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ARS Home » Northeast Area » Orono, Maine » New England Plant, Soil and Water Research Laboratory » Research » Publications at this Location » Publication #164019


item Fortuna, Ann Marie
item FRYE, W
item GROVE, J

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2007
Publication Date: N/A
Citation: N/A

Interpretive Summary: During the 1970 s, the public began to focus on prevention of non-point source pollution caused by soil erosion. Soil conservation practices such as no-tillage agriculture were recommended to help prevent top soil loss. Over time, acreage in conservation tillage increased replacing the mold-board plow. During 2004, forty percent of cropland in the US employed conservation tillage, systems that leave at least 30% of the soil surface covered with residues. Once this shift occurred, organizations such as the National Resource Conservation Service began emphasizing the importance of maintaining and improving soil quality. The bulk of soil organic matter is concentrated in the top soil. Degradation of top soil reduces soil quality because many nutrients such as N are contained in or associated with soil organic matter. Farming practices that prevent loss of soil organic matter or add to soil organic matter increase soil nitrogen and carbon resulting in improved soil quality. The type of tillage, cropping system, and cover crop a grower chooses effect the amount of nitrogen available to a crop during a growing season and in future seasons. Our study looked at the effect of different tillage and cropping systems on the amount of nitrogen available for plant uptake and leaching, as well as, these management effects on soil carbon. Tillage reduced soil quality by speeding up the decomposition of soil carbon and nitrogen. Cropping systems that contained cover crops increased soil nitrogen and carbon supplies. Greater additions of crop residue added to the soil nitrogen and carbon pools as they decomposed and became incorporated into soil organic matter. Thus, management that included legume cover crops and no-tillage reduced the nitrogen fertilizer requirement of corn by supplying greater amounts of plant-available nitrogen, and improved soil quality.

Technical Abstract: Tillage, cropping system, and cover crops have seasonal and long-term effects on the N cycle and total soil organic C, which in turn affects soil quality. Our study evaluated the effects of crop, cover crop, and tillage practices on: inorganic N levels and total soil N, the timing of inorganic N release from hairy vetch and soybean and the capacity for C sequestration. Cropping systems included: continuous corn (Zea mays L.) and stalk residue, continuous corn and hairy vetch (Vicia villosa Roth), continuous soybeans (Glycine max L.) plus residue, and two corn/soybean rotations in corn alternate years with hairy vetch and ammonium nitrate (0, 85, and 170 kg N/ha). Sub-plot treatments were moldboard-plow and no-tillage. Legumes coupled with no-tillage reduced the N fertilizer requirement of corn, increased plant available N, and augmented total soil C and N stores.