Optimization Of Fertilizer Recommendation Technology Based On Soil Test For Winter Wheat On Weibei Dryland

Weibei dryland is the second largest wheat growing region in Shaanxi province, For thepurpose of sustainable production of wheat, it is of great significance to optimize fertilizerrecommendation method, solve the problem of nitrogen (N) fertilizer over application, andprecisely manage and effectively utilizthe the regional nutrient resources on dryland. Sincethe lack of regional fertilizer recommendation theoretical basis and accurately fertilizer ratequantifying method, field experiments were carried out at24sites of six counties on WeibeiArid Tableland in Shaanxi Province from2010to2013to optimize the recommendation offertilization based on soil test. The obtained main results as below：1. The responses of wheat yield to precipitation and N, phosphate (P), potash (K)fertilizer were determined. Wheat yield and fertilizer effects were significantly affected byprecipitation, the wheat yield was5335kg·hm-2and3310kg·hm-2, respectively in2012and2013, with the average of4479kg·hm-2and the former being1.6folds of the latter. Comparedto no N fertilizer application, wheat yield under NPK fertilization were increased by14.2%(718kg·hm-2) and9.3%(298kg·hm-2), respectively. Contribution of NPK fertilizer on wheatyield in the order: N＞P＞K.2. The response of N, P (P2O5), K (K2O) requirement for100kg grain production weredetermined. The accumulation of N, P, K were found averaged to be132.9kg·hm-2,30.5kg·hm-2128.8kg·hm-2in wheat shoot, of which75.3%(100.4kg·hm-2),81.8%(24.9kg·hm-2)and16.2%(19.9kg·hm-2) were in grain, respectively. In the yield ranges of＜3000,3000～4000,4000～5000,5000～6000,＞6000kg·hm-2, the N requirement for100kg grain ofwheat were2.93,2.65,2.81,2.77,2.71kg, and P2O5requirement were0.72,0.68,0.71,0.61,0.57kg, and K2O requirement were2.17,2.12,2.68,2.92,3.00kg, respectively.3. Motheds of “Recommendation of N fertilizer based on monitoring nitrate N in1msoil (RNBM)” has been optimized, and that of “Stablizing phosphorus and potassium supplyby monitoring soil available P and K” has been improved, with the realized results asstabilized whinter wheat yield, and reduced nitrate N residual and leaching. The N applicationrate determined by the optimized RNBM was128.4kg·hm-2,(30.0-247.3kg·hm-2), being43.2kg·hm-2(25.2%) lower compared to the farmer’s practic（eFP）.The averaged wheat grain yield of RNBM and FP was avereaged to be5658kg·hm-2and5489kg·hm-2, grain N concentrationwas avereaged to be20.8g·kg-1and20.3g·kg-1, showing no significant difference betweentwo treatments respectively. Compared to FP, RNBM increased significantly N use efficiency（NUE）and N partial fertilizer productivity（PFPN）. NUE and PFPN were increased by24.0%（from46.3%to57.3%）and130.1%（from34.9kg·kg-1to80.3kg·kg-1）respectively.At harvest time, NO3--N residual in0-100cm soil layer under FP was avereaged to be70.6kg·hm-2（variable from17.4to203.4kg·hm-2）, however the RNBM was avereaged to be51.4kg·hm-2（15.6-113.9kg·hm-2）, just below the expective target value55.0kg·hm-2. During therain intensive summer fallow, NO3--N leached from0-100cm soil layer under RNBM wasobserved to be reduced by47.9%compared to FP.