Response of Sorghum-groundnut to Row Arrangement and Orientation under Nominal Nitrogen Management

Abstract

Aim: A study was conducted in eastern Uganda to rationalise sorghum-groundnut mixtures through manipulation of row arrangement and orientation, under nominal N management. Study Design: Treatments included row arrangements, viz. alternating 1:1 (single rows) and staggered 2:2 (double rows); row orientation viz. north-south and east-west; and N application, viz. 0 and 40 kg ha-1. Treatments were laid down in a randomized complete block design, in a split-split plot arrangement. Nitrogen rate was the main plot, row orientation as subplot and row arrangement as sub-subplot. Place and Duration of Study: The study was conducted in eastern Uganda for two cropping seasons (2010b-2011a). Methodology: Sorghum (Sekedo variety) and groundnut Red beauty variety (Emoit), were the component intercrops. Measurements included plant height, grain yield, solar radiation interception and intercropping financial advantage. Light interception was determined using a digital Lux light sensor (Lutron Model: Lx-101). The light available to the under storey intercrop was computed as a fraction to the total available (ambient) PAR. The data collected were analysed using GenStat software Version 11, and significant treatment means were separated using LSD at 5% probability level. Results: Staggered double rows gave better groundnut grain yield irrespective of row orientation and N regime. The E-W row orientation resulted in a greater groundnut yield by up to 50%, than those facing N-S. Sorghum yield, however, was slightly increased by N rate, but not by row orientation and arrangement. Groundnut rows oriented E-W intercepted more solar radiation than those in the N-S direction, in both alternate single and double row arrangements. Conclusion: The staggered double rows, oriented east-west and subjected to application of 40 N kg ha-1 is technically and financially the superior management option for sorghum production in eastern Uganda.