Phosphorus Management In Chinese Agroecosystem Based On Forecasting The Change Of Soil Phosphorus Fertility

The application of phosphorus (P) fertilizer can have a continuous effect on soil P fertility. P accumulation in soil not only desirable increased in the soil available P of agricultural land, but also caused to risk of environmental problems associated with the loss of P from agricultural soils. In order to feed an increasing population and keep environmental safety, China must try to realize a double target of obtaining both high grain yields and alleviating the pressures on the environment, by improving the techniques of P fertilization management and searching for a corresponding theoretical foundation. In this study, the results of long-term experiments were used to finding the key factor which affected the change of soil P fertility; incorporating these parameters and agricultural statistics into long-term model for soil phosphorus prediction, the increase of P fertility and the demand of P fertilizer in the future of China was predicted; P budget for national and regional level in China were calculated, and their spatial and temporal variability were analyzed to estimate the potential impacts of P surpluses or deficits to soil, and help to develop an effective P management strategy.The increasing of soil Olsen-P caused by each 100 kg hm^-2 P accumulation was 1.44, 1.60, 2.60, 2.75, 3.53, 4.44 and 5.74 mg kg^-1, respectively, for the Xinjiang Grey desert soil, Beijing Fluvo aquic soil, Henan Fluvo aquic soil, Hunan Red soil, Shaanxi Loess soil, Chongqing Purplish soil and Jilin Black soil. These results could be used to predict the long-tem change of soil available P by annual P budgets, and would provide useful information to properly manage P fertilization.On average, about 3.1% of the accumulated P was considered as soil Olsen-P improvement in the arable areas in China. The total accumulative P balance in arable areas in China was about 392 kg hm^-2 from 1980 to 2003, the present soil Olsen-P of arable area is calculated as about 19 mg kg^-1 at the national lever due to this phosphorus accumulation. If the soil available phosphorus will be increased to 40 mg kg^-1 during the future thirty years, the demand of phosphorus fertilizer should be 10.5 to 12.5 million tons. After 2035, the soil available phosphorus level should be kept at 40 mg kg^-1, meanwhile the demand of phosphorus fertilizer should be 10.5 million tons.Using a statistic data which based on a GIS plat, P budget for national (1952-2004) and...