Nitrogen Fertilizer Application Rate And Cultivation Techniques Adapted To Mechanized Harvest Of Spring Maize In Loess Plateau Region

At present,there are problems of high cost,low economic benefit and low production efficiency in domestic maize planting.The high input of labor cost is one of the important factors affecting the economic benefit of maize.Increasing mechanization investment,especially the application of mechanization harvest can greatly reduce the cost,improve production efficiency,is one of the important ways to obtain high economic income.There is a significant difference between the mechanized yield rate of maize and that of rice and wheat.The main reason is that there are many technical difficulties in mechanical direct harvest.The machine-harvested maize requires a strong lodging resistance,and the stalk strength is an important index of lodging resistance.The grain moisture content of maize affected the damage rate and quality of maize grains,and the damage could be reduced to a lower level only when the grain moisture content was controlled at 25%.Nitrogen plays an important role in the growth stage of maize.The amount of nitrogen fertilizer applied affects the material accumulation and thus affects the stem strength.Planting density directly determines the distribution of light,nutrients,water and other resources,and affects the stalk strength and grain dehydration of maize.With regard to mechanized harvest,China has approved a number of maize varieties,and the selection of nitrogen fertilizer amount and density of maize varieties needs to be demonstrated in practice.To popularize large-scale planting and mechanized harvesting of maize,it is necessary to set reasonable nitrogen application and planting density,select suitable maize varieties,and form suitable maize varieties and cultivation and fertilization techniques.Through the research of maize varieties suitable for mechanized harvesting and the corresponding fertilization technology,this paper provides theoretical support for the popularization of large-scale,efficient and mechanized planting of maize.It provides theoretical basis and technical support for local agriculture sustainable development,farmers' income increase and ecological environment protection.This project studied the effects of N fertilizer application(no nitrogen,225 kg N·ha and 180 kg N·ha),maize varieties(Pioneer 335,Shandan 609),planting density(65000 plants·ha and 85000 plants·ha)three factors on grain yield and yield composition,the mechanized harvest index(stem strength,grain dehydration rate,grain moisture content,etc.),morphological indicators.The experiment adopted the design of split-split-plot experiment,with a total of 12 treatments.The main results were as follows:(1)Nitrogen application increased grain yield,plant height,stem diameter and spike height,and stem strength of 225 kg N·ha treatment was higher than that of 180 kg N·ha and no nitrogen treatment,which showed stronger lodging resistance.(2)The grain yield and plant height of Pioneer 335 variety were significantly higher than shandan 609 variety,with faster grain dehydration rate,lower grain moisture content and smaller spike height coefficient.(3)Stalk strength of 65,000 plants ·ha density was significantly higher,and grain dehydration rate was faster.Based on the above results,the appropriate mechanized nitrogen application amount and cultivation technique for spring corn could be summarized as follows: 225 kg N·ha was recommended as nitrogen application amount,Pioneer 335 was recommended as spring corn variety,and 65,000 plants ·ha was recommended as planting density,.