Evaluating the maize production potential of a semi-arid ecotope with four production techniques

Abstract

Water conservation production techniques are needed to boost crop production in semi-arid areas. The in-field rainwater harvesting (IRWH) technique has been developed for this purpose, and found to be successful on clay and duplex soils, but has not yet been tested on well-drained, medium textured soils. The maize production potential of the semi-arid Glen/Hutton-Ventersdorp ecotope in the Free State Province was evaluated to compare IRWH with conventional tillage. Two planting dates were also evaluated. Using a yield prediction model, together with long-term climate data, maize grain yields were simulated for 80 growing seasons (1922/23–2001/02). The following four production techniques were evaluated: conventional tillage with November planting (CON-N), conventional tillage with January planting (CON-J), IRWH with November planting (IRWH-N), and IRWH with January planting (IRWH-J). Cumulative probability functions (CPFs) of yields were computed for the four treatments. The CPFs indicated that the long-term mean yields, at 50% probability of achievement, were 2653, 2685, 3108, and 3355 kg ha−1 for CON-N, CON-J, IRWH-N and IRWH-J respectively. Stochastic dominance analysis of the CPFs indicated that the IRWH-N and IRWH-J production techniques had well defined first degree stochastic dominance over the CON-N and CON-J techniques. January planting showed only second degree stochastic dominance over November planting. The Kolmogorov-Smirnov (K-S) test indicated that the CPFs of the IRWH techniques were significantly different from those of the CON techniques, whereas, within the IRWH or CON techniques, there was no significant difference between the January and November planting.