“Some experiences with developing rain water harvesting technologies in semi-arid Zimbabwe: challenges and possible solutions” “Some experiences with developing rain water harvesting technologies in semi-arid Zimbabwe: challenges and possible solutions” Isaiah Nyagumbo CIMMYT Global Conservation Agriculture Program CIMMYT Global Conservation Agriculture Program 28 Sep 2015 AFRHINET Project presentation

1. Introduction –High levels of land degradation across the region –Erratic rainfall seasons characteristic of most of the countries (about 70% of Southern Africa estimated to be semi-arid) –Climate Change predictions suggest Southern Africa will get drier and food insecurity bound to increase % decreases in maize yields in Southern Africa by 2030 (Lobell et al., 2008). –More recent estimates still suggest yields in SSA will decline by-5 to -15 % by 2050 from base estimates of 2000 (Tesfaye et al., 2015) –Poor access to irrigation infrastructure e.g. Malawi < 3%, Zimbabwe <5% (FAOSTAT) –Increasing food prizes –RWHT and CA could be cheaper options to increased AWM compared to irrigation infrastructure

Climate change predictions suggest most of SSA will be in the negative for maize High N simulations: N.B: CSIRO(cooler, drier), MIROC (warmer, wetter) (Source: Tesfayen et al., 2015; )

Relative changes in maize yield (%) by 2050 and 2080 in different regions of Africa (Source: Tesfaye et al 2015)

2. What is water harvesting? Water harvesting is defined as the collection of run-off for its productive use (FAO,1993) Has two main components Rainwater Harvesting -rooftops, rock outcrops soil is used for storage -in-situ water harvesting: soil is used for storage Floodwater Harvesting (dams, weirs and lakes).

6 Increasing investment costs Use of improved seed eg hybrids Use of organic and inorganic fertilizers CA+ In-situ water conservation & harvesting technologies Supplementary irrigation technologies eg wetlands, surface irrigation Increasing yields Hi- tech irrigation Techns Eg drip Costly Upper limit for shf without capital Hypothetical scheme of Options for improved water productivity Options for improving green water productivity in rainfed systems Options for blue water productivity

Irrigation potential is unquestionable: Dryland maize yields in SHF sector of Zimbabwe Adapted from: CSO (2004,2005) and MLARR (2001)

3. So what experiences do we have in Zim…….. Need to harness water in cropping systems realized since the 1980s (Zvishavane water projects ….)Need to harness water in cropping systems realized since the 1980s (Zvishavane water projects ….) Work on other techniques: infiltration pits (dead level ungraded contours), fanya juus in the 1990s, cross tied graded contours and a shift away from the standard contours usually designed to safely dispose of excess run-offWork on other techniques: infiltration pits (dead level ungraded contours), fanya juus in the 1990s, cross tied graded contours and a shift away from the standard contours usually designed to safely dispose of excess run-off Work on in-field techniques in the 1990s: tied furrows (Nyamudeza et al, tied ridges, ripping techniques, CA basinsWork on in-field techniques in the 1990s: tied furrows (Nyamudeza et al, tied ridges, ripping techniques, CA basins

Fanya juu(Chivi) Deepened contours (Zvishavane) infiltration pits (Buhera In-field techniques No-till tied ridges In-field rainwater harvesting (SA) Rip & potholing (Shurugwi) CA basins (Masvingo) Tied furrows (Chiredzi) Some examples…..

Roof top and rock outcrop systems Rock-outcrop water harvesting in Murehwa : mainly stock watering Roof top systems : domestic uses Rock outcrop systems: gravity fed small gardens irrigation eg Mtoko

Relative yield benefits of integrated water and nutrient management techs Source: Nyagumbo, 2011

Improved rainfall use efficiencies (Shurugwi) Control = no fertility amendments; Manure only = 10 t/ha pit stored manure banded in crop rows; Manure + Fertilizer = 10 t/ha pit stored manure plus 100 kg/ha Ammonium Nitrate fertilizer. Error bars denote tillage fertility interaction l.s.d (0.05) for comparing means within each year.

