Terraced Paddy Research Articles

Effect of N-fertilizer application on return flow water quality from a terraced paddy field in Northern Taiwan

Intensive use of chemical fertilizer for crops may be responsible for nitrogen and phosphate accumulation in both groundwater and surface waters. The return flow polluted by nutrients not only results in the limitation of water reuse goals but also creates many environmental problems, including algal blooms and eutrophication in neighboring water bodies, posing potential hazards to human health. This study is to evaluate the N-fertilizer application of terraced paddy fields impacting return flow water quality. Water quality monitoring continued for two crop-periods around subject to different water bodies, including the irrigation water, drainage water at the outlet of experimental terraced paddy field, and shallow groundwater were conducted in an experimental paddy field located at Hsin-chu County, Northern Taiwan. The analyzed results indicate that obviously increasing of ammonium-N (NH4 +-N) and nitrate-N (NO3 −-N) concentrations in the surface drainage water and ground water just occurred during the stage of basal fertilizer application, and then reduced to relatively low concentrations (<0.1 mg/l and <3 mg/l, respectively) in the remaining period of cultivation. The experimental results demonstrate the potential pollution load of nitrogen can be reduced by proper drainage water control and fertilizer application practices.

Soil nutrient distribution in two typical paddy terrace wetlands along an elevation gradient during the fallow period

Soil nutrient concentrations in the top soils from two paddy terraces were determined in order to investigate spatial distributions of soil nutrients along the elevations on the Yunnan plateau of China during the fallow period. Results showed that soil nutrients in both terraces were higher than the reference concentrations except for SOC, TN, TP and Fe. Soil macronutrients didn't show significant differences in both terraces except for Mg and Ca, so did soil micronutrients except for Mn. Spatial distribution patterns of soil nutrients along the increasing elevations were different in both terraces. However, soil nutrients in both terraces were generally not significantly influenced by the elevations and soil pH values. The findings of this study can contribute to soil fertility management and ecological protection of Hani terraces.

Recovery and conservation of abandoned terraced paddy field in Osaka Nose district by utilizing old variety of rice plants

Recovery and conservation of abandoned terraced paddy field in Osaka Nose district by utilizing old variety of rice plants

新潟県佐渡島の耕作放棄棚田における下層植物の種多様性に影響を及ぼす要因

The effects of microtopography, soil water, and light conditions on the species diversity of understory plants were studied in abandoned terraced paddy fields on Sado Island, Niigata Prefecture, Japan. The study area was abandoned about 40 years ago and plant succession has progressed to various types of plant community since that time. A wide variety of soil water conditions formed in the abandoned terraced paddy fields, according to the microtopography, namely, paddy plane, levee, and levee slope. The number of species of both woody and lianous plants decreased significantly as the soil water content increased. Conversely, many herbaceous species adapted to various soil water conditions. In particular, many herbaceous plants grew in the understory in good light conditions, even in soils with high water contents. The understory of the forest community was shaded, whereas various light conditions occurred in the understories of the shrub and reed communities. Such mosaic arrangements of various soil water and light conditions among different landscape elements maintained a high species diversity of understory plants in the terraced paddy fields, abandoned many years ago.

Terraced paddy field rainfall-runoff mechanism and simulation using a revised tank model

Terraced paddy fields play important roles in water and soil conservation because their water storage effect reduces and delays flood peaks. This study applies the terraced paddy field rainfall-runoff mechanism to the tank model. Though the traditional four-section tank model can easily simulate rainfall-runoff in a terraced paddy field, it has many parameters that are difficult to calibrate. To address the shortcomings of the traditional four-section tank model, this study develops a revised tank model to simulate rainfall-runoff. This study selects a terraced paddy field located in Hsuing-Pu village in Hsiuing-Chu County as the experimental field. The field under investigation was equipped with automatic monitoring stations, water-stage, and rain gauges. These stations collected data on rainfall and water flow to simulate the rainfall-runoff model in that region. To simulate the runoff behavior of the experimental terraced paddy field, two rainfall events were selected from the gathered data and five normal evaluation indexes based on static and hydrological theory were applied to calculate the results of simulation simultaneously. The revised tank model performed better than expected, and precisely predicted the variations and trends in flow charge. Comparison with representation indexes proved that the revised tank model is an appropriate and valuable tool for rainfall-runoff simulation.

