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This article in AJ

  1. Vol. 78 No. 1, p. 19-23
    Received: Sept 4, 1984

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Alfalfa Dry Matter and Nitrogen Production, and Fertilizer Nitrogen Response in Legume-Corn Rotations1

  1. O. B. Hesterman,
  2. C. C. Sheaffer,
  3. D. K. Barnes,
  4. W. E. Lueschen and
  5. J. H. Ford2



Nondormant alfalfa (Medicago sativa L.) germplasms have been selected for increased storage of reduced N in roots and crowns. It is important to learn how this improved germplasm will affect yield of a subsequent nonlegume crop in a cropping sequence. Our objectives were to (i) compare effects of two harvest systems on the forage yield, quality, and N incorporated for the nondormant experimental ‘MN ROOT N’ population and the moderately dormant cultivar ‘Saranac AR’ and (ii) evaluate effects of previous cropping and fallow treatments on grain yield and N response of a subsequent corn crop. Field studies were conducted in 1982 and 1983 at four Minnesota locations on a Hubbard loamy sand (Udorthentic Haploboroll), Webster silt loam (Typic Haplaquoll), Normania clay loam (Aquic Haplustoll), and Webster clay loam (Typic Haplaquoll). Firstyear rotation components included seeding year alfalfa, corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and fallow. The secondyear component was corn. Alfalfas were subjected to two harvest systems. The two alfalfas did not differ in total forage production, but Saranac AR tended to have higher crude protein and digestible dry matter concentrations than MN ROOT N. MN ROOT N had greater root dry matter yield and N concentration than Saranac AR. Total N incorporated was 14% greater for MN ROOT N than Saranac AR under the one-cut system and 41% greater under the threecut system. Total N incorporation was 84% greater for the one-cut (157 kg ha−1) than for the three-cut (85 kg ha−1) system. Differences in second-phase corn yields were correlated with differences in firstphase alfalfa N incorporation at one of four locations. Alfalfa was a more effective first-phase rotation crop for corn than corn, soybean, or fallow. With no N applied, second-phase corn grain yields were 84% greater after first-phase alfalfa (6.8 M g ha−1), 33% greater after soybean (5.1 M g ha−1), and 61% greater after fallow (6.1 Mg ha−1) than after corn (3.7 Mg ha−1). Alfalfa cultivars and harvest systems affected the yield of a subsequent corn crop; however, harvest system effects were greater.

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