A soil erosion study on two clay soils in Malta

Abstract

Soil erosion is considered one of the main threats to the limited soil resources in Malta. This research compares soil sediment losses, between a site with zero tillage management and another managed conventionally. Both sites are composed of clay soils, on inclined terrain, which have been afflicted by erosion and are undergoing afforestation in an attempt to curb soil erosion. The study also examines the changes in soil surface throughout the rainy season. Comparisons are also drawn on the differences that soil surface treatments have on the amount of soil eroded. Soil erosion traps (modified Gerlach troughs) were installed at each site, collecting the soil sediment that was carried down slope through the effects of precipitation and runoff. Sediment was collected over two observation periods. The first between the autumn I winter season, when soil was more vulnerable and precipitation events more intense. The second between winter I spring, when vegetation was established and precipitation less intense. In addition, enclosed erosion plots were installed at one of the sites to compare differences between: tillage, vegetation cover and bare soil. Sediment from these sources was collected on the same two observation periods. Finally, a series of erosion pins were installed along a rough transect at the other site, to examine the dynamics of soil surface changes and deposition of sediment, on a monthly basis. Zero tillage management was found to be marginally more effective than the conventional management at controlling erosion, but the large variability in the collected data suggests caution in further interpretation. Once established, vegetation cover provided the greatest protection against soil erosion, from the tested treatments. No statistically significant difference was observed when comparing between the other treatments. The erosion pin setup showed a net accumulation of sediment throughout the study period, but there was a fluctuation in deposition and loss of soil that was influenced by precipitation patterns.