Establishing Fertilization Recommendation Index Of Maize Based On The Manure Trial In Low Hilly Regions Of Sichuan

Chemical fertilizers plays an important role in ensuring food security. For the pursuit of high yield, a large number of fertilize application has led to soil nutrient imbalance, low fertilizer use efficiency, economic decline in part of the region. Soil testing formula fertilization is an important technology to make scientific fertilization decisions, has become the main means to solve these problems. It can applying only as much fertilizer as is needed. The study established the plentiful-lack of soil nutrition and fertilization recommendation index in different ecological subregions, according to the regional soil nutrient status and production status, and based on the results of the maize "3414" experiments in low hilly regions of Sichuan basin from 2005～2010, and then compared the fertilizer effect between the formula fertilization and conventional fertilizer. The main results were as follows:(1) Organic matter (OM) and available potassium (AK) content had decreased to a certain degree; total nitrogen (TN), available nitrogen (AN) and available phosphorus (AP) content had risen in different degrees, compared with soil fertility in Sichuan from the second national soil survey. So the original soil nutrient index was not suitable for guiding the current agricultural production. The regression determination coefficient R2 among soil organic matter (OM) and maize relative yield of nitrogen deficiency was 0.267, significantly higher than total nitrogen (TN) (0.122) and available nitrogen (AN) (0.165). Therefore, organic matter (OM) was more suitable for soil nitrogen supplying index. Organic matter (OM), available phosphorus (AP) and available potassium (AK) were divided into lower, low, medium, high, higher and highest by relative yield of 55～95%, Were:OM (<6,6～10,10～20,20～30,30～40, and>40 g/kg); AP (<3,3～5,5～10,10～25, 25～50, and>50 mg/kg); AK (<30,30～50,50～80,80～120,120～180, and>180 mg/kg). Compared with original level, the content of organic matter (OM) had no obvious change; the content of available phosphorus (AP) had a certain degree rise, high, higher and highest fertility level increased 2.5,7.5,5 mg/kg; the content of available potassium decreased greatly, medium, high, higher and highest fertility level decreased 10,25,25 and 10 mg/kg.(2) Soil testing formula fertilization was better than the target production method, when calculated the economic optimum amount. It could guarantee the output and reduce the amount of fertilizer. The one factor model had the highest success rate (43.5-74.5%), the second was the two quadratic plus plateau model (33.3～59.O%), however the success rate of three factor model, square root plus plateau model and linear plus plateau model were lower. This paper adopted the two fertilization model whose success rate were high to calculate the economic optimum amount, and adopted quadratic plus plateau model at first, and then adopted the one factor model when the fit was not successful.(3) Because the cropping system, crop variety and fertilization habits are different, recommended fertilization of each ecological subregions were imparity. The nitrogen fertilizer recommendation rates of different levels showed that low mountain regions of north basin> hilly regions of middle basin> low hilly regions of south basin> plains regions of west basin. Among them, recommended dosage was lowest in plains regions of west basin, and highest in low mountain regions of north basin, both differed 10-55 kg/ha. The phosphorus fertilizer recommendation rates of different levels showed that low mountain regions of north basin> low hilly regions of south basin> hilly regions of middle basin> plains regions of west basin. Among them, plains regions of west basin was lower low mountain regions of north basin than 10～15 kg/ha. The potassium fertilizer recommendation rates of different levels showed that low mountain regions of north basin> plains regions of west basin> hilly regions of middle basin> low hilly regions of south basin. Among them, recommended dosage was lowest in low hilly regions of south basin, and highest in low mountain regions of north basin, both differed 10-30 kg/ha. Overall, maize dosage of nitrogen, phosphorus and potassium fertilizer recommendation were lowest in plains regions of west basin and highest in low mountain regions of north basin, objectively reflected the different ecological characteristics of fertilizer input in the subregion of maize production.(4) Soil testing formula fertilization increased 14.6% production, compared with conventional ertilization. The nitrogen and phosphorus use efficiency were obviously enhanced, however the potassium use efficiency decreased. Nitrogen agronomy efficiency increased by 2.6 kg/kg, nutrient recovery increased by 8.0 percentage points; phosphorus fertilizer agronomy efficiency increased by 3.1 kg/kg, nutrient recovery increased by 4.1 percentage points; potassium fertilizer agronomy efficiency and nutrient recovery decreased by 1.7 kg/kg and 10.7 percentage points. This is mainly because the increment of potassium application. Inconsistent, fertilizer effect were different in each ecological subregions, mainly for hilly regions of middle basin> low hilly regions of south basin> plains regions of west basin> low mountain regions of north basin. The production and fertilizer use efficiency of maize were high in hilly regions of middle basin, because the amount of fertilizer and the ratio of fertilization rate were reasonable(1:0.51;0.34).