Evaluation of Biomass Yield and Silage Quality of Maize-cowpea Intercrop in the Highlands of Eritrea

Abstract

The primary challenges confronting livestock production in Eritrea include inadequate feed quality and quantity. Small-scale farmers often struggle to afford high-protein concentrates to enhance low-quality fodder. This study evaluated the impact of intercropping maize and cowpea on forage biomass yield and quality, as well as to assess the silage quality of maize/cowpea forage mixtures. The study was conducted at the National Agricultural Research Institute (NARI) in southern highlands of Eritrea. Five treatments including maize monocrop, M:25%C, M:50%C, M:75%C and cowpea monocrop (C) in additive planting plan, replicated three times were compared in a randomized complete block design. A 1.4 m2 forage area from each plot including cowpea in the intercrops was harvested at half milk stage of the maize crop to determine biomass yield (122 days). The forage material was ensiled in 24 litre capacity plastic barrel ‘minisilos’ for 53 days before opening. Data on biomass yields, chemical composition of fresh and ensiled forage, silage fermentation and physical quality parameters were collected. The biomass yield in tons dry matter per hectare (tDM/ha) was significantly higher in Maize:50%Cowpea (22.67 tDM/ha) compared to maize monocrop (21.25 tDM/ha) and cowpea monocrop (9.22 tDM/ha). The land equivalent ration (LER) for the intercrops was 1.33-1.39, an indication that a forage yield advantage of intercropping. The crude protein (CP) content improved from 7.32% in maize monocrop, to 8.04%, 8.30% and 8.61% in TR2, TR3 and TR4, respectively. The silage of all intercrops treatments and the monocrop maize had a pH level of (3.91-4.04) and (3.93), respectively. The silage of the intercrops had ammonia-N ranging from 15.51-18.81 g/kg with a dry matter loss of 8.47 to 11.85 g/kg. It can be concluded that intercropping increased the forage DM yield, improved the CP content and maintained the acceptable silage quality levels (pH 3.7 – 4.3, ammonia N < 12% DM).