Introduction to Stream Restoration - Hydro-Environmental Analysis: Freshwater Environments - page 224

some stormwater pollution prevention plans) and the establishment of BMPs has been voluntary.
However, with more stringent requirements for load reductions, in compliance with the CWA, such
as in the execution of watershed implementation plans (for example in the Chesapeake Bay), the use
of agricultural BMPs will become mandatory.
There are a wide variety of agricultural BMPs (e.g., 160 NRCS conservation practices), and a
complete discussion would not be possible in the context of this text. However, a few representative
methods are discussed in the following sections, including conservation tillage, crop nutrient man-
agement, pest management, and conservation buffers, which are the four core practices used in train-
ing by the Conservation Technology Information Center (CTIC). In addition, tailwater recovery and
reuse will be discussed as a common example of a water conservation (and load reduction) practice.
8.4.1.1 Conservation Tillage
This practice includes leaving crop residue (plant materials from past harvests) on the soil surface
in order to reduce runoff and soil erosion, conserve soil moisture, help keep nutrients and pesticides
on the ield, and improve soil, water, and air quality. Three primary conservation tillage practices
include:
8.4.1.1.1 Residue and Tillage Management No Till/Strip Till/Direct Seed (Code 329)
This practice applies to all cropland and consists of managing the amount, orientation, and distri-
bution of crop and other plant residue on the soil surface year-round, while limiting soil-disturb-
ing activities to only those necessary to place nutrients, condition residue, and plant crops (NRCS
Practice Code 329; Figure 8.8).
8.4.1.1.2 Residue Management, Mulch Till (Code 345)
This practice applies to all cropland and consists of managing the amount, orientation, and distribu-
tion of crop and other plant residue on the soil surface year-round, where the entire ield surface is
tilled prior to planting. The residue is partially incorporated using chisels, sweeps, ield cultivators,
or similar farming implements (NRCS Code 345, Figure 8.9).
8.4.1.1.3 Residue and Tillage Management: Ridge Till (Code 346)
This practice consists of managing the amount, orientation, and distribution of crop and other plant
residue on the soil surface year-round, while growing crops on preformed ridges alternated with
furrows protected by crop residue (NRCS Code 346; Figure 8.10).
FIGURE 8.8 Residue and tillage management no till/strip till/direct seed. (From NRCS Code 329 network
effects diagram, revised 4/2010.)