The Effect Of Straw Returned To Soil Nitrogen Loss

Nitrogen is one of the most important nutrients to crop, applied nitrogen is an effective way to improve the production of crops, but the utilization of nitrogen fertilizer is low generally speaking,30%-50%of the nitrogen into the soil will be lost. Straw returned is an effective to improve the quality of the soil, but the straw returned with different treatments how to affect the nitrogen tending towards of the soli is uncertain.The content of the nitrogen in soil, will affect the output of crops directly. Straw returned is an effective measure to increase the content of the nitrogen in soil,and the different measures have a different effect to the soil nitrogen content. This study through1year indoor soil column simulated experiment, to explore the straw returned with different treatments about nitrogen and returning ways to affect the loss and retain of nitrogen in the soil, in order to provide a scientific basis for straw returned,the main conclusions are as follows:1. Through straw returned with different fertilizer, study the effects of different carbon and nitrogen ratio on nitrogen loss in the soil.Different treatments of carbon and nitrogen ratio is15:1,20:1,25:1,30:1,35:1, CK(without the straw and fertilizer). Results show that, after a period of time(within60d), for the soil total nitrogen, with a higher carbon and nitrogen ratio fertilizer, the effect will be better, in the end of experiment, carbon nitrogen ratio25:1-35:1, within the scope,the content of total nitrogen is higher than other treatment.The nitrate nitrogen and ammonium nitrogen have a similar result.The soil urease activity in the early is better than the later, And th lower carbon and nitrogen ratio have a higher activity of urease, in the end of experiment(after120d), there are little different with different carbon and nitrogen ratio to urease activity.2. Through the straw returned with different proportions fertilizer, explore the effect of straw returned to nitrogen leaching in the soil.The above test set the proportion of nitrogen fertilizer.The results showed that the straw returned with nitrogen to nitrogen leaching have a good inhibitory effect, nitrate nitrogen leaching129.57mg,123.68mg,103.02mg,122.59mg,100.12mg,96.11mg, accounting for11.05%,13.68%,10.89%,14.75%,15.15%,22.14%of the total amount of nitrogen leaching. Leaching loss proportion of treatment group were less than control group, and based on carbon and nitrogen ratio25:1effect is best, nitrate nitrogen leaching loss is minimum;ammonium nitrogen leaching21.33mg,18.61mg,9.57mg,12.30mg,5.59mg,7.57mg, accounting for1.82%,2.06%,1.01%,1.48%,0.85%,1.74%of the total amount of nitrogen leaching,carbon and nitrogen ratio of25:1and35:1loss ratio is less. Comprehensive consideration, taking carbon nitrogen ratio25:1when nitrogen leaching loss is minimum. 3. Through the orthogonal experiment, set nine treatment, explore the effects of different factors on soil nitrogen loss with straw returned, Factors choose the different soil types, different ways of returning of the straw, straw returnred with different quantity.straw returned with different ratio of nitrogen fertilizer, The results showed that the straw returned in different period, the main influence factors are also different, but the type of the soil at most of the time are the main influence factors. During the experiment,deal with nine is bettr than others.It is means that, the loam returning the straw directly, and with the amount of500kg/mu, with the combination of carbon and nitrogen ratio of nitrogen to15:1,is the best one in this test.