Spatio-temporal Variation Of Soil Nutrients And Salinity In Cultivated Land Of Yanqi Basin

Located in the middle of the Ten-zan mountains,the Yanqi Basin includes Yanqi Hui Autonomous County,Hejing County,Hoxud County and Bagrax County.In 2020,the area of cultivated land in Yanqi basin is 2815.64 km~2,accounting for 2.5% of the total area of cultivated land in Xinjiang.After many years of improvement,the development and management level of Yanqi Basin has been improved greatly,and the soil nutrient and salinity have changed in different degree under the condition of poor basic condition of cultivated land and more increase of cultivated land area.The continuous development for many years has also resulted in the spatial variation of soil nutrients and salinity.By analyzing the spatio-temporal variation of soil nutrients and salinity in Yanqi basin,the improvement effect of Yanqi Basin can be comprehensively evaluated,provide the theory support for the follow-up improvement.Based on the soil survey data of 1980,2010 and 2020,this study used geostatistical method and mathematical statistical method,under several scenarios,such as distance from city and town,distance from Bosten Lake,terrain position,soil type,and administrative territorial entity,the trend and reason of soil nutrient spatial variation were analyzed,and the influencing factors of nutrient variation in Yanqi basin were studied.The results show that:(1)the average salt content of cultivated layer in yanqi basin decreases from 3.92 g/kg to 3.04 g/kg,the distribution of highvalue areas changed from scattered distribution in the middle and lower reaches of alluvial fan,lakeside plain and old farming area to concentrated distribution in the drainage channel system around Bosten Lake.(2)the high value areas of organic matter,alkali-hydrolyzable nitrogen and available potassium are all moving away from the Bosten Lake area,and the high value areas of available phosphorus and salt in the plough layer tend to concentrate in the Bosten Lake area.(3)the organic matter and available potassium were in a decreasing state,the organic matter was reduced from 19.32 g/kg to 17.90 g/kg,the available potassium was reduced from 263 mg/kg to 128 mg/kg,the available n and P were in an increasing state,and the available n was increased from 50 mg/kg to 81 mg/kg,the available phosphorus increased from 7.7 mg/kg to 34.4 mg/kg.(4)the available potassium decreased by up to 51% and the available phosphorus increased by up to 346%.In general,soil nutrients in Yanqi basin experienced a pattern of decreasing and then increasing,and the salt content in the plough layer decreased steadily.The nutrient content decreased and the salt content increased with the increase of distance from cities and towns,which indicated that the human influence was still the main reason for the change of soil nutrient and salt.It is necessary to increase the input of organic matter and available potassium in the cultivated land of Yanqi basin so as to increase its nutrient content.When improving cultivated land,we should take into account the relationship between land and lake production and ecology,and build Yanqi basin with all-round development of ecological economy.