Contrasting infection frequencies of Neotyphodium endophyte in naturalized Italian ryegrass populations in Japanese farmlands

Abstract Neotyphodium endophytes often confer benefits to their host grasses and may enhance invasiveness of some grasses. The knowledge of infection frequencies of endophytes among invading weed populations is necessary to understand the relationships between endophyte infection and invasiveness. Here we present data on infection frequencies of Italian ryegrass (Lolium multiflorum Lam.), an important weed in some farmlands in Japan, persisting in contrasting farmlands: a terraced paddy field and a wheat‐soybean double‐cropped field in the western region of Shizuoka prefecture, Japan. The terraced paddy site is a mosaic of several landscape elements such as paddy fields, levees, fallow and abandoned fields, with a high percentage of non‐crop area. Rice (Oryza sativa L.) has been cultivated for more than a decade with no application of chemical fertilizers, pesticides and fungicides. The wheat‐soybean field is characterized by the aggregation of large‐scaled fields that were originally reconstructed paddy fields, showing a low percentage of non‐crop area. Wheat and soybean have been grown as winter and summer crops, respectively, using chemical fertilizers and herbicides. We examined the presence or absence of endophytes in a total of 1200 seeds sampled from the two Italian ryegrass populations. The terraced paddy population exhibited a markedly high infection frequency (91.0%), due possibly to selective feeding of non‐infected seeds by insects. In contrast, the wheat‐soybean farmland population showed almost no infection (1.1%), whereas the putative source of the invasion in the proximity exhibited a relatively high infection rate (64.4%). Such a micro‐scale variation in infection frequencies may be attributable to a loss in endophyte viability within the wheat‐soybean field. The findings suggest that endophyte infection frequency may markedly differ among the Italian ryegrass populations even within the same region, presumably depending on the abundance of the seed‐eating insects, farmland management regimes and/or environmental conditions such as soil humidity.

Assessment of heavy metal contamination of surface soils from typical paddy terrace wetlands on the Yunnan Plateau of China

Little research has been done to investigate heavy metal contamination in paddy soils along different altitudes under domestic sewage irrigation. Total concentrations of As, Cr, Cd and Pb were determined in surface paddy soils from Mengpin (MP) and Quanfuzhang (QFZ) paddy terraces on the Yunnan Plateau of China in December, 2004, in order to assess their contamination status. Results showed that the average concentrations of As and Cd in both terrace soils were significantly ( p < 0.01) greater than the reference concentrations, while lower for Pb in both soils. However, as for Cr, the average concentrations are higher in MP soils while lower in QFZ soil than the reference concentration, while. Compared with MP soils, QFZ soils had lower heavy metal concentrations. However, only Cd greatly exceeded the guide value of soil quality. The contamination factor ( C f i ) values were generally moderate for As and Cd, and low for Pb in both sites. As for Cr, they were moderate in MP soils but low in QFZ soils. The contamination degree ( C d ) values were generally moderate, showing a decreasing tendency along the increasing altitudes in MP terrace, while slowly increasing tendency in QFZ terrace.

Sediment induced soil spatial variation in paddy fields of Northwest Vietnam

The aim of this study was to assess the impact of various sedimentation pathways (flooding, irrigation and runoff) on the spatial variability of soil fertility in rice paddy terraces in tropical mountainous regions of Northwest Vietnam. Topsoil samples were taken during two subsequent rice cropping seasons and analyzed using a combination of diffuse reflectance mid infrared spectroscopy and conventional lab analysis. A mixed model was used (i) to evaluate the spatial variability among and within paddy cascades before planting in function of field position to the main irrigation channel, and (ii) to assess the impact of various sediment deposition pathways on soil nutrients and textural changes. The topsoil taken before planting contained on average 1.75 ± 0.57 g 100 g − 1 soil organic carbon (SOC), 0.18 ± 0.06 g 100 g − 1 total nitrogen (TN) with silt being the dominating soil fraction (0.68 ± 0.11 g g − 1 ). Moderate sediment delivery of high quality through the irrigation system resulted in a significant enrichment in lower lying paddies following a linear trend for SOC (SOC (g 100 g − 1 ) = 1.4 + 0.02 Distance (m), R 2 = 0.31 − 0.62), total nitrogen (TN (g 100 g − 1 ) = 0.11 + 0.004 Distance (m), R 2 = 0.33 − 0.61) and a significant linear decrease in the sand fraction (sand (g g − 1) = 0.3 − 8 E − 04 Distance (m), R 2 = 0.28 − 0.48) with increasing distance from the irrigation channel along the cascade. Comparison of the samples taken before planting and after harvesting proved that the spatial variability in the topsoil was induced by sediment deposition resulting in a decrease of 0.11 g 100 g − 1 of SOC and 0.01 g 100 g − 1 of total N and an increase of 0.02 g g − 1 of the sand fraction in paddies close to the irrigation channel which received less nutrient rich sediment deposition. However, besides the effect of sediment rich irrigation water, direct sediment depositions originating from the highly eroded and unfertile uplands or deposited during flooding events (typhoons) strongly decreased soil fertility in the rice fields due to their low nutrient and high sand content. In conclusion, the alterations and maintenance of soil fertility of rice fields depended on the balance of the various sediment sources, i.e. quality and quantity, and is thus, strongly related to both upland management and extreme weather events and irrigation practices. These findings are relevant in the framework of site-specific fertilizer management by taking advantage of spatial variability in soil fertility along cascades of rice paddy terraces in tropical mountainous regions.

