Yield and Quality of Soybean Hay as Influenced by Stage of Growth and Plant Density
1983
Munoz, A. E. | Holt, E. C. | Weaver, R. W.
Soybeans [Glycine max (L.) Merr.] are known to have potential for hay production but additional cultural and harvest practice information is needed to optimize production and forage quality. Nodulating ‘Lee’ cv. of soybeans was grown on Ships clay (very fine, thermic, Udertic Haplustolls) at densities of 97,100, 194,200 and 291,300 plants/ha in 68-cm row widths to evaluate the effect of stage of maturity at harvest and planting density on the quality (percent digestibility and crude protein) and dry matter yield of the soybean hay. The plant tops were separated into leaflets, stems plus petioles, and pods plus grain. Dry weight, in vitro dry matter digestibility (IVDMD) and crude protein (percent N ✕ 6.25) were determined for each sample. Plant density had a small negative effect on IVDMD, a large positive effect on dry matter (DM) yield and no significant effect on the percent crude protein of the soybean plant. Age had a significant effect on the proportion and DM production of plant components, IVDMD of leaves and stems but not pods and total plant, and protein content. When the pods were filled and leaves were beginning to turn yellow, the percentages of leaves, stems, and pods were 28, 36, and 36, respectively with a total DM yield of 12.4 metric ton/ha. The highest protein (20.2%) and IVDMD (62.2%) values for the total plant were at the pod-filled stage. For optimum yield, crude protein and digestibility, the best time to cut soybean for hay appears to be when pods are filled and some leaves are starting to turn yellow.
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