Methodology Of Fertilizer Recommendation Based On Yield Response And Agronomic Efficiency For Maize

Maize（Zea mays L.） is one of the important food crops in China. Rational fertilization is animportant approach to achieve high yield and high benefit and also protect environment. However,unreasonable fertilization in maize planting regions in China has brought about the low fertilizer useefficiency and restricted yield potential of maize in recent years. It is significance to study the scientificfertilization method to guide maize fertilization and to improve crop yield. Geostatistics method, modelanalysis and agronomy analysis were adopted to study spatial variations of soil nutrients, characteristicof crop nutrients requirement, yield response and agronomic efficiency for maize, to establish fertilizerrecommendation method. The main results are as follow:(1) Statistics and geostatistics methods were used to study spatial variations of soil nutrients includingtotal nitrogen (N), available N, available phosphorus (P), available potassium (K), organic matterand pH in top soils from nine counties/cities in main production areas of Jilin province. The resultsindicated that the variation coefficients of six indexes showed moderate or strong spatialself-correlations. The GIS-based nutrient spatial variability figures can reflect spatial distributions ofthe soil nutrients. Soil quality with IFI value mainly ranged from0.55to0.85, which accounted for97.84%of the study region, based on Analytical Hierarchy Process (AHP) and Fuzzy mathematicsmethod. Soil organic matter, soil texture, soil types, soil available P and slope direction were themain factors influencing soil fertility.(2) QUEFTS model was used to evaluate the nutrient requirement with data collected from2001to2010dealing with N, P and K treatments across the spring and summer maize growing regions in China.The model predicted a linear increase in grain yield if nutrient are taken up in balanced until yieldreached about50-60%of the yield potential. Amount of16.9kg N,3.5kg P and15.3kg K nutrientby aboveground part was required to produce1000kg of spring maize grain yield, and thecorresponding IEs (kg grain per kg nutrient in the above-ground plant dry matter) were59kg grain/kg N,287kg grain/kg P and65kg grain/kg K. Requirement of22.5kg N,4.4kg P,15.9kg K wasneeded to produce1000kg summer maize grain in the linear part, and the corresponding IEs were44kg grain/kg N,227kg grain/kg P and63kg grain/kg K. QUEFTS analysis also indicated that abalanced N, P and K removal by grain to produce1000kg grain was9.0kg N,2.4kg P and3.5kg Kfor spring maize, and corresponding values were13.1kg N,3.6kg P and3.5kg K for summermaize.(3) Correlation analysis with data of multiple sites/years showed that the average yield response to N, Pand K application were2.14,1.19and1.15t/hm~2, respectively; the average relative yield to N, P andK were0.77,0.87and0.87, respectively; the average INS, IPS and IKS were137.53,40.65and123.68kg/hm~2, respectively. The higher the relative yield, the higher soil indigenous nutrient supply,and thus the less yield response was observed. There was a significant negative linear correlationbetween yield response and relative yield, and a significant negative exponential relationshipbetween yield response and soil indigenous nutrient supply. The lower agronomic efficiency, the lower yield response was achieved, and therefore a significant quadratic relationship was existedbetween yield response and agronomic efficiency.(4) Fertilizer recommendation system was developed based on yield response and agronomic efficiencyand field validation was conducted across40farmer sites in Gongzhuling city, Jilin province. Theresults showed that the system based fertilizer recommendation increased both grain yield and profit,and improved nutrient use efficiency, and thus is feasible fertilizer recommendation method formaize.