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Water is a precious resource in Southern Africa, where it is often in short supply for much of the year. The rainy season lasts only four to five months with frequent dry spells in between, while the rest of the year is hot and dry. However, anyone with some farming or gardening land can harvest water by following a few easy steps.
Rainwater harvesting methods vary in their suitability and compatibility for different situations and often complement one another. Swales, basins, and terraces are effective ways to harvest water, but they require costly and labour-intensive digging, planning, surveying, and building of rock walls along the contour. Tanks, subsurface reservoirs, and gutters are also expensive.
Mulching to the rescue
You can still conserve water effectively even if the methods mentioned above are not feasible for you. There is a simple, cheap, and natural way of water harvesting that also boosts soil health and even has benefits when the rain stays away.
It is called mulching, and it involves covering the soil with organic matter such as leaves and plant debris. This mimics indigenous forests, where the forest floor is rich in organic matter. The trick is to learn from nature and adopt its principles for your land. This method can be easy and affordable, and it has extra advantages, but we have to change our mindset.
Perennial plants shed their leaves and stems every year, while annuals die off completely. The dead plant material accumulates on the ground and creates a layer of mulch that covers the soil. This mulch protects the soil from erosion, moisture loss, and temperature extremes. It also enhances the soil’s water retention and makes it easier to dig through.
The mulch layer captures water from rain or irrigation and slows its runoff. This allows more water to be absorbed into the soil compared to bare ground. Another benefit is that it slows evaporation during dry spells.
You can mimic this natural process on your land by leaving plant debris on the ground. If you need to clear some areas of plant debris, you can relocate it to places where it can act as a sheet mulch.
Additional benefits
An additional benefit of a layer of leaf and plant debris on the soil surface, is that it provides favourable conditions for soil life, which enhances and sustains soil fertility. These organisms need moisture and a moderate temperature of around 28 °C to thrive. These conditions are provided by the layer of mulch.
Various larger soil organisms as well as micro-organisms break plant material down into smaller particles. Earthworms tunnel into the soil, thereby aerating the soil, and simultaneously moving the broken-down organic material into the soil. In this way, carbon is added to the soil, which improves soil fertility, and boosts the soil’s ability to retain water.
The result is a healthier, more fertile and drought-resistant landscape. – Fanie Vorster, ARC-Natural Resources and Engineering – Agricultural Engineering Campus
For more information, send an email to vorsters@arc.agric.za.
