Productivity of maize after strip intercropping with leguminous crops under warm-temperate climate

Use of legume cover crops has been reported to improve maize productivity through various mechanisms that include improved soil mineral N supply and weed control. However, in the smallholder irrigation farming sector, where maize is the staple crop, strategies for intercropping summer legume cover crops are often a challenge for farmers. Field experiments were conducted in a warm-temperate region of South Africa during the summer season of 2007/08 and 2008/09 to investigate the effects of strip intercropping patterns (3:2; 4: 2 and 6:2 patterns) on the productivity of maize (cv. PAN 6479) together with mucuna or sunnhemp. The strip-intercrop patterns did not result in improved soil mineral N or weed control. Maize yields from rows adjacent to the cover crop strips were significantly (P < 0.01) lower than other rows. The 3:2 strip intercropping pattern slightly depressed yields; however, yield reduction was more pronounced in the 1st season where water stress was experienced with maize partial land equivalent ratios (PLER) of 0.55 and 0.98 in the 2007/08 and 2008/09 seasons respectively. A long winter fallow period reduced the positive impact of legume cover crops on soil mineral N and weed control benefits, resulting in no observable yield increase in a subsequent maize crop. Summer legume cover crops may enhance productivity of winter food/cash crops; however, this requires further investigation.