Organic crop production is about using natural materials to improve soil fertility, mainly of humus and micro-organisms that break down the organic material so plants can use it.
Humus (an end product of compost) and globulin (produced by micorisa fungi) are particularly important. Humus retains up to 80% of water; globulin protects plant roots and increases drought resistance.
The biggest problem in conventional gardening is using instantly soluble synthetic nitrogen and phosphate fertilisers. Regular use makes plants grow lusciously at first, but excessive free amino acids soon build up in the leaves, weaken disease resistance and cause insect invasions (eg thrips, red spider).
Most plants thrive in soil with a pH of 6 to 7. Monitoring the pH of your soil regularly is essential; farmers will also benefit from twice-yearly soil analyses. If the soil is fertile and well-drained, plants will grow lushly, and have few diseases.
CARING FOR THE SOIL
Fertile soil holds millions of good soil micro-organisms, which need carbon and nitrogen to stay alive. Nature supplies them; but man has interfered, with practices such as turning the soil regularly and using synthetic fertilisers, which make the soil barren. Fertile soil is porous, and the gardener should use compost and a mulch to feed and protect it.
Compost ready within 18 to 21 days (50% green material; 50% brown)
Green material: Nitrogen-rich (N) material such as green grass cuttings, vegetable peels, seed-free weeds, fresh or old cow dung or chicken droppings, lucerne (green or hay). Don’t add citrus, bones, meat or excreta from carnivores.
Brown material: Carbon-rich (C) materials such as leaves, newspapers, wheat chaff or straw, bits of brown cardboard.
- Don’t add material that’s been subjected to weed killers.
- Cut all material into small pieces. Mix them well and dampen them (squeezed by hand, they should hardly exude a drop).
- A 1% water solution of micro-organisms (EM) could be added.
- Cover with a plastic tarpaulin, black refuse bags or a black refuse bin.
- Turn the compost every second day.
- Aerate the heap if it gets too hot (70°C or higher).
The red compost earthworm eats kitchen waste such as vegetable or fruit peels, tea and coffee bags, newspaper and egg boxes, citrus peel (in small quantities); it really likes watermelon. The excreta contains 30% humus (black gold).
Always cover the soil with a 10 cm to 15 cm thick layer of mulch (covering material). It controls weeds, conserves moisture and keeps plant roots cool. The best mulch is lucerne hay (which also fertilises). Others are wheat chaff or pine bark.
LOOK AFTER PLANTS ORGANICALLY
- Don’t turn the soil too often.
- Use a garden fork to turn lightly (top 5 cm) and aerate by inserting the fork in the ground and twisting it slightly.
- After winter, you can dig deeper around plants that don’t have a shallow root system.
- Apply good-quality compost twice a year and cover with a mulch.
- Fertilise plants twice a year (depending on type of plant) using an organic fertiliser such as lucerne pellets or meal, ostrich pellets and organic fertilisers available from nurseries.
- Use very little synthetic, instantly soluble chemical fertilisers and never use raw manure, which could spread disease.
- Spray plants regularly with organic leaf food.
- Make your own using lucerne pellets or meal.
- Add 2 cups to 1 litre water, leave overnight and add this “tea” to 10 litres water the following day.
- Spray both sides of the leaf.
- You could also use a 1% worm compost “tea”.
- Use organic sprays to control insects.
- Avoid chemical organophosphates and imidacloprids which are harmful to bees and lady-birds.
- Rather use insect deterrents that contains garlic, chilli and pepper extract.
- If there’s a serious infestation and organic preparations aren’t effective, use a contact insecticide that has a minimal impact on the environment.
- Control fungal diseases with organic fungicides.
- A synthetic copper fungicide not harmful to micro-organisms and other insects may be used for black spot on roses.
- Spray both sides of leaf.
- Systemic fungicides can affect the formation of protein negatively.
- Lucerne (alfalfa) in the form of hay, meal or pellets is a must for organic gardening.
Also read: How to plant for better performance
- This article was written by Gerrit van Tonder and first appeared in Farming SA.