Water budget, water use efficiency in agriculture in Olifants catchment
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Date
2009-01-27T13:03:18Z
Authors
Rasiuba, Thabo Cecil
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Abstract
Eighty percent of the agricultural land worldwide is under rain-fed agriculture that
takes place on most soils that are generally low in fertility with attendant high on
farm water losses, thereby resulting in low crop yields. This is particularly
significant in sub-Saharan African states where a higher percentage of the
population is involved in agriculture and the economy is predominantly driven by
rural-based rain-fed agriculture. In the Olifants catchment, the challenges in rainfed
agriculture are compounded by erratic, highly variable rainfall patterns in
space and time.
The study area (Sekororo, B72A quaternary catchment) is within lower Olifants
region. It is located between latitude 24000’00” and 24025’00” South and between
longitude 30015’00” and 30045’00” East. The survey sites within the B72A
quaternary catchment are Worcester, Enable, Ha-Fanie, and Sofaya. The results
on soil nutrients indicate that the soil fertility is very poor, indicative of poor land
management which also impacts adversely on water use and crop yields.
The data from Statistics South Africa indicate that average number of people per
household dwelling at B72A quaternary catchment is five. Taking into account
maize consumption of 100kg per person per annum and average number of
persons per household, maize required to achieve food security would be 500kg
per household per annum and at current average crop yield of 300kg/ha, food
insecurity is very high for rain-fed farmers.
The data on rainfall partitioning indicate that at least 38% of the received rainfall
is lost to run-off. The modeled results indicate that crop yield can be improved to
800kg/ha if significant portion of rainfall lost to run-off is harvested, thereby
eliminating food insecurity for rain-fed farmers.