Agriculture Reference
In-Depth Information
climate stabilization; (2) nitrate conservation that improves water quality by reduc-
ing leaching of nitrate into ground and surface waters; (3) greenhouse gas mitiga-
tion including N
2
O abatement and lower CO
2
emissions; (4) energy efficiency that
saves fuel; and (5) pest suppression that reduces pesticide use.
No current agricultural system can maximize the delivery of all services—
almost always the delivery of one service affects the potential delivery of others.
Thus, trade-offs must be considered. The most important trade-off for farmers is
profitability—the opportunity cost of providing a particular service. No-till man-
agement, for example, builds soil C, reduces fuel use, and reduces nitrate leaching,
but it can compress the spring planting period and requires specialized equipment.
Biologically based management conserves nitrogen, builds soil C, and reduces
pesticide loading, but it has associated costs of timely labor requirements and
yield reductions not recoverable without the price premiums provided by organic
certification.
Key findings from over 20 years of KBS LTER row-crop research on ecosystem
services include:
1. Crop (rotational) diversity—planting legumes, in particular—provides
enhanced opportunities for biological N fixation and pest regulation.
2. Planting a forage or cover crop makes an annual row-crop system more
perennial. Such plantings extend the duration of living cover, support soil C
sequestration, reduce N losses, and can lower reliance on chemical inputs.
3. Reducing soil disturbance through conservation tillage enhances soil C
sequestration, energy efficiency, and crop yield.
Economic trade-offs were also documented:
1. Compared with conventional crop management, direct costs associated with
alternative management practices depend on requirements for extra inputs,
labor, and associated costs, as well as any reduction in requirements for
chemical inputs.
2. Indirect opportunity costs associated with cover crops include allowing time
for biological decomposition to occur, which often requires late plantings of
cash crops after cover crops, with associated yield penalties, particularly for
corn.
3. Diversification is associated with lower production where moderate-yield
crops or cover crops are substituted for high-yield crops such as corn,
although economic returns can still be high from moderate-yield crops
depending on product prices.
In summary, organic and reduced input management systems deliver more eco-
system services (Table 15.3). However, there is an apparent yield penalty, as shown
for organic-managed corn relative to conventional in both the LFL and MCSE.
In contrast, conservation tillage is consistently associated with high corn yields
relative to conventional management. Further, biologically based soybean yields
were consistently high. A simplistic approach to evaluating the yield trade-offs of
environmental services provided by these management systems is to examine yield
trends over time relative to annual estimates of soil C gain and nitrate leaching