姨捨棚田における区画形態の動態的産業遺産価値による文化的景観保全

Cultural landscape planning of terraced paddy fields requires dynamic conservation. In this approach, alteration of field plot shape is permitted, allowing cultivation to continue; a dynamic approach stands in contrast to preservation, which is commonly applied to cultural heritages. We developed a cultural landscape conservation plan for the Obasute terraced paddy field in Chikuma City, Nagano Prefecture incorporating the following: I) field plots shapes of Obasute were classified into four zones with different historical characteristics corresponding to the following cultivation-technology stages, (1) the modern stage, (2) the mechanization stage, (3) contemporary farmland-consolidation stage and (4) stage of cultivation by non-farmers; II) these four zones have value as industrial heritages of agricultural-engineering, and we term them “dynamic industrial heritages”; and III) the Obasute field, which commands a panoramic view of these zones, and is recognized as a rare cultural landscape.

Dynamics of dissolved ions in the soil of abandoned terraced paddy fields in Sado Island, Japan

We investigated the soil and soil water chemistry in abandoned terraced paddy fields (reed stand) and a thicket of deciduous broad-leaved trees (thicket stand) on the same slope in Sado Island, Japan. The soils gathered from these plots were incubated under different water conditions to examine the dynamics of dissolved ions. The organic carbon pool in the soil in the reed stand at the lower slope position was greater than the thicket stand at the middle slope position. The high concentration of base cations and an almost neutral pH of the soil water at the reed stand corresponded with the high exchangeable cation concentrations and base saturation in the soil. These results reflect the mineral-rich groundwater percolating down the slope, which may be produced by chemical weathering. An in situ sulfate reduction in the reed stand at deeper soil horizons was identified. The different water conditions in the incubated soils affected the soil pH(H2O), transformation of Fe, and dominant anions (NO3−, HCO3−, and SO42−). These biogeochemical processes were more conspicuous in the reed stand at the lower slope position where the concentrations of organic matter and base cations were high. When the abandoned terraced paddy field is developed for the conservation of the Japanese crested ibis (Nipponia nippon) habitat in Sado Island, the reductive subsoil at the lower slope position should be kept waterlogged to limit sulfuric acid generation.

Abandonment and intensified use of agricultural land decrease habitats of rare herbs in semi-natural grasslands

Although traditional agricultural land use maintains biodiversity, recent land-use changes involving abandonment or use intensification have rapidly reduced the biodiversity of agricultural landscapes. Organisms living in agricultural landscapes are likely to respond differently to these changes, with some species declining rapidly and others remaining unchanged. However, few studies have focused on this interspecific difference in susceptibility to land abandonment and intensification in agricultural landscapes. We hypothesize that rarer herb species are more susceptible to both abandonment and intensification than are common herbs due to habitat preferences in the semi-natural grasslands of agricultural landscapes. To test this hypothesis, we examined the distributions of two pairs of congeneric grasslands species on abandoned and consolidated (production-intensified) paddy fields to assess differences in vulnerability to paddy abandonment and consolidation between the rarer and the more common species in an agricultural landscape. We found that higher, steeper fields farther from roads in the upper areas of paddy terraces were more frequently abandoned in our study area. The two rarer species had significantly more overlap with the distribution of fields at risk of abandonment than did the two more common congeneric species. In addition, the two rarer species were significantly less widely distributed in consolidated fields. Thus, both land abandonment and intensification appear to asymmetrically decrease habitats of rarer species. In light of our findings, we also discuss biodiversity conservation in agricultural landscapes with changing land use.

