Nitrogen Contribution to Succeeding Corn from Alfalfa and Red Clover
1987
Bruulsema, T. W. | Christie, B. R.
The use of leguminous crops as plowdown has stimulated interest in their contribution to soil fertility. The contribution of N from single-year plowdown to a succeeding corn (Zea mays L.) crop was evaluated in two field experiments located at Elora, Ontario, on a Guelph-London loam series Grey-Brown Luvisolic (Typic Hapludalf) soil. In Experiment 1, 20 cultivars of alfalfa (Medicago sativa L.) and 10 cultivars of red clover (Trifolium pratense L.) were compared. Experiment 2 included two cultivars each of alfalfa and red clover under three management treatments. Nitrogen yield of plowdown legumes was considered in relation to the yield and wholeplant N concentration of the succeeding corn crop. In both experiments, whole-plant N concentration of corn was significantly higher following alfalfa than following red clover. This suggested that alfalfa N was more readily mineralized than that of red clover, as predicted by a decomposability index based on the C/N ratio and lignin concentration of the plowdown material. However, corn yield following alfalfa plowdown was not always greater than that following red clover. Factors other than N-supply may have influenced corn yield response to legume plowdown. Although significant cultivar variation in plowdown N yield was observed, there appeared to be no association with succeeding corn yield and N concentration. In general, legume plowdown supported corn yields equivalent to those achieved with 90 to 125 kg ha⁻¹ of fertilizer N.
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