Malaysian Journal of Sustainable Agriculture (MJSA)

Keeping pigs in the outdoor pasture convey a high risk of environmental pollution through nitrate leaching. Integrating grassland based free-range pigs with energy crops has been proposed as an alternative approach to reduce pollution. This study investigated the Nmin distribution and potential NO3-N leaching at various soil depths (0-25, 25-50, 50-100 cm) and distances (0.5, 2.5, 4.5, 6.5 and 9.5) from willow trees in the lactating sows’ paddocks. The results observed the highest levels of Nmin close to the huts and adjacent to feed troughs and the lowest Nmin levels close to the willow trees with a 1 m soil depth. For soil water analysis, the nitrate leaching as expected was the highest near the huts with an average of 37 mg NO3-N/liter followed by 28 Mg NO3-N/liter at 6.5 m with the lowest levels close to willow trees. The lowest NO3-N leaching around willow zone could be subjected to high water and nutrients uptake by trees. The 9.5 m close to feeders had the low leaching which could be due to low NO3-N as NH4-N dominated with 90% of the total Nmin with about 79% of this being in topsoil. Therefore, with a long growing season and deep root system of energy crops, the paddock design should maximize the trees uptake potential near this zone as pigs are known to have high excretion activities near shelter zones. As a result, a substantial N loss through nitrate leaching could be minimized.