Natural Reseeding by Forage Legumes following Wheat in Western North Dakota

Abstract

rated into rotations with wheat and other grain crops in the Canadian prairie region (Entz et al., 1995). Addi-Legume pasture is rotated with wheat (Triticum spp.) to enhance tional benefits and synergies between crop and livestock grain production sustainability. The legume species maintain or enhance wheat yield and regenerate from the soil seed bank. Our objec-enterprises can occur when grazed pasture is rotated with tives were to determine: (i) grain yield when wheat followed legume wheat or other grain crops (Entz et al., 2002). A review forages and (ii) if legume species regenerated naturally following by Martin (1996) suggested that grassy weed invasion wheat in western North Dakota. Ten to 30 legume species were estabwas reduced by rotating grazed legume forages with lished in field experiments in 1999, 2000, and 2001. Legumes that rewheat compared with cropping systems that did not generated or persisted in the second year were terminated chemically include pasture. before seeding wheat in the third year. Plots were fallowed in the sec-Integrated crop-livestock systems have been develond year where legumes failed to regenerate or persist. Grain yield oped in response to the environmental degradation and ranged from 1290 to 4100 kg ha Ϫ1 across the 3 yr when wheat followed poor economic returns that occur when growing wheat yellow-flowered sweetclover (Melilotus officinalis Lam.) and was equal in regions outside of the Great Plains. For example, wheat or enhanced compared with fallowed plots where legumes did not reseed in 2 yr (P Ͻ 0.05). Grain yield never was enhanced and some-is rotated with clover (Trifolium spp.) and medic (Medtimes was reduced when wheat followed other legume forages com-icago spp.) pastures in Australian ley farming in an inpared with fallowed plots. Legume seedlings regenerated following tegrated crop-livestock approach that provides flexibilwheat in birdsfoot trefoil (Lotus corniculatus L.) plots in all 3 yr, and ity and diversity to dryland agriculturists (Carter et al., forage production exceeded 3 Mg ha Ϫ1 in 2 yr. Other legume species 1982). The annual clovers and medics regenerate from failed to regenerate or produced less forage than birdsfoot trefoil in the soil seed bank and provide forage during the pasture at least 1 yr. Birdsfoot trefoil has potential as a regenerating pasture phase for sheep (Ovis aries L.) and cattle (Bos taurus species, but strategies are needed to enhance grain yield in legume-

Review: Redesigning Canadian prairie cropping systems for profitability, sustainability, and resilience

“…Carr et al (2005b), in North Dakota, reported yield reductions in systems with self-seeding forage legumes in some cases, due to soil water depletion, while in other cases there was no effect on yield. At Indian Head, SK, May et al (2010) found that after several years of including black medic in annual crop rotations, crop yields were increased by up to 57%, but only where fertilizer was applied at 20% of the recommended rate, suggesting that medics may provide the greatest benefit in organic and low-input crop production systems.…”

“…(1 in North Dakota and Saskatchewan (Carr et al 2005b;May et al 2010). Available soil moisture appeared to be the main factor affecting biomass production in both studies.…”

“…Grazing ruminant livestock may promote increased legume reseeding by removing crop residue while simultaneously burying legume seeds through hoof action (Carr et al 2005b). …”

Determination of Maximum Herbaceous Production in Anyigba, a Derived Savanna

“…Low production is obtained in the Sudanian zone as a result of excessive grazing (Carr et al, 2005). The climatic factor of moisture regime and possibly temperature, together with heavy livestock grazing during the rainy-season has led to high proportion of annuals and short perennial grasses and low total crop weight.…”

Black medic (Medicago lupulina) germplasm screening for use as a self-regenerating cover crop on the Canadian Prairies

“…This rating was later associated with numerical estimates based on the quantity of seed collected from selected plots, with a rating of 1 indicating very poor seed production (estimated at < 200 seeds m -2 ), 3 indicating adequate seed production (estimated at 1000 seeds m -2 ) and 5 indicating excellent seed production as typically exhibited by George (estimated at 3000 seeds m -2 ). A seed production rating of 3 or higher was considered to be adequate for self-regeneration from the soil seed bank since a minimum of 200 seedlings m -2 is necessary for self-regenerating legumes to maintain productivity (Carr et al 2005b) and seedling recruitment rates for black medic in the prairie provinces are approximately 20% (Braul 2004;Wilson 2005).…”