Mulching as a mitigation agricultural technology against land degradation in the wake of climate change

Abstract

The sloping topography of the island of Rodrigues (an outer island dependency of the Republic of Mauritius) makes it very prone to soil erosion, and loss of fertile topsoil. Climate variability and climate change in the form of increasing temperatures, long periods of drought followed by short periods of torrential rains are exacerbating this situation. Mulching is a cheap, affordable, sustainable agricultural technology for sustainable soil and land management and reducing soil erosion, which can be adopted by small as well as large farmers. The present work on mulching was carried out in Rodrigues in farmers’ fields that were prone to severe soil erosion (8% slope) Banana (Musa sp) leaves, coconut (Cocos nucifera) leaves, and vetiver (Vetiveria zizanoides) grass, at 0tha −1, 10tha −1, 20tha −1 and 40tha −1, were used as natural organic mulches after seeding the plots with maize in a randomised block design with four replicates. Runoff and sediment were collected from the treated and control plots, and analysed for total sediments, total runoff, and nutrient content (N, P, K). Results showed that all the mulches tested contributed to lowering of soil and nutrient losses, albeit in varying amounts. Coconut leaves mulch was found to be the most efficient, followed by vetiver and then banana leaves. Percentage mitigation in soil and nutrient erosion was found to be 28. 9% for banana leaves at 10tha −1, and 57. 3% for coconut leaves at 40tha −1. The reduction of soil and nutrient losses was attributed to the mechanical barrier provided by the mulches, and also to the reduction in the momentum of raindrops acting on the soil aggregates. Mulching also contributed to increasing infiltration rate, lowering temperature and therefore lowering evaporation.