Effects of ground cover management on improving water and soil conservation in tree crop systems: A meta-analysis

Abstract

Tree crops are mainly planted on sloped farmland, which can lead to soil erosion caused by runoff. As an important tree crop management strategy, ground cover management has been effective in controlling runoff generation and soil loss. However, a global overview is needed to comprehensively quantify the effectiveness of ground cover on water and soil conservation. This study aims to conduct a worldwide meta-analysis of 85 peer-reviewed publications from Web of Science and China National Knowledge Infrastructure (CNKI) databases, to quantify the effectiveness of ground cover in reducing runoff, soil and nutrient losses. Overall, ground cover management significantly reduced runoff, soil loss, and nitrogen and phosphorus losses in runoff by 48.5%, 70.5%, and 53.4% and 56.9%, respectively. The magnitude of the effect of ground cover management mostly depended on ground cover types, land slope and climatic conditions. Cover cropping showed more efficiency in reducing runoff, soil and nutrient losses than mulch management. Legume cover crops were less effective than non-legumes, which was mainly attributed to the greater vegetation coverage of the perennial non-legume grasses than the annual legumes. Ground cover showed the most capacity to conserve water and soil at slopes between 10 and 15°, with the tendency to lose effectiveness when field slopes were greater than 15°. When pooling data according to different climatic conditions, the reduction of runoff, soil and nutrient losses were highest when mean annual precipitation and temperature were above 800 mm and 20 °C, respectively. This study can serve as a scientific basis for policy makers and tree crop managers in controlling soil erosion and land degradation based on ground cover type, physical topography and the climate where the agroecosystem is located.