The shade caused by forests is estimated by creating a GIS drawing of the average distribution of forests using numerical cadastre data and adding the postulated or measured tree height to the mesh altitude for that forest. We tested the precision of this method on a flower farm located in a hilled rural area of Kochi Prefecture. We estimated the area of shade based on the measured tree heights of a nearby forest that shields the farmland, and compared it with the area obtained from photographs that have varying sun elevations. Based on these results, we clarified the reason of error occurrence. Following analysis of precision for this method, it became clear that most of the farm was shaded only by nearby forests when sun elevation reaches a maximum in autumn and winter. The effects of partial forest cutting on changes in the shaded area can be simulated by this method using the assumption that tree height in any cut area is zero meters.

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In recent years, low-input dairy farming has been receiving significant attention in Japan. It is expected not only to increase the feed self-sufficiency rate and agricultural income, but also to mitigate environmental pollution. “My-pace dairy farming (MPDF)”, which is practiced in the Konsen region in Hokkaido, is a case of low-input dairy farming. MPDF farmers set their overall quality of life above milk production. This study analyzed whether a decline in environmental pollution was caused by the transition from intensive dairy farming to MPDF. The characteristic of this study was the adoption of life cycle assessment (LCA) for determining whether MPDF had advantages for the cutting of environmental pollution. The sample farm for this study was a representative MPDF farm, which abandoned intensive dairy farming for MPDF in 1993. In this LCA, the functional unit was 1 ton of 4% fat corrected milk, and the environmental impact categories were energy consumption, global warming, acidification, eutrophication, ground water quality and surface water quality. The results of this paper were as follows. First, a decrease was observed in all environmental impact categories except ground water quality. Second, the reduction rate of environmental pollution was large in descending order of energy consumption, surface water quality, acidification, eutrophication and global warming. These results indicated that MPDF might have more advantages in the mitigation of environmental pollution than intensive dairy farming.

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Recently the conscious to environment ascend, Land Improvement Act is revised. In this law, the maintenance technology considered against ecosystem is required. In this maintenance, at first the evaluation of agricultural canal as ecological environment is needed. In this study, against agricultural canal we aim the development of evaluation way for agricultural canal as ecological environment. For that, we consider agricultural canal as system, at first we make the fish ecological network map that evaluates the connection and interruption of agricultural canal. Secondly we divide agricultural canal system into system element and evaluate velocity and canal material. Thirdly we synthesize the system evaluation, the element evaluation and captured fish data, and make evaluation figure of fish ecological environment. Using this figure, we examine ecological environment of agricultural canal. The difference between upper basin and lower basin make climate condition and topography differ, so different fish habit in upper basin and lower basin. Besides agricultural canal system character is difference. It is important to compare upper basin and lower basin. We select Nyunomiya canal system as lower basin field and Tsujun canal as upper basin field. The evaluation figure shows that in system unit evaluation interruption of ecological network is main factor. Compared lower basin and upper basin, in lower basin water use facility is main factor of network interruption in upper basin drop and velocity is main factor. So we need different type provision in upper basin and lower basin. When we plan and design the maintenance considered ecological environment, at first we should watch agricultural canal as system, and consideration the network connection and habitat position. Secondly we watch system element and selection optimum constrictions that are fish block etc.

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The development of agriculture as well as the growth of population in Vietnam in the last 40 years has caused serious environmental problems such as contamination of ground water with nitrate, and eutrophication of lakes and reservoirs. Although those environmental problems have been recognized, only a few quantitative evaluations of the nitrogen loading have been conducted on a countrywide scale. This paper presents the countrywide estimation of N loads generated from various sources such as agriculture, livestock waste, human waste, and forest in Vietnam by using the native statistical data in addition to the FAO database from 1961 to 2001. N loads were calculated by the difference between input and output of N in each compartment. N loads in 2010 were also calculated using the data provided by the Ministry of Agriculture and Rural Development in Vietnam. Total N load increased 7 times from 171 x 10³ to 1,191 x 10³ ton y^-1 during the last 40 years. The increase in N load from agricultural area (upland and paddy fields) was prominent (851 x 10³ ton in 2001), reflecting the marked increase of chemical fertilizer use. N load derived from humans waste increased 3-fold from 85 x 10³ to 265 x 10³ ton y^-1, and that of livestock waste increased about 5-fold from 30 x 10³ to 145 x 10³ ton y^-1. N load from forest remained small (71 x 10³ ton in 2001). Large N load were observed in intensive agricultural areas such as the Red River Delta and the Mekong River Delta. Further noticeable increase in N loads from agricultural area and livestock waste was predicted in the next 10 years, and the total N load might reach 1,790 x 10³ ton y^-1 in 2010. Serious nitrate pollution will occur in the both deltas, but N loads in the other rural regions might remain low level due to their low population density and stagnant activity in agriculture.

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