Alex Lwakuba, the acting commissioner for crop resources at the agricuture ministry, Ugandan farmers still think that Uganda’s soils are still fertile enough, and others do not know how to enhance their soil fertility because they do not know how to find out the missing nutrients.
“The rewards of nature must not make Ugandan farmers complacent, assuming that the soil is fertile and thus there is no need for fertilisers,” Lwakuba, says.
He says Uganda’s soils have been used for agriculture for over 500 years and now are tired.
“We must not prolong the tale of the natural gift of God because it is affecting our yields,” Lwakuba, who is also a soil scientist said.
Prof. Kitungulu Zaake, a soil scientist points out that soil fertility in terms of the proportions is low.
The proportions where fertility is between high to medium in Ugandan soils stands at 26%. Meanwhile, medium to low fertility stands at 47% and low to negligible fertility stands at 27% across the country.
“We cannot talk about sustainable agriculture when we have soils with negative nutrient balances, that cannot yield well,” Lwakuba says.
He thus says farmers must usage of soil fertility enhancers like fertilisers now.
Soils at a glance, according to Prof. Zaake;
-Very old, therefore, deeply weathered-hardly stores nutrients.
-Inadequate supply of the major nutrients.
-Low nutrient holding capacity – poor retention of water resulting in poor yields.
-Deficient or toxic of trace elements – being acidic means that even if you use fertilisers, they will not be effective.
-Soluble nutrients prone to leaching – losses, especially to nitrogen and potassium.
-These above characteristics show major shortcomings relating to plant growth requirements.
One survey done by Prof. Zaake indicated:
-High to medium fertility was 26%
-Medium to low fertility was 47%
-Low to negligible fertility was 27%
So what determines soil fertility?
Soil has large and small spaces. The small spaces take in water, while the large spaces take in oxygen. For the plants to grow as expected, the soils must have all the nutrients like nitrogen, phosphorus and potassium (NPK). Other nutrients are magnesium, calcium and sulphur, required in small quantities. Iron, copper, manganese, zinc, chlorine and sodium are required in minute amounts. All these contribute to the growth of crops.
-There is a misconception among farmers that NPK is a single fertiliser or nutrient for the soil, whereas not. Zaake says NPK is a combination of three nutrients needed by plants for the different stages of growth.
-When planting, the first interest is root formation, so farmers should apply phosphorus.
-When leaves start to show, nitrogen should be applied and when it comes to fruiting, that is when potassium can be added to make a complete set of NPK.