Study On Nitrogen And Phosphorus Supply And Utilization Under Completely Mulched Alternating Narrow And Wide Ridges With Furrow Planting Of Maize In Semi-arid Area

Maize under a treatment of completely mulched alternating narrow and wide ridges with furrow planting (CMRF) was taken as a research object, four treatments namely flat-planting with no mulching (NM), half-mulching with flat-planting (HM), complete-mulching with flat-planting (CM) and completely mulched alternating narrow and wide ridges with furrow planting (CMRF) were designed under the treatments of film mulching and three other treatments namely no-tillage with stubble standing(NTSS), no-tillage and maize stalk standing(NTMS), no-tillage with maize stalk covering(NTMC) were also designed under the treatments of stalk covering and stubble remaining, being to study the effect of different mulching patterns on the rules of N, P nutrients uptake, accumulation and transformation and temporal-spatial variation of soil total nitrogen(TN), nitrate nitrogen(NO3-N) and total phosphorus(TP). The objective of this study was to find the rules of nutrients uptake, accumulation and transportation and the dynamics of soil nutrients, giving a scientific suggestion for extending of CMRF and inherent mechanism of its yield increasing effect. The main results were showed as follow:1. A root-friendly zone was provided under the mulching treatments for maize roots, the absorption to deeper nutrients was greatest under CMRF and the proportion of TP in 0~60cm soil layers to that in the entire 200cm soil body had no significance under different mulching patterns. Under mulching treatments, nitrogen absorption was greatest in 40~60cm layer under complete-mulching treatments from July to August, CMRF greatly affected nitrogen contents of the soil layers deeper than 110cm in the whole growth stage. TN and TP were all highest in NTMC plots under treatments of stalk covering. TP decreasing range of 20~40cm layer in whole growth stage under CMRF was 0.255g/kg, higher than the other treatments. TP contents of each treatment in 110~140cm showed a slow decreasing with no regulation with the growth stage proceeding, the decreasing range under CMRF was greatest (0.152g/kg). Spatial trends of TN and TP exhibited an"S"line, the soil layers of TN and TP absorption under mulching treatments were deeper than those of no mulching treatment by 20~40cm from July to August. The proportion of TN in 0~60cm soil layers to that in the entire 200cm soil body was highest under CMRF, while that of TP of the four treatments had no significance.2. CMRF could siginificantly promote nitrate nitrogen accumulation in soil. NO3-N content in 0-40cm layer changed significantly in whole growth stage of maize, the changes became weaker with the layer deeper. The total content in 0-200cm soil body was highest from June 10 to July 10 while lowest from September 10 to October 10, making a smaller difference between top and deep layers. The content of CMRF in 0-200cm on Oct.10 was highest. The contents under stalk covering and stubble standing treatments changed insignificantly. The range of content variation in 0-20cm in whole stages was larger than 3.438mg/kg while in 140-200cm less than 1.663 mg/kg.3. Treatments of complete mulching and maize stalk covering could siginificantly promote N, P accumulations in plant. N, P concentration was generally decreased with maize growing stage promoting, but the nutrients accumulation was increased. N, P accumulation dynamics of maize could be described by"S"curve, except that of NM treatment. N, P accumulation tendencies of maize were increased with its growing stage promoting, the highest N and P accumulations were in maturity. N maximal accumulation of maize was in August, while P in October. The N, P accumulations in kernel of CMRF were greater than other treatments, NTSS and NTMS had no significant effect on N, P accumulation in kernel of maize. N,P harvest indices of complete mulching treatments were higher than those of other treatments, stalk covering and stubble standing treatments had no significant difference in N,P harvest indices; N use efficiency among treatments of complete mulching, NTSS and NTMC had no significant difference because of much N remainder in plant under complete mulching treatments. P use efficiency of complete mulching treatments was significantly higher than that of stalk covering and stubble standing treatments; recovery of N,P fertileizer of CMRF was siginificantly higher than that of other mulching treatments, as well as NTMC higher than that of other stalk covering and stubble standing treatments.