Effects Of Different Nitrogen Fertilizer Types And Its Reduction On Yield Of Wheat And Maize And Soil Nutrients

Huang-Huai-Hai region is a concentrated area of winter wheat and summer maize in China.Long-term unreasonable fertilization and management measures have led to imbalance of soil carbon-nitrogen ratio and increased loss of active nitrogen in farmland in the main wheat and maize producing areas,thus causing widespread concern about agricultural non-point source pollution.The objective of this project is to alleviate the non-point source pollution caused by chemical fertilizers through the use of new nitrogen fertilizers.The field randomized block experiment was used to compare the effects of common nitrogen fertilizer（CN）,humic acid nitrogen fertilizer（HFN）and polyaspartic acid nitrogen fertilizer（TMN）and their decrement measures on wheat/corn growth,yield and soil nutrient changes,and to explore the synergistic effect of humic acid nitrogen fertilizer and polyaspartic acid nitrogen fertilizer and the feasibility of reducing the amount of nitrogen fertilizer applied.The main research results are as follows:1.Effects of different nitrogen fertilizer types and reduction on wheat yield and soil nutrients.Compared with common nitrogen fertilizer,humic acid nitrogen fertilizer and polyaspartic acid nitrogen fertilizer can both improve wheat yield to a certain extent.When the two synergistic nitrogen fertilizers are applied in a reduced amount of 15%(204 kg·hm^-2),the wheat yield is increased by 7.23%and 4.84%respectively compared with the conventional application amount of common nitrogen fertilizer(240 kg·hm^-2).Humic acid nitrogen fertilizer mainly increases wheat yield by increasing spike number and grain number per spike.When humic acid nitrogen fertilizer and polyaspartic acid nitrogen fertilizer were applied without reducing nitrogen fertilizer,the nitrogen accumulation of wheat increased by 27.22%and 20.85%respectively.When nitrogen is reduced by 15%,the nitrogen accumulation of wheat increases by 19.89%and 25.51%,respectively,which indicates that humic acid nitrogen fertilizer and polyaspartic acid nitrogen fertilizer can improve the nitrogen absorption and accumulation of crops.Under the condition of the same amount of nitrogen application,applying humic acid nitrogen fertilizer and polyaspartic acid nitrogen fertilizer,the alkali-hydrolyzable nitrogen content of the soil increased by 6.89%-26.34%and 3.21%-8.15%respectively compared with applying common nitrogen fertilizer.Under the condition of no reduction of nitrogen fertilizer,the available phosphorus in the soil with humic acid nitrogen fertilizer and polyaspartic acid nitrogen fertilizer increased by 9.46%-53.03%and 6.04%-14.75%compared with the common nitrogen fertilizer.Under the condition of 15%reduction of nitrogen fertilizer,the available phosphorus in soil increased by 3.00%-22.15%and 3.53%-10.38%when humic acid nitrogen fertilizer and polyaspartic acid nitrogen fertilizer were applied.2.Effects of different nitrogen fertilizer types and reduction on maize yield and soil nutrients.Compared with common nitrogen fertilizer,humic acid nitrogen fertilizer and polyaspartic acid nitrogen fertilizer can both improve the yield of corn to a certain extent.The yield of corn reduced by 10%,20%and 30%respectively increased by 0.75%-9.78%and3.51%-4.52%compared with common nitrogen fertilizer.Humic acid nitrogen fertilizer and polyaspartic acid nitrogen fertilizer mainly increased the yield of corn by increasing1000-grain weight and grain number per spike.Under the condition of the same amount of nitrogen fertilizer application,the nitrogen accumulation of maize with humic acid nitrogen fertilizer and polyaspartic acid nitrogen fertilizer increased by 2.15%-8.52%and0.84%-4.84%,which indicated that humic acid nitrogen fertilizer could increase the nitrogen absorption of plants.Under the condition of the same amount of nitrogen fertilizer application,the alkaline hydrolysis nitrogen of the soil with humic acid nitrogen fertilizer and polyaspartic acid nitrogen fertilizer increased by 1.57%-20.8%and 0.56%-13.54%compared with the common nitrogen fertilizer,and the available phosphorus increased by 1.04%-11.20%and0.99%-12.43%compared with the common nitrogen fertilizer.This shows that humic acid nitrogen fertilizer can increase the contents of alkali-hydrolyzable nitrogen and available phosphorus in soil,and can promote the absorption of nutrients by plants.The results showed that polyaspartic acid nitrogen fertilizer could increase the contents of alkali-hydrolyzable nitrogen and available phosphorus in soil and promote the absorption of nutrients by plants.