Gradient phosphorus application affects soil chemical properties and cotton yield and composition
The effects of different P levels on soil chemical properties and cotton yield and composition were explored in gray desert soil cotton fields in northern Xinjiang to provide practical guidance for determining the best P application amount and understand the current fertility of the cotton fields and cotton production.In this experiment,the P fertility succession characteristics of cotton soil at the"National Gray Desert Soil Fertility and Fertilizer Benefit Monitoring Station"over 5 years was used as the research object.Soil chemical properties,P availability characteristics,and cotton yield and composition were analyzed under conditions of no fertilization,no P application,conventional P application at 100%,P reduction of 25%,P increase of 25%,and P increase of 50%.The results showed that:With the increase in P application,the soil nutrient content was improved.The increases in available N,P,and K ranged from 3.0%to 16.10%,29.20%to 111.77%,and 70.10%to 72.10%,respectively.Compared with the initial period of fertilization,the annual maximum increases of available nutrients were 2.12,1.53,and 22.85 mg·kg-1,respectively.Total N,P,and K increased by 21.10%-35.10%,1.60%-54.0%and 9.30%-10.90%,respectively.Compared with the initial period of fertilization,the annual maximum increase of total nutrient content was 0.03,0.06,and 0.41 g·kg-1,respectively.With the application of 150 kg·hm-2 P,the soil available P content and P activation capacity were the highest,and the P activation coefficient reached 2.13%,which effectively promoted the conversion of total P to available P.With the increase in P application rate,soil organic matter and organic C levels increased significantly when P application was 150 kg·hm-2,with an increase rate of 11.86%to 36.50%,and the average annual growth rate of organic matter was approximately 0.33 g·kg-1.Owing to the natural characteristics of calcareous soil and climatic conditions in northern Xinjiang,combined with the ratio of C,N,and P,soil organic matter was deficient.Soil pH and total salt decreased and increased in the range of 7.91-8.05 and 1.55-1.85 g·kg-1,respectively,but the effects were not significant.Applying 150 kg·hm-2 P for 5 consecutive years can ensure the nutrient requirements of cotton plants during the entire growth period,deliver savings in the amount of P fertilizer used,and has the best effect on increasing cotton production.The seed cotton yield reached 4658 kg·hm-2 and production was significantly increased by 16.83%,15.01%,and 11.63%compared with that at no fertilizer,no P application,and conventional fertilizer with 100%P,respectively.Based on soil nutrients,fertilizer input,and cotton yield,applying 150 kg·hm-2 P to cotton field of gray desert soil in northern Xinjiang is feasible.
cottonphosphorus gradientsoil chemical propertycarbon,nitrogen and phosphorus ratioyield
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