Factors Influencing Interannual Variation Of Spring Corn Yield And Fertilization Stragedy

【Objectives】Under the rain-fed condition, corn yield is influenced by multi-factors. The objectives of this study were to find out the main factors limiting the corn yield and to supply the foundation for the fertilization.Experiments were conducted during three consecutive years from 2007 to 2009 on black soils, respectively in A Cheng research and teaching work center of North-east Agricultural University in 2007, Xiangfang research and teaching work center of North-east Agricultural University in 2008 and 2009. The soil was black soil and the corn cultivar used in this study was Fengtian No. 6. Field experiments followed the same"3414"experimental design in which nitrogen, phosphorus and potassium were respectively set at four levels, but only 14 treatments were chosen. This is a completely randomized block design. Data were processed using the SPSS 15.0 in order to establish nutrient response functions to obtain the recommended fertilizer rates. Other data such as Chlorophyll readings by chlorophyll meter 502 were recorded to monitor the nitrogen status with growing stages of corn.The results showed that, (a) in 2007, the maximum ecomomical yield was 11408.7 kg·ha^-1, and the recommended nitrogen, phosphorus and potassium rates were respectively 167.0 kg·ha^-1, 45.0 kg·ha^-1 (in P₂O₅ form), and 37.2 kg·ha^-1 (in K₂O form); in 2008, the maximum ecomomical yield was 7264.5 kg·ha^-1, and the recommended nitrogen, phosphorus and potassium rates were respectively 171.4 kg·ha^-1, 44.5 kg·ha^-1 (in P₂O₅ form), and 61.7 kg·ha^-1 (in K₂O form); in 2009, the maximum ecomomical yield was 8547.4 kg·ha^-1, and the recommended nitrogen, phosphorus and potassium rates were respectively 162.0 kg·ha^-1, 35.2 kg·ha^-1 (in P₂O₅ form), and 75.8 kg·ha^-1 (in K₂O form). With results averaged through three years according to treatments, the recommended nitrogen, phosphorus and potassium rates were respectively N 169.4 kg·ha^-1, 37.5 kg·ha^-1 (in P₂O₅), 70.6 kg·ha^-1 (in K₂O). The results also show that, nitrogen fertilizer had greater effect on corn yield than phosphorus and potassium. (b) Nitrogen increased significantlyaccumulation of dry matter of corn, whereas both phosphorus and potassium had no significant effect on the accumulation of dry matter of corn. (c) Well balanced fertilization of nitrogen, phosphorus and potassium increased not only the yield but also the recovery of these three elements. (d) Under rain-fed conditions, precipitation was the most limiting factor to corn yield. Shaortage of precipitation during any growing stages of corn may damage the accumulation of dry matter of corn, uptake of nutrients, finally the yield of corn. (e) the slope of field, which influence the distribution of precipitation, influenced the corn yield too. Lower position increased the corn yield. (f) Relative readings of chlorophyll meter had a good positive correlation with foliar nitrogen content, and may be used to guide the application of nitrogen.