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In mountainous watersheds, agricultural land use cause changes in ecosystem services, with trade-offs between crop production and erosion regulation. Management of these watersheds can generate environmental land use conflicts among regional stakeholders with different interests. Although several researches have made a start in mapping land use conflicts between human activities and conservation, spatial assessment of land use conflicts on environmental issues and ecosystem service trade-offs within agricultural areas has not been fully considered. In this study, we went further to map land use conflicts between agricultural preferences for crop production and environmental emphasis on erosion regulation. We applied an agricultural land suitability index, based on multi-criteria analysis, to estimate the spatial preference of agricultural activities, while applying the Revised Universal Soil Loss Equation (RUSLE) to reflect the environmental importance of soil erosion. Then, we classified the agricultural catchment into four levels of land use conflicts (lowest, low, high and highest) according to preference and importance of farmland areas, and we compared the classes by crop type. Soil loss in agricultural areas was estimated as 45.1 t ha yr, and agricultural suitability as 0.873; this indicated that land use conflicts in the catchment could arise between severe soil erosion (environmental importance) and agricultural suitability (land preferences). Dry-field farms are mainly located in areas of low land use conflict level, where land preference outweighs environmental importance. When we applied farmland management scenarios with consideration of services, conversion to highest-conflict areas (Scenario 1) as 7.5% of the total area could reduce soil loss by 24.6%, while fallow land management (Scenario 2) could decrease soil loss 19.4% more than the current scenario (Business as usual). The result could maximize land management plans by extracting issues of spatial priority and use-versus-conservation conflicts as ecosystem service trade-offs from arguments over land use policy. [ABSTRACT FROM AUTHOR]

Non-sustainable agricultural practices can alter the quality of soil and water. A sustainable soil management requires detailed understanding of how tillage affects soil quality, erosion, and leaching processes. Agricultural soils in the Haean catchment (South Korea) are susceptible to erosion by water during the monsoon. For years, erosion-induced losses have been compensated by spreading allochthonous sandy material on the fields. These anthropogenically modified soils are used for vegetable production, and crops are cultivated in ridges using plastic mulches. To evaluate whether the current practice of ridge cultivation is sustainable with regard to soil quality and soil and water conservation, we (i) analysed soil properties of topsoils and (ii) carried out dye tracer experiments. Our results show that the sandy topsoils have a very low soil organic matter content and a poor structure and lack soil burrowers. The artificial layering induced by spreading sandy material supported lateral downhill water flow. Ridge tillage and plastic mulching strongly increased surface runoff and soil erosion. We conclude that for this region a comprehensive management plan, which aims at long-term sustainable agriculture by protecting topsoils, increasing soil organic matter, and minimizing runoff and soil erosion, is mandatory for the future. [ABSTRACT FROM AUTHOR]

We introduce an explicit indicator and the Land Use Management Support System to assess the resource-use efficiency of land use (RUE) at the landscape scale. To estimate RUE, we relate land-use performance with regard to ecosystem services indicators to the maximum possible land-use performance based on an optimised land-use configuration. The test application of the RUE assessment in the Haean catchment, South Korea, shows that the land-use system's RUE could be increased by 11% for both nitrate and sediment loss. The estimated headroom could indicate whether potential contaminant reduction targets for the downstream water reservoir Lake Soyang could be achieved with the current land-use system. The recurring RUE assessment for a given region might indicate the effectiveness of spatial planning and policy measures to improve the RUE in that region. Future work should address the integration of RUE into a participatory spatial planning or resource-management framework. [ABSTRACT FROM AUTHOR]

The Asian agricultural landscape, which accounts for approximately 12.6% of the world’s agricultural land, is highly heterogeneous due to the multicultural cropping system. Information regarding CO 2 exchange and carbon (C) balance of these agro-ecosystems is scarce, even though they are likely to immensely contribute to the global C budget. Net Ecosystem CO 2 Exchange (NEE) and Ecosystem respiration ( R eco ) were measured between 2009 and 2010 on 5 dominant crops (potato, rice, radish, cabbage and bean) in the Haean catchment of South Korea, using a closed chamber system to quantify CO 2 fluxes in this agricultural landscape characteristic of the Asian cropping system. Parallel measurements were conducted on leaf area index (LAI), plant biomass and climatic variables, mainly photosynthetic active radiation (PAR), air temperature, soil temperature and soil moisture. Biomass and LAI development differed among the crops likely as a result of differences in light use efficiencies ( α ) and carbon allocation patterns. The peak total biomass for radish, cabbage, potato, rice and bean were 0.53 ± 0.07, 0.55 ± 0.12, 1.85 ± 0.51, 2.54 ± 0.35 and 1.01 ± 0.26 kg m −2 , respectively, while the respective maximum LAI were 2.8, 3.7, 6.4, 6.3 and 6.7 m 2 m −2 . Variations in seasonal patterns, magnitudes and the timing of maximum NEE and gross primary production (GPP) among the crops were likely the result of differences in LAI and α . The lowest peak R eco rate was 3.8 ± 0.5 μmol m −2 s −1 , measured on rice paddies while the highest was 34.4 ± 4.3 μmol m −2 s −1 measured on the cabbage fields. The maximum NEE rates were −29.4 ± 0.4 and −38.7 ± 6.6 μmol m −2 s −1 , measured in potato and cabbage fields, respectively. Peak GPP rates in potato and cabbage fields were 39.5 ± 0.6 and 63.0 ± 7.2 μmol m −2 s −1 , respectively. PAR explained more than 90% of the diurnal variations in GPP, while LAI and α determined the seasonal trends of maximum GPP. The timing of maximum CO 2 assimilation (GPP Max ) differed among the crops, thus, even though maximum CO 2 uptake in the respective crops only lasted a couple of weeks, the effect of the staggered peak GPP resulted in extended period of high CO 2 uptake. These differences among crops were significant, hence, modeling approaches need to consider the heterogeneity in ecosystem CO 2 exchange associated with these multicultural agriculture landscapes. [ABSTRACT FROM AUTHOR]

Highlights: [•] DOC dynamics in 1st order forested streams controlled by monsoonal climate. [•] DOC dynamics in higher order agricultural streams driven by rice paddy water inputs. [•] Monsoonal climate controls river-aquifer exchange dynamics. [•] Frequent hydraulic gradient reversals are specific to the monsoonal climate. [ABSTRACT FROM AUTHOR]