GRASS-LEGUME BICULTURES AS WINTER ANNUAL COVER CROPS

Citation
Nn. Ranells et Mg. Wagger, GRASS-LEGUME BICULTURES AS WINTER ANNUAL COVER CROPS, Agronomy journal, 89(4), 1997, pp. 659-665
Citations number
19
Categorie Soggetti
Agriculture
Journal title
ISSN journal
00021962
Volume
89
Issue
4
Year of publication
1997
Pages
659 - 665
Database
ISI
SICI code
0002-1962(1997)89:4<659:GBAWAC>2.0.ZU;2-Y
Abstract
Grass-legume bicultures as winter annual cover crops may combine the N scavenging ability of grasses and the biological N-2 fixation capacit y of Legumes to improve N management in crop production systems of the southeastern USA. A 3-yr field experiment was conducted on a Norfolk loamy sand (fine-loamy, kaolinitic, thermic: Typic Kandiudults). The f ocus of this research was to examine the differences among legume mono cultures and grass-legume bicultures with regard to early spring dry m atter (DM) and N accumulation, and related effects on soil inorganic N levels and subsequent corn (Zea mays L.) yield. Austrian winter pea [ Pisum sativum E. subsp. sativum var. arvense (L.) Poir.], crimson clov er (Trifolium incarnatum L.), common vetch (Vicia sativa L.), and hair y vetch (Vicia villosa Roth) were grown in monoculture and in bicultur es with rye (Secale cereale L.), oat (Avena sativa L.), and wheat (Tri ticum aestivum L.). Aboveground plant material was harvested in early March, late March, and mid-April. Biomass was separated into component species and analyzed for total N and C concentrations. Averaged over 3 yr, legume component DM accumulation in monoculture and biculture ra nged from 0.87 to 2.53 Mg ha(-1), with a ranking of Austrian winter pe a > hairy vetch > common vetch > crimson clover. For the same period, the grass component DM accumulation ranged from 1.31 to 2.28 Mg ha(-1) , in the order rye = oat > wheat. Three year mean N accumulation value s for the legume component followed the same relative ranking and rang ed from 24 to 93 kg N ha(-1). Grass factor N content ranged from 18 to 39 kg N ha(-1) in the order rye > oat > wheat. For all bicultures, th e average C:N ratio over the 3-yr experiment was <30, suggesting that net N mineralization would occur from the decomposing cover crop resid ues. Profile soil inorganic N (0 to 90 cm) was greater in legume monoc ulture than in grass-legume biculture: treatments, indicating the abil ity of grasses to capture sail N. Corn yield was affected by the treat ments in 1 of 3 yr, with greater yields following a Legume monoculture than a grass-legume biculture. Collectively, these results suggest th at grass-legume bicultures as winter annual cover crops have the poten tial to utilize residual soil NO2 and thereby minimize leaching while adding fixed N to cropping systems in the southeastern USA.