Effect Of Phosphate Fertilizer Reduction After Straws Returning To Field On Plant Nutrient Accumulation And Yield In Wheatmaize Rotation Model

Crop straw is rich in nutrients including carbon,nitrogen,phosphorus,potassium,and so on,which are necessary for crop growth.After returning to the field and decomposition,they can improve the physical and chemical properties as well as biological properties of the soil,improve soil fertility,increase crop yield and nutrient utilization efficiency.Wheat-corn rotation is the main planting model in the Huanghuaihai region.The directly return crop straw to field is the main approach to use the straw resources.Reasonable application of chemical fertilizers after crop straw returning to the field is of great significance to increase crop yield and nutrient utilization efficiency.The domestic documents were collected,and the optimal quantities of NPK fertilizer for higher corn yield,economic and environmental benefits in Huanghuaihai region were analyzed.A two-year field experiment was conducted in Shajiang black soil in northern Anhui province to study the effects of phosphorus reduction on soil phosphorus content,plant phosphorus absorption and accumulation,wheat-corn yield and nutrient utilization efficiency after wheat straw returning to the field.The contribution of nitrogen and phosphorus deposition to soil nutrients balance was also examined.The appropriate ratio of phosphorus in crop straw can replace chemical phosphorus fertilizers after wheat straw returning to the field were also calculated.Results from this work provided a theoretical basis for the rational application of phosphorus fertilizers after crop straws returned to the field.The main findings are as follows:1.In Huanghuaihai region,the average fertilization formula for the best corn yield is 19.2-4.9-9.4;the average fertilization formula for the best economic benefits is 17.9-4.6-8.7,and the average fertilization formula for the best environmental benefit is186.34 kg·hm^-2.2.The content of soil available phosphorus decreases with the decrease of phosphorus fertilization after wheat-corn straw returning to the field.The content of soil available phosphorus in the wheat season firstly decreased and then increased with the extension of the wheat growth period.The content of soil available phosphorus in the maize season firstly increased with the extension of the corn growth period.In 2019 and 2020,atmospheric nitrogen deposition fluxes are 21.43 kg·hm^-2 and 17.86 kg·hm^-2;phosphorus deposition fluxes are 0.55 kg·hm^-2 and 0.44 kg·hm^-2,respectively.Under the wheat and corn rotation system,the net phosphorus increase in soil decreased with the decreasing of phosphorus fertilizer application.3.In 2019 and 2020,compared with formula phosphate fertilizer（P100）,a 20%reduction in phosphate fertilizer（P80）increased the total accumulation of phosphorus by 43.11% and 22.42%,and wheat yield increased by 7.61% and 3.22%,respectively.The total accumulation of phosphorus in maize increased by 22.22% and 8.40% at the mature stage,and the maize yield increased by 1.23% and 4.56%,respectively.Compared with formula fertilization（P100）,the agronomic efficiency in treatment with20% phosphate fertilizer（P80）reduction increased by 6.65%³9.87%,partial productivity increased by 20.01%²0.85%,and phosphorus absorption and utilization efficiency increased by 32.78%⁴2.11% in wheat growing season,while the agronomic efficiency increased by 30.43%⁴9.61%,the partial productivity increased by26.53%²9.24%,and the phosphorus absorption efficiency increased by 40.85%⁷5.03%（P>0.05）at corn growing season.4.In 2019 and 2020,compared with the formula fertilization（P100）treatment,the total phosphorus accumulation in wheat increased by 5.55% and 6.75%,and the wheat yield increases by 1.59% and 1.38%,in the treatments with the phosphorous fertilizer reduction 10%（P90）respectively,;The total accumulation of phosphorus in 2019 was8.89% higher than that of formula fertilization（P100）,and it was 1.26% lower than that of formula fertilization in 2020;corn yields were reduced by 8.55% and 7.01%（P>0.05）.5.In 2019 and 2020,compared with formula fertilization（P100）,the total phosphorus accumulation in wheat in treatments with 30% phosphate fertilizer（P70）reduction was decreased by 8.11% and 9.07%,and wheat yield was declined by 1.19%and 2.69%;the total phosphorus accumulated in corn was decreased by 28.57% and53.46%,and corn yield decreased by 18.83% and 15.87%,respectively.In summary,the reduction of phosphate fertilizer by less than 20% after the wheatcorn straw returning to the field will not have a negatively significant impact on the wheat and corn yield,whereas increased the phosphate utilization efficiency.This phosphorus management strategy realized the reduction of fertilizer application and increase nutrient utilization efficiency,which is worth to extend in wheat-corn rotation region.