Land Degradation and Drought

Denuded lands contribute to drought vulnerability, but this can and needs to be reversed, with particular reference to Zimbabwe.

John MacRobert, April 2024

Zimbabwe has a long history of frequent drought. Rainfall records from over 100 years show high average annual and intra-seasonal variation. Thus, we should not be surprised when a drought occurs. Rather, farmers should be continually preparing for and managing their farms with the prospect of a drought in mind. The water cycle is the most crucial natural cycle farmers should be concerned about. Closely related, and, in fact, highly connected to this is the organic carbon cycle. Both these cycles have been greatly disrupted by farming practices carried out over the last fifty or more years, and these disruptions exacerbate the negative impact of drought on crop and livestock performance.

For decades, the ox-drawn plough has been promoted and used extensively in Zimbabwe. Along with this, especially on larger scale farms, the disc has been used widely for seed bed preparation. Both these tillage implements reduce soil organic matter, eliminate vegetative ground cover, create oxidizing soil conditions, increase rainfall runoff, disrupt soil aggregation, harm soil life, increase soil temperature fluctuations, and cause soil erosion.  In a similar way, the significant over-grazing that takes place across parts of the country has led to denudation of rangelands, with similar impacts as the plough on soil health. These multitude negative effects on the soil result in less water available and a poorer environment in the soil for plant and edaphon growth.  

The extent of this disruption of the water and carbon cycles is illustrated clearly in a Google Earth pictures of Zimbabwe taken in December (Figure 1). The lighter areas on the graphic are where there is little or no vegetative cover. As further evidence, on a smaller scale, this denudation is very apparent (Figures 2 and 3). And these denuded areas are like this for a significant part of the year, from May through November, so for an extended period soils are drying out and then when the rains come in October to December, they are prone to runoff and erosion.

While it is good that the government is initiating interventions to help farmers and the country survive the present impact of the 2024 drought on farmers’ livelihoods, livestock and national food security, such interventions will likely make little impact to the long-term resilience of Zimbabwean agriculture. They are short-term interventions, albeit important, but will make little difference in mitigating our long term vulnerability to drought. It is my view that unless the nation applies itself to countering the negative global impacts of denuded lands on the carbon and water cycles, drought will be an ever increasingly difficult phenomenon to cope with.

The kinds of interventions that are needed to regenerate the denuded lands of Zimbabwe include, inter alia:

1. Ban the use of the plough and discing for maize, soyabean, cotton, sunflower, sorghum and millet production. This could be tied to Input Provision schemes, so that only those farmers who plant with reduced or zero tillage qualify for receipt of inputs.
2. Ban the burning of crop residues and promote maintenance of as much residue on fields as possible. Where farmers remove residues for animal feed, the feeding and manure capture systems should be covered (roofed) and protected.
3. Educate farmers and promote the use of cover crops, minimum tillage, crop rotations, inter-cropping, agroforestry, pastures, hedges, erosion control works, improved manure conservation and composting systems.
4. Instigate improved grazing systems, with use of hedges, fences, controlled grazing and resting, and planting of fodder plants (browse trees, grasses and legumes).
5. Ban indigenous tree harvesting for fuel and fencing and replace with renewable plantations.

These interventions can be fleshed out in more detail and contextualized for the agro-eco zones of the country, but the principles of each are self-evident. These should have full purposeful support from the government for implementation. This is the time for the nation to be serious about reversing land degradation and promoting land regeneration. The future of the country is at stake, and without implementing these changes, the country will be continually challenged with increasing drought impacts.