Soil Fertility Dynamics Of Wheat-Maize High Yield Field In Piedmont Plain Of Hebei

This study is designed for wheat-maize high yield key project field (HF) and cultivating high yield field (CHF) under straw returning in piedmont plain of Hebei. The methods of tracking investigation and many soil layers sampling in the key crop growth stages were adopted. We have revealed the soil space and time variation change low of physical and chemical characteristics in HF, and confirmed the status of high-yield soil fertility and quality. We have studied the affects of high efficient cultivating measures to the soil physical and chemical characteristics. The cultivating high yield field (CHF) measure was confirmed which made the yield be increased, the water-fertilizer using be efficient, and soil environment be friendly. It provided reasonable evidences of improving water and fertilizer resources production efficiency and soil productivity for ensuring the safety in food production of Hebei province.The main conclusions shows as follows,1 The HF soil configuration as a "Mongolian gold soil"and the ability of retaining water and nutrients is stronger. The CF from top to bottom layer is not obvious, texture of a single whole body and the ability of retaining water and nutrients is weaker.2 The content of SOM and ASOM in HF becomes lower with the soil depth going deeper. There is little difference in the content of SOM between HF and CF in the whole winter wheat and summer maize rotation. There is a notable difference in the content of ASOM in HF, while no significant difference between HF and CF. The change of soil available P and available K in both HF and CF is regular. Contrast to the CF, the HF gets a higher content of soil available P and available K in the layer 0-20 cm。But in the following 2 layers, there is significantly difference. The nitrate mainly distributes in the layer of 0-20 cm. The content of nitrate is higher in winter wheat than summer maize, there is no significant difference between HF and CF in summer maize, and HF is higher than CH in winter wheat.3 Generally, there is a surplus of N, P, K in winter wheat and summer maize rotation of HF. Contrast to CF, HF gets a higher surplus of N and P but a lower surplus in K . The yield could be high with high fertility inputing, but fertilizer utilization efficiency of HF is not improved, and the soil NO3--N is easy to accumulate.4 The nitrate accumulation of every growth stage in 0-100 cm soil layers of HF is more than CF, and a high leaching risk in HF. But there is no soil salinization in HF with high fertilizer input.5 In CHF, the bulk density of plough layer is high. The physical characteristics of soil top layer should be improved, mainly relies on the improvement of tillage and the employment of organic fertilizer.6 There are four treatments of the experiment with cultivating high yields field in Xinji, and they are treantment A (The local traditional managment), treatment B (The existing recommending managment), treatment C (The management with high fertility input) and treantment D (The management with high water-fertility efficiency). The result shows that, the soil nutrients variation of the fore treatments shows the same tendency. There is little change of SOM in winter wheat. The change of ASOM is regular. The SOM and ASOM content of C and D which was inputed with organic fertilizer are higher than A and B. Available P and K reduce, while C and D is higher than A and B. The nitrate mainly distributes in the layer of 0-40cm, reducing in whole growth period, existing obvious nitrate accumulation.7 The winter wheat yield of CHF shows as follows: D>C>B>A, and we reach the aim of yield recrease, and the water-fertilizer efficiency is also improved.8 There is much nitrate accumulation in 0-100 cm soil layer of CHF with big change, and the tendency is C>B>D>A. but there is no threat of soil salinization.In the study of cultivating high yield field, the soil nutriunt of treatment D (The management with high water-fertility efficiency) is more, and the winter wheat yield is highest to 10360 kg/hm2, but the fertilizer inputing is not the most. So, this cultivating masure is good to increase the yield, improve the water-fertilizer efficiency and keep the sustainability of soil productivity.