Foraging ecology of a local wild bee community in an abandoned Satoyama system in Kanazawa, Central Japan

AbstractSatoyama is a traditional land management system in Japan that emphasizes the importance of a harmonious relationship between humans and their environment. It has been in a state of abandonment and destruction since the late 1960s. In 2000, the Japanese government initiated a new environment policy encouraging the use of Satoyama in biodiversity reservation areas. Before the initiation of active restoration works, an assessment of the potential of the Satoyama system is needed. To assess this potential, a study that focused on the foraging ecology of wild bees in a small abandoned Satoyama terraced paddy was carried out from June to October 2003. A total of 372 foraging bees belonging to 35 species in nine families was collected: two species of social bee (Apis cerana and Bombus diversus) and two of solitary bee (Lasioglossum japonicum and Lasioglossum ohei) dominated. The foraging activities of wild bees were highly influenced by the requirement of food for the colony and the active time of solitary bees. In the study, most wild bees showed a strong preference for abundant flowering plant species that produced a large number of flowers (Achyranthes japonica and Polygonum thunbergii). The results showed that an abandoned Satoyama system was an agricultural system that benefited pollinating bees. Careful and planned restoration practices to increase the diversity of foraging resources, microenvironment diversity and potential nesting areas for wild bees are needed to improve the ability of the Satoyama system to support more diverse and abundant wild bee populations.

Cultural Landscape and Ecotourism in Bali Island, Indonesia

This paper describes the role of ethnoecology in supporting tourism. We conducted a case study on the island of Bali (Indonesia), the famous tourism destination. We review the culture, nature and ecotourism prospects of Bali and then extend our discussion to examine the role of indigenous philosophies in building the destination’s image. Bali has a rich culture and natural resources that have been utilized and managed through an indigenous philosophy called Tri Hita Karana. Ethnoecology is widely applied and appreciated in the society and has produced Balinese cultural landscapes that have become significant tourism attractions. There has been a recent increase in tourist desire to explore genuine Balinese culture, so ethnoecology has a significant role in the quest to preserve and conserve such indigenous cultural landscapes. Ethnoecology is a key to ensuring and sustaining the images and authenticity of Bali Island. In this paper, we considered the landscape of rice paddies as a cultural landscape and resource for tourism. The structure and function of paddy terrace landscapes is based on the ethnoecology of Tri Hita Karana; therefore, in order to understand nature and ecotourism in Bali Island, knowledge of indigenous philosophy is indispensable. Cultural landscapes that link human and natural systems are not only places of natural beauty but also provide background information about the history of human adaptations to nature.

Water losses through paddy bunds: Methods, experimental data, and simulation studies

Summary Irrigated rice landscapes increasingly experience water scarcity, and the bunds surrounding paddy rice fields (also referred to as dikes, banks or levees) have been pointed out as possible causes for low water productivities. Yet, detailed experimental data to confirm this assumption is missing, as well as an identification of the most decisive factors for bund infiltration. The objective of this study was therefore to quantify water fluxes through bunds in a terraced paddy landscape both experimentally and by numerical analysis. Two bunds with a respective age of 20 (young bund: BY) and 100 years (old bund: BO) were investigated at the end of the rice-growing season. Soil core samples revealed a compacted hard pan at 30 cm depth in both bunds. Hydraulic conductivity was very high and variable especially in the upper part of the bunds. For direct measurements of infiltration into the bund, a double-frame infiltrometer was introduced analogous to a double ring infiltrometer. Measured infiltration rates in bund BO at ponding water depths (PWDs) of 3, 5 and 7 cm amounted to 480, 270 and 550 cm2 d−1, respectively, and no cross-flow was observed. At bund BY, the infiltrating water resulted in an increasing water level on the lower field, and the cross-flow was 807, 4205 and 5506 cm2 d−1 at corresponding PWDs. However, no reliable infiltration measurements could be recorded. Tensiometers installed in the bunds during the infiltration experiments revealed a nearly instantaneous rise in pressure head after flooding throughout the profile in bund BY, indicating preferential water fluxes. In bund BO, contrarily, pressure heads underneath the hard pan rose slowly and with a time lag and thus show dominant matrix fluxes. Different infiltration rates in the investigated bunds could be mainly attributed to a lower bulk density and enhanced macroporosity in the young bund BY. The existence of a hard pan in a bund does not necessarily reduce percolation losses, as it might become perforated by macropores originating from bio-activity. A sensitivity analysis realized with HYDRUS 1.05 revealed that under-bund percolation is most strongly influenced by the hydraulic conductivity in the upper and middle bund. Ponding water depth and groundwater table are less important, while soybean cultivation, bund width and elevation difference only play a minor role. For each conductivity profile, there is a critical bund width underneath which cross-flow occurred. A detailed description of the bunds’ water fluxes needs to be included in hydrologic modelling of irrigated rice landscapes.

