Conservation Strategies for Effective Management of Eroded Landform

Abstract

Water erosion remains a major threat to soil and water conservation in the humid tropics and, thus, requires effective conservation measures to curb it. To quantify the efficacy of vetiver grass (Chrysopogon zizanioides L.) strips and mulch in soil structural quality buildup and in reducing the eutrophic quality index and enrichments ratios of major nutrients, a study was conducted between 2007 and 2009 on eroded landform (8% slope) of a Typic Kanhapludalf in a subhumid region of southwestern Nigeria. Treatments were vetiver buffer strips (10 m vetiver grass strip [VGS]), vetiver mulch (6 Mg ha j1 vetiver grass mulch [VGM]), combined vetiver strips and mulch (10 m VGS + 4 Mg ha j1 VGM), and a control (no buffer strips or mulch). Soil structural quality estimated by water-stable aggregates at 0-to 5-cm depth increased by 36%, 73%, and 64% under 10 m VGS, 6 Mg ha j1 VGM, and 10 m VGS + 4 Mg ha j1 VGM, respectively, more than the control. The corresponding increase in mean weight-diameter under the vetiver systems was 30%, 42%, and 47% higher than the control. The waterstable aggregates and mean weight-diameter at the 5-to 15-cm depth followed a similar trend in the 0-to 5-cm layer. The resistive potentials of the vetiver systems in reducing soil loss, sediment-associated nutrients, total suspended solids, and eutrophic quality index were significantly higher than the control because of an increase in surface hydraulic roughness, which were in the order of 6 Mg ha j1 VGM G 10 m VGS G 10 m VGS + 4 Mg ha j1 VGM. Application of 6 Mg ha j1 VGM appear to be better than 10 m VGS and contributed to the reduction of runoff and enrichment ratios, thus, changing the order to 10 m VGS G 6 Mg ha j1 VGM G 10 m VGS + 4 Mg ha j1 VGM. The results indicate that an integration of vetiver buffer strips and mulch (10 m VGS + 4 Mg ha j1 VGM) had a better control of runoff, soil loss, sediment-associated nutrients, and water quality degradation, as well as improving soil structural quality buildup when compared with vetiver buffer strips or mulch alone.

Assessing soil quality issues for crop production function based on farmers’ perception: An experience from Itapaji Watershed in Southwestern Nigeria

“…Other benefits from cover crops include protection of the soil from water and wind erosion, improved soil tilth and suppression of soil-borne pathogens (Gugino et al, 2007). Are et al (2011) also submitted that vegetative cover crop is necessary to protect the soil surface from raindrop impact, runoff, erosion and rapid desiccation. Another way of soil protection or organic matter build-up is by plantation crops in form of agroforestry where food crops are grown with permanent tree crops before the canopy is closed up.…”

Optimizing Straw Mulching Methods to Control Soil and Water Losses on Loess Sloped Farmland

“…Many studies have found that covering entire plots has lower runoff and sediment yields than covering partial plots, but there were no significant differences [43]. Are et al [44] even observed that covering a single strip was more effective at capturing sediment and associated nutrients than covering the whole patch, although the difference was slight. Therefore, it is necessary to explore the effectiveness of runoff and sediment reduction when straw covers only part of the bottom of the slope.…”

Spatial Variation of Dissolved Nutrient and Heavy Metal Concentrations in River Bed Sediments as Influenced by Land-Use Patterns in Ogun-Osun River Basin, Nigeria

“…This agricultural intensification has led to a substantial increase in the rates of fertilizer applications, use of sludge, animal and industrial wastes, which both improve yields and have deleterious consequences for downstream aquatic systems, where nutrient loading can drive eutrophication [13]. Efforts have been channeled to understand the water quality status of rivers in Nigeria, even though very often, the spatial scale does not always encompass the immediate hydrological basin in such investigations.…”