Evaluation of Nitrogen Fertilizer and Lime on Grain Yield, Protein Content and Kernel Weight of Barley (Hordeum vulgare L.) in Kenya

Abstract

Barley requires adequate nitrogen (N) for high grain yields and quality malting, but the balance between adequate and excessive N is important therefore field experiments were set up between July 2011 and July 2012 to evaluate the effects of nitrogen fertilizer rates and liming on the grain yield and malting qualities of barley (grain protein content and kernel weight). The experiments were conducted at medium altitude at University of Eldoret (2185 m asl) and at high altitude in Mau-Narok (2740 m asl) in Kenya. Nitrogen as C.A.N fertilizer was applied at 5 levels 0, 30, 40, 50 and 60 kg N/ha, at planting. Phosphorus (TSP) at 20 Kg P/ha, and potassium (muriate of potash) at 35 kg/ha as K20, were applied as blanket in plots with nitrogen treatments. There were two controls; absolute control (no fertilizer) and the other one having phosphorus applied. Lime was applied at  1.5 t/ha. Split plot arrangement in RCBD design was adopted. Both sites were acidic (soils) and deficient in phosphorus with Mau-Narok having more soil N. The effect of nitrogen on grain yield was highly significant (P=.001). Increasing N rates beyond 40 kg N/ha increased the grain protein content beyond the malting range. Effect of lime on grain yield was significant (P≤.01) for both sites. Lime treatments had higher grain protein contents. Lime-nitrogen interaction on kernel weight was highly significant (P≤.001) but not for grain yield. Application of lime in combination with N rates at 30 and 40 N kg/ha produced best results for grain yield (>7 t/ha), kernel weight and grain crude protein (10-13.5%). Nitrogen rates at 30 N and 40 N kg/ha produced highest grain yield, highest kernel weight and recommended maltable grain protein content and therefore is recommended as optimum agronomic rates for both sites. In addition, liming is recommended for Eldoret site while phosphorus use for Mau-Narok.