Tropes

ScienceDaily_2014 13502.txt

#True value of cover crops to farmers, environmentplanting cover crops in rotation between cash crops--widely agreed to be ecologically beneficial--is even more valuable than previously thought according to a team of agronomists entomologists agroecologists horticulturists and biogeochemists from Penn State's College of Agricultural Sciences. As society places increasing demands on agricultural land beyond food production to include ecosystem services we needed a new way to evaluate'success'in agriculture said Jason Kaye professor of biogeochemistry. This research presents a framework for considering a suite of ecosystem services that could be derived from agricultural land and how cover crops affect that suite of services. Cover cropping is one of the most rapidly growing soil and water conservation strategies in the Chesapeake bay region and one we are really counting on for future improvements in water quality in the bay. Our analysis shows how the effort to improve water quality with cover crops will affect other ecosystem services that we expect from agricultural land. The research published in the March issue of Agricultural Systems quantified the benefits offered by cover crops across more than 10 ecosystem services. Benefits included increased carbon and nitrogen in soils erosion prevention more mycorrhizal colonization--beneficial soil fungus that helps plants absorb nutrients--and weed suppression. Lead researcher Meagan Schipanski explained that commonly used measurements of ecosystem services can be misleading due to the episodic nature of some services and the time sensitivity of management windows. For example nutrient-retention benefits occur primarily during cover crop growth weed-suppression benefits occur during cash-crop growth through a cover crop legacy effect and soil-carbon benefits accrue slowly over decades she said. By integrating a suite of ecosystem services into a unified analytical framework we highlighted the potential for cover crops to influence a wide array of ecosystem services. We estimated that cover crops increased eight of 11 ecosystem services. In addition we demonstrated the importance of considering temporal dynamics when assessing management system effects on ecosystem services. Trade-offs occurred between economic metrics and environmental benefits said Schipanski who was a postdoctoral scholar at Penn State when she led the cover crop study. Now an assistant professor in the department of soil and crop sciences at Colorado State university she noted that the planting of cover crops will become more attractive if fertilizer prices rise or if modest cost-sharing programs like the one currently in place in Maryland are developed. Researchers simulated a three-year soybean-wheat-corn rotation with and without cover crops in central Pennsylvania which presented agroecological conditions broadly representative of the Northeast and Mid-atlantic regions. The cover crop rotation included red clover frost-seeded into winter wheat in March and winter rye planted after corn was harvested in the fall. The research funded by the U s. Department of agriculture used simulated management practices including tillage synthetic fertilizer use and mechanical weed control. The planting of cover crops already is accepted as an environmentally prudent practice. It is so beneficial in fact that the National Resource Conservation Service last month set a goal to increase the acres planted nationally in cover crops from the current 2 million to 20 million by 2020. According to NRCS in 2006 only 5 percent of cropped acres in the Chesapeake bay region had planted cover crops every year and 88 percent of acres never had planted any cover crops. In 2011 52 percent of acres had planted cover crops at least once every four years and 18 percent of acres had planted cover crops every year. The NRCS estimated that the increased annual use of cover crops in 2011 led to an average 78 percent reduction in sediment loss 35 percent less nitrogen surface loss a 40 percent cut in nitrogen subsurface loss and a 30 percent decrease in total phosphorus loss. But many farmers have not planted cover crops because they have not seen financial incentives to do so according to Kaye. That is largely because the traditional method of calculating the economic value of cover crops used by agricultural producers--only estimating the resulting increase to cash-crop yields over a short period--was not compelling. The most common metrics for evaluating cropping systems are grain and forage yields and short-term profitability he said. Within this context cover crops are treated as a tool to be used only if they do not interfere with cash-crop production. Story Source: The above story is provided based on materials by Penn State. Note: Materials may be edited for content and length. Journal Reference e

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