
TY  - JOUR
A1  - Evans, J. 
A1  - Scott, G. 
A1  - Lemerle, D. 
A1  - Kaiser, A. 
A1  - Orchard, B. 
A1  - Murray, G. M. 
A1  - Armstrong, E. L. 
T1  - Impact of legume &#39;break&#39; crops on the residual amount and distribution of soil mineral nitrogen
JF  - Australian Journal of Agricultural Research
JO  - Aust. J.  Agric. Res.
Y1  - 2003
VL  - 54
IS  - 8
SP  - 763
EP  - 776
KW  - forage conservation, nitrogen fixation.
UR  - https://doi.org/10.1071/AR02149 
N2  - Important factors in the successful uptake of grain legumes by cereal growers have been their capacity to increase soil N and control cereal disease, as these have underpinned high yields in following wheat crops. However, alternative 1-year legume crops are required to introduce additional biodiversity and management flexibility for cereal growers. The effects on soil mineral N and potential contribution to soil total N of other legume enterprises were studied. These included vetch (Vicia bengalhensis) or clovers (mix of Trifolium alexandrinum, T. versiculosum, T. resupinatum) managed for green manure; pea (Pisum sativum), vetch, or clovers managed for silage; and clovers managed for hay. These were compared with pea and lupin (Lupinus angustifolius) managed for grain production. Wheat was also included as a control. The legumes were grown in acidic Red Kandasol soil at Wagga Wagga in southern New South Wales, in 1996, 1997, and 1998. Mineral N was measured in the autumn or winter of seasons 1997 and 1998 respectively. Amounts of stubble residue N were measured in all seasons. The green manure crops, particularly vetch, produced more mineral N than both grain legumes. The forage conservation crops (silage or hay) produced similar amounts of mineral N to grain pea and more than grain lupin. For the grain and green manure legume crops, variation in amounts of mineral N was explained by the total N content of legume stubble residue, but for the forage conservation crops, more mineral N was measured than was predictable from stubble N. The amounts of mineral N at different soil depths differed between legume treatments and experiments (sites and years). Based only on above-ground plant N, the green manure crops contributed more to increasing total soil N than grain legumes; in turn, the grain legumes contributed more than the forage conservation crops. It was concluded that alternative annual legume enterprises to grain legumes may provide at least similar enrichment of soil mineral N early in the following season, and that all annual legume enterprises may accumulate nitrate deep in the soil profile in some seasons. 
ER  -

