April2010

The good news is …

Reducing livestock mortality associated with improving soil fertility and  dual purpose cultivars will not only improve water productivity but also increase incomes and livelihoods

And the not so good news is …

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.

Conversion of Rangelands to crop fields increases human and  livestock pressure on crop lands thereby facilitate land degradation and water depletion

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;

I. Dual purpose cultivars enhance water productivity Lessons from Bulawayo, Zimbabwe with 20 sweet sorghum varieties:

1) Significant variation exists between cultivars in grain & stover yield, stover digestible, metabolizable energy and rain water use efficiency (Table 1);

2) Trade-off between grain yield and feed quality across sorghum cultivars (R2 - 0.85); while few cultivars offer dual purpose benefits;

3) Livestock Water productivity increases with increasing feed quality (metabolizable energy (ME)) and declining harvest index;

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;

II. Reducing livestock mortality enhances water productivity and returns In SSA, animal mortality is so high; seriously undermines all other efforts.

1) High livestock mortality is caused by interrelated factors such as diseases, drought and high stocking rates;

2) In Zimbabwe, annual mortality ranges between 10-22% for cattle; with mortality being the major cause of outflow. Highest is with juveniles (17-22%) followed by sub-adults (10-15%);

3) Above 80% of mortality is caused by diseases;4) Poor veterinary services is partly responsible; investing on it pays off.5) With high mortality rates it takes14 Years to recover from a severe drought; 6) With mortality rates reduced to less 10% it still takes 8 Years to recover from a severe

drought;7) A 10% decrease in mortality could improve WP by at least 20%.

III. Soil fertility effects degree of water productivity of systemsSystem productivity in SSA (particularly in Zimbabwe), is constrained by nutrient mining

1) Nutrient removal through harvest was consistently higher than application of external inputs;

2) These systems are responsive to application of chemical fertilizers; WP trends positively correlate with levels of chemical fertilizers (Fig 2);

3) Crop residue production under traditional, low-input systems cover only about 20% of the 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.

Table 1. Differences in grain yield, feed quality and water use efficiency of sorghum cultivars in Zimbabwe.Cultivars Grain

yield Stoveryield

Harvest Index

Digestible stover

MERain water use efficiency; kg m-3

(tha-1) (tha-1) (%) Stover Grain

JJ1041 4.53 2.55 0.62 42.9 5.58 1.5 2.40

ICSR 93034 3.83 4.20 0.45 45.8 6.64 2.55 2.03

ICSV 93046 2.08 5.70 0.24 50.6 7.74 3.64 1.10

MateebeSweet

1.12 2.31 0.31 55.1 8.66 1.40 0.60

0

1

2

3

4

5

6

maize

stover

t/ha

FP

MD

RC

20%

40%

60%

Table2. Reduced mortality rate increases offtake and improves water productivity (Van Rooyen etal)

Fig 2. Trends in contribution of maize stover to dry season feed at 20, 40 and 60% of daily DM requirements under different treatments. Horizontal lines show stover different % of total feed required. FP = farmer practice, MD = micro-dose, RC = recommended rates

0

100000

200000

300000

400000

500000

600000

700000

800000

900000

1.00 0.95 0.90 0.85 0.80 0.75 0.70 0.70 0.70

Reduction in mortality

Off

take

Increased fertility to 0.85

Increased prolificacy to 1.2

T. Amede, K. Descheemaeker, E. Mapedza, P. Masikati, M. Munyaradzi, A.Sibanda, D.Nkomboni, S.Homann, A.van Rooyen

Three Ways to Improve Water Productivity in Zimbabwe

Fig 1. Livestock production systems in Nykai, Zimbabawe