INTEGRATING MICRO‐FLOOD IRRIGATION WITH IN‐FIELD RAINWATER HARVESTING: MAIZE YIELD AND WATER USE EFFICIENCY

Abstract

ABSTRACTThis study integrated micro‐flood irrigation (MFI) and in‐field rainwater harvesting (IRWH) for the purpose of improving soil water balance (SWB), crop yields and water use efficiency (WUE). The integrated system was tested in Parady's Experimental Farm of the University of the Free State, a semi‐arid region of the Free State Province (South Africa). Three water regimes (WR), dryland (DL), supplemental (SPI) and full irrigation (FI), were evaluated with 1, 2 and 3 m runoff strip width (RSW). The WR and RSW factors were studied using a 3 × 3 split plot factorial experiment design with four blocks. Plots were 30 m long with a width that constituted a standard 1 m basin strip and no tilled RSW. According to the BEWAB + irrigation scheduling software, the crop water requirement for FI amounted to 625 mm of which 50% was contributed by rainfall, while that of SPI was fixed at 60% of FI. Water from rainfall, FI and SPI amounted to 282, 330 and 210 mm, respectively. Soil water storage and transpiration were found to be affected by both the RSW and WR factors, while evapotranspiration (ET) and deep drainage were affected by RSW and WR, respectively. For the 1 m RSW, crop biomass and grain yield were respectively 19 and 32% above average. Correspondingly, seasonal ET and transpiration (T) were 10 and 44% above average. Full irrigation increased crop biomass and grain yield by 200%, while corresponding increases for SPI were 74 and 77% higher than DL. In conclusion, the 1 m RSW and FI produced optimum maize yields and WUE for the integrated MFI–IRWH system. Copyright © 2012 John Wiley & Sons, Ltd.