Soil Nutrients Change And Supply Capability In The Rotation System Of Winter Wheat And Summer Maize In Hebei Province

At present, the continuous accumulation of farmland soil nutrients resulted in a marked increase in the soil fertility, and yield increasing effect of nitrogen, phosphorus and potassium were gradually decreased. Soil nutrients present situation and changes within 30 years in the winter wheat-summer maize rotation system of Hebei, and the crop growth, the yield responses, soil supplying nutrient capability, nutrient balances and utilization of winter wheat-summer maize system with the high soil nutrient to N, P and K fertilizations have been studied systematically by the method of combining macroscopic-soil nutrient test with microscopic-field experiment of yield effect. The purpose of the present study is to provide a basis for the scientific and safety management of nitrogen, phosphorus and potassium under the background of crop sustainable high yielding. The results were as following:Ever since the 2nd national soil survey completed in the early 1980s, the conditions of soil nutrient in Hebei has significant changes. Compared with the result of the 2nd national soil survey, the soil organic matter, total nitrogen and available phosphorus of the districts that were surveyed have previous improvement, increased by 2.61-6.10g/kg, 0.12-0.23g/kg and 7.89-20.68mg/kg respectively. The Quick-acting Potassium of farmland soil in Baoding, Cangzhou, Handan, Shijiazhuang and Xingtai remanined almost no changes, and have previous improvement in Hengshui and Langfang.In contrast to the NPK treatments, Winter wheat yield of the treatments of nutrient deficiency （-N, -P, -K） declined by 832.5kg/hm², 1200kg/hm² and 266.3kg/hm² respectively. The soil N, P, K-supplying capacities is 89.3%, 84.6%, 96.6% respectively. The yields of 1/2N, 1/2P, 1/2K treatments were 96.2%, 98.1% and 97.4% of the NPK treatment. In the NPK treatment, the N, P and K apparent utilization were 24.6%, 17.1% and 41.0%, respectively. While in the 1/2N, 1/2P, 1/2K treatments, the N, P and K apparent utilization were 31.6%, 26.0% and 49.1%, respectively. The yields of all treatments were in an order of NPK > 1/2P, 1/2K > -K, 1/2N > -N, -P > CK. Therefore, the nutrient limiting factors of Winter wheat in the studied soil were in an order of N > P > K. Based on the yield responses and nutrient balances in this study, the N, P and K fertilization rates of 180-202.5 kg N /hm², 27-54 kg P₂O₅/hm² and 0-18 kg K₂O /hm² were recommended for winter wheat production.In contrast to the NPK treatments, Summer maize yield of the treatments of nutrient deficiency （-N, -P, -K） declined by 2090.9kg/hm², 922.3kg/hm² and 1744.1kg/hm² respectively. The soil N, P, K-supplying capacities is 70.7%, 90.1%, 82.6% respectively. The yields of 1/2N, 1/2P, 1/2K treatments were 71.7%, 94.0% and 93.0% of the NPK treatment. In the NPK treatment, the N, P and K apparent utilization were 35.38%, 20.78% and 55.70%, respectively. While in the 1/2N, 1/2P, 1/2K treatments, the N, P and K apparent utilization were 7.61%, 25.44% and 62.13% respectively. The yields of all treatments were in an order of NPK>1/2P, 1/2K>-P>-K>-N>1/2N. Therefore, the nutrient limiting factors of Summer maize in the studied soil were in an order of N > K > P. Based on the yield responses and nutrient balances in this study, the N, P and K fertilization rates of 225-240 kg N/hm², 15-30kg P₂O₅/hm² and 30-45kg K₂O/hm² were recommended for winter wheat production.