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Yield, Nutritive Value, and Profitability of Direct‐Seeded Annual Forages following Spring‐Terminated Alfalfa
Author(s) -
Noland Reagan L.,
Sheaffer Craig C.,
Coulter Jeffrey A.,
Becker Roger L.,
Wells M. Scott
Publication year - 2017
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2017.03.0182
Subject(s) - agronomy , forage , fertilizer , neutral detergent fiber , biology , legume , sorghum , weed , biomass (ecology)
Core Ideas Forage yield increased with fertilizer N only when conditions were cool and wet. Weed biomass was frequently increased with the addition of fertilizer N. Fertilizer N did not increase economic net return in 2 of 3 site‐years. Annual ryegrass often resulted in consistent establishment and greatest economic return.Winter‐kill of alfalfa ( Medicago sativa L.) causes substantial yield losses in northern environments, requiring alternative forages to meet livestock needs. This study explores the forage yield, nutritive value, and N response of seven annual forage species and one grass–legume biculture, no‐till planted into spring‐terminated alfalfa. Forages were planted in late May at Rosemount, MN, in 2014 and 2015 and at Waseca, MN, in 2015 with split‐plot factors of three N fertilizer rates (0, 56, and 112 kg N ha −1 ) and were harvested on approximately 30‐d intervals. When successfully established, teff [ Eragrotis tef (Zuccagni) ‘Summer Lovegrass’] and sudangrass [ Sorghum bicolor (L.) subsp. drummondii (Nees ex Steud.) ‘PCS 3010’] were among the highest‐yielding species, with yields ranging from 4.2 to 9.9 Mg DM ha −1 and 6.8 to 8.9 Mg DM ha −1 , respectively. Fertilizer N increased yields of all species at Rosemount in 2014; however, N needs were met by terminated alfalfa at both locations in 2015. Weed biomass increased with added fertilizer N in site‐years when weeds were present. Nitrogen fertilization improved forage nutritive value through decreased neutral detergent fiber concentration and increased crude protein concentration and neutral detergent fiber digestibility (48‐h in‐vitro) in all site‐years. However, N fertilization had no effect on economic net return in 2 of 3 site‐years. Annual ryegrass [ Lolium multiflorum (Lam.) ‘Jumbo’] most consistently resulted in the greatest net return. No‐till planting annual forages into terminated alfalfa can provide forage to offset losses and utilize alfalfa N in situations of alfalfa winter‐kill.