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Growing Legumes in Orchard Alleys as an Internal Nitrogen Source

Granatstein, D.;J.R. Davenport;E. Kirby. 2017.


The drive alley in modern apple (Malus X domestica Bork.) orchards often receives enough light to grow plants other than the typical perennial grass cover. By planting leguminous species in this area, it is possible to produce a portion of the nitrogen needs of the orchard by mowing the vegetation and blowing it onto the tree row where it mineralizes and releases available N over the tree roots. Four perennial legume species [alfalfa (Medicago sativa L.), ladino white clover (Trifolium repens L.), birdsfoot trefoil (Lotus corniculatus L.), kura clover (Trifolium ambiguum L.)] were compared with the resident grass cover crop in a mature apple orchard. All legumes were direct-seeded into the alley to avoid any soil disturbance and were successfully established. Legume biomass and tissue N were monitored, along with biweekly monitoring of tree row soil nitrogen with both soil sampling and ion exchange resins using Plant Root SimulatorÒ probes. Four mowings of alfalfa contained 43 kg total N/ha that was added to the tree row during the second season (2009), with a dry matter C:N of 10.8. Economically, legume nitrogen appears to be less expensive than other sources of organic N and may be cost competitive with synthetic fertilizer N when prices are high.

Key Words

apple, alfalfa, clover, trefoil, direct seeding, ion exchange probes