Effects Of Organic-inorganic Fertilizer Applications On Double-rice And Its Action Mechanism

To achieve the utilization of agricultural organic waste resources,reduce fertilizer application in agricultural production and improve agricultural production efficiency has been the focus of agricultural research and development.Combined application of organic and inorganic fertilizers is a wide-spread fertilization practice,which plays an important role in achieving the utilization of agricultural organic waste,reducing fertilizer application and protecting the agricultural environment.In order to provide scientific basis for rational fertilization,long-term experients were conducted and organic manure resource such as pig manure,biogas manure,pig manure pile,green manure,straw and other agricultural organic waste were taken to evaluate the effects of organic manure and inorganic fertilizer combined application on rice growth,yield,nitrogen use efficiency,soil carbon pool management index,soil microbial activity,nitrogen?N?and phosphorus?P?runoff loss and the greenhouse gas?GHG?emission in double-rice paddy field.The experiment was conducted in Xiangyin and Liuyang,respectively.there were 6 treatments in Xinglong,Xiangyin:1)without fertilizer?CK?,2)without N?WN?,3)chemical fertilizer?CF?,4)pig manure alternative 20%N fertilizer?ZF?,5)compost alternative 20%N fertilizer?DF?,and 6)biogas slurry and biogas residue alternative 20%N fertilizer?ZYF?.There were 6 treatments in Yanxi,Liuyang:1)without N?WN?,2)chemical fertilizer?HF?,3)pig manure alternative 20%N fertilizer?ZF?,4)biogas slurry and biogas residue alternative 20%N fertilizer?ZYF?,5)compost alternative 20%N fertilizer?DF?,and 6)green manure in early rice and straw in late rice alternative 20%N fertilizer?LDF?.The results were as follows:1.Compared with chemical fertilizer application,combined application of organic manure and inorganic fertilizer was beneficial for rice growth and significantly increased rice yield and nitrogen use efficiency.Compared to CF treatment,the annual average yield,nitrogen agronomic use efficiency,uptake efficiency,physiological use efficiency,partial factor productivity of DF treatment were increased by 13.51%,50.94%?26.13%?20.78%and 13.51%,respectively.2.The contents of labile organic matter,oxidizable organic carbon?EOC?,water-soluble organic carbon?WSOC?in paddy soil and soil carbon pool management index?CMPI?were significantly increased by combined application of organic manure and inorganic fertilizer.DF is the best.Compared with chemical fertilizer application,CMPI of DF were increased by 8.95%and 6.97%respectively both in early rice and late rice.Total nitrogen and available nitrogen were increased by 0.24 g/kg and 20.38 mg/kg respectively after two-year combined application of organic manure and inorganic fertilizer.3.Compared with chemical fertilizer application,cultivable bacteria,fungi,actinomycetes abundance were increased by combined application of organic manure and inorganic fertilizers,and SMBN and SMBC contents in double-rice paddy soil were increased simultaneously.In 2012,SMBN and SMBC contents in DF treatment in early rice were increased by 75.44%,19.83%and by 50.17%,17.96%in late rice.4.The GHG?CO₂?CH₄?N₂O?emission flux were increased in organic and inorganic fertilizer combination application treatment when compared with chemical fertilizer application.Furthermore,the rice yield and NEEB were also increased significantly.The NEEB of DF,ZF and ZYF were increased by 16.48%,6.60%,7.94%respectively.5.Total N,nitrate,ammonium,total P and water soluble P in runoff water decreased gradually after base fertilizer and topdressing application.In double-rice paddy field,total N,ammonium and nitrate of HF treatment reached 5.91 mg/L,3.65 mg/L and 0.82 mg/L respectively,which were higher than other organic-inorganic fertilizers treatments.Compared with HF treatment,total N,ammonium and nitrate of organic materials instead of fertilizers treatments had been significantly decreased,and the reduction of DF treatment had reached up to 1.18 mg/L,0.71 mg/L and 0.14 mg/L respectively.Moreover,manure instead of 20%N fertilizer treatments significantly increased total P and soluble P concentration in the runoff water with DF treatment exception.Compared to HF treatment,other organic-inorganic fertilizers treatments decreased runoff N loss.In addition,total N,ammonium and nitrate loss of DF treatment was 10.25 kg/ha,6.17 kg/ha and 1.71 kg/ha respectively,which were nearly equal to HF treatment.Take together,organic-inorganic fertilizers applications are benefit for promoting organic matter and soil microbial activity,and improving rice yield,nutrient uptake and utilization efficiency,and reducing runoff N and P loading in double rice field at the meantime.It was worth mentioning that,NEEB was increased though GHG emission had a slightly increase with organic-inorganic fertilizer application.In conclusion,organic-inorganic fertilizer application is of great importance in protecting environment and controlling non-point pollution.