| As the largest grain crop in my country,ensuring high and stable corn yield is an important means to ensure my country’s food security.In corn planting,traditional quickacting urea requires repeated fertilization to achieve high yield.With the emergence of labor shortages in rural areas,farmers have adopted unreasonable fertilization methods such as "one bombardment" and excessive nitrogen application,resulting in reduced fertilizer utilization,A series of problems such as environmental pollution and production reduction.Therefore,on the basis of sufficient investigation,this study adopts the fertilization method of slow-release fertilizer and urea combined application.A field experiment will be set up in Yangling District,Shaanxi Province in 2020.The following five slow-release fertilizers(C)and urea(N)are set as follows: 0:1(C0N1),1:3(C1N3),1:1(C1N1),3:1(C3N1),1:0(C1N0),CK was treated with no nitrogen fertilizer as the control,a total of 6 treatments.Mainly to study the physiological growth traits,aboveground dry matter accumulation,grain filling characteristics,yield,nitrogen accumulation,soil nitrate nitrogen distribution and residues,water and nitrogen use efficiency of summer maize under different application ratios,in order to obtain slow-release fertilizers in Guanzhong area of Shaanxi Province.The optimal ratio of urea and urea application provides a theoretical basis for the promotion of the one-time basal application mode.Concluded as follow.(1)The application of slow-release fertilizer can prolong the functional period of summer maize leaves and avoid premature senescence compared with single application of urea.The chlorophyll content and net photosynthetic rate of each treatment reached the maximum value in the silking stage and then decreased.In the grain filling stage,the chlorophyll content and net photosynthetic rate of the slow-release fertilizer treatment increased with the increase of the slow-release fertilizer combination ratio,and both were significantly higher.Treated with urea alone.(2)Combined application of slow-release fertilizer can promote the growth of summer maize in the middle and late stages while ensuring sufficient nutrients in the early stage.In the jointing stage,the growth indexes and dry matter accumulation of C1N0 treatment were significantly lower than those of C0N1 and each combination treatment;The growth index and dry matter accumulation of C3N1 treatment were significantly higher than other treatments.(3)Combined application of slow-release fertilizer can optimize the grain filling process and significantly increase the 100-grain weight and yield.The combined application of slow-release fertilizer is beneficial to improve the initial growth potential,shorten the time for the grain to reach the maximum grain filling rate,increase the 100-grain weight when the maximum grain filling rate is reached,prolong the active grain filling period,prolong the duration of the rapid growth period and the slow growth period,and increase the The grouting rate in turn increases the 100-grain weight.The 100-grain weight and the number of grains per row were the decisive factors for the increase of summer maize yield under the combined application of slow-release fertilizer.The yield and yield components increased first and then decreased with the increase of the proportion of slow-release fertilizers.The yield and yield components of C3N1 treatment were the best.(4)Compared with the single application of urea,the combined application of slowrelease fertilizer can significantly increase the nitrogen absorption of summer maize and reduce the risk of leaching.With the increase of the proportion of slow-release fertilizer,the nitrogen uptake increased first and then decreased.Compared with other treatments,the C3N1 treatment increased by 6.56%-29.85% at the silking stage,and increased by 4.84%-21.58% at the mature stage.The nitrate nitrogen content of the urea single application treatment was significantly higher than that of the slow-release fertilizer combined application treatment at the silking stage,and the nitrate nitrogen content in the soil was higher than the demand of corn,which intensified nitrogen leaching;The nitrate nitrogen content in the ～40cm soil layer decreased the nitrate nitrogen content in the soil layer below40 cm,which reduced nitrogen leaching while ensuring the nitrogen demand of corn.Compared with single application of urea,the combined application of slow-release fertilizer can significantly reduce the residual amount of nitrate nitrogen in the mature stage,and the C3N1 treatment is the lowest,and it is mainly concentrated in 0-40 cm to reduce the risk of leaching.(5)The combined application of slow-release fertilizer can significantly improve the efficiency of water and nitrogen use.With the increase of the proportion of slow-release fertilizer application,the water consumption,water use efficiency,apparent nitrogen utilization efficiency,nitrogen absorption efficiency,nitrogen fertilizer agronomic efficiency and partial productivity of summer maize all showed a trend of increasing first and then decreasing.Process the highest.Combined application of slow-release fertilizers can significantly increase the amount of nitrogen uptake after the silking stage of summer maize,promote the transport of nitrogen from vegetative organs to the grain,and improve the amount and efficiency of nitrogen transport.Organ nitrogen transport capacity and transport efficiency were the highest.In conclusion,C3N1 treatment was optimal for physiological growth indicators,grain filling process,water and nitrogen use efficiency,and yield,reducing the residual nitrate nitrogen and reducing the risk of leaching.Therefore,in the one-time basal application mode in Guanzhong area of Shaanxi Province,the recommended ratio of slow-release fertilizer to urea is 3:1. |
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