For a long time now, the crop yield per unit area of production in Uganda has been on the decline. The main contributing biophysical factors are inherent soil fertility particularly nitrogen and potassium deficiencies, exacerbated by soil fertility depletion.
Loss of soil nutrients through crop harvests as well as soil erosion is on the increase in many parts of the country. Many farmers are unaware of the losses, so they are doing nothing about it.
It is hard to sustain food production without using fertilisers. Studies around Lake Victoria basin, Bunyoro and eastern Uganda have shown that the soils can no longer sustain crops to meet challenges of a growing population. This has prompted soil experts in Uganda to highlight soil nutrients depletion as a crisis.
Although soil testing services are available in the country, very few farmers in Uganda carry out soil testing on their land; yet doing so would help them a lot in deciding what crops to grow or fertilisers to apply.
The general assumption is that soil sampling is such a costly exercise that only large-scale commercial farmers can afford it. This is of course wrong. Actually it can be more costly for a farmer to start growing crops without first testing the soils.
Currently, about 3,000-5,000 soil samples submitted by farmers and researchers are analysed annually by the Soils and Soil fertility Management Unit. The unit is based at the National Agricultural Research Laboratories (NARL) at Kawanda National Agricultural Research Organisation.
Farmers have to collect soil samples from their farms and deliver them to Kawanda for testing. However, according to the soil experts at Kawanda, very few farmers bother to seek advice on soil management from them. Different soil types are suitable for different plants. By getting to know the right type of soils, farmers will plant the right crops resulting into bumper harvests.
Soil testing services will soon be available to all farmers in Uganda, irrespective of their scale of operation. Uganda’s soils were last mapped in the 1950s.
The National Level Soils Map unit is developing a comprehensive up-to-date soil map of Uganda which, when completed, will help bring soil sampling services closer to the ordinary farmer. So far four out of the 17 soil map sheets covering Uganda have been digitised and updated at a scale of 1:250,000.
Why is soil testing necessary?
- Soil maps are used in planning and decision making both at the national and local administration level.
- They are used to determine location or relocation of farms, plantations, forests, industries, buildings and many other developments.
- Soils maps are used to develop other maps that will be useful to farmers.
- Besides determining soil suitability for different agricultural enterprises, the maps can help in preventing destructive happenings such as soil erosion. The National Level Soils Map unit will also soon publish a book on the soils of Uganda. The unit has built its capacity in soil testing and plant analysis over the years. This includes sensitising potential users on the availability and applications of the data.