The Impact of Intercropping Annual ‘Sava’snail Medic on Corn Production

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Interseeding a leguminous cover crop into corn (Zea mays L.) may reduce corn yields. By understanding the mechanisms responsible for yield reductions, improved management strategies can be developed. The objective of this study was to determine the influence of an annual medic (Medicago scutellata Mill cv. Sava) interseeded into corn at planting on N and water stress in corn. Field research was conducted at three South Dakota sites. Treatments were two broadcast medic (0 and 33 kg ha−1) and two N (0 or recommended) rates. Water infiltration was measured at Aurora in 1997 and 1998. Carbon-13 discrimination (Δ) in corn grain was measured at Aurora in 1998 and Beresford in 1998. Medic biomass at Aurora in 1997, Aurora in 1998, and Beresford in 1998 was 1290, 215, and 913 kg ha−1, respectively. At Aurora, on 11 July 1997, medic increased water infiltration from 0.0156 to 0.035 cm s−1Similar results were measured at Aurora in 1998. Medic reduced corn growth as early as 17 July at Aurora in 1997 and 19 June at Beresford in 1998. Associated with reduced corn biomass production in the fertilized treatments were lower N concentration and fertilizer efficiency. Interseeding medic into corn did not increase Δ in corn at Beresford in 1998 or Aurora in 1998. These results suggest that the negative effects of medic on corn primarily resulted from N stress and not increased water stress. Given these results, management strategies that reduce the competition between medic and corn for N should be developed.

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Agronomy Journal





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