Effects Of Sowing Date On Yield,quality And Economic Benefits Of Silage Maize And Forage Rape Multiple Cropping

With the development of animal husbandry in Yunnan Province,the demand for silage is increasing.Solving the shortage of silage and developing silage planting have become an important issue in the development of animal husbandry industry.In response to this problem,from May to December 2022,the research on silage maize(Zea mays L.)multiple cropping forage rape(Brassica campestris L.)was carried out in the modern agricultural education and research base of Yunnan Agricultural University in Xundian County,central Yunnan.The split-plot design was used in the experiment.The sowing date of maize(Qiaodan 6)was the main treatment,and three sowing date levels were set on May 1,May 16 and May 31.The harvest was a sub-treatment,with two levels of grain harvest(A1)and silage harvest(A2).Different treatments were used to plant forage rape(Huayouza 62)after maize harvest.The effects of different sowing date combinations on the yield and output value,feeding quality and comprehensive benefits of silage maize and forage rape were studied.The results show that:1.With the delay of sowing date,the effective accumulated temperature and rainfall during the growth period of silage maize increased,the growth period of silage maize shortened,and the yield decreased with the delay of sowing date.The highest yield of silage maize was 112950 kg/hm~2at May 1,which was significantly higher than that of the third sowing date 96018.8 kg/hm~2(P<0.05),and was not significantly different from the second sowing date 105900 kg/hm~2.Early sowing can increase the yield of silage maize.Forage quality:With the delay of sowing date,the crude protein content and crude fat content increased first and then decreased.The crude protein content of May 16 sowing date reached 9.42%,which was significantly higher than that of the other two sowing dates(P<0.05).The crude fat content was 9.42%,which was also significantly higher than the other two sowing dates(P<0.05).Sowing date had no significant effect on acid detergent fiber;the neutral detergent fiber decreased first and then increased with the delay of sowing date,and the third sowing date was significantly higher than the second sowing date.2.The sowing date significantly affected the yield of forage rape,and its yield showed a downward trend with the delay of sowing date.The highest yield of forage rape sown on August 25 was 76.35 t/hm~2,which was significantly higher than that of the other four sowing dates(P<0.05).Quality:The crude protein content decreased with the delay of sowing date,and reached the highest of 24.02%on August 25,which was significantly higher than the other four sowing dates(P<0.05).Sowing date had no significant effect on crude fat content and acid detergent fiber.The content of neutral detergent fiber did not change significantly with the delay of sowing date,but its content was the highest at21.66%on September 22,which was significantly higher than that of the other four sowing dates(P<0.05).It indicated that early sowing was helpful to increase crude protein content,reduce neutral detergent fiber content and improve feed quality.3.Silage maize was planted on May 1 and May 16,and forage rape was replanted after harvest.The comprehensive yield reached 189332 kg/hm~2and 169014 kg/hm~2respectively,and the comprehensive output value was 75733 yuan/hm~2and 67606 yuan/hm~2respectively.There was no significant difference in silage maize yield between the two sowing dates,but there was significant difference in forage rapeseed(P<0.05),but the yield of forage rapeseed in the second sowing date also reached 62995kg/hm~2.They can be harvested in mid-November without affecting the planting of small spring crops with short growth period.In summary,timely and early sowing is helpful to improve the yield and quality of silage maize and forage rape,and the feeding grade of silage maize has reached the second-level feeding standard.Sowing silage maize in mid-May,sowing rapeseed in late August,and harvesting rapeseed in mid-November can realize the multiple cropping mode of planting silage maize and increasing one-season forage rapeseed in the two-cropping area of central Yunnan.Forage rape does not affect the planting of short-growing spring crops after harvest,making it possible to triple cropping in one year in central Yunnan,and improving multiple cropping index,land utilization rate and economic income.