Characterization of Preferential Flow Pathways through Paddy Bunds with Dye Tracer Tests

In terraced paddy landscapes, water losses through the bunds surrounding paddy rice (Oryza sativa L.) fields may significantly reduce water use efficiency. The objective of this research was to identify the dominant pathways active for water flow and solute transport in bunds, and to detect differences between the bunds and adjacent field areas. Two earthen bunds aged 20 and 100 yr were investigated by means of dye tracer experiments in Jiangxi Province, China. Most prominently, the bunds were shown to be distinctly more vulnerable to preferential transport of solutes toward the groundwater than the actual paddy fields. The younger bund showed greater water losses than the old one, caused by a greater macroporosity, lower bulk density, and a less effective hard pan. Three successively operating transport processes could be distinguished: (i) dye solution infiltrated vertically into the field and laterally into the bund; (ii) the plow pan underneath the field and the hard pan in the bund then acted as flow barriers, and horizontal spreading occurred on top of the hard pan toward the outer bund and cross‐flow to the adjacent field was observed; and (iii) macropore flow occurred through the hard pan and partly in the subsoil down to the groundwater level, initiated on top of the saturated hard pan and routed through earthworm burrows and root channels as well as shrinkage cracks in the younger bund. In conclusion, compaction of a bund may significantly reduce infiltration rates but does not prevent preferential solute losses.

Ecological safe management of terraced rice paddy landscapes

Ecological safe management of rice paddy landscapes is in focus of a joint research project comprising five German working groups and Chinese partners. The project is aiming at characterizing the scale-depending structures and processes of agricultural landscape of terraced paddy fields in southeast China. The specific objectives were the enlightenment of the linkage between remote sensible information and the spatial distribution of soil features, as well as soil structural processes and their relation to vertical and lateral water losses and solute leaching. The experimental watershed is located in southeast China. The soils which either developed from quaternary clay or red sandstone exhibit a (man-made) layered structure with three hydraulic-functional horizons: puddled layer, plough pan and the (water unsaturated) subsoil. The analysis of soil texture and selected chemical parameters on the catenary and catchment scale confirmed that even in old terraced and thoroughly modified landscapes, the original structures (unaffected by man) of catenary soil property distributions persist. Thus, the application of co-regionalization techniques incorporating topographical attributes as explaining variables was found to be suitable to characterize soil property distributions on both the catenary and the catchment scale. On-site field scale investigations revealed that paddy soils exhibit a dynamic soil–water system which is driven by the mechanical seed bed preparation (puddling) on the one hand and drying and wetting cycles including ponded/flooded periods on the other. It was found that the hydraulic properties depend mainly on the duration of cultivation as a rice paddy. In contrast to earlier studies, we found that a further decrease in the saturated hydraulic conductivity of the plough pan may still occur after 20 years. Even in older rice paddies, however, water losses may be significant mainly because of ineffective functioning of the surrounding bunds. Pedon and aggregate investigations demonstrated the pronounced dual porosity nature of the paddy soils with a macropore network consisting of cracks and biopores penetrating both the plough pan and the bunds. The shrinkage potential of the puddle layer was higher in older paddy fields than in younger ones while it was vice versa for soil from the plough pan. Swelling and shrinkage affected also the living conditions for soil microorganisms especially after drainage when the habitable pore space was significantly reduced. Pore scale and micro-biological investigations revealed that drainage induced stress reduced micro-biodiversity and decreased abundances of soil inhabiting microorganisms. In addition to newly proposed management strategies with recurrent wetting and drying cycles, we suggest maintaining (saturated) equilibrium conditions over longer periods to reduce soil structural dynamics and the risks of water losses and chemical leaching involved with preferential flow.

