Using manure on acidic soil

If your soil is acidic, simply applying manure won’t improve your yield, so you need to add lime or wood ash.

If you farm in a high rainfall area, the soil is probably acidic, and simply adding manure won’t improve your yield. That’s because plants can’t take in nutrients that remain fixed, or “trapped”, in acidic soils.

Applying lime to soil
First make sure the soil is acidic by taking soil samples for testing. This costs money, but it’s worth it if you want high yields. If soil is acidic, lime is usually applied in large quantities. You may have to apply 2t/ha to 3t/ha of lime to neutralise or “combat” soil acidity. And lime isn’t cheap, especially if you live in a remote area.

Using wood ash in manure
If lime isn’t available, or you can’t afford it, use wood ash. Save the ash from cooking fires and mix it with the manure before applying it to your plot or land. The wood ash will make the nutrients from the manure available to your crop, at least for a short time. Sprinkling wood ash around the base of your plants will also repel insects, slugs and snails, because it draws water out of these creatures. Remember, once the ash gets wet, it loses this property. Too much ash in fertiliser can also increase pH or lead to high levels of salts that can be harmful to some plants, so use it carefully.

For more information, call the institute on 040 602 2011.