Effects of nitrogen drip application timing on the distribution of water,salt,and nitrogen in saline soil in northern Xinjiang,China
To investigate the effects of different timing of nitrogen fertilizer application on the distribution of water,nitrogen,and salt in saline and non saline soils.In this study,the typical saline drip irrigation cotton field soil in Karamay,Xinjiang,was used as the test material,and the non saline soil was used as the control.Three treatments were set up,namely,first dripping for 1 h,then adding nitrogen fertilizer(S1),first dripping for(1+1/3t)h,then adding nitrogen fertilizer(S2),and first dripping for(1+2/3t)h,adding nitrogen fertilizer(S3)(where t is the length of an irrigation cycle that farmers are accustomed to during the flowering and ringing period,which equal to 7 hours).The indoor simulated soil tank experiment was conducted by using the 15N tracing method.The results showed that under the same nitrogen application timing,the migration and distribution of nitrogen in saline soil are significantly different from those in non saline soil.Nitrogen in saline soil is more easily leached to the lower layer,while nitrogen in non saline soil exhibits surface aggregation characteristics.The abundance of 15N in non saline soil was 79.07%higher than that in saline soil under 0-20 cm soil layer.Under saline conditions,different timing of nitrogen fertilizer application did not have a significant effect on soil profile water and salt distribution,but there was a significant difference in the abundance of 15N among different soil layers(P<0.05).The soil profile under S2 treatment had the highest 15N abundance,which was 24.39%and 4.08%higher than that under S1 and S3 treatments,respectively.indicating that a reasonable delay in nitrogen fertilizer application time was beneficial for the enrichment of nitrogen in the soil,thereby improving nitrogen fertilizer utilization efficiency.Therefore,it is suggested that the drip of nitrogen fertilizer application for cotton in saline alkali land in northern Xinjiang should be reasonably delayed compared to the fertilization habits of farmers,which is beneficial for salt removal and nitrogen enrichment in the root layer of cotton and can improve nitrogen fertilizer utilization efficiency.However,further field experiments are still needed to verify this.
timing of drip applicationsalinized soilwater contentsalt15N
万方数据
维普
