Berseem clover seeding rate and harvest management effects on forage yields and nutrient uptake in a swine effluent spray field



A 3-year study was conducted on a Prentiss sandy loam near Pheba, Mississippi to determine optimum berseem clover (Trifolium alexandrinum L.) seeding rate (SR) for dry-matter (DM) yield and nutrient uptake in an annual clover–perennial bermudagrass [Cynodon dactylon L. (Pers.)] sward, fertilized in April to October with swine effluent. Seed of annual berseem clover (cv. ‘Bigbee’) was drill-seeded in October at 4, 8, 12, 16, 20 and 24 kg ha−1 and harvested either twice in April and May (spring) or once in May. Yield of clover harvested twice was less than that harvested once (5410 vs. 7566 kg ha−1), but N and P uptake were greater in the double-harvest regime. Annual clover responses to SR were described by quadratic trends. Pooled across years and harvest regimes, the optimum SR for DM yield was 16·5 kg ha−1 and for P, Cu and Zn uptake, it was 15·7, 14·8 and 16·0 kg ha−1, respectively. Bermudagrass DM yield decreased linearly as SR increased by approximately 6·3 and 66·7 kg DM kg seed−1 in double- and single-harvest regimes, respectively. For clover–bermudagrass, the optimum SR for DM yield was 14·0 kg ha−1, and for P, Cu, and Zn uptake, it was 15·1, 14·6 and 15·3 kg ha−1, respectively. A SR of 14·0–14·9 kg ha−1 and a first harvest of clover in April appeared to optimize hay yields and uptake of nutrients in clover–bermudagrass. Because bermudagrass N requirement is usually met by swine effluent irrigations, overseeding annual clover would chiefly satisfy producer needs for early forage production.