Agronomic benefits of alfalfa mulch applied to organically managed spring wheat.

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Weins, M.J.
Entz, M.H.
Martin, R.C.
Hammermeister, A.M.

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Agricultural Institute of Canada


Field experiments were established at two locations in Manitoba in 2002 and 2003 to determine N contribution, moisture conservation, and weed suppression by alfalfa mulch applied to spring wheat (Triticum aestivum L). Mulch treatments included mulch rate (amount harvested from an area 0.5×, 1× and 2× the wheat plot area), and mulch application timing (at wheat emergence or at three-leaf stage). Positive relationships were observed between mulch rate and wheat N uptake, grain yield, and grain protein concentration. At Winnipeg, the 2× mulch rates (3.9 to 5.2 t ha–1) produced grain yields equivalent to where 20 and 60 kg ha–1 of ammonium nitrate-N was applied in 2002 and 2003, respectively. Where mulch and ammonium nitrate produced equivalent grain yield, grain protein in mulch treatments was often higher than where chemical fertilizer was used. N uptake was also observed in the following oat (Avena sativa L.) crop. The highest mulch rate (2×) produced higher N uptake and grain yield of second-year oat compared with ammonium nitrate treatments. N use efficiency of mulch-supplied N by two crops over 2 yr [calculated as (treatment N uptake – control N uptake)/total N added] was between 11 and 68%. Mulch usually suppressed annual weeds, with greater suppression with late- than early-applied mulch. Increased soil moisture conservation was observed with high mulch rates (≥ 4.3 t ha–1) at three sites. Alfalfa mulch holds promise for low-input cropping systems when used on wheat at the 2× rates.



Legume N,, low-input farming, integrated weed management, wheat protein, N des légumineuses, agriculture rationnelle, lutte intégrée contre les mauvaises herbes, protéines du blé


Wiens, M.J., Entz, M.H., Martin, R.C. and Hammermeister, A.M. "Agronomic benefits of alfalfa mulch applied to organically managed spring wheat." Canadian Journal of Plant Science 86 (2006): 121-131