Chemical fertilisers may be expensive, but they are needed for optimal vegetable production. When funds are limited, use at least 25% of the recommended chemical fertiliser, then apply organic fertilisers, like manure, compost and comfrey, to improve soil fertility.
Decomposed manure is an excellent soil conditioner. The dung of animals that have eaten Lucerne, good quality hay, silage and concentrates makes better manure than that of animals that have grazed only veld. Animal bedding contains valuable nutrients, particularly nitrogen.
Poultry manure is usually the best, followed by sheep, horse, cattle and pig manure. One warning – use poultry manure carefully, it is high in nitrogen and may burn crops. A light application of 150g to 200g/m² should be well worked into the soil before planting. Don’t use poultry manure on a root crop.
Liquid manure is applied as a top dressing and is good for most vegetables. To make liquid manure empty a bucket of manure into a hessian sack and hang the sack in a drum of water. Some of the manure will dissolve. After two weeks, fill a bucket or watering can a quarter full with the dissolved manure, then top it up with water. This should be enough for about 1m².
Green manure, or cover crops, are plants grown to benefit the soil. Green manure replaces and holds nutrients, improves soil structure and increases soil organic content. Cowpeas, pigeon peas, clover, lupines, oats, millet and grazing rye are all good cover crops.
They can be planted in fallow fields and grown out for four to six weeks before being disced or dug into the soil to rot down before the next crop goes in. Don’t let cover crops go to seed as they all have the potential to become weeds.
Comfrey leaves are a source of nitrogen, phosphorus and potassium. Freshly cut, the leaves can be used as a mulch for fruit trees and vegetables. They can be used as fertiliser in planting holes because of the rapid breakdown of nutrient-rich leaf material.
To make liquid fertiliser half fill a plastic bin or barrel with fresh comfrey, add water, cover and leave to stand for three to six weeks. Use this comfrey tea at full strength or dilute it to half strength.
Compost is made up of decomposed plant and animal materials; organic waste, plant debris, animal dung and chicken manure. Bacteria, fungi, earthworms, snails, insects and birds help with decomposition and turn it to humus. Compost increases water retention capacity and nutrient availability.
Cover your manure to protect it from the rain which washes out many nutrients.