Effects Of Long-term Different Fertilization Treatments On The Physicochemical Properties And Nitrogen And Phosphorus Loss Of Phaeozem

The Northeast China Plain of China is one of the four phaeozem belts in the world,with a total land area of 1.09×10⁵km².However,over the years,the extensive application of fertilizers has led to serious agricultural non-point source pollution problems,and soil quality has been continuously declining.By analyzing the spatiotemporal changes in soil physicochemical properties and the main pollutants nitrogen and phosphorus in agricultural non-point source pollution,it is possible to monitor and control agricultural non-point source pollution to a certain extent from the source.This study relies on the long-term positioning detection project of non-point source pollution of the Heilongjiang Academy of Agricultural Sciences,and took the phaeozem in Northeast China as the research object.Ten different fertilization treatments were set up to measure soil physical and chemical properties,nitrogen and phosphorus loss,and nitrogen and phosphorus nutrient absorption by maize.The effects of different fertilization treatments on soil nutrients were explored;Using canonical correlation analysis（CCA）and TOPSIS entropy method,revealed the correlation between soil physical and chemical properties and nitrogen and phosphorus loss and absorption,and obtained the optimal fertilization treatment.The main research findings are as follows:（1）Compared with CK treatment,all fertilization treatments couuld improve soil physical and chemical properties,and the single application of organic fertilizer treatment（M）had the best overall effect.M treatment increased organic matter,total nitrogen,alkali hydrolyzed nitrogen,total phosphorus,available phosphorus,and available potassium by 221.99%,74.46%,34.80%,47.64%,140.39%,and 42.70%compared to CK treatment.（2）Excessive application of organic fertilizer（M and OM）significantly increased the concentration of nitrogen and phosphorus in surface runoff,resulting in water pollution.The organic fertilizer and chemical fertilizer combination treatment（OM）had the highest average concentration of total nitrogen and phosphorus in surface runoff,which were 3.88 mg·L^-1and 0.61mg·L^-1,respectively;Compared to CK treatment,it increased by 70.59%and 192.38%,respectively.（3）The crop yield of high fertilization treatment was significantly higher than that of low fertilization treatment,with the highest yield of 826.72 kg·667m^-2in M treatment and the lowest yield of 134.62 kg·667m^-2in CK treatment.The highest yield contribution rate of M was 83.72%,indicating that the application of organic fertilizer played an important role in crop yield and yield contribution rate.At the same time,organic fertilizer treatment had a significant promoting effect on the nitrogen and phosphorus content of maize grains,which was more conducive to the accumulation of nutrients in maize.The nitrogen and phosphorus contents in grains of M treatment were 1.50 g·kg^-1and 0.36 g·kg^-1,respectively,while those of CK treatment were 0.98 g·kg^-1and0.16 g·kg^-1.（4）The results of canonical correlation analysis showed that there was a close positive correlation between the two comprehensive variable groups of soil physical and chemical properties and corn quality.According to the TOPSIS entropy method,based on the comprehensive analysis of soil physical and chemical properties,corn quality,and yield,treatment M with organic fertilizer alone was the best..Comprehensive analysis showed that applying organic fertilizer can optimize soil physical and chemical properties,achieve the effect of promoting corn yield and improving corn quality.However,under the condition of applying organic fertilizer for ten consecutive years,the soil nitrogen and phosphorus content was higher than that of chemical fertilizer treatment,which was more likely to cause nitrogen and phosphorus loss.