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Three ways to improve water productivity in Zimbabwe


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Poster prepared by T. Amede, K. Descheemaeker, E. Mapedza, P. Masikati, M. Munyaradzi, A.Sibanda, D.Nkomboni, S.Homann and A.van Rooyen for the ILRI Annual Program Meeting (APM) 2010, held at ILRI campus, Addis Ababa, Ethiopia, April 14-17, 2010.

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Three ways to improve water productivity in Zimbabwe

  1. 1. Three Ways to Improve Water Productivity in Zimbabwe T. Amede, K. Descheemaeker, E. Mapedza, P. Masikati, M. Munyaradzi, A.Sibanda, D.Nkomboni, S.Homann, A.van Rooyen Water Productivity in Farmers’ words 1) Drought has been with us for decades; what has changed is its frequency and impact on our livelihoods; 2) Most degraded are croplands (50%), followed by communal trees, forests, rivers and wetlands; 3) When drought occurred in the past, our neighbors would grow enough food and feed; now every village is drought-prone, even livestock mobility doesn’t help; 4) Local varieties were more tolerant to drought; modern varieties need more water, more fertilizer and more labour. We like them only when the season is good; 5) Changing rangelands to crop fields is happening to produce food; but we are not getting as much feed from crop lands compared to rangelands; 6) We keep our goats: to sell and buy food, send our kids to school and feed our family. However, Goats die before they reach markets; leaving us in duress; 7) If research has solutions, help us growing more food with our shrinking land, decreasing livestock numbers and frequent droughts; Fig 1. Livestock production systems in Nykai, Zimbabawe I. Dual purpose cultivars enhance water productivity Lessons from Bulawayo, Zimbabwe with 20 sweet sorghum varieties: Table 1. Differences in grain yield, feed quality and water use efficiency of sorghum cultivars in Zimbabwe. 1) Significant variation exists between cultivars in grain & stover yield, stover digestible, Cultivars Grain Stover Harvest Digestible ME yield yield Index stover Rain water use metabolizable energy and rain water use efficiency (Table 1); efficiency; kg m-3 2) Trade-off between grain yield and feed quality across sorghum cultivars (R2 - 0.85); while (tha-1) (tha-1) (%) Stover Grain few cultivars offer dual purpose benefits; 3) Livestock Water productivity increases with increasing feed quality (metabolizable energy JJ1041 4.53 2.55 0.62 42.9 5.58 1.5 2.40 (ME)) and declining harvest index; ICSR 93034 3.83 4.20 0.45 45.8 6.64 2.55 2.03 4) Dual purpose, taller varieties produce more biomass, quality feed but are also less drought resistant; higher water productivity (WP) in good years and low WP in dry years; ICSV 93046 2.08 5.70 0.24 50.6 7.74 3.64 1.10 Mateebe 1.12 2.31 0.31 55.1 8.66 1.40 0.60 Sweet Table2. Reduced mortality rate increases offtake and improves water II. Reducing livestock mortality enhances water productivity and returns productivity (Van Rooyen etal) In SSA, animal mortality is so high; seriously undermines all other efforts. 900000 800000 Increased prolificacy to 1.2 1) High livestock mortality is caused by interrelated factors such as diseases, drought and 700000 Increased fertility to 0.85 high stocking rates; 600000 2) In Zimbabwe, annual mortality ranges between 10-22% for cattle; with mortality being the Off take 500000 major cause of outflow. Highest is with juveniles (17-22%) followed by sub-adults (10- 400000 15%); 300000 3) Above 80% of mortality is caused by diseases; 4) Poor veterinary services is partly responsible; investing on it pays off. 200000 5) With high mortality rates it takes14 Years to recover from a severe drought; 100000 6) With mortality rates reduced to less 10% it still takes 8 Years to recover from a severe 0 1.00 0.95 0.90 0.85 0.80 0.75 0.70 0.70 0.70 drought; Reduction in mortality 7) A 10% decrease in mortality could improve WP by at least 20%. Fig 2. Trends in contribution of maize stover to dry season feed at 20, 40 and 60% of daily III. Soil fertility effects degree of water productivity of systems DM requirements under different treatments. Horizontal lines show stover different % of total feed required. FP = farmer practice, MD = micro-dose, RC = recommended rates System productivity in SSA (particularly in Zimbabwe), is constrained by nutrient mining 6 1) Nutrient removal through harvest was consistently higher than application of external 5 maize stover t/ha 4 FP inputs; MD 3 2) These systems are responsive to application of chemical fertilizers; WP trends positively 2 RC 20% correlate with levels of chemical fertilizers (Fig 2); 1 40% 60% 3) Crop residue production under traditional, low-input systems cover only about 20% of the 0 daily dry matter feed requirement, low quality; 4) Maize stover produced under microdose, recommended application (100 kg ammonium nitrate) contributed up to 40% and 60% of the feed requirement, respectively, while combination of stover and mucuna commonly satisfy daily protein requirements; 5) Livestock Water productivity has doubled due to the application of optimum chemical fertilizers; significant gain in crop residue for livestock feed. The good news is … And the not so good news is … Reducing livestock mortality associated with improving  Conversion of Rangelands to crop fields increases human and   soil fertility and  dual purpose cultivars will not only  livestock pressure on crop lands thereby facilitate land  improve water productivity but also increase incomes and  degradation and water depletion April 2010 livelihoods We would like to acknowledge BMZ-Germany for supporting the project on Improving productivity of mixed crop-livestock systems in sub-Saharan Africa, ICRISAT-India and Dr. Michael Blummel of ILRI-India for their technical support in the dual purpose varieties research.