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This article in AJ

  1. Vol. 88 No. 4, p. 527-535

    * Corresponding author(s): torbert@brcsun0.tamu.edu
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Winter Legume Cover Crop Benefits to Corn: Rotation vs. Fixed-Nitrogen Effects

  1. H. Allen Torbert ,
  2. Donald W. Reeves and
  3. Richard L. Mulvaney
  1. U SDA-ARS Grassland, Soil and Water Research Laboratory, 808 East Blackland Rd., Temple, TX 76502
    U SDA-ARS Natl. Soil Dynamics Lab., Box 3439, Auburn, AL 36831-3439
    D ep. of Agronomy, 1102 S. Goodwin Ave., Univ. of Illinois, Urbana, IL 61801



The use of winter legume cover crops for erosion control and to provide additional N to the soil is well established. Other potential benefits to legume cover crops besides N additions have been recognized, but have not been quantified. The objective of this study was to separate the fixed-N effects from the rotation effects in a winter legume cover cropping system. A field study was initiated in 1989 on a Norfolk loamy sand (fine, loamy, siliceous, thermic Typic Kandiudult) in east-central Alabama. Corn (Zea mays L.) was grown following (i) ‘Tibbee’ crimson clover (Trifolium incarnatum L.), (ii) a partially ineffective-nodulating crimson clover, CH-1, (iii) rye (Secale cereale L.), and (iv) winter fallow. The plots were split into four rates of fertilizer N (0, 56, 112, and 168 kg N ha−1) in a split-plot experimental plan. An evaluation of different methods of distinguishing fixed-N vs. rotation effects of the winter annual legume cover crop to a subsequent corn crop was made. Regression analysis of the effect of N application rates on N2 fixation by crimson clover (fertilized with 45 kg N ha−1) indicated that CH-1 clover biomass contained approximately 40 and 101 kg N ha−1 and Tibbee clover contained approximately 51 and 119 kg N ha−1 in 1990 and 1991, respectively. In both years of the study, crimson clover substantially increased corn yield compared with winter fallow, with a yield increase at the highest fertilizer N application level of 7 and 22% for 1990 and 1991, respectively. Estimates of yield increases due to rotation ranged from negative to 40%. The data indicated that winter cover crops improve corn yield and that besides soil N availability, there was very little difference between the beneficial effects of clover and the rye cover crops to corn.

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