Minimum tillage means loosening the soil only where the seed goes. Farmers do this with planting basins or with ripping lines (oxen-drawn). The rest of the field is left undisturbed. It is one part of conservation farming, which also asks for crop residue cover and crop rotation. Extension services promote these practices to improve yields, conserve soil moisture and reduce land degradation. Climate planners also recognise them as potential mitigation measures under the Agriculture, Forestry and Other Land Use (AFOLU) sector. But are they delivering the expected benefits for farmers?
What AFOLU says
AFOLU covers greenhouse gas emissions and carbon storage associated with agriculture, forestry and other land uses. The IPCC’s Sixth Assessment Report says the sector can provide 20 to 30 per cent of the global mitigation needed for a 1.5°C or 2°C pathway by 2050. However, this figure applies to the entire AFOLU sector, not minimum tillage alone.
Among the proposed mitigation options are improved cropland management, reduced tillage and crop residue retention. These practices can reduce soil disturbance, improve soil conditions and potentially increase soil organic carbon.
The logic behind minimum tillage
Less soil disturbance means less carbon lost from the soil, and healthier soil should give better yields. Yet the carbon evidence from Sub-Saharan Africa is thin. A 2016 study covering 125 trials across four southern African countries found that soil carbon increases under conservation agriculture were lower than anticipated. A 2017 Zambian study also found relatively small effects on soil quality and carbon stocks. The mitigation case therefore leans heavily on a practical question. Does minimum tillage raise yields enough for farmers to keep using it?
What recent studies show
1. Early land preparation can improve yields: A national study of nearly 48,000 maize plots from 2008 to 2011 found that ripped plots out-yielded ploughed plots when ripping was done before the rains, by an average of 577 kg per hectare nationwide and 821 kg per hectare in low rainfall zones. Planting basins gained 191 kg per hectare over hand hoe tillage under the same early timing. The authors stressed that these gains are only reached when farmers follow the recommended practices. An earlier survey of 1,231 households in six districts found minimum tillage raised maize productivity by about 26 to 38 percent.
2. Higher yields have not always meant higher income: A study of 751 fields found an average yield gain of 334 kg per hectare across maize, groundnut, sunflower, soybean and cotton, but no significant effect on crop income. The author concluded that the gains may be too small to cover the cost of implementation in the short term.
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3. Pests and weeds can erase the benefit: A 2021 study of 1,048 maize plots looked at fall armyworm years. It found that none of the minimum soil disturbance practices, including the full conservation farming package, had a significant effect on maize yield. An older trial in eastern Zambia found that zero tillage gave lower maize yields than conventional tillage, with more weeds and heavier weeding labour.
4. Adoption remains a challenge: A 2010–2014 study found fewer than 5% used minimum tillage as their main tillage method nationally. Newer work explains why. Farmers take about four years on average to adopt once trained, and extension access and farming experience help them keep going. A 2024 Zambian panel study found that impatience and risk aversion reduce the area farmers put under basins, ripping and minimum tillage. Research across Malawi, Zambia and Zimbabwe found that awareness rarely turns into adoption, while training and demonstration plots work much better.
What does this mean for Zambia?
Minimum tillage can improve maize productivity, especially when land preparation is completed early and farmers manage weeds and crop residues effectively. However, the benefits are not guaranteed. Poor implementation, pest outbreaks and additional labour requirements can reduce its effectiveness.
Most of the yield-impact studies above are from 2014 to 2021. The newest research is mainly about adoption, which suggests the field has shifted from asking whether it works to asking why farmers stop. Evidence of additional soil carbon storage under conservation agriculture in Zambia remains limited. Programmes will do better with multi-year training, demonstration plots, help with weeding labour and some protection against bad seasons.
Minimum tillage has potential in Zambia, but its success should be measured by more than the number of farmers adopting it. Sustained yield improvements, farm profitability and measurable environmental benefits are what ultimately matter.
