No abstract

The nonbloating perennial legume birdsfoot trefoil (BFT, Lotus corniculatus L.) is well suited for ruminant production on pastures, supporting greater weight gain and milk production than other forages. This study evaluated establishment options available to organic producers on subsequent BFT stands. We applied all combinations of spring vs. autumn planting, broadcast seeding rates of 3, 7, 20, and 34 kg pure live seed (PLS) ha−1, and use of an annual oat (Avena sativa L.) companion crop during establishment. These options were assessed using a split‐split‐split plot experimental design with four replications. Dry matter (DM) production and forage nutritive value under irrigation were assessed for 3 yr, and foliar cover was assessed on mature stands. In the first year after planting, DM production was less at 3 kg PLS ha−1 than at 20 or 34 kg ha−1, greater at 34 than at 7 kg PLS ha−1, and was reduced by a companion crop. Second and third year DM production for all treatments was similar and greater than 6000 kg DM ha−1. In the first year after planting, crude protein concentration was less, while neutral detergent fiber and acid detergent fiber concentrations were greater compared with subsequent years. In the third year after planting, cover of BFT was greater than 70% for all treatments. On the basis of this study, early autumn planting of BFT without a companion crop at rates from 7 to 20 kg PLS ha−1 is recommended for organic establishment of BFT.

Stem dry matter accumulation is correlated with a decline in digestibility in both birdsfoot trefoil (Lotus corniculatus L. [BFT]) and alfalfa (Medicago sativa L.), and the shear force required to harvest mature BFT stems can inhibit BFT grazing by ruminants. Decline in digestibility and increase in shear force are both correlated with increase in stem lignin content. Alfalfa stem development has been well documented, and our objective was to analyze stem development, lignification and tannin in BFT stems using alfalfa as a benchmark. The sixth internode from the base of ten BFT and two alfalfa control plants was sampled from 3 to 15 wk of stem regrowth in midsummer. Lignification occurred primarily in stem secondary xylem and was apparent in the xylary ring of Internode 6 by 5 wk of regrowth. The xylary ring reached maximum thickness by 7.5 wk of regrowth in both BFT and alfalfa but developed at a more rapid rate and to a greater thickness in BFT. Flowering in BFT began at 5.5 wk of regrowth, and full bloom was reached by 6.5 wk of regrowth. The number of cells containing tannin remained constant with stem development, which would decrease stem tannin concentration with internode maturation. Internode 6 of BFT is located 60 to 120 mm from the base of stems, within the recommended cutting height of 75 mm, with sufficient leaves and branches at subtending nodes to support shoot regrowth. These data relate growth and lignification in lower stems of BFT to grazing management recommendations.