Effects of Farming Patterns on Nitrogen Forms of Soil Aggregates with Different Particle Sizes and Nitrogen Pool Management Index in Cold and Arid areas of Bashang,Northwest Hebei Province
In order to study the effect of soil aggregate structure on nitrogen stability mechanism under different farming patterns,soil samples from different farming patterns in Bashang,northwest Hebei were taken as the research objects.A combination of field investigation sampling and indoor experimental analysis were used to de-termine the total nitrogen(TN),dissolved total nitrogen(DTN),ammonium nitrogen(NH4+-N),and nitrate nitrogen(NO3--N)content of soil.The soluble organic nitrogen(DON)content and nitrogen pool management index(NPMI)were calculated,and the distribution of soil nitrogen in aggregates with different particle sizes and NPMI changes were analyzed.The results showed that soil nitrogen was mainly stored in medium-sized aggregates(1.00-2.00 mm).The application of organic fertilizer promoted the distribution of nitrogen towards oversized aggregates(＞5.00 mm),thereby in creasing the content of NH4+-N and NPMI in large-sized aggregates.Applying inorganic fertiliz-ers increased the content and distribution ratio of TN in medium-sized aggregates,increased the NPMI of NO3--N in aggregates(＜0.25 mm),and increased the activity index of NO3--N in large-sized(2.00-5.00 mm)aggregates.Adequate irrigation can promote the increase and distribution of TN and NH4+-N content in small-sized aggregates(0.25-0.50 mm),and improve the NPMI of aggregates of various particle sizes.Extensive management promoted the increase and distribution of NH4+-N content in small and micro-sized aggregates,and reduced NPMI.The most sensitive to agricultural practices was large aggregates.Applying organic fertilizer increased the nitrogen content and activity of large aggregates,improving soil fertility supply and soil protection capacity.The application of inorganic fertilizers promoted the improvement of nitrogen utilization efficiency by increasing the content and activity of nitrogen in medium-sized aggregates.Extensive management and returning forests and grasslands enhance nitrogen fixation capacity by increasing the nitrogen content of small-sized aggregates.In the cold and arid areas of northern Hebei,increasing the application of organic fertilizer can increase the number of aggregates,and moderate irrigation can be carried out to achieve the goal of maintaining fertilizer supply.
Farming patternsAggregatesSoil nitrogen formsNitrogen pool management index
NETL
NSTL
万方数据
