Effect of poplar trees on nitrogen and water balance in outdoor pig production - A case study in Denmark.

Nitrate leaching from outdoor pig production is a long-standing environmental problem for surface and groundwater pollution. In this study, the effects of inclusion of poplar trees in paddocks for lactating sows on nitrogen (N) balances were studied for an organic pig farm in Denmark. Vegetation conditions, soil water and nitrate dynamics were measured in poplar and grass zones of paddocks belonging to main treatments: access to trees (AT), no access to trees (NAT) and a control without trees (NT), during the hydrological year April 2015 to April 2016. Soil water drainage for each zone, simulated by two simulation models (CoupModel and Daisy), was used to estimate nitrate leaching from the zones in each paddock. N balances (input minus output) for the treatments were computed and compared. The results showed that, in terms of annual water balance and regardless of treatment, simulated evapotranspiration of poplar was 560-569 and 489-498 mm for CoupModel and Daisy, respectively, and corresponding evapotranspiration of grass-clover was 250 and 400 mm, against precipitation of 1076 mm. Simulated drainage below the root zone varied as 620-723 mm for Daisy and 568-958 mm for CoupModel, the higher end of the latter being probably overestimated. Annual nitrate leaching ranged from 32 kg N ha-1 in the poplar zone of NAT up to 289 kg N ha-1 in the control grass zone of NT. The poplar zone showed significantly lower nitrate leaching, by 75-80%, compared to the grass zone. For the control NT treatment, nitrate leaching was approximately 50% higher in the grass zone closest to the hut compared to the grass zone further away. NT treatment also had the largest surface N balance of 468 kg N ha-1 compared to 436 and 397 kg N ha-1 for AT and NAT, respectively. When N losses by leaching and volatilisation were included, soil N balances were 118, 157 and 113 kg N ha-1 for AT, NAT and NT, respectively. Overall, the two simulation models were found useful tools for analyses of water balance for complex agroforestry systems. The findings collectively suggest that it is possible to decrease nitrate leaching from outdoor pig production on sandy soils by inclusion of poplar trees. Additional measures are nevertheless needed to reduce N losses on a mean area basis in paddocks with 20% tree cover.

Identifying Land Use and Land-Use Changes (LULUC): A Global LULUC Matrix.

Land use and land-use changes (LULUC) information is essential to determine the environmental impacts of anthropogenic land-use and conversion. However, existing data sets are either local-scale or they quantify land occupation per land-use type rather than providing information on land-use changes. Here we combined the strengths of the remotely sensed MODIS land cover data set and FAOSTAT land-use data to obtain a database including a collection of 231 country-specific LULUC matrixes, as suggested by the IPCC. We produced two versions of each matrix: version 1, identifying forestland based on canopy cover criteria; version 2, distinguishing primary, secondary, planted forests and permanent crops. The outcome was a first country-based, consistent set of spatially explicit LULUC matrixes. The database facilitates a more holistic assessment of land-use changes, quantifying changes that occur between land classes from 2001 to 2012, providing crucial information for assessing environmental impacts caused by LULUC. The data allow global-scale land-use change analyses, requiring a distinction between land types based not only on land cover but also on land uses. The spatially explicit data set may also serve as a starting point for further studies aiming at determining the drivers of land-use change supported by spatial statistical modeling.

Increased Foraging in Outdoor Organic Pig Production-Modeling Environmental Consequences.

Consumers' motivations for buying organic products include a wish of acquiring healthy, environmentally friendly products from production systems that also ensure a high level of animal welfare. However, the current Danish organic pig production faces important challenges regarding environmental impact of the system. High ammonia emissions arise from outdoor concrete areas with growing pigs and sows on pasture possess an increased risk of nitrogen (N) leaching. Direct foraging in the range area is suggested as a way to improve the nutrient efficiency at farm level and to support a more natural behavior of the pig. Thus, by modeling, we investigated the environmental consequences of two alternative scenarios with growing pigs foraging in the range area and different levels of crops available for foraging-grass-clover or a combination of Jerusalem artichokes and lucerne. It was possible to have growing pigs on free-range without increasing N leaching compared to the current practice. The alternative system with Jerusalem artichokes and lucerne (high integration of forage) showed the lowest carbon foot print with 3.12 CO2 eq kg-1 live weight pig compared to the current Danish pasture based system with 3.69 kg CO2 eq kg-1 live weight pig. Due to positive impact on soil carbon sequestration, the second alternative system based on grass-clover (low integration of forage) showed a similar carbon foot print compared to current practice with 3.68 kg CO2 eq kg-1 live weight pig. It is concluded that in practice there is room for development of organic farming systems where direct foraging plays a central role.