“The causes of degradation cut across so many factors in Uganda. These include poor tillage and poor choice of crops, overgrazing in the cattle corridor, bush burning and non-application of fertility enhancers,” says Dr Robert Muzira, a soil scientist from Mbarara Zonal Agricultural Research Institute.
Soil is made up of different nutrients and organic matter which is always on top of the soil is washed away through soil erosion and bush burning leading to the loss of nutrients like nitrogen, sulphur as this escape.
This leaves the soil bare; when these are missing from the soil, the fertility of the soil is lost.
-Soil erosion-loss of top fertile soil, occurs when it rains heavily.
-Bush burning causes loss of Nitrogen and potassium.
-Over tillage/over ploughing –causes loss of soil structure due to compaction.
-Overgrazing leaves the soils bare, hence affected by direct sunshine, which leads to loss of moisture.
-Not replacing removed nutrients leading to negative nutrient balance of around: -21, -8 and -43 for NPK.
-Mono cropping deprives soils of possible nutrient-enhancing crops like legumes. This is why intercropping is important.
-Use of undegradable materials – polythene, because they prevent water from seeping into the soils.
-Cemented elements near the farmland, for example, graves. Cement affects the nutrients in the soil. Such soils cannot allow root penetration, but also the larger spaces that take in air, will be blocked and nutrients including oxygen will not find their way into the soil to get to the roots.
-Continuous tillage/ploughing affects the larger spaces for air which tend to disappear, especially where there is clay, affecting fertility.
-Weeding, removing all the weeds and placing them onto the boundary exposes the soil to direct heat and rain. This again takes away fertility in the top soils. The best thing to do is to weed, but let the cut grass remain and rot on top of the soils