Many of the advantages of no-tillage crop production are due to the presence of a mulch from a cover crop or from crop residue. Legumes can be used to provide the mulch and biologically fixed N to nonlegumes in the system. Field experiments were conducted from 1977 through 1981 to determine the amount of biologically fixed N provided to no-tillage corn (Zea mays L.) by winter annual legume cover crops of hairy vetch ( Yicia villosa Roth), big flower vetch ( Yicia grandiflora W. Koch var. Kitailbeliana), and crimson clover (Trifolium incarnatum L.). The legumes were compared to a co,ver of corn residue only and a cover crop of rye (Secale cereale L.). The soil was a Maury silt loam (Typic Paleudalfs, fine-silty, mixed, mesic). Fertilizer N treatments of 0, 50, and 100 kg ha·• were combined with each cover treatment. Corn was planted by no-tillage directly into the cover treatments and the cover crops were killed with herbicides. Hairy vetch produced more dry matter with a higher N percentage which resulted in a higher N concentration in corn plants and substantially more inorganic N (KCI extractable NHt and

Change in frequency and intensity of tillage practices alters the soil properties, distribution of nutrients, and soil organic matter in the soil profile. We hypothesized that 8 yr of no‐till (NT), chisel plow (CP), and moldboard plow (MP) treatments would affect chemical properties and organic matter of eroded soil. The corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation study was established in tall fescue (Festuca arundinacea L.) sod on a previously eroded, moderately well‐drained, Grantsburg (Fine‐silty, mixed, mesic Oxyaquic Fragiudalf) soil in southern Illinois. In the eighth year, soil pH, exchangeable Ca, and Bray P‐1 were greater in NT than in CP and MP in the 0‐ to 5‐cm soil depth. In the 0‐ to 5‐cm soil depth, exchangeable K and Mg were greater with the CP than with the NT and MP. In the 5‐ to 15‐cm soil depth, exchangeable Ca and Mg were greater in the MP and CP than in NT, due to mixing. Soil pH and P were greater for CP than MP and NT in the 5‐ to 15‐cm layer. Exchangeable K in the 5‐ to 15‐cm soil depth was greater in the MP than CP and NT. In the 0‐ to 5‐cm soil depth, NT, CP, and MP had 38, 35, and 31% of their total C as particulate organic matter (POM), respectively. After 8 yr, CP and MP had less total organic C than NT in the 0‐ to 5‐cm depth. In the 0‐ to 5‐cm depth, CP and MP had less POM C than NT. The greater reduction of organic C in the POM fraction than in whole soil showed that POM was the most tillage‐sensitive fraction of organic matter. After 8 yr of study, the water‐stable aggregates in the 0‐ to 5‐cm soil depth of MP and CP was reduced compared with NT. The effects of tillage treatment and associated soil erosion either resulted in different findings from tillage treatments on uneroded soil or affected the trend and magnitude of the soil property differences between treatments. For the 10‐yr period prior to the establishment of the tillage experiment the site was managed as hayland. At the end of 8 yr, the NT maintained or improved nutrient retention and aggregate stability in the 0‐ to 5‐cm layer compared with MP and CP.

A 12-year cover crops study on the effects on SOC sequestration, storage, retention and loss and corn and soybean yields was conducted in southern Illinois. The use of cover crops for the maintenance and restoration of soil organic carbon (SOC) and soil productivity of previously eroded soils were evaluated. No-till (NT), chisel plow (CP), and moldboard plow (MP) treatment plots with and without cover crops were established in 2001. The plot area was on sloping with a moderately well drained, eroded soil. The average annual corn and soybean yields were statistically the same for NT, CP, and MP systems with and without cover crops. By 2012, the cover crop treatments had more SOC stock than that without cover crops for the same soil layer and tillage treatment. The NT, CP, and MP treatments all sequestered SOC with cover crops. A pre-treatment SOC stock baseline for rooting zone was used to validate the finding that cover crops sequestered SOC in the topsoil, subsoil and root zone of the NT, CP and MP treatments during the 12-year study. Additional sequestered SOC was lost as a result of being transported off of the plots and retained in lower slopes, transported to the stream or released to atmosphere.

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