Chapters 5.65
5.65 -Zai Pits to Grow Crops in Dry Regions
Josh Fredericks, University of Guelph, Canada
Suggested citation for this chapter.
Fredericks,J. (2022) Zai Pits to Grow Crops in Dry Regions, In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org
Introduction To Zai Pits
Improving soil productivity and water availability is critical to improving the lives of people living in drought-prone, semi-arid areas. Efforts to enhance soil fertility and save water in Sub-Saharan Africa aim for environmentally friendly and financially viable solutions (Kimaru-Muchai et al., 2021; Kebenei et al., 2023), paving the path for long-term food production. There have been claims that combining water-collection systems with soil fertility improvements have increased the potential for enhancing agricultural production in arid areas (Kimaru-Muchai et al., 2021; Kebenei et al., 2023). A wide range of strategies have been attempted to meet the restrictions of low soil moisture and to boost agricultural output in semi-arid environments. An excellent solution to conserve soil and water is the Zai pit strategy which can be used to grow a diversity of crops including maize on gentle slopes (1-15% grade) in dry regions (Figure 1) (Muriu-Ng’ang’a et al., 2017; Kebenei et al., 2023).
Originally from either Burkina Faso or Mali in West Africa, but now also adopted in East Africa (Kebenei et al., 2023), the Zai pit technique focuses on improving soil moisture, soil health, and agricultural production. Zai pits commonly called planting pits and mini water harvesting pits have dimensions of 20 to 60 cm wide and 10 to 30 cm deep, typically with a 60 to 80 cm spacing between each Zai pit (Muriu-Ng’ang’a et al., 2017; Kimaru-Muchai et al., 2021; Kebenei et al., 2023). In the case of maize, depending on their size, a single Zai pit can store a 4-8 maize seeds and is then fed with organic animal manure and dried plant debris. This process increases bacterial activity in the soil, which then can improve water penetration rates when a rainstorm hits the area (Kimaru-Muchai et al., 2021; Kebenei et al., 2023).
Figure 1- Maize crops growing on Zai Pits https://plantvillage.psu.edu/blogposts/139-zai-pits-in-arid-regions-of-kenya
Benefits and Cost Analysis
Smallholder farmers can benefit greatly from Zai pits due to their high crop output and cost-effectiveness. Zai pits are a very effective technique that improves soil conditions and permits the growth of plants in arid regions. Additionally, they do a great job of preventing seeds and organic soil materials from being carried away by water runoff. Zai encourages the planting of new trees in the fields (agro-forestry) as well (Kebenei et al., 2023). Studies have shown that Zai pits can significantly boost crop yields. For example, in West Africa, sorghum production has increased dramatically from 300 kilograms per hectare to as high as 1,600 kilograms per hectare with the use of Zai pits (Sawadogo, 2011). This notable enhancement is credited to the pit's capacity to concentrate water and nutrients where plants need them the most, effectively addressing challenges related to inadequate rainfall and depleted soils. The cost-effectiveness of Zai pits is also noteworthy. Despite the labor process of digging the pits initially, the substantial increase in crop yields leads to a favorable return on investment. For small-scale farmers, the labor investment can be recovered within a single growing season due to enhanced productivity and subsequent improvements, in food security and income levels. The initial expenses, for labor to dig the pits and organic material to fill them could vary (Kebenei et al., 2023). However, the benefits of using Zai pits can be impressive with some case studies reporting yield increases of up to 200% or more (Kebenei et al., 2023). Thus the cost-to-yield ratio can be quite favorable often recovering the costs multiple times over within a single growing season. This ratio highlights how Zai pits are effective, in improving food security and economic stability for small-scale farmers dealing with climatic conditions (Kebenei et al., 2023).
How to Set up Zai Pits
Small-scale farmers often lack access to guidance, so I will outline a step-by-step guide on how they can effectively cultivate Zai pits for growing maize, as an example (Figure 2). To start it's crucial to consider the timing. Start to cultivate just before the onset of the rainy season (Mucheru-Muna et al., 2021; Kebenei et al., 2023). Mark out spots for your Zai pits using a stick or hoe ensuring they are spaced 60 to 80 cm apart in all directions to allow sufficient room for plants to thrive (Mucheru-Muna et al., 2021; Kebenei et al., 2023). To dig the pits, use a hoe or shovel to create pits that are approximately 20 to 30 cm deep and wide with the option of shaping them round or square based on your preference (Mucheru-Muna et al., 2021; Kebenei et al., 2023). Once the pits are dug, fill each one with materials like compost, manure, or decomposed leaves to enhance soil fertility and attract beneficial microorganisms. Finally plant two to four maize seeds in pit, lightly covering them with soil. The organic matter, within the pit will aid in moisture retention and nutrient provision as it breaks down over time (Mucheru-Muna et al., 2021; Kebenei et al., 2023). Step six involves watering. Try to provide water to each pit to kickstart the germination process especially if the rain is late. The seventh and last step is maintenance; watch out for any weeds growing in your pits and remove them when necessary. These pits assist in directing rainfall to your maize roots lessening the requirement, for constant watering (Mucheru-Muna et al., 2021; Kebenei et al., 2023).
