Study On The Absorption And Utilization Of Rice Nutrients And Environmental Effects Under The Coupling Effect Of Biogas Slurry Returning To Field

In recent years,agricultural waste such as biogas slurry and straw has been produced in large quantities.On the one hand,they are regarded as organic fertilizers due to nutrient enrichment.On the other hand,there are recycling challenges to crop safety production and environmental quality.At present,there are many studies on the application of biogas slurry and straw returning to the field at home and abroad,and there are few studies on the coupling of biogas slurry and straw.This experiment was carried out in Jiangsu Gaoyou Suzhong Dadi Farm from 2016 to 2017,with Nanjing 9108 as the tested rice variety,with blank(CK),biogas slurry(B),biogas slurry combined with chemical fertilizer(BF),and biogas slurry straw coupling to the field(BS),biogas slurry straw coupling to return field with chemical fertilizer(BFS),conventional fertilization(CS)6 treatments.Rice plant samples and soil samples were taken during the key growth stages such as rice tillering stage,jointing stage,heading stage and maturity stage.Rice fields were sampled on the 1st,2nd,3rd,5th,7th and 9th day after the application of biogas slurry.The time is recorded as T1～T6.The rice yield,quality,main nutrient absorption and utilization,heavy metal content,soil physical and chemical properties,and rice field water environment were studied,which provided more ideas for the further rational and effective application of biogas slurry and straw in agricultural production.The main findings are as follows:1、The dry matter accumulation of stems and leaves in the mature stage of rice under the biogas slurry treatment was higher than that of the blank treatment,and the return of the biogas slurry was beneficial to increase the dry matter accumulation of rice.The dry matter accumulation of stems and leaves in the mature stage of rice under the coupling of biogas slurry and straw returning was higher than that of conventional fertilization.2、The biogas slurry returning to the field can increase the nitrogen content and nitrogen uptake of stems and leaves from jointing to maturity,while the nitrogen content of stems and leaves from rice tillering to jointing stage is lower than that of single application of biogas slurry.The nitrogen effect is obvious.Single application of biogas slurry can increase the phosphorus content of ear,and the phosphorus content of ear under the coupling of biogas slurry and returning to field is not significantly different from conventional fertilization.At the same time,the coupling of biogas slurry and straw to the field is also conducive to increasing the potassium content of leaves in rice maturity.3、The yield of each treatment was BF>BFS>CS>B>BS>CK,and the difference between BF and BFS treatment was not significant.The difference between B treatment and BS treatment was not significant,indicating that the biogas slurry was coupled to the field for rice yield under the same fertilization background.The effect was not significantly different from that of the biogas slurry alone.After the biogas slurry was coupled to the field and applied with chemical fertilizer,the yield of rice was higher than that under conventional fertilization.The main factors were the increase of panicle number and the increase of 1000-grain weight.4、Under the coupling of biogas slurry,the whitening rate and chalkiness of rice were lower than those of conventional fertilization,which improved the appearance quality.The ratio of rice roughness,polished rice rate and whole milled rice rate were higher than that of conventional rice straw.Fertilization treatment,under the action of biogas slurry returning to the field,reduced the grain protein content,amylose content and the rice taste quality.5、Under the coupling of biogas slurry,the soil organic matter,alkali nitrogen and available phosphorus in rice heading to maturity were significantly higher than conventional cultivation;the coupling of biogas straw also improved soil catalase,urease,alkaline phosphatase and invertase activities.6、The concentration of ammonium nitrogen and total nitrogen in paddy field was significantly higher than that in conventional fertilization after the application of biogas slurry as base fertilizer and manure.The concentration of ammonium nitrogen in the surface water of each treatment was significantly higher than that of nitrate nitrogen.The concentration of total nitrogen in the surface water treated by the combination of biogas slurry and straw returned to the field was significantly lower than that of the single application of biogas slurry.The returning of straw to the field was beneficial to the digestion of nitrogen in the biogas slurry.