The Effects Of Straw Return On Water Quality Of Paddy Field

This experiment adopt potted method to simulate straw return,researched the effects of different straws return on water quality of paddy field. The main results were as follows:(1)the p H of all treatment groups appeared a trend of first rising then falling, rising followed.The peak-to-valley value of p H of blank was higher than it of straw groups,and the valley value turned up earlier. The range of treatment groups were:blank 0.20,rape groups 0.48,wheat groups 0.60.Straw return could ruduce water’s p H,and the influence degree weren’t obvious between different straws.With straw of sludge,the p H was ruduced earlier,and the more sludge quantity,the larger of p H in rape groups,meanwhile,this was opposite in wheat groups.(2)TN(total nitrogen) of water appeared a trend of declining,and TN increased by straw return. In the same phase,the TN concentration of rape was 37.7% higher than it of blank, the TN concentration of wheat was 14.2% higher than it of blank.With straw of sludge,TN concentration reduced in a small extent,the change of TN concentration accelerated.The ration of ammonium nitrogen and TN was reduced and TN existed mostly in form of organic nitrogen in wheat groups,this was opposite in rape groups.TN was reduced by the absorption of plant mostly,the difference of TN was tiny.(3)TP of water appeared a trend of increasing quickly in the first 7 days then declining,TP increased by straw return.In the same phase,the TP concentration of rape was 37.5% higher than it of blank, the TP concentration of wheat was 57.5% higher than it of blank.With straw of sludge,TP increased largely,TP increased 12.8%~29.1% in rape groups,and 15.9%~41.3% in wheat groups.The more sludge quantity,the larger of TP.