Figure 2 – Examples of Zai pits. Source: https://www.greener.land/index.php/product/zai-pits/
Critical Analysis
The use of Zai pits to boost crop production in dry and semi-arid areas has received praise for its ability to improve soil moisture enhance fertility and ultimately increase crop yields. However, upon examination, several obstacles could impede the efficiency and scalability of this method. To begin with, the labor-intensive process of creating Zai pits presents a challenge. The manual work involved in Zai pits can be overwhelming for small-scale farmers potentially demanding 450 hours of labor per hectare to dig the holes, 250 hours per hectare to add fertilizers and amendments, and 15-20 days per hectare to maintain the pits (Reviewed in Kimaru-Muchai et al., 2021). This initial time investment may prove to be a hindrance for some individuals, those with limited access to labor resources. However, when considering the cost-effectiveness aspect, the yield boost from using Zai pits can be considerable, doubling or even tripling yields (Kebenei et al., 2023). Another common issue revolves around the availability and cost of materials needed to fill these pits. In areas where agricultural residue or manure is not easily accessible, the advantages of Zai pits may be diminished. Furthermore, the demand for resources within a community can lead to increased expenses, making the cost-effectiveness analysis more complex. Despite these obstacles, suggestions like work-sharing programs at the community level and the creation of compact machinery for automating the excavation of Zai pits have been put forward to lessen labor requirements. Moreover combining Zai pits with environmentally friendly methods like agroforestry can improve soil quality and decrease reliance, on external organic supplies. To summarize, although Zai pits offer an approach to enhancing crop harvests in tough conditions, their extensive use hinges on dealing with the expenses related to labor and materials. It is essential to make investments in support systems, within communities and advancements in technology to surmount these challenges and unlock the complete benefits of Zai pits in promoting sustainable agricultural growth (Kebenei et al., 2023).
Practical Resources to Get Started
https://plantvillage.psu.edu/blogposts/139-zai-pits-in-arid-regions-of-kenya More information on Zai Pits for Maize
https://youtu.be/bz82xywPP94?si=dQ4aTwBWREbysnPj Video explaining overall planting of Zai Pits
https://youtu.be/sn-2HFUnLKw?si=sbCJqqh1IuHBLVD7 Video explaining how to plant Maize in Zai Pits already set up
https://johnnjue.blogspot.com/2012/05/maize-production-using-modified-zai.html Blog about Maize production using modified Zai Pits
References
1.Kebenei, M. C., Mucheru-Muna, M., Muriu-Ng’ang’a, F. (2023) The potential of Zai pit technology and Integrated soil fertility management to enhance crop productivity in semiarid regions of Sub-Sahara Africa: A review. International Journal of Environment, Agriculture and Biotechnology 8 (1), 63-73. https://ijeab.com/upload_document/issue_files/8IJEAB-110202218-Thepotential.pdf
2.Kebenei, M. C., Mucheru-Muna, M., Muriu-Ng’ang’a, F., & Ndung’u, C. K. (2021). ZAI technology and integrated nutrient management for improved soil fertility and increased sorghum yields in Kitui County, Kenya. Frontiers in Sustainable Food Systems. 5(1), 2-11. https://www.frontiersin.org/articles/10.3389/fsufs.2021.714212/full
3.Kimaru-Muchai, S. W., Ngetich, F. K., Mucheru- Muna, M. W., & Baaru, M. (2021). Zai pits for heightened sorghum production in drier parts of Upper Eastern Kenya. Heliyon, 7(9), 2-11. https://doi.org/10.1016/j.heliyon.2021.e08005
4.Mwangi, P. (2020) A climate-smart agriculture approach using double digging, Zai Pits and Aquacrop model in rain-fed sorghum cultivation at Wiyumiririe location of Laikipia County, Kenya. Africa Journal of Physical Sciences 4(2), 2313-3317. http://journals.uonbi.ac.ke/index.php/ajps/article/view/1904
5.Muriu-Ng’ang’a, F., Mucheru-Muna, M., Waswa, F. and Mairura, F.S. (2017) Socio-economic factors influencing utilisation of rain water harvesting and saving technologies in Tharaka South, Eastern Kenya. Agricultural Water Management 194, 150-159. https://www.sciencedirect.com/science/article/abs/pii/S0378377417303001
6.Sawadogo, H. (2011). Using soil and water conservation techniques to rehabilitate degraded lands in northwestern Burkina Faso. Int. J. Agric. Sustain. 9, 120–128. doi: 10.3763/ijas.2010.055
7.World Economic Forum. (n.d.). How the zaï technique is helping farmers adapt to climate change in the Sahel. World Economic Forum. https://www.weforum.org/agenda/2023/08/zai-technique-sahel-farmers-adapt-climate-change/