No-till perennial forage establishment in western Montana
Strauch, Oscar Eduardo
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No-till forages offer an opportunity to convert old forage stands to high-yielding pastures. Sod, soil water control and forage species are key factors in determining the success of no-till application. Experiment 1 was conducted to determine optimum vegetation control and moisture on alfalfa in the spring. In experiment 2, adapted grasses and legumes were compared under tilled and no-till seedbed preparation to assess their performance. In Experiment 1, the effects of timing of glyphosate [N-(phosphonomethyl) glycine] application, two alfalfa cultivars (including a roundup ready alfalfa) and five irrigation levels were investigated in Bozeman, MT in an old alfalfa stand in a subirrigated location. Experiment 2 was planted contiguous to Experiment 1; 11 forage species were planted in early summer (24 June) and late summer (28 August) under irrigation. During establishment year, applying glyphosate four weeks before planting resulted in a higher plant population and alfalfa yield than all the other treatments. Differences were not detected in the post-establishment year. The establishment of no-till alfalfa was very low in the second planting year, likely due to wet and colder weather. Alfalfa yield during the establishment year responded significantly to irrigation level and the effect was not relevant for yield in the post-establishment year. No-till legumes and grasses in the summer resulted in yields similar to those following conventional seedbed preparation although higher in early summer than late summer. Grasses had about four times higher yields than legumes in part, because post-emergence broadleaf control was less effective in legumes. Late summer planting resulted in high weed encroachment and low target forage yields. These results indicate that delaying planting four weeks after spraying with glyphosate and controlled irrigation is a promising no-till alfalfa planting system but highly dependent on establishment weather conditions. No-till grasses offer an opportunity to impact the wide use of no-till to increase yield in an old alfalfa stand, but post-emergence weed control would be a key management especially in legumes.