>0)without fertilizing;Combing of application of manure and fertilizer,total nitrogen loss and runoff had no significant functional relationship,while there were positive linear correlations between nitrate nitrogen,ammonia nitrogen loss and runoff.Moreover, single application of fertilizers,total nitrogen, nitrate nitrogen and ammonia nitrogen loss and runoff were also positive linear correlation.If fertilization was increased or contour plowing,total nitrogen loss and runoff had no significant functional relationship,nitrate nitrogen and ammonia nitrogen showed by y=ae(-b/x).The relationship between phosphorus loss and runoff,total phosphorus in the no fertilizer,combing of application of manure and fertilizer and single application of fertilizer were linear functions,while increased fertilizer was a quadratic function,it was a power function in cross-slope tillage.The relationship between soluble phosphorus loss and runoff was described by y=1/(ax2+bx+c) in no fertilizer,and it was linear related in the combing of application of manure and fertilizer and cross-slope tillage,at the same time it was power function in the single application of fertilizers and increased fertilizer.Simultaneously,this experiment found that in the cases of combing of application of manure and fertilizer,increased fertilizer and single application of fertilizers in cross-slope tillage the amount of nitrogen and phosphorus loss in runoff mainly came from heavyrain.(4)According to relative losses of nitrogen and phosphorus in runfall on different fertilization levels,total nitrogen varied from 0.96 kg.hm-2.a to 17.26kg.hm"2.a,and varying trend was:T2>T3>T4>T1, nitrate nitrogen varied from 0.28kg.hm-2.a to 2.30kg.hm-2.a,ammonia nitrogen varied from 0.21 kg.hm-2.a to 1.83 kg.hm"2.a,and varying trend wasT3>T2>T4>T1;total phosphorus varied from 0.0174 kg.hm-2.a to 0.0618kg.hm"2.a,and varying trend was T3>T2>T4>T1;soluble phosphorus varied from 0.0001 kg.hm-2.a to 0.0017 kg.hm-2.a, and varying trend was:T3>T1>T2>T4 Total nitrogen in sediment carrying nutrient varied from 0.0353 kg.hm-2 to 0.3376 kg.hm-2,and total phosphorus varied from 0.2882 kg.hm-2 to 4323 kg.hm"2. In the main, CK (To) was maximum, and contour plowing was minimum,effective nutrient loss accounted for the highest proportion in chemical fertilizer and combined application of manure and fertilizer.(5)Study displayed that nutrient content of soil surface increased to some extent,nutrient content of sediment occurred enrichment and enrichment ratio varied from 0.998 to 2.120,on different fertilizer levels. The enrichment ratio of sediment available nutrient is greater than total nutrient in combing of application of manure and fertilizer,the enrichment ratio of sediment total nutrient is greater than the available nutrient in chemical fertilizer,with the increasing of fertilizer the total nutrient enrichment ratio is enhanced.(6)On different fertilization levels,the total nitrogen loss varied from 5.441 kg.hm"2.a to 22.576 kg.hm-2.a,in which runoff loss accounted from 93.79% to 99.66%,sediment loss only accounted from 0.34% to 6.21%,and effective nutrient loss in runoff accounted from 40.45% to 60.2%,and nitrogen loss was mainly in runoff;Total phosphorus loss varied from 0.359 kg.hm-2.a to 0.549kg.hm-2.a,in which runoff loss accounted from 15.17% to 21.20%,sediment loss accounted from 78.80% to 84.83%,and phosphorus loss was mainly in sediment,however,soluble phosphorus content loss in runoff could not be ignored,because it was higher than it in sediment.(7)On different fertilization levels,absolute nitrogen loss factor varied from 1.491% to5.466%,relative nitrogen loss factor varied from 0.174% to 4.419%;And absolute phosphorusoss factor varied from 0.218% to 0.262%,relative phosphorus loss factor varied from 0.0005% to0.0765%.According to relative loss factor, nitrogen was ordered as follows:T2(4.419%)>T4(1.229%)>T3(1.121%)>T1(0.174%),that was chemical fertilizer>cross ridge>chemical fertilizer with increasing fertilizition>combined application of manure and fertilizer;And phosphorus was ordered as follows:T3(0.0765%)>T2(0.0441%)>T4(0.0228%)> T1(0.0005%), that was chemical fertilizer with increasing fertilizition>cross ridge as>chemical fertilizer> combined application of manure and fertilizer.