Influence of manure, compost additions and temperature on the water repellency of tropical soils

Soil water repellency is a major concern in many systems as it substantially reduces infiltration and enhances surface runoff. While it is recognised that repellency is affected by the soil organic matter in natural ecosystems, the impact of manure and compost additions on the development and persistence of repellency in agroecosystems, particularly in the tropics, is poorly understood. We therefore examined the impact of different manure, compost additions and temperature on soil water repellency of tropical soils. We monitored the change in repellency in a Cambisol (Talparo – clay loam), Acrisol (Piarco – silt loam) and Arenosol (Arena – loamy sand), amended with three different manure and compost combinations at three different concentrations and four temperatures. Water repellency was the strongest among soils with higher clay content, which was likely due to the higher levels of organic matter observed in the clay loam. The cattle manure produced the most severe repellency despite having the lowest total organic carbon, whereas the sugarcane bagasse produced the lowest repellency. The increases in temperature had the strongest influence on repellency in sandy soils. Our results strongly support the findings of other studies that the quality of the organic material is more important than the total organic carbon in controlling the severity of repellency. This exploratory work also highlighted the importance of plant compost in reducing the level of repellency caused by cattle manure while still having a positive influence on the nutrient status of soils.