Water conservation

This category contains 3 resources

Rooftop water collection, drip irrigation and plastic mulching in home garden conditions in drought prone areas of Cambodia

In Cambodia, drought can have different impacts: delay of rainfall onset in early wet season, erratic variations of rainfall onset, early ending of rains during wet season, and longer dry spell in July and August. This technology describes three different technologies and analyses the costs and benefits of their combined application: rooftop water harvesting, drip irrigation and plastic mulching in home garden conditions. As a result of the combined application of those good practices (GPOs), the resistance against drought is increased and a second cropping period is possible. The GPOs have been tested and validated in 19 Farms in the Kampong Speu (3) and Oddar Meanchey (16) Provinces in Cambodia.

Composting associated with planting pits

Compost is produced in shallow pits, approximately 20 cm deep and 1.5 m by 3 m wide. During November and December layers of chopped crop residues, animal dung and ash are heaped, as they become available, up to 1.5 m high and watered. The pile is covered with straw and left to heat up and decompose. After around 15–20 days the compost is turned over into a second pile and watered again. This is repeated up to three times – as long as water is available. Compost heaps are usually located close to the homestead. Alternatively, compost can be produced in pits which are up to one meter deep. Organic material is filled to ground level. The pit captures rain water, which makes this method of composting a valuable option in dry areas. The compost is either applied immediately to irrigated gardens, or kept in a dry shaded place for the next sorghum seeding. In the latter case one handful of compost is mixed with loose soil in each planting pit (zai). These pits are dug 60 cm by 60 cm apart. Three to four grains of sorghum are planted in each pit. Compost in the pits both conserves water and supplies nutrients. The planting pits also help by harvesting runoff water from the microcatchments between them. Boulgou experiences erratic and variable rainfall with frequent droughts.

Improved trash lines

Trash lines of organic material across the slope constitute a traditional land husbandry practice in south-west Uganda. Improved trash lines are smaller, closer spaced, and of longer duration than the traditional type. They are more effective in controlling runoff and maintaining soil fertility. All trash lines (improved and traditional) are composed of cereal stover (straw) and weeds that are collected during primary cultivation (hand hoeing), and heaped in strips along the approximate contour. The recommended spacing between the improved trash lines is 5–10 m, depending on the slope: the steeper the closer. Improved trash lines are left in place for four seasons before they are dug into the soil. Much of the material used has, by this time, decomposed or been eaten by termites. Through incorporation into the topsoil, they improve soil fertility acting effectively as ‘mobile compost strips’. Improved trash lines are multipurpose in retarding dispersed runoff while, as discussed, maintaining soil fertility. They are a low-cost option for soil and water conservation.