Study On Key Technique Of High-quality And High-efficiency Forage Cultivation In Yangtze River Basin

It is an effective way to develop animal husbandry in South China through establishing high-quality and high-efficient annual planting pattern of forage crops in the situation of insufficient livestock and poultry products.The production efficiency of 4 multiple cropping patterns based on summer maize were studied.Four winter forage crops,ryegrass,hairy vetch,rapeseed and milk vetch were selected for field experiment with three sowing dates and four densities.The optimum sowing date and planting density of four winter forage crops were determined,and the mechanism of annual feed yield difference under different multiple cropping rotation patterns was studied.Maize intercropped with soybean is an effective way to solve the problem of low protein content in feed corn,but the shade tolerance of soybean restricts the overall benefit of intercropping.In order to simplify the screening procedure of forage soybean shade tolerance under intercropping,8 and 12genotypes of soybean were selected for field test in two years.The evaluation system of soybean shade tolerance was established and the evaluation indexes of soybean shade tolerance were screened out by setting up five treatments:soybean intercropping with maize,monocropping,shading at seedling stage,shading at branching stage,shading at flowering and podding stage.The main results are as follows:1. The sowing date and density of winter forage crops have significant effects on their yield.In this experiment,the maximum biomass(dry weight)of ryegrass,hairy vetch,rapeseed and milk vetch were 21.21 t/hm~2,7.59 t/hm~2,21.30 t/hm~2 and 4.94 t/hm~2,at the density of 20.25 kg/hm~2(seeds),37.5 kg/hm~2(seeds),6×10~5 plant/hm~2,40.5 kg/hm~2(seeds),respectively when sown in late September.The crude protein content of hairy vetch was the highest.The crude protein content of rapeseed and milk vetch was similar,about 40%of that of hairy vetch,and about 30%higher than that of ryegrass.2. There were significant difference in soil physical and chemical properties among the highest yield plots(ryegrass:P1D1;hairy vetch:P1D3;rapeseed:P1D4;milk vetch:P1D4)after winter forage crops harvest.Soil compaction in 5?30 cm soil layer in ryegrass field was higher than other treatments.Soil microbial diversity in rapeseed field was the highest,while the relative abundance of Bacteroidetes(dominant bacteria)in hairy vetch was the highest.The contents of total nitrogen,alkali nitrogen and available phosphorus in the ryegrass soil were significantly lower than other treatments.The contents of total nitrogen and alkali nitrogen in the hairy vetch and milk vetch soil were the highest,while the content of available phosphorus in the rapeseed soil was the highest.3. The growth of feed corn in summer was significantly affected by different previous crops.The results showed that the net photosynthetic rate,stem bleeding flow and soluble sugar content in bleeding sap of maize leaves of maize with ryegrass as previous crop were significantly lower than those of hairy vetch,rapeseed and milk vetch.The results showed that different previous crops had significant effects on the nutrient absorption of summer maize.When the previous crops were hairy vetch and milk vetch,it was beneficial to the absorption of N by the subsequent maize,but not conducive to the absorption of P.It was beneficial to the absorption of P but not N by the subsequent maize when the previous crop was ryegrass.While to the previous crop rapeseed,it was beneficial to the absorption of P and N by maize.There was no significant difference in K uptake of the subsequent maize using different previous crops.The biomass of maize was the highest under the hairy vetch-maize multiple cropping pattern.4. There were significant differences in annual forage yield and crude protein yield among different multiple cropping patterns.The highest crude protein yield was obtained under the multiple cropping pattern of hairy vetch-maize and rapeseed-maize,the yield of crude protein was 3.47 t/hm~2 and 3.38 t/hm~2,respectively.The highest forage biomass yield was obtained under the multiple cropping pattern of ryegrass–maize and rapeseed–maize,the forage biomass yield was 35.12 t/hm~2 and 36.97 t/hm~2,respectively.Considering both forage biomass and crude protein yield,rapeseed-maize multiple cropping pattern was better than the other three multiple cropping patterns.5. The results showed that there was a significant difference of shade tolerance between soybean varieties under intercropping.Shade tolerance of shading at flowering and podding stage are positive correlation to shade tolerance of intercropping.Thus,the treatment shading at flowering and podding stage could be used to screen feed soybean varieties suitable for intercropping with maize.According to the comprehensive evaluation of shade tolerance under shading at flowering and podding stage,the varieties used in this study were clustered into three groups,and the results were highly consistent with the shade tolerance of intercropped with maize.The regression equation was used to predict the shade tolerance of the tested varieties,and the results were highly consistent with the comprehensive evaluation value(D value).The results showed that the regression equation established by STC of a few single indexes at flowering and podding stage could be used for rapid evaluation and screening of shade tolerant materials under intercropped with maize.