HOME GARDEN TECHNOLOGY LEAFLET 9
Cover cropping is a technique of growing low-lying crops, such as sweet potato, melon, pumpkin, beans and pea. Many leafy vegetables also cover the ground when their seeds are scattered (broadcast) widely. Cover cropping helps prevent soil from washing away during rains. Erosion of the humus layer and topsoil from a home garden greatly reduces crop growth and yield at harvest (see Figure 1).
Cover cropping is also a long-term weed control technique for the home garden. Unlike mulching (see Home Garden Technology Leaflet 6, "Special techniques for improving soil and water management"), which is used primarily for moisture retention and some weed prevention, cover cropping has multiple functions. Cover crops are more efficient in controlling both weeds and soil erosion, and they also improve the structure and nutrient content of the soil.
HOW COVER CROPS WORK
Cover crops such as trailing vines and leaves shade the soil's surface and protect it from the impact of rain, wind and passing humans and animals. A dense mat of cover crops provides strong competition for any weed seeds.
FIGURE 1
Vegetable cover crops
KINDS OF COVER CROPS
Food crops can be used as cover crops (see examples in Table 1). Planting different food crops together, or multiple cropping, is also a good method for covering the soil. See Home Garden Technology Leaflet 12.
Non-food leguminous crops also can be planted as cover crops and later used as green manure to improve soil fertility. Cover crops occupy the space between taller crops. This extends the area available for food production and makes maximum use of all available land. Figure 2 shows how cover cropping can be done between tree crops.
TABLE 1
Cover crops
Crops |
Establishment and care |
Food crops |
|
Sweet potato |
Feed these with compost to help growth of cover and food plants |
Pumpkin, melon, cucumber |
Most of these can be interplanted with other food crops |
Other |
|
Vetiver |
Uproot a clump of the grasses and split into pieces (splits) that include roots and leaves. Plant about 30 cm apart (closer for small grasses such as Manila grass) |
Centrosema sp. |
Broadcast legume seeds or dig them 2 cm into the soil, 30-50 cm apart. Hard, dry seeds may need to be scarified (i.e. have their skin removed) before planting |
FIGURE 2
Cover cropping between trees
HOW TO ESTABLISH A COVER CROP
To support growth of food cover crops, such as sweet potato or pumpkin, the soil must be cultivated and mixed with compost. Weeding should be done once or twice in the first month, until the crop is well established.
Sweet potato. Use vine cuttings 12 to 20 cm in length (best with roots) and place them upright or angled, with about 10 cm of the cutting buried in the soil. The top 2 cm of a sweet potato tuber with shoot buds also can be planted in this way.
Sweet potato cuttings of about 30 cm in length (with roots) or the tops of the tuber (with shoot buds) are planted about 30 cm apart. It is best to plant sweet potato in rows, mixing in compost in each row before planting to help the tubers grow.
Pumpkin, cucumber and melon. Dig planting holes that are 1 m apart. Take the soil that is removed and mix it with two handfuls of compost, place the mixture back in the planting hole, and then plant two to three seeds in each hole. Place the pumpkin seeds roughly 4 cm deep. The seeds of cucumber and melon should be placed 2 cm deep.
Legumes. Cover crops such as cowpea will not usually require weeding and can survive without compost in reasonable soil. The local agricultural extension worker can provide advice on where to get planting materials and how to treat seed.
FIGURE 3
Planting sweet potato cuttings
