Effect of Fertilization on Soil Nutrients and Yields in Tianjin Area

Experiments were conducted in farmland water cycle experiment base of Tianjin Agricultural University in two years,2008.10-2009.6 and 2010.10-2011.6.The effect of different fertilization on soil nutrients and yields of wheat fields in Tianjin area is studied with sampling on fields and laboratory analysis.The results show that: at the 0~20 cm soil layer,the contents of nitrate nitrogen and rapidly available phosphorus seem much higher than the other layers,then decrease gradually with the deepening of soil depth,60cm below the soil nitrate and available phosphorus content changes slowly.The maximum nitrate nitrogen contents show much the same trend as the fertilizing amount in high,medium,low,zero fertilization treatments,but the rule of the maximum available phosphorus content is less obvious than the relation to fertilization.Nitrate nitrogen and available phosphorus contents in the 0~40 cm soil layer change very significantly compared to that in other soil layers.In Tianjin Area,the multiple-cropping index is higher,so during the winter wheat planting,fertilization with basal 300 kg/hm2 and dressing 150 kg/hm2 is enough,not only conserve resources,but also protects environment.