Farmers participatory action research programme Tank silt as an organic amendments for improving soil and water productivity.

Abstract

Loss of soil quality due to soil erosion remains a major factor of low crop productivity in tropical and subtropical countries. Soil and water conservation (SWC) efforts should therefore be geared toward soil erosion control for enhanced maintenance of soil organic matter and soil physical properties. The main factors causing soil erosion can be divided into three groups: (1) energy factors, e.g., rainfall erosivity; (2) protection factors, e.g., plant cover and land management; and (3) resistance factors, e.g., soil erodibility. This entry mainly covers soil erosion by water. Soil erosion is a major threat to the soil resource, soil fertility, productivity, and, lastly, to food and fiber production (Boardman et al. 2009). According to Ighodaro et al. (2013), soil erosion is the biggest environmental problem the world faces second only to population growth. Worldwide, erosion on cropland averages to about 30 t/ha/year, and each year about 10 million ha of cropland is © Springer Nature Switzerland AG 2019 W. Leal Filho et al. (eds.), Zero Hunger, https://doi.org/10.1007/978-3-319-69626-3_91-1 rendered unproductive and abandoned due to soil erosion (Nyawade et al. 2018a, b). Pimentel (2006) reports that soil erosion is highest in Asia, Africa, and South America where soil losses range from 30 to 40 t/ha and that it is severe in small farms located in marginal areas where soil quality is poor and the topography often steep (Plate 1). Soil erosion is severe in small farms located in marginal areas where soil quality is poor and the topography is often steep (Plate 1). Although the problem is as old as settled agriculture, its extent and impact on human welfare and global environment are more now than ever before. However, human alterations of land use and cover have caused erosion rates to increase for many areas of the world, resulting in considerable land and environmental degradation (Valentin et al. 2008; Martínez-Casasnovas et al. 2009; Farhan et al. 2014; Tesfahunegn et al. 2014). While temporary solutions such as increased fertilizer have offset some of the effects of erosion on soil productivity, they are not complete substitutes for topsoil (Gachene et al. 1997) and represent the greatest input cost for compensating yield losses caused by erosion (Pimentel 2006). Studies conducted on a humic Nitisol at Kabete, Kenya, indicated that soil erosion by water can lead to substantial loss in maize growth and grain yield (Gachene et al. 1998) (Table 1). Thus, in order to maintain long-term productivity and preserve soil and environmental quality, it is important to implement SWC practices that prevent and minimize soil erosion, rather than manage the effects of erosion after it has occurred (Yannelli et al. 2013). Runoff and soil loss prediction has been widely used as a tool to guide in SWC planning (Murillo et al. 2011; Renschler and Harbor 2009; Gobin et al. 2004).