THE NATURE AND FUNCTION OF THE IN-FIELD RAINWATER HARVESTING SYSTEM TO IMPROVE AGRONOMIC SUSTAINABILITY†

Hensley et al. (2000) proposed an in-field rainwater harvesting (IRWH) technique for rural farmers located east of Bloemfontein South Africa, a semi-arid environment. This technique combines the advantages of water harvesting, no-till and basin tillage to stop ex-field runoff on high clay soils. The full agronomic potential of the IRWH technique has not, however, been reached because the main cause of water loss is evaporation. Evaporation dominates the hydrological cycle in semi-arid environments. This paper reviews the nature and design of the IRWH system, specifically the effect of mulch type on evaporation and yield. The effect of mulch type on yield is described by an infiltration ratio of the basin versus the runoff area over a period of three years. The function of the basin and catchment area is also discussed. The function of the basin area was to stop ex-field runoff completely, to maximize infiltration and to store the collected water in the soil layers beneath the evaporation sensitive zone. The catchment area was designed to promote in-field runoff and to act as a storage medium for water. Results from this research provide a new perspective on mulch management within water harvesting systems. Copyright © 2012 John Wiley & Sons, Ltd.