千葉県房総半島南部の棚田水田域におけるネズミ類の分布に関する研究

Recently, the changes in the habitation of living organisms and degradation of biodiversity caused by transfiguration of rural landscape have emerged as serious issues in rural areas. For future landscape planning, it is imperative to examine the relationship between each landscape element and habitation. In this study, the relationship between rural landscape elements and the distribution pattern of several species of wild mice was investigated in south Boso peninsula, Chiba prefecture. The results showed that the distribution of forest dependant Apodemus argenteus, forest and grassland dependant A. speciosus, cultivated land dependant Mus musculus, and strongly grassland dependant Micromys minutus species of mice corresponded almost with each landscape element. These results suggest that the local mice in the study area were largely sustained by forests and grasslands and that the distribution and habitation of M. minutus depended on the variations in the grassland structure caused by cultivation management within terrace paddy fields.

Land-use change and irrigation systems in the agricultural landscape of terraced paddy fields in Awaji Island, central Japan

We analyzed changes in land use from 1963 to 2000 in the northern part of Awaji Island in central Japan, using topographical maps and aerial photographs. We compared these changes between two different irrigation systems: tazu, in which a community group jointly owns the rights to a water source, and private management. The study area consisted of 57.3% paddy field, 22.2% woodland, 7.2% urban land use, 6.3% grassland, 5.8% water body, and 1.2% dry field in 1963. In 2000, the area consisted of 44.3% paddy field, 21.0% woodland, 12.6% urban land use, 11.6% grassland, 5.3% water body, and 5.0% dry field. The proportion of agricultural use had decreased markedly over the 37-year period. In the tazu area, 38.1 and 37.7% of former paddy field had changed into urban land use and grassland, respectively, and 19.3% of former paddy field had become dry field by 2000. In contrast, 30.6% of former rice paddy had become dry field in the private management area. About half of the former rice paddy had changed into grassland (26.3%) and urban land use (24.0%) in the private area, and 18.6% had become woodland in 2000. In the tazu area, there were fewer abandoned fields, because farmers still manage their fields according to strict regulations. In the private management area, the set-aside or abandoned fields had changed into woodlands as a result of vegetation succession, because farmers had abandoned fields located far from their homes or on steep slopes. These results suggest that the irrigation system may influence the pattern of change in land use.

The Change of Vegetation, Fauna of Frogs and Mousse as Small Animals, on Different Management Level in Step-like Paddy Fields

The changes in vegetation and small animal fauna were investigated in terraced paddy with stone masonry in the hilly and mountainous areas of northeast Kyushu where cultivation has been progressively abandoned. Grassland which includes Imperata cylindrical - Miscanthus sinensis community and Juncus effusu community was formed depending on the soil moisture in the extensively managed sites. With the progression of vegetation succession in the abandoned managed sites, the M. sinensis community has attained dominant status. Although frog species diversity increased in the mountainside terraced paddy, the abandonment of paddy field cultivation led to a decline of frog composition. Rana ornativentris and Rhacophorus schlegelii had continually inhabited the moorland vegetation since the open water bodies required for breeding in frogs were disturbance-created by the rooting behaviour of mammals. With regard to the mouse fauna, Apodemus speciosus had colonized the extensively managed sites, and A. argenteus was found in the abandoned sites characterized by dense coverage of tall plants such as M. sinensis. Though the Micromys minutus population had increased in the extensively managed sites subject to continued mowing, they were absent from sites that had been abandoned for approximately 15 years. It was clarified that the vegetation succession is dependent on both land-form and management practice, and that vegetation and soil moisture are important factors in determining small animal fauna.

中山間地域等直接支払政策と農地管理型第三セクター―岐阜県旧東白川村を事例に―

The former Higashi-Shirakawa village formed a public agricultural corporation, 'Shinseiki Kobou', based on the fund from direct payments support policy for hilly and mountainous areas in order to prevent farmland abandonment due to ageing farm households. As the result, it plays an important role to maintain terraced paddy fields in mountainous areas. However, the corporation remains some significant tasks; such as improving profitability from farming support service and retaining the number of operators.