Study On Precise And Quantitative Nitrogen Rate And Its Application In Wheat

To obtain high wheat yield and quality with the least fertilizers and to receive results of saving fertilizers amount, high efficiency and friendly to environments, the precise and quantitative N application technologies should be established, which was one of the most important duties for wheat modernized planting. The systemic experiments were conducted in Huaibei and Huainan wheat zones in Jiangsu province to study the effect of the different soil types, fertility, variety types, N application amount, N topdressing ratios, N application period, planting models, indigenous N supply of soil, etc. on N supply amount of soil in wheat season, N requirement amount for target yields and N use efficiency of Stanford equation. The change characteristic of the three parameters were confirmed and proper values were also presented, which resulted in the precise and quantitative N application technologies for Jiangsu wheat zone.The mail results were as follows:1. Study on the proper N requirement amount for target yields. (1)The high yielding and site-specific experiments results within five years showed that wheat yields had an obviously positive linearity correlation with basal fertility levels, and the same trend varied in the different soil fertility levels. The wheat yields had a significantly secondary parabola correlation with N application amounts in the high and medium soil fertility levels zone, from which the high yields values could be obtained. Wheat yields in low fertility zone had a significantly linearity correlation with N amounts, and the highest target yields ranked as sand soilmiddle soil fertility level>low soil fertility level, in the same way, clay soil type>sand soil type. (2)The N supply amount of soil in wheat season had an obviously positive correlation with wheat yields of basal soil, rice yield(proceeding crop), soil total nitrogen contents and soil alkali-N contents, the linearity regression equations in different wheat zones, soil types and fertility levels were also gained. (3)The different wheat varieties had an obvious effect on N supply amount of soil. (4) With the increase of the nitrogen in rice (proceeding crop), N supply amount of soil varied in an increase trend. Therefore, the proper soil N supply amount in wheat eason was confirmed by the integrative factors such as wheat zones, soil types, soil fertility levels, nitrogen application amount in rice season and so on.3. Study on the proper N use efficiency at season. (1)The site-specific experiments under the same varieties, N amounts and N managements within five years showed that wheat yields had a significantly linearity correlation with N use efficiency. In Huaibei wheat zone, the N use efficiency varied with the range of 33.31%～50.05%( 42.36%, averagely). The N use efficiency in high, medium and low yield level was 45.28%, 40.71%, 35.73% respectively, whereas 44.25%, 40.58%, 36.89% in high, medium and low soil fertility level. In Huainan wheat zone, the N use efficiency varied with the range of 30.75%～51.60%(40.52% averagely), N use efficiency in high, medium and low yields level was 44.66%, 40.21%, 35.20%, whereas 45.73%,42.68%,39.05% in high, medium and low soil fertility. (2)N application amounts had an obviously effect on N use efficiency of 36 wheat varieties, it was respectively 52.93%, 48.11%, 43.25% in 9, 12, 15kg/667m2 treatments. Under the same N application amounts, N use efficiency of 3 wheat varieties types ranked as weak-gluten wheatflag leaf stage>returning green stage> overwintering stage> 3-leaf stag>1-leaf stage> basal stage, which reached the significant level. The period of maximal N efficiency was at jointing stage. It varied with the range of 27.87%～49.78% for Ningmai9, 28～51.96% for Yangmai10, 30.33%～57.44kg for Jinan17. (6)The N use efficiency in Ningmai9 and Yangmai10 were higher in band seeding type than in interplanting wheat in rice, which were higher about 5%, averagely. (7)With the increase of N application amounts at rice season, the N use efficiency varied in decrease trend. It was respectively reduced 6.7%, 5.1%, 1.8% in the R20W15 treatment than R0W15, R10W15, R15W15 treatments, which was 17.45%, 12.75%, 4.16% respectively.4. Application and verification of precise and quantitative nitrogen fertilizer application in wheat. In order to investigate the stability and applicability of the three parameters of precise nitrogen application in wheat cultivation, verification experiments were conducted in Donghai County (clay), Meiduo township (sand) and Shengao town (clay) in Jiangyan city with the amount of nitrogen fertilizer calculating from the three parameters. It was also applied and demonstrated in large area of wheat production. Results shown that the yield of experimental wheat reached to or close to the target value, the difference was less than 5%. Most of the differences between actual values and target values were less than 5%. And it also achieved high yield and saving fertilizer by using the technology of precise nitrogen fertilizer application. Compared with farmers'traditional fertilization management,the precise nitrogen fertilizer application method can greatly reduce the amount of nitrogen fertilizer, averagely by 7.65%, and increased nitrogen use efficiency more than 10% without any loss of yield. Those were indicated that the parameter value was consistent with the actual value and the parameter value was applicable. Thus the results of our research could be applied in large area of wheat production.