Abstract

The aim of this study was to determine the production of improved Brachiaria grass in comparison with indigenous Brachiaria under low rainfall and aluminium toxicity areas of Rwanda. Three varieties and five hybrids of Brachiaria grass from CIAT and two local grasses (control) were used for on-farm participatory trials without fertilizer application. Twelve farms were selected in each study area and on each farm ten grasses were established in 2 × 3 m plots. Herbage was harvested six times during the year at two monthly intervals. Each cut, dry matter (DM) was measured. The crude protein (CP), calcium (Ca) and phosphorus (P) were also measured once in the wet season and once in the dry season. In the low rainfall area, Brachiaria brizantha cv. Toledo and Brachiaria decumbens (local) had the highest DM yields (5.71 and 5.61 t ha^-1 respectively), while DM of the rest of the grasses ranged from 1.2 to 5.13 t ha^-1. In the acidic soil area, Brachiaria hybrid Bro2/1485 had higher DM (5.95 t ha^-1) than the rest of the grasses (1 to 4.47 t ha^-1). The highest quality grass was Brachiaria hybrid Bro2/1485 which obtained a CP value of 12.15% in the low rainfall area, whereas in the acidic soil area hybrid cv. Mulato II obtained the highest CP value of 11.6%. In the low rainfall area the Brachiaria hybrid cv. Mulato obtained a high mean Ca value of 2.15% while in the acidic soil area, cv. Marandu obtained a high Ca value of 2.41% during the wet and dry seasons. The cv. Toledo had high P (0.28%) compared to the other grasses (0.07 to 0.11%) in the low rainfall area. In the acidic soil area, the Brachiaria hybrid Bro2/1485 had high P of 0.53% as compared to other grasses in which P varied between 0.16 and 0.47%. Local control grasses had lower nutrients than the improved Brachiaria grass in the low rainfall and acidic soil area. Although, Brachiaria hybrid cv. Mulato II was not the most productive grass, it was selected by farmers as the preferred cultivar at both sites because of its adaptability to low rainfall and acidic soil stress, and its production of green forage year round without any input of fertilizer.

Key words: Dry matter production, forage quality, forage selection.