Forage Sorghum Response to N Fertilization and Harvest Intervals

Abstract

Differences between locations, hybrids, N levels, cutting intervals and cuttings, and interactions of locations x hybrids, locations x N, locations x cutting intervals, locations x cuttings, cutting x N, and cutting intervals x N were significant for most traits in a study of the effect of N applications and cutting intervals on dry forage and crude protein yields, crude protein content, plant height and leaf area of three sorghum-sudangrass hybrids (Sorghum bicolor L. Moench) at two locations in Puerto Rico. Treatments included sidedressed N at 0, 80 and 160 kg/ha and three cutting intervals of 60, 75 and 90 days. Dry forage yields increased significantly with N fertilization, especially with the initial increment and with cutting intervals. Crude protein content was highest at 60 days and diminished as cutting interval increased. A three-way forage hybrid (A Tx624 x B Rhodesian sudan) x Common sudan produced the highest dry forage and crude protein yields and crude protein content compared with the single-crosses A Tx23 x Greenleaf sudan and A Tx624 x Common sudan.