No-till alfalfa stand termination strategies: Alfalfa control and wheat and barley production

Abstract

alfalfa stand termination strategies: Alfalfa control and wheat and barley production. Can. J. Plant Sci. 79: 71-83. Crop rotations involving perennial alfalfa (Medicago sativa L.) present the unique problem of terminating the alfalfa stand. Intensive tillage currently used to terminate alfalfa increases the risk of soil erosion and reduces many of the rotational benefits from alfalfa. Inadequate alfalfa termination results in severe competition to the following crop by surviving alfalfa plants. Field experiments were conducted in Manitoba between 1991 and 1993 with the following objectives: 1) to investigate no-till vs. tillage management systems for successful alfalfa termination, 2) to compare fall vs. spring alfalfa termination, 3) to compare the performance of barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) seeded into alfalfa residue, and 4) to determine the relationship between alfalfa escapes and grain yield. Fall termination produced higher grain yields than spring termination, however this advantage was only achieved with the better termination treatments capable of lowering alfalfa regrowth below a critical level. The best herbicide treatment tested here was glyphosate at 1.78 kg a.i. ha -1 . Successful treatments would have to reduce residual alfalfa basal crown area (a measure of alfalfa regrowth potential) after cereal grain harvest to below 2%. Alfalfa escapes reduced yield of following wheat and barley crops similarly (P > 0.05). When alfalfa termination treatment method allowed some regrowth, in-crop herbicide treatments significantly reduced alfalfa basal crown area. Results of this study indicate that it is feasible to terminate alfalfa with herbicides in the absence of tillage, however an overall cropping strategy, including adequate consideration of weeds present in alfalfa fields at time of termination, must be considered.Key words: Herbicides, competition, recropping, no-till, alfalfa regrowth, soil conservation, sustainable cropping Bullied, W. J., Entz, M. H. et Smith, S. R. 1999. Strategies d'interruption de la culture de luzerne en régime de semis direct : maîtrise de la luzerne dans la production de blé et d'orge. Can. J. Plant Sci. 79: 71-83. Les rotations des cultures comportant une ou plusieurs années en luzerne (Medicago sativa L) présente le problème particulier d'avoir à arrêter la croissance de la sole de luzerne. D'une part, les façons culturales intensives couramment utilisées jusqu'ici pour détruire la luzerne accroissent les risques d'érosion du sol et effacent une bonne partie des avantages apportés par la légumineuse, de l'autre côté, un peuplement de luzerne mal maîtrisé impose une forte compétition à la sole suivante de la part des plantes de luzerne survivantes. Les expériences au champ réalisées au Manitoba entre 1991 et 1993 avaient pour objet 1) de comparer l'efficacité du semis direct et du travail classique du sol relativement à la destruction de la luzerne, 2) de comparer l'automne au printemps comme meilleure époque pour détruire la luzerne, 3) de c...

Preharvest glyphosate in alfalfa for seed production: Effect on alfalfa seed yield and quality

“…A preharvest application of glyphosate is registered for forage alfalfa just before the final cut in the termination year. When used in this manner, glyphosate kills alfalfa plants and facilitates crop rotation (Bullied et al 1999). On the other hand, there is evidence to suggest that glyphosate application during the reproductive stage of alfalfa can be much less injurious with a 22-33% stand reduction at 800 g a.i.…”

Soil Water Dynamics after Alfalfa as Influenced by Crop Termination Technique

“…Yields of crops sown after alfalfa may or may not be affected by stand termination technique. Bullied et al (1999) observed similar yields with tilled and no-till systems, provided that complete alfalfa suppression was achieved. Higher crop WUE under no-till (Lafond et Abbreviations: WUE, water use efficiency.…”

“…Capturing and storing fall and overwinter precipitation is especially important in alfalfa systems, where soil often is drier (Campbell et al, 1990). Effective herbicide termination systems are available for alfalfa (e.g., Bullied et al, 1999); however, only those that leave 15 to 20 em of standing crop residue on the surface would be expected to trap significant amounts of snow (de Jong and Steppuhn, 1983). Because including alfalfa in a crop rotation increases soil aggregation (Raimbault and Vyn, 1991) and adds organic matter (Campbell et al, 1990), water infiltration rates and soil water storage capacity may well be higher in alfalfa-containing than in annual crop rotations.…”

Natural Reseeding by Forage Legumes following Wheat in Western North Dakota

“…Wheat growth and grain yield were suppressed in plots where persisting legume plants occurred. Alfalfa was controlled by applications of clopyralid, glyphosate, and other herbicides before seeding wheat in a subhumid region (Bullied et al, 1999), but these same treatments did not control alfalfa consistently in western North Dakota (Carr, unpublished data, 2004). The efficacy of many herbicides declines when hot and dry conditions develop, as commonly occurs in late summer in much of the northern Great Plains.…”