Effects Of Different Nitrogen Application Rates On Corn Yield And Nitrogen Absorption And Utilization Under Straw Returning To The Field

This experiment investigated the effects of nitrogen fertilizer amount on the growth,nitrogen uptake of maize under straw returning and soybean corn rotation system over consecutive years.The experimental results provide theoretical data for determining the nitrogen fertilizer application rate for maize cultivation in the regional area of the Nine-Three Division.The experiment was conducted in the Daxijiang Farm,Jianshan Farm,and Qixingpao Farm under the management of the Nine-Three Division of the Beidahuang Farming and Land Reclamation Group Co,Ltd.in Heilongjiang Province from 2021 to 2022.The experiment set up five experimental groups:no fertilizer control(CK),no nitrogen fertilizer(N0),80%of the locally recommended nitrogen application rate(N1),the locally recommended nitrogen application rate(N2),and 120%of the locally recommended nitrogen application rate(N3).The experiment was conducted in five field sites for two years to study the effects of nitrogen application rates on the growth,yield,nutrient absorption,and utilization of maize.The results are as follows:1.The maize yield of the non-fertilization treatment(CK)ranged from 5346 to 8530 kg/hm~2,accounting for 53.55%to 70.30%of the maize yield under the locally recommended nitrogen fertilizer dosage,indicating that nitrogen fertilization has a significant effect on increasing maize yield.2.During the Dalabakou stage(the Silking stage)of maize,there was no significant difference in chlorophyll content,nitrate reductase activity,and root vitality between the treatment group with 80%of the locally recommended nitrogen fertilizer and the control group using the locally recommended nitrogen fertilizer.3.Increasing nitrogen fertilizer dosage increased the stalk thickness of maize,but had no significant effect on plant height.Nitrogen fertilization significantly increased the dry matter accumulation of various maize organs.The total dry matter accumulation was significantly higher at the nitrogen fertilizer dosage of 120%of the locally recommended level than at the dosage of 80%.Increasing nitrogen fertilizer dosage had no significant effect on the grain dry weight of maize.4.Compared with non-fertilization,nitrogen fertilization significantly increased maize yield,but different nitrogen fertilizer dosages had no significant effect on maize yield.Using regression equation to predict,under the condition of maintaining maize yield without a significant decrease,there is a 20%～59%reduction space in nitrogen fertilizer dosage on the three farms.5.Nitrogen uptake increased with the increase of nitrogen fertilizer dosage.The total nitrogen uptake of maize was significantly higher at the nitrogen fertilizer dosage of 120%of the recommended level than at the dosage of 80%during the maturity stage.There was no significant difference in the nitrogen fertilizer apparent utilization efficiency among the three nitrogen fertilization treatments,within the range of 33.62%to 60.46%.The nitrogen fertilizer agronomic efficiency at the dosage of 80%of the recommended level was 2.62%to 8.56%higher than that at the dosage of 120%,and the partial factor productivity was increased by 19.56%to 31.42%.6.The nutrient transport rate at the nitrogen fertilizer dosage of 80%of the recommended level was 20.25%～34.76%higher than that at the dosage of 120%.The contribution rate of transport nutrients was increased by 1.54%～7.41%,while the contribution rate of accumulated nutrients was reduced by 1.81%～7.59%.According to the comprehensive analysis,under straw returning and soybean corn rotation system over 6 to 7 years,the typical black soil nitrogen fertilization still has a significant effect on maize growth,nitrogen uptake,and yield increase.Excessive use of nitrogen fertilizer only increases the weight of maize organs and nitrogen uptake,but does not significantly increase maize yield.When the nitrogen fertilizer application rates at Daxijiang,Jianshan,and Qixingpao farms were 143,142,and 132 kg/hm~2 respectively,it significantly improved nitrogen fertilizer agronomic efficiency and partial productivity,and had no significant effect on the contribution of nitrogen transport of nutrient organs to grain yield.The maize yield can be maintained in the range of 8-12 t/hm~2.