Project study on Material Cycle in Paddy Field Biotope

为了保持健康的水田生态系统，对灌溉水中农药、化肥等化学物质的扩散通量进行估算是十分重要的。灌溉水中溶解的农药和肥料在水田中的运移表现为扩散和动态阶段。观察了模拟水田入口附近灌溉水的流动规律，灌溉水在进入水田时呈旋涡状流动，且流量越大。水流形成了高速流和极慢流两个区域。前者灌溉水中的溶质以平流运动，后者以扩散运动。指出在调查农药在稻田中的扩散情况等时，必须通过适当的地点和适当的取样量等进行评价。渡边博士研究了农药在稻田中的命运和迁移及其在水稻生产中灌溉和排水控制等良好农业规范中的应用。因此，建议采用高排水闸自动灌溉系统，在重大降雨事件中储存水稻水分并防止径流。此外，不建议采用常规灌溉水或有大量农药径流的连续灌排方案来保护水田生态系统和水田生物群落。本案例拟采用ppe -1模拟模型，但结果低估了观测值。因此。okazaki博士测量了本町大学实验稻田的Cd平衡，考虑到水稻中镉的吸附量为6mg/ha/年等，本町稻田的Cd流入量估计为5mg/ha/年，其流通量为10mg/ha/年。丰田博士在本町大学试验水田对施氮和不施氮条件下的饲料水稻植株进行了实地考察。根据估算的氮素预算，施肥处理和不施肥处理分别将248kgN/ha和118kgN/ha的量从水田土壤中储存到成熟植株中，并与直接播种和移栽栽培进行比较，考察了干重产量和氮素积累情况。结果表明，由于叶片在生育期接受了大量的太阳辐射，而且在生育期其他影响生物的环境条件与移栽栽培有所不同，直接播种的生物量更多。福岛博士指出，在梯田和谷田的植物群落差异较大。观察到的梯田植物群落有348种，谷田有309种。在地理特征上，崖田地区有水生植物群落，位于河谷部分。然而，为了利用雨水对高原进行定位，梯田的植物群落种类是不同的。根据不同的地形，可以观察到不同的生态。少

In order to preserve healthy paddy field ecosystem, it is important to estimate diffusive flux of chemical substance in irrigation water such as pesticide and fertilizer that flows into paddy field. The transport phenomenon of dissolved pesticide and fertilizer in irrigation water was characterized as diffusive and dynamic phase in the paddy field.The behavior of irrigation water near by the inlet of the modeled paddy field was observed such that the irrigated water flowed into paddy field with a whirl-motion with increasing its size as it move into the paddy field. Water flow formed the two zones of high speed flow and very slow speed flow. The former the solute in the irrigation water moves by the advection the latter by the diffusion. It was indicated that it had to be evaluated by appropriate places and appropriate quantities of the samplings, etc., when diffusive conditions of the pesticide in paddy field, etc. were investigated.Dr.Watanabe studied pesticide fate and transport in … More paddy field and its application for the good agricultural practices such as irrigation and drainage controls for the paddy rice production. As the result, Automatic irrigation system with high drainage gate that can store the paddy water and prevent runoff during the significant rainfall event can be recommended as the best management practice. Also, usual flow through irrigation or continuous irrigation-drainage scheme having significant amount of pesticide 'runoff from paddy field is not recommended for preserving aquatic ecosystem and paddy field biotope. Simulation model of PCPE-1 was intended to use in this case however the result underestimated the observation. Hence. this system has the necessity of the improvement.Dr.Okazaki measured Cd balance of the Honmachi university experimental paddy fleld Considering adsorbed cadmium in the rice was 6mg/ha/year, etc., the inflow of Cd from the Honmachi paddy field estimated to be 5mg/ha/year, and its ninoff with 10mg/ha/year. This indicated that the attention was needed for the Cd Japanese regulation.Dr.Toyoda carried out the field investigation of the feed rice plant under the condition of fertilization and non-fertilization of the nitrogen fertilizer in the Honmachi university experimental paddy field. As the result of estimated nitrogen budget, the quantity of 248kgN/ha in the fertilization treatment and 118kgN/ha in the non-fertilization treatment was stored into the ripe plant from paddy field soil.Dr.Hrasawa compared with direct seeding and transplantation cultivation practice, and examined for the dry weight production and nitrogen accumulation.The result showed that there were more biomass in direct seeding, because the leaf received a great amount of solar radiation d***ing the growing period, and that the environmental condition of other influencing organism during the growing period for direct seeding practice is some what different from that of the transplantation cultivation.Dr.Fukushima showed that the considerable deference in plant community in terraced paddy field and in Yachida. Observed plant community had 348 kinds in the terraced paddy field, on the other hand, there were 309 types in Yachida. There was the hydorphyte conmmunity in Yachida to locate valley part in geographical feature. However, in order to locate the highland using rain water, the kind of plant community in terraced paddy field was different. It is considered that the different ecology was observed depending on the landform. Less