Effects Of Harvest Time On Biomass And Silage Quality Of Straw In Zea Mays

In this study,the influence of harvesting time（mid dough stage,late dough stage,early full ripening stage,mid full ripening stage,late full ripening stage）of maize on its grain yield,nutritional value of straw and silage were investigatedto determine the optimum harvesting time of Zea mays“zhenghong 505”with“Maize-Soybean”relay intercropping system in the southwestern China.The influence of different additives（urea,rice bran,wheat bran）on the fermentation qualities of corn straw on optimum harvesting time was investigated.Our results were as follows.1.The harvesting time has a significant effect on corn grain yield.With the delay of harvesting time,grain mass and the grain yield significantly increased,and keep stableat the early full ripening stage.The maximum yield of corn grainwas10882 kg·hm^-2in 2015,and 10487 kg·hm^-2 in 2017,and the growth rate was 6.74%in 2015 and 15.39%in2017.Therefore,the appropriate harvesting time for greater grain was theearly full ripening stage.2.The harvesting time had significantly impacted the biomass and nutritional quality of maize straw.The fresh yield and dry yield of corn stalk decreased by delayed harvesting date and the lowest corn stalk yield was recorded at the early full ripening stage.Along the harvesting time,DM,NDF,and ADF increased significantly,but the content of WSC decreased significantly after the early full ripening stage.The p H value of straw silage at all harvesting time was less than 4.2,but with the increasing of harvesting date p H value and AN/TN increased,the content of LA has a significant reduction.The change of nutritional quality after silage is consistent with the material.In terms of the biomass yield and nutritional quality of corn stalk,the appropriate harvesting time of corn should not be late for the early full ripening stage,in which the DM content of straw is about 35%,and the WSC content is as high as 10%DM.3.The additivessignificantly affected the silage quality of corn stalk harvested atthe early full ripening stage.The p H value of the silage in all treatment groups was lower than4.2.Different additives（urea,rice bran and wheat bran）significantly increased the DM content of silage,compared to the control treatments.Urea and wheat bran improved the CP content of silage,the effect of urea was significantly higher than that of wheat bran.The value of AN/TN（13.72%）and the content of AA（2.08%）with ureawere significantly higherthan that of other treatments and,but the content of LA（0.84%）was significantly lower.The content of LA and BA with 5%and 10%wheat bran was significantly higher than that of other treatments.The value of AN/TN（4.30%）and the content of CP（6.95%）with 10%rice bran was significantly lower than other treatments.The mixture of rice bran and urea,rice bran and wheat bran can improve the CP content of silage,and guarantee the safe range of AN/TN at 10%.Therefore,in the case of not add any additives（control group）,silage modulation can succeed,adding 10%rice bran+0.5%urea,10%rice bran+5%wheat bran,and 10%rice bran+10%wheat bran can further improve the nutritional quality of silage.To sum up,considering the corn grain yield and quality of straw and silage processing after harvest,the suitable harvest time shall not be more than the early full ripening stage.The appropriate harvesting time of corn stalk made a relatively good silage with no additives,adding 10%rice bran+0.5%urea,10%rice bran+5%wheat bran and 10%rice bran+10%wheat bran to improve the quality of the silage is feasible and effective.