Water scarcity and abundance, water productivity and their relation to poverty - Water Scarcity, Livelihoods and Food Security - page 24

the Limpopo, but seasonal unreliability of rainfall affects it almost as much.
Rainfed agriculture only uses 14 percent of the basin's rainfall, but drought
years and within-year dry spells, together with the infertility and low water-
holding-capacity of the soils, cause low crop yields and WP (PN55) (Lemoalle,
2008). Even in the high-rainfall highlands of the Nile Basin, drought and the
intra-seasonal variability of rainfall causes crop failures, livestock deaths and
livelihood disasters (Nile 2) (Amede et al., 2007).
Seasonal unreliability adversely affected many CPWF projects. A project in
the Limpopo Basin noted that, “Rainfed smallholder cropping in semi-arid
Zimbabwe is constrained by frequent droughts and mid-season dry spells . . .
In southern Zimbabwe, it is actually rare for drought or mid-season dry spells
not to occur and this has led to permanent food insecurity for the majority of
households” (PN17) (Mupangwa et al., 2011). In another Limpopo project,
rainfall was so erratic that researchers could not establish cropping trials or the
trials failed with no grain harvest. In drier years, structures to harvest rainwater
were ineffective because there was not enough rainfall to collect, while in
wetter years they were often washed out (PN1) (Siambi, 2011).
Rainfall variability causes risk and uncertainty. Early sowings can fail if there
is early-season drought, while late-season drought or competition from early-
season weed growth can reduce the yields of late sowings. In either case, mid-
season dry spells can further reduce yields. Farmers mostly know the risks of
unreliable rainfall and use many strategies to manage it (Scoones, 1996;
Harrington and Tow, 2011) (Box 2.1).
Unreliable rainfall constrains the use of fertilizer and other inputs when the
risk of crop failure outweighs their potential benefits (CIMMYT, 1999). Under
some conditions, however, fertilizer micro-dosing or applying low levels of
Box 2.1 Farmers' strategies to manage risk of seasonally
unreliable rainfall
Staggered planting dates;
early-maturing varieties;
varieties with different crop durations;
crop combinations (for example both maize and sorghum or millet);
dry-season plowing to control weeds and allow earlier sowing;
reduced planting density;
intercropping;
matching crop species to land niches;
supplementary irrigation;
rainwater harvesting; and
seasonal use of wetlands.
(PN55) (Cooper et al., 2008; Terrasson et al., 2009)