Average maize yields across the different water harvesting technologies for the three cropping seasons in Shurugwi. CRCT = Cross-tied Graded Contour CRCT, FJ = Fanya Juu, IF = graded contour reinforced with infiltration pit, SC = Standard contour. Source: Nyagumbo, Nyamadzawo et al, upcoming

Soil moisture with increasing distance (0, 1,2 and 3m) downslope of infiltration pits hardly noticeable Source: Nyakudya et al., 2014

4. Where does CA fit in this?

Magoye ripper Basin planting Jab-planter AT Direct seeder Dibble stick Hoe-planter CA techniques tested in various locations in Southern Africa

Cumulative soil loss (kg/ha) comparing CA and conventional mouldboard ploughing over 3 seasons at Hatcliffe, Harare (Nyagumbo, 2011) soil loss target= 3.5t/ha/yr

Error bars denote +/- SE of mean Effects of CA and Conventional Mouldboard Ploughing on cumulative runoff in 3 consecutive seasons at Hatcliffe, Harare, Zimbabwe Total seasonal run-off amounted to 7.4, 16 and 8.1 % of seasonal rainfall for CMP compared to 0.5, 0.8 and 0.6 % for CA over the 3 seasons Total rainfall 774 mmTotal rainfall 481 mmTotal rainfall 956 mm Source: Nyagumbo ( 2011) So CA reduces run-off and thus harvests water effectively!

Does resource status matter in outscaling RWHT? Capacity to outscale RWHT related to resource ownership eg land size, labour, equipment, gender (Munamati, et al., 2010) Land ownership and area under rainwater harvesting technologies in Gwanda

Which techniques are popular ? (Shurugwi, 2006) Most popular of new techs Contour ridges were mandatory prior to independence

CA basins Status in Zimbabwe CA basins Status in Zimbabwe Source:Marongwe, Agritex 2012 data 59 % of the households practising CA without any support!

Opportunities for IRWH Most of the techs do not require the application of crop residues hence can work in residue constrained environments Labour inputs initially high but can serve for more than 5 years! Cross tying standard contours can ease labour requirement a one does not have to dig pits

5. Key challenges and way forward Farm level: poor awareness, labour, unattractive markets, costs with increasing sophistication Beyond the farm: poor research funding (donor dependent research => global priorities), policy, more technical back up to farmers Need for more site specific and user responsive research on RWHT RWHT can be an alternative in CA residue constrained environments where residue application is not feasible Govt supported construction of RHW structures The need to encourage and facilitate farmer experimentation & development of innovations eg solar pumping, animal pumping, wind systems for water supply systems. Each system type has its niche!! Its neither this only or the other!!

Some useful literature Munamati, M., Nyagumbo, I., In situ rainwater harvesting using dead level contours in semi-arid southern Zimbabwe: Insights on the role of socio-economic factors on performance and effectiveness in Gwanda District. Phys. Chem. Earth 35, 699–705. Nyagumbo, I., Mugabe, F.T., Water and Soil Conservation with drought in mind, Small Holder Drought Mitigation Programme. Swedish Cooperative Centre - SADC Centre for Communication and Development., Harare. Nyagumbo, I., Rurinda, J., An appraisal of policies and institutional frameworks impacting on smallholder agricultural water management in Zimbabwe. Phys. Chem. Earth 47-48, 21–32. Nyakudya, I.W., Stroosnijder, L., Nyagumbo, I., Infiltration and planting pits for improved water management and maize yield in semi-arid Zimbabwe. Agric. Water Manag. 141, 30–46. doi: /j.agwat Nyamudeza, P., Jones, E., The effects of growing sorghum (sorghum bicolor) in furrows and on the flat at three populations and three row widths in semi-arid region of Zimbabwe 2: Soil water regime throughout the season. Zimbabwe J. Agric. Res. 31, 11–21.

Thanks

Thank you for your interest! Photo Credits (top left to bottom right): Julia Cumes/CIMMYT, Awais Yaqub/CIMMYT, CIMMYT archives, Marcelo Ortiz/CIMMYT, David Hansen/University of Minnesota, CIMMYT archives, CIMMYT archives (maize), Ranak Martin/CIMMYT, CIMMYT archives.