Page 108 - Soil Degradation, Conservation and Remediation

3.4 Control of Water Erosion 95

Fig. 3.17 Grassed waterway (Photo courtesy of USDA-NRCS)

structures (terraces) can be unachievable. Benefi ts of buffers include yield of good
quality water, enhanced agricultural production, secured wildlife habitat, and
desired landscape aesthetics. Buffers can trap > 70 % of sediments and > 50 % of
nutrients depending on the plant species, management, and climate (Blanco and Lal
2008 ). Buffers are multifunctional systems. Above the surface, buffers reduce the
runoff velocity and trap sediments and nutrients, and below the surface, they stabi-
lize the soil in place, bind the soil aggregates, improve the structural characteristics,
and increase soil organic matter content and water transmission characteristics.

3.4.12 Grassed Waterways

Grassed waterways are natural or constructed channels established at an appropriate

place over the field for safe transport of concentrated water at a reduced velocity
using adequate grass cover (Fig. 3.17 ). They are generally broad and shallow drain-
ways to transport surface water across farmland without causing soil erosion.
Grassed waterways are used as outlets to prevent rill and gully formation. The grass

cover slows the flow of water and minimizes channel erosion. Effi cient grassed
waterways can transport large water flows downslope without causing any harm.

Grassed waterways also act as diversion channels. Grasses trap suspended sedi-
ments and absorb dissolved nutrients. It also traps dissolved nitrates, phosphates,
herbicides, and pesticides and improves water quality of adjacent reservoirs.