Effect Of Carbon-nitrogen Addition On Nitrogen Supply Capacity In Dry Cropland Soil In The Loess Plateau Of Central Gansu Province

In order to find out the effect of carbon and nitrogen addition on soil nitrogen supply capacity of dryland farmland in Central Gansu Loess Plateau,the effect of carbon and nitrogen addition on soil nitrogen mineralization characteristics and the relationship between mineral nitrogen and organic nitrogen components were studied in Lijiabu,Dingxi,Gansu Province.The experiment involved three factors:straw?S?,biochar?B?and nitrogen?N?.Nitrogen was set at three levels:no nitrogen application,50 kg·hm^-2 pure nitrogen application and 100 kg·hm^-2 pure nitrogen application,for a total of nine treatments.The effect of carbon and nitrogen addition on soil nitrogen mineralization characteristics and the relationship between mineral nitrogen and organic nitrogen components were studied by using stanford intermittent leaching ventilation culture method and bremner method to study the effect of carbon and nitrogen addition on soil nitrogen mineralization characteristics and the relationship between mineral nitrogen and organic nitrogen components.The results showed that?1?During the culture period of 120 days,the accumulation of ammonium nitrogen was only in the early and middle stage of culture?0-30 days?,but there was no accumulation of ammonium nitrogen in the later stage of culture,while the accumulation of nitrate nitrogen ran through the whole culture period,and the accumulation of ammonium nitrogen was larger than that of ammonium nitrogen.?2?The soil nitrogen mineralization potential in the soil was 44-68 mg/kg,and the soil nitrogen mineralization potential decreased by 5.37%-16.58%in the 0-30 cm soil layer compared with the single-application nitrogen.?3?With the increase of culture time,the content of total acid-hydrolyzed nitrogen and the content of unhydrolyzed nitrogen in 0-30 cm soil of dry farmland in central Gansu Loess Plateau decreased,and the decrease of total nitrogen content of acid hydrolysis was greater than that of unhydrolyzed nitrogen,and the decrease of amino acid nitrogen was the largest among the total acid-hydrolyzed nitrogen.In conclusion,it was found that the nitrate nitrogen accounted for 68%of the accumulated mineral nitrogen during the culture period,and the addition of carbon and nitrogen could effectively reduce the content of soil mineral nitrogen,and straw decreased more easily than biomass carbon at the same nitrogen application level.Acid hydrolyzed amino acid nitrogen was the main source of soil mineral nitrogen.