| Green manure is a non-polluting,nutrient-complete source of clean organic fertilizer,and most winter fields in southern rice areas are planted with the leguminous green manure Chinese milk vetch,and also with winter green manure crops such as camas,broad beans and common vetch,but the unreasonable imperfections in cultivation practices and fertilizer utilization have led to low yields.This experiment,based on the rice field in north-central Hubei province,was conducted in Heping Village,Zengdu Street Office,Zengdu District,Suizhou City,Hubei Province,to promote the growth and development of green manure crops and improve the fresh grass and seed yield of green manure in rice fields through reasonable nutrient management,in combination with the paddy cultivation system,aiming to ensure the healthy development of the green manure industry through reasonable fertilizer application.The main research results are as follows.(1)Late sowing is not benefit for the growth and development,nutrient uptake and accumulation of Chinese milk vetch,and reduced fresh grass and seed yield by affecting the number of branches,plant height,number of pods,and number of grains per pod.In this experiment,the combined application of nitrogen and phosphorus fertilizer optimized the yield composition and compensated for the adverse effects of late sowing on nutrient accumulation of Chinese milk vetch at bloom and seed at maturity to obtain higher yields.Compared with the normal sowing,under the combined application of N,P and K,the fresh and dry yield increased by 7.1%,21.5%and 6.7%,6.3%,respectively,and the seed yield increased by 37.7%and16.5%,and the nutrient accumulation in the above ground,roots and seeds all reached the same level as that in the normal sowing,and the reasonable combined application of nitrogen and phosphorus fertilizers could alleviate to some extent.The reasonable application of nitrogen and phosphorus fertilizers could alleviate the adverse effects of late sowing,improve the utilization and accumulation of nutrients in above ground parts,enhance the nutrient uptake and transfer capacity of roots and seeds,optimize the composition of seed yield,and ensure stable and high yield of fresh grass and seeds,but the compensating effect of fertilizer on late sowing was not significant.Under medium fertility soil conditions,single and combined applications of nitrogen,phosphorus and potassium fertilizers can promote the growth and development of Chinese milk vetch,enhance the ability to absorb,accumulate and transfer nutrients,and increase fresh grass and seed yields,looking only at single applications,nitrogen fertilizers are more effective in increasing fresh grass yields and phosphorus fertilizers are more effective in increasing seed yields.(2)Under medium fertility soil conditions in the hilly-grandiose rice area of northern central Hubei province,single and combined application of nitrogen,phosphorus and potassium fertilizers promoted the growth and development of Chinese milk vetch,increased fresh grass and seed yield by 37.2%and 36.0%,enhanced the ability to absorb,accumulate and transfer nutrients,and increased above ground N,P and K nutrient accumulation by 71.7%to 96.0%,108.9%to 149.5%and63.0%to 87.5%,and seed nutrient accumulation increased by 22.7%to 32.5%,18.7%to 22.9%,and 37.2%to 45.7%.If we only look at single fertilizer application,phosphorus fertilizer was more effective in increasing fresh grass and seed yield by25.2%and 28.4%compared to no fertilizer application,while nitrogen application significantly increased above ground nutrient accumulation in Chinese milk vetch at blooming stage,and additional potassium fertilizer application on top of matching nitrogen and phosphorus fertilizer did not exert the maximum absorption utilization of fertilizer,therefore,Chinese milk vetch was more efficient in utilizing nitrogen and phosphorus nutrients and less responsive to potassium.(3)In addition to the base application of nitrogen,phosphorus and potassium fertilizers,the base application and foliar spraying of trace element fertilizers molybdenum and boron increased fresh grass yield by 7.1%to 9.3%and 28.8%to54.0%,and increased seed yield by 8.2%to 11.5%and 20.9 to 21.5%,with the peak fresh grass and seed yield of 37.37 t/hm~2and 601.33 kg/hm~2,respectively,under foliar spraying of boron fertilizer at the early flowering stage of Chinese milk vetch.In general,the effect of boron fertilizer was better than that of molybdenum fertilizer,and the effect of spraying was better than that of basal application,especially the effect of boron fertilizer was the most significant in this experiment.(4)The yield of the four green manures species were higher than that of Chinese milk vetch(CMV;Astragalus sinicus L.)>smooth vetch(Vicia villosa Roth.Var.)>hairy vetch(HV;Vicia villosa Roth.)>common vetch(CV;Vicia sativa L.),and the overall effect of fertilizer was NP>P>N.Among them,Chinese milk vetch and smooth vetch had the highest yield of 27.3 kg/hm~2and 25.8 kg/hm~2under the application of N and P.The nutrient accumulation of smooth vetch was higher than that of Chinese milk vetch,while that of hairy vetch and common vetch were lower.The accumulation of nutrients was higher for smooth vetch than for Chinese milk vetch,and lower for hairy vetch and common vetch.The planting of green manure species increased the organic matter,total nitrogen and effective phosphorus concentration of the paddy soils,while the quick-acting potassium concentration was lower than that of the winter rice fields,and the nutrient concentration of the cultivated layer of Chinese milk vetch at the blooming stage was the highest under nitrogen and phosphorus fertilizer.In summary,in the middle north region of Hubei province rice area,the best green manure for winter planting is smooth vetch and Chinese milk vetch,which,when applied with nitrogen and phosphorus fertilizers,can obtain higher yields and nutrient accumulation,effectively improve soil structure and increase soil fertility,and smooth vetch are excellent paddy green manure species to replace Chinese milk vetch. |
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