成都平原菌渣还田下稻田田面水氮磷动态变化特征

Dynamic Changes of Nitrogen and Phosphorus in Surface Water of Paddy Fields with Fungi Residues Return in Chengdu Plain

为合理利用菌渣,以化肥施氮量为基准,设置1,1.5,2,2.5倍氮量的菌渣还田处理,采用田间定位监测并结合室内分析实验,以期通过研究稻田田面水中氮素和磷素的动态变化探明菌渣还田下面源污染风险。结果表明:与化肥处理相比,菌渣还田处理显著降低田面水TN、DTN、DON、PN和NH4+-N含量,显著提高NO3--N/TN比例(P<0.05);其田面水TN、DTN和NO3--N含量在施肥后均呈下降趋势,NH4+-N含量则表现为"先增后减",施肥后第5d达最大值,其中TN、DTN和NH4+-N含量变化均可用指数降低模型Y=C0×ekt(k<0)拟合,NO3--N含量变化可用倒数模型Y=C0+k/x拟合;受田面水中氮含量等因素的影响,其TP、DTP和PP含量均显著降低(P<0.05),TP和DTP含量表现为"先降后升再降"。总体来看,较化肥处理,菌渣还田不会延长田面水氮磷素流失风险期,同时显著降低田面水NH4+-N含量,缩短NH4+-N流失风险期,但等氮量还田会显著降低水稻产量及糙米氮含量(P<0.05),超过2倍氮量还田会增加NO3--N流失风险。综合环境风险与粮食生产,应以1.5倍氮量还田为宜。

In order to find out a rational way of fungi residues utilization and investigate the non-point pollution risk of surface water in paddy fields with fungi residues return,this study combined field monitoring and laboratory chemical analysis to study the dynamic changes of nitrogen and phosphorus in surface water of paddy fields with fungi residues return.A control treatment（CK：No fertilization）and a chemical fertilizer treatment（CF）were established in the field experiment,as well as 4treatments with fungi residues return,in which nitrogen content of fungi residues was 1（N1）,1.5（N1.5）,2（N2）,2.5（N2.5）times that of chemical fertilizers in CF treatment（N1）,respectively.The results showed that compared to chemical fertilizer treatment,treatments with fungi residues return significantly decreased the contents of total nitrogen（TN）,dissolved total nitrogen（DTN）,dissolved organic nitrogen（DON）,particulate nitrogen（PN）and ammonium（NH4＋-N）,but significantly increased the ratio of NO3--N/TN（P〈0.05）,in surface water of paddy fields.After returning fungi residues to fields,the contents of TN,DTN and NO3--N in surface water of paddy field continuously decreased,while the content of NH4＋-N reached its peak value on the fifth day after fertilization and then decreased.The dynamic changes of TN,DTN and NH4＋-N in surface water were fitted by an exponential equation：Y=C0×ekt（k〈0）,while the changes of nitrate could be described with an inverse equation Y=C0＋k/t.Because of influence of nitrogen in surface water,the contents of TP,DTP and PP decreased（P〈0.05）,and the first two decreased at first,then increased andfinally decreased again.Overall,compared to chemical fertilizer treatment,residues return treatments would not extendthe period with risk of N and P loss and significantly decreased the content of ammonium（NH4＋-N）in surface water of paddy soils,which shortened the period with risk of ammonium loss.However,N1 treatment significantly decreased the rice yield and the nitrogen content in brown rice（P〈0.05）.When the returning amount of fungi residues exceeds that in N2 treatment,the risk of NO3--N loss increased.Considering the environmental risks of agricultural residues and their effects on food production,we suggest that the returning amount of fungi residues should not be more than that in N1.5treatment.