Management and Environment Effects on Dry Matter Yields of Three Brassica Species
- M. Hagemann Wiedenhoeft
Brassica crops have potential use as a forage during summer, fall, and early winter months. The influence of planting date and harvest date on the initial and regrowth herbage yields for three Brassica species: rape (B. napus L., ‘Winfred’ in 1987 and ‘Emerald’ in 1988 and 1989), turnip (B. rapa L., ‘Purple Top’), and a turnip hybrid (B. rapa × B. pekinensis L., ‘Tyfon’) were investigated. The species were planted in late May to early June, late June to early July, and late July to early August in 1987, 1988, and 1989. Herbage yields before grazing were taken 64, 76, or 85 d after planting. The remaining herbage was allowed to regrow for 60, 70, or 80 d and then harvested. Averaged over planting dates, harvest dates, and species, initial and regrowt herbage dry matter yields were 3.4 and 1.2 Mg haha−1, respectively. The turnip hybrid produced the greatest amount of total herbage yield, 4.5 Mg haha−1, followed by the rape species, 4.1 Mg haha−1. The total herbage yield, 2.7 Mg ha−1, for the turnip species was low because there was little regrnwth. The herbage yields for 1987 and 1988 were not significantly different; 1989 yields were much lower, probably due to the wet climate conditions and high weed population. The earliest planting date produced the greatest herbage yields, followed by the mid-summer planting date. Because of cold temperatures and short days no regrowth herbage was produced from the late summer plantings. Forage Brassica crops could provide adequate herbage yields during the late summer months and well into early winter months, thereby reducing the need for purchased feed.
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