Effect Of Manure And Straw On Rice Growth And Soil Acidification

Soil acidification is the integrated result of series of anthropogenic activities in the soil-plant system and it has been a major problem in soils of intensive Chinese agricultural systems. Soil acidification can alter the biogeochemistry of ecosystems and adversely affect biota. However, anthropogenic acidification of soils has received little attention. Irrational applications of chemical and organic fertilizers were major contributors to soil acidity accelerating in farmland. Several studies have revealed that the soil pHs and cation exchange capacities in rice-wheat system of Taihu-lake region was decreasing over time. Therefore, the research of plant residues and pig manure application on soil productivity and acidification characterstics in paddy soil in rice-wheat system will reveal the mechanisms of rice yield increasing and nitrients absorption and utilization, and provide a framework to rational apply of pig manure and plant resdiues to restoration of acidified soil.Our preliminary study showed that chemical fertilizer plus pig manure application accelerating soil acidification rate. As a result, depending on the location test of long term application of pig manure, this study will clarify its potential mechanism by analyzing the chief driving forces towards soil acidification, including N cycling, selective absorption of cation by rice and wheat as well as dicarbonate leaching. The contribution of each factor towards soil acidification as well as soil acidification pattern under chemical fertilizer application and chemical fertilizer plus pig manure application will be determined. Investigate the effect of returning straw associated with combined swine manure and reduced chemical fertilizer application on grain yield, uptake and use efficiency of nitrogen under rice-wheat rotation system. An experiment was laid out with randomized design with three replicates of six treatments, respectively, CK (non-fertilization), N2 (inorganic fertilizer that N application was 270 kg/hm2), N1 (80% N2), N1M (80% N2 with 4.89 t/hm2 swine manure), N2M (N2 with M), N1MR (N1M with 2.44 t/hm2 straw). The soil in ploughed layer before the experment contained 19.3 g/kg soil organic matter,1.4 g/kg total nitrogen,15.6 mg/kg available phosphorus,57.4 mg/kg available potassium and pH 6.29. The grain yield and yield component, accumulatiom, distribution and translocation of nitrogen and dry matter (aboveground and underground). The results showed the change rule of grain yield in treatments as follows:N2M treatment yield was the highest in two years 9315?9514 kg/hm2, urea applying with swine manure can increase rice yield 2.96%?17.95%; Average yields of CK treatment 5786 kg/hm2 was the lowest, but The nitrogen accumulation in grain of CK treament in first year was more than 10.34% of the value in second year; The fertilization of nitrogen use efficiency for the second year was more than 6.82%?15.94% in first year. The increased dry matter at mid-late growth stage by application of returning straw or swine manure, especially N1MR, improved nutritional conditions at mid-late growth stage of crop, and laid a foundation for increment of grain yield. Conclusion:According to experiment result of two rice, returning straw associated with combined swine manure and urea application improved assimilation of dry matter at filling stage and thereby promoted nitrogen use efficiency than urea application of single. At the same time, it also improved accumulation of dry matter and nitrogen accumulation about rice root as same to dynamic changes trend of aboveground.Paddy field surface water NH4+-N and TN concentrations increased with the amount of urea increasing. NH4+-N and TN concentration peaked after 4-5 days with urea base application, base of urea NH4+-N peak was 47.6mg/L and TN peak was 54.5mg/L, urea NH4+-N peak was 34.3mg/L and TN is peak 36.8mg/L. NO3--N concentration peaked occurred 5-7 days; Organic nitrogen concentration increased rapidly at first and then slow down for 9.38mg/L peak on the 11th day. Either urea or a mixture of pig manure or straw field surface water TN and NH4+-N were positively correlated with nitrogen,NH4+-N in fertilized field surface water TN was dominant. Application of swine manure paddy surface water phosphorus content is rapidly on the rise. The experiment explains that NH4+-N and TN may be the key measure indexes about the water of out of paddy field, fertilizer with swine manure a degree can increase crop yields but compared to single application of chemical fertilizer has increased the loss risk of phosphorus, risk assessment of paddy field surface water is also associated with inputs of organic material.Soil buffering capacities had a good relationshipwith pHs.Titration curves for mineral horizons were S-shaped with ambient pH roughly in the middle of the least buffered part of the curve.significant differencces in soil ANC among fertilizations at these experimental sites were in the order of inorganic nitrogen<non-nitrogen<organic plus inorganic nitrogen with variations at each site. Our results improve our understanding of the mechanism of acid-base buffering in croplands.The expected results will provide theoretical basis for rational field application of animal manure and will be of great scientific significance on prevention and restoration of soil acidification.