Sustainable Agriculture Literature Review - Boulder County

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! !! "#$%&!'())!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!*+!,-./!01#/2&! 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 ! "%&" !,342#.5#6/1!78$.%3/23$1! 9.21$#23$1!:1;.1
! !! "#$%&!'())!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!*+!,-./!01#/2&! ! Graph 8: Irrigated Continuous Corn Grain Yields in Comparison to Nitrogen Fertilizer Rates for Conventional-till and No-till Farming, 2000-2004 373 David Archer, an Agricultural Research Service economist, found no-till was more profitable than conventional-till on irrigated continuous corn crops because of lower machinery and labor costs, as well as a decrease in fossil fuel use. While Graph 8 shows higher yields (crop production) for conventional-till agriculture when nitrogen fertilizer rates are equal, Graph 9 demonstrates that no-till farming earns higher net returns (financial income) when nitrogen fertilizer rates are equal. 374 Comparing the data from the two charts, as nitrogen fertilizer rates stay constant, no-till farming earns higher net returns even with lower yields. Additionally, future water supply issues could prove no-till farming to be the more desired method since it tends to need less irrigation. 375 Graph 9: Irrigated Continuous Corn Net Returns in Comparison to Nitrogen Fertilizer Rates for Conventional-till and No-till Farming, 2000-2005 376 "%'" !,342#.5#6/1!78$.%3/23$1! 9.21$#23$1!:1;.1
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SUSTAINABLE AGRICULTURE LITERATURE
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Sustainable Agriculture Literature Review - Boulder County

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