Modelling the Relationship Between Summer Maize NPK Uptake and Yield on the Basis of Soil Fertility Indices

Quantitative estimation of fertilizer requirements can help to increase maize （Zea mays L.） yields and improve the fertilizer use efficiency. The model for the Quantitative Evaluation of the Fertility of Tropical Soils （QUEFTS） was calibrated for maize by use of soil fertility data and fertilizer trials at different sites of the Huang Huai Hai river plain in China. The QUEFTS model accounts for interactions between nitrogen （N）, phosphorus （P） and potassium （K）. It describes the effects of soil characteristics on maize yields in four steps： （1） assessment of the potential supply of N, P and K based on soil chemical data; （2） calculation of the actual uptake of N, P and K, in function of the potential supply as determined in step 1 ; （3） draft the yield ranges as a function of the actual uptake of N, P and K as determined in step 2; （4） calculation of the maize yield based on the three yield ranges established in step 3. Data of field experiments with different fertilization treatments of various regions in China during the years of 1985 to 1995 were used to calibrate the QUEFTS model for summer maize. In step 1 the N, P and K recovered from their amount applied were described by new equations. The minimum and maximum accumulated N, P and K （kg grain kg^-1） in summer maize were determined as （21-64）, （126-384） and （20-90）, respectively. The simulated yields were in good agreement with the observed ones. It was concluded that the calibrated and adjusted QUEFTS model could be useful to improve fertilizer recommendations for maize in the Huang Huai Hai plain of China.

Modelling the Relationship Between Summer Maize NPK Uptake and Yield on the Basis of Soil Fertility Indices

Quantitative estimation of fertilizer requirements can help to increase maize (Zea mays L.) yields and improve the fertilizer use efficiency. The model for the Quantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) was calibrated for maize by use of soil fertility data and fertilizer trials at different sites of the Huang Huai Hal river plain in China. The QUEFTS model accounts for interactions between nitrogen (N), phosphorus (P) and potassium (K). It describes the effects of soil characteristics on maize yields in four steps: (1) assessment of the potential supply of N, P and K based on soil chemical data; (2) calculation of the actual uptake of N, P and K, in function of the potential supply as determined in step 1; (3) draft the yield ranges as a function of the actual uptake of N, P and K as determined in step 2; (4) calculation of the maize yield based on the three yield ranges established in step 3. Data of field experiments with different fertilization treatments of various regions in China during the years of 1985 to 1995 were used to calibrate the QUEFTS model for summer maize. In step 1 the N, P and K recovered from their amount applied were described by new equa tions. The minimum and maximum accumulated N, P and K (kg grain kg-1) in summer maize were determined as (21-64), (126-384) and (20-90), respectively. The simulated yields were in good agreement with the observed ones. It was concluded that the calibrated and adjusted QUEFTS model could be useful to improve fertilizer recommendations for maize in the Huang Huai Hai plain of China.