The influence of date of planting and fertilizer application on growth components of Columbus grass (Sorghum almum)
Trials were conducted at Gangara in the Northern Guinea Savanna ecological zone of Nigeria during the 1990 and 1991 rainy seasons. The effects of date of planting (4th, 14th, 24th June and 4th July) and levels of nitrogen fertilizer (0, 5O, 100, 150 and 200 kg/ha) on growth components of Sorghum almum were investigated. Planting in mid-June (14th June) in 1990 and early-July (4th July) in 1991 resulted in superior stand establishment and dry matter yields (P < 0.05) than older dates. In mid-June and early-July planting 14 days post-planting, plant densities were 7 .0 and 9.0 culms/m2 while plant heights were 20.4 and 11.3cm for the respective years. It had high tillering capacity and irrespective of date of planting (except for early-June planting) plant densities by 56 days post-planting (OPP) were greater than, 100 culms/m2 Plant heights at this stage were greater than 100 culm//m2 and were generally above 200cm. Ninety DPP the pasture was at full bloom/hard dough stage. DM yields then ranged from 8.0 to 11.4 tDM/ha in 1990 and 9.6 to 14.7 tDM/ha in 1991. Similarly seed yield for the respetive years were 894.7 and 836.3 kg/ha. Fertilizer application (P < 0.05) plant vigour, tillering and dry matter yield up to the higliest N applied. In the first year's trial, plant density at 35 days post-planting ranging from 12.0 to 29.0 culms/m2 while in the second year the range was 13.0 to 26.0 culms/m2 'The corresponding values at 56 DPP (i.e.. 42 days following N application were 32.0 to 81.0 and 45.0 to 101.0 culms/m2 Dry matter yields rose steadily from 6.5 to 12.5 tDM/ha m 1990 and from 8.9 to 13.6 tDM/ha in 1991 as fertilizer was increased from 0 to 200 kgN/ha. Seed yield during the same period for the respective years varied from 416.0 to 753.0kg/ha. This study has shown that planting between mid-June and early-Joly with fertilizer application or 100 to 200 kgN/ha favour S. almum establishment and production in the Northern Guinea Savanna of Nigeria.
Key Words: Columbus grass, planting date, fertilizer, plant density, height, seed yield, Guinea Savanna.