Sustainable Agriculture Literature Review - Boulder County

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A long-term study of cereal crop production in the Northern Great Plains region found
that a zero-tillage management system had greater soil water retention than
conventional tillage during a six-year drought period. Mean crop biomass in the zerotillage
system was 53-66 percent greater than the conventional system. Furthermore, the
amounts of carbon and nitrogen in the soil surface residues were 23-141 percent greater
than in the conventional tillage system. 365
While there are many soil benefits to conservation tillage practices, like no-till agriculture,
there are two main concerns: economic viability and the increased use of nitrogen
fertilizers. No-till farming methods have been reported to produce lower total yields
compared to conventional-till methods when nitrogen levels are comparable. A study
conducted outside of Fort Collins, Colorado, attempted to fill the information gap on the
economic effect of conventional-till versus no-till systems. The study concluded that a
no-till system required more nitrogen fertilizer to produce equal yields, but less irrigation
and machinery were necessary. 366 A study done in Southwest Colorado and Southeast
Utah had similar findings; minimal-till and no-till methods increased water storage in the
soil, but also relied more on fertilizers. While conventional-till methods produced higher
yields for corn in this study, they cost more to produce. 367
Although organic farming has been shown to supply high organic matter inputs to soil
with reduced reliance on synthetic fertilizers and pesticides, the high reliance on tillage
for organic production can reduce soil and water conservation through erosion and
compaction. 368 The common use of synthetic fertilizers and pesticides in conservation
tillage is not an option for organic farmers, 369 making some organic farmers more
cautious than conventional growers to implement conservation tillage as it would limit
using tillage as a management method for weeds and cover crops. 370 A study evaluating
the suitability of conservation tillage for organic agriculture found multiple tradeoffs
including: 371
Potential advantages: Potential disadvantages:
- Reduced erosion - Greater pressure from grass weeds
- Increased microbial activity and carbon - Less suitable than ploughing for poorly
storage
drained, unstable soils
- Less run-off and leaching of nutrients - Restricted N availability and restricted
- Reduced fuel use and faster tillage crop choice
The authors of the study found that the success of conservation tillage in organic farming
hinges on the choice of crop rotation to ensure weed and disease control and nitrogen
availability, and acknowledged that additional research is needed to further evaluate
conservation tillage in organic agriculture.
A recent study conducted by National Resource Conservation Service (NRCS) in
Colorado looked at the economic viability of using strip tillage for sugar beets in the
Front Range of Colorado. The study found that yields were less than traditional sugar
beet tillage, but net profit was higher. During the study, NRCS found that strip tillage for
sugar beets is a new concept in Colorado, as there is a “ belief that sugar beets would
only grow from a fine tilled seedbed.” NRCS’s “final conclusion from observations on the
project is that a producer should do several years of strip till corn before going to strip till
sugar beets to learn the system.” 372
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