Effect of Different Land Use on Farmland Soil Nutrients

The study investigated the effect of land use on farmland soil organic matter and nutrients and their temporal-spatial variability in Qiyang County,Hunan Province.The results showed that,the paddy soil organic matter,total nitrogen,alkali-hydrolysable nitrogen and available phosphorus contents were higher than upland field,while available potassium contents were lower than it.Compared with the results of the Second Soil Census,total nitrogen,available nitrogen and available phosphorus contents both in paddy field and in upland field were significantly increased,with higher increased rates in paddy field,while available K content declined at different degrees in paddy field and upland field.Soil organic matter,total nitrogen and total phosphorus contents in paddy soil profile were higher than upland soil profile,and the total potassium content were slightly lower than upland field.Fertilizer levels,fertilizer structure,farming system and field management in different land use patterns may be the main factors to the change of soil nutrients.