Study In Characters Of Nitrogen Utilization And Runoff Of Rice-Duck Farming Systerm Under Machine-Transplanting

Wujing15(japonica variety) and Shaoxing ducks were used in this study and rice in this study was transplanted by machine.1.Rice-duck farming system and normal machine-transplanted rice was compared to study the effects of ducks on the condition of paddy field and the growth of rice in rice-duck farming system,the result showed as follows:cluck in complex system increased the content of available nitrogen in soil,and it also increased catalase activity of soil;In rice-duck farming system the water over paddy field had a higher NO₃^-N,NH₄⁺-N and total N.Moreover,when no N was applied,rice-duck farming system got a higher top point of tiller number and when normal amount of N was applied,rice-duck farming system got a lower top point of tiller number;When no N was applied,rice-duck farming system had a higher dry matter accumulation in each growth stage of rice,when normal amount of N was applied,rice-duck farming system increase the dry matter accumulation in the stage between heading to maturity;In rice-duck farming system,rice had a reasonable C/N,and,the growth of rice was advanced.2.Four different amount of basal and tillering nitrogen fertilizer(BN) were conducted to investigate the effects of Nitrogen fertilizer on the population quality and nitrogen utilization of machine-transplanted rice in rice-duck farming system.The results showed as followed:(1) In rice-duck farming system,Along with the reduction of the amount of BN, the maximum number of tillers and the speed of tiller appearance and dying decreased;the proportion of effective leaf area,high effective leaf area and the ratio of spikelets number to leaf area increased;dry matter and nitrogen accumulated from heading to maturity decreased;nitrogen uptake decreased at each stage especially from jointing to heading.(2) when the amount of BN at a suitable level,and the ratio of BN to topdressing Nitrogen was 4.5:5.5 the ratio of panicle number to maximum number of tillers was higher under the machine-transplanted rice-duck farming system which at the same time contained a suitable LAI and reached the highest amount of day matter accumulated from heading to maturity. Moreover,higher BN utilization efficiency before jointing stage,nitrogen utilization efficiency,nitrogen harvest index,nitrogen agricultural efficiency and nitrogen partial factor productivity were achieved at that point also.(3) machine-transplanted rice-duck farming system not only enhanced the nitrogen fertilizer use efficiency before jointing and of the whole planting season,but also improved the population quality and thus strengthen the ability of day matter producing and eventually rice yield.3.Moreover A field experiment was conducted to study the nitrogen leakage and runoff of check(OK),rice-duck farming system(MRD) and normal paddy field(MR).The result showed as followed:(1) Compared with the check which has the same irrigation, rice-duck farming system,had a higher NO₃^-N and NH₄⁺-N concentration in the leakage liquid taken from 60cm depth under the soil however it was still low;Compared with normal paddy field,the leakage liquid from rice-duck system had a lower nitrogen concentration especially NO₃^-N.(2) In rice-duck farming system,the water over paddy field has a higher nitrogen concentration.While,without draining paddy field and having a higher band,rice-duck farming system had a sharp reduction in water runoff which finally resulted in a lower N-element runoff.(3) Compared with normal paddy field,rice-duck farming system has an addition of nitrogen supply in the form of duck's dung,a reduction of N leakage and runoff,a reduction in the dosage of chemical nitrogen fertilizer,and had more nitrogen absorption of rice crop.the reduction of income nitrogen and the reduction of output nitrogen of rice-duck farming system was nearly the same in this study.