Description
Similar names: Chololo pits (Tanzania), Zaï pits (Burkina Faso), tassa (Niger), agun pits (Sudan), kofyarpits (Nigeria), yamka (Kyrgyzstan), planting pits.
The name Zai pits refers to small basins in which the seeds of annual or perennial crops are planted. The pits are then filled with mulch, manure, compost or good soil to increase soil fertility and the capacity of the soils to capture water. Zai pits can be beneficial for soil conditions and they are a very successful method which can allow for the growth of vegetation in dry areas. They are also very efficient in protecting seeds and soil organic matter from being washed away from water runoff. One of the major advantages of Zai Pits is that it increases water filtration, through the collection and concentration of water for the plants due to increasing termite activity. What is more, Zai pits can collect more than 25% or more of run-off water. This as a result decreases water run-offs and evaporation. When looking at the bigger picture, Zai Pits can improve soil fertility and agricultural productivity of several crops and can increase production by up to 500% if well executed.
The Zai Pit intervention is an efficient method to increase yield productivity due to more water and nutrients available. This intervention is most suitable for flat or gently sloped terrains (0-5%) with a precipitation range of 350-600 mm/y. Overall, Zai Pits can also work with other techniques such as stone contours and hand-dug trenches.
PRE-CONDITIONS FOR IMPLEMENTATION
- Rain higher than 800mm annual can cause waterlogging of pits. Avoid loose sandy soils and steep slopes or the pits will be very unstable.
- Because of labor times (especially because pits are created during dry and warm season), it is most effective if the measure is undertaken by groups of farmers together, instead of individuals.
- The construction of planting pits can be done with machines.
- Zai pits are even more efficient when combined with other interventions such as organic and inorganic soil inputs such as mulching.
METHOD OF APPLICATION
Materials required
- A Chaka hoe
- Digging stick
- Wheelbarrow to transport manure, mulch and/or good-quality soil to fill the pits
- Seedlings or seeds
Steps of implementation
- Pits usually are 20-30 cm both wide and deep, placed 60 cm – 1 m apart from each other and dug by hand. Dig holes with a diameter of 15-20 cm and depth of 10-15 cm or more, distance between each other from 70 to 80 cm apart, resulting in about 10,000 pits per ha.
- Make sure they are dug perpendicularly to the slope and put the soil from the hole in the direction of the downslope (to create a small soil wall/bund to keep the water in the hole). The excavated soil is placed downslope on the border of the pit to form a small ridge that further improves rainfall and runoff capture.
- When available, crop residue, mulch or manure is added to every pit to help vegetation grow in the first phases. To optimise the efficiency of the Zai pits intervention, pits can be constructed in combination with stone lines, especially on degraded and crusted lands because the synergy of these two interventions helps the land to be suitable again for agricultural purposes. In this case, when planting pits are used in combination with stone lines, growing grass between the stones is recommended because it helps to further increase infiltration and improve the accumulation of fertile sediment.
- Row crops are then planted in the pits. For trees: dig deeper holes and increase the distance from the pits so the tree will have the space to grow
There are currently new ways of mechanising the construction of pits, click here to know more about it.
BENEFITS
This intervention contributes to:
COSTS
Estimation of costs and benefits of intervention:
| Establishment costs | US $160/ha + manure (2.5t for US $5)
(Sorghum plantations combined with Tithonia diversifolia: US $2561.43/ha) |
| Labor time p/ha | 100 person days (US $150) (about 10,000 pits/ha) * |
| Maintenance costs | 20 person days (US $30) to remove sand from pits + apply compost/manure 1.25t (3.5) every second year = US $33.5/ha/year |
| Materials required | Hoe, digging stick (US $5) |
| Products example | Maize, pearl millet grain, sorghum, pigeon peas, lablab (black beans), fruit trees such as mango |
*more time needs to be calculated if the soil contains a lot of stones
(Source)
CASE STUDIES
Description
The farm in Tanzania is an example of a smallholder cultivating maize, pigeon peas and sunflowers on 2.2 hectares of land. The farm serves as one of the demonstration areas for climate-smart agricultural technologies. Chololo pits are planting basins that help conserve moisture in the soil and improve soil fertility. They increase crop production and mitigate drought effects. The technology involves digging a square hole with sides 20 cm in length and a depth of 30 cm then adding a handful of farmyard manure.
Description
Implementation of Zai pits in combination with stone lines to achieve the rehabilitation of 40 km2 of degraded land. This technology is mainly applied in semi-arid areas on sandy/loamy plains, often covered with a hard pan, and with slopes below 5%. Check out Stone Lines for more information. In semi-arid areas with sandy or loamy soil, farmers use a combination of planting pits and stone lines to restore degraded land for crop cultivation. This method is effective on flat lands with gentle slopes. The major benefits are 1) Water Management: Captures and holds rainwater, improving water infiltration into the soil; 2) Nutrient Availability: Which enhances soil fertility through the use of manure and the accumulation of fertile sediment; 3) Plant Growth: Better water and nutrient availability leads to improved crop growth and 4) Soil Protection: Stone lines prevent soil erosion and protect the planting pits from sediment buildup. Overall, this technique helps turn barren land into productive farmland without the need for heavy machinery, making it accessible for small farmers. Regular maintenance, like adding manure every few years and removing sand annually, ensures the system remains effective.
Description
In the Sahel, the traditional zaï system rehabilitates poor, crusted land by manually digging holes to concentrate runoff water and organic matter. However, this manual process is labour-intensive, requiring over 300 man-hours per hectare. A study in Burkina Faso investigated mechanising this process with animal-drawn equipment on tropical ferruginous soils at Saria and Pougyango. Mechanised digging took 36 hours per hectare at Saria and 22 hours per hectare at Pougyango, with average tractive efforts of 11.6 daN and 10.1 daN, respectively. The dimensions of mechanised holes matched manual ones, though soil roughness increased by 14.7%. Sorghum grain production increased by 34% compared to conventional methods, yielding a positive income of up to 165,000 FCFA per hectare. This mechanisation offers a promising alternative for boosting small farmers' income and preserving the environment.
