Sixty-eight percent of soils in the Amansie East, Bosomtwe and Bosome Freho districts of the Ashanti region are reported to be turning more acidic.

This is contained in a recently conducted research by the Soil Research Institute of the Council for Scientific and Industrial Research (CSIR-SRI) under its first fertility mapping project for the entire country.

The researchers attribute the unhealthy nature of the soils to excessive application of inorganic fertilizer, and poor farming practices.

Farmers in these communities are lamenting the pain of growing on infertile land which is affecting their production over the years.

Augustine Fosu and his colleague farmer, Augustine Nkrumah join a team of researchers to fetch samples of sand from their farm to be tested at the laboratory.

The exercise is to know the soil profile of their parcel of land. They both farm in Yaase Adwafo – a suburb of Kuntenase – the district capital of Bosomtwe in the Ashanti region.

In recent years, the two farmers have failed to cultivate enough from the piece of land handed to them by the forefathers.

“Last year, I planted okra and harvested 15 to 25 large baskets of it. But this year, I harvested only two baskets,” Augustine Fosu said.

His colleague, Augustine Nkrumah, added: “We don’t know what is wrong with the soil. Before, we could make good harvest of cabbages. But this year whenever the cabbages grow, they turn yellow -what we call here Bright. We now can’t even harvest twenty bags. But initially, we could get 100 to 150 bags”.

The unhealthy and dwindling harvests prompted their overreliance on pesticides and other inorganic fertilizer applications in hope of curing their farms. But the situation never really changed.

“We used to apply ammonia and N-P-K (15-15-15) but nothing really is happening. We are unable to make good yields. We also have to pay our labourers,” Augustine Nkrumah said. 

Farmers in the Kuntenase enclave are mainly into the cultivation of grains, horticultural crops like vegetables, and other staple crops.

The farmers fondly abuse fertilizers to boost growth in order to gain income and profits within the shortest possible time after cultivation.

“Because vegetables are cash crops, so the farmer doesn’t want to even apply the poultry manure, but just the fertilizer. They feel the poultry manure will delay them. So, they usually abuse the fertilizer to hurriedly gain more,” Agric extension officer for the area, Patricia Boamah, said.

Their situation reflects that of many farmers across the country who overly depend on the sole application of inorganic fertilizers to increase their yields.

Excessive fertilizer applications have been found to destroy the natural soil integrity and profile.

Acidic soils impacting crop production

The sand samples taken from the farms of Augustine were tested for their acidity, organic matter levels and phosphorus and other essential soil nutrient contents.

After the series of tests, the sample was found to be unhealthy for plant growth – it had higher acidic levels of 4.7 and declining nutrients.

This confirms a recent study by the CSIR-SRI with support from the OCP Foundation of Morocco which revealed soils in the Bosomtwe, Bosome Freho and Amansie East districts were declining in fertility.

68% of soils in these three farming areas were proven to be more acidic – a limit beyond the approved acidic range of 6 to 7 for soils.

Lead scientist, Dr. Francis Tetteh says declining soil fertility is the main challenge to crop production in Ghana.

“We have to correct this underlying problem of acidity before we can improve crop production. We’re talking of a wide yield gap. Cocoa grown here is only about 380kg per hectare. But we can get 1 tonne per hectare,” he said.

Soils harbour the essential nutrients needed for plants and crop production ultimately consumed by humans for all the crucial nutritional values.

The declining soil fertility is impacting yields, especially fresh maize which is the main crop cultivated in the area.

N-P-K contents desperately needed in soil for plant growth

Acidity is not the only prevailing challenge: essential nutrients like Phosphorus and Potassium (K), which are critical for plant growth, are deficient in the soils here.

Eighty-nine percent of the soils in the three communities were found to be deficient in phosphorus contents while eighty-one percent had low Potassium levels.

“Phosphorus is needed for root development and also for fruiting. So, when the farmers are talking about fruit abortion and leaf fall, it is as a result of phosphorus deficiency,” Dr. Tetteh said.

Just as the human body needs some nutrients to fight infections, Potassium (K) is needed for plant health. Without adequate levels of the nutrient, plants are easily attacked by viruses, bacteria and other pathogenic organisms.

Potassium helps the plants to develop thicker cuticle – a protective film covering the skin layer – to ensure when spores of the pathogenic organisms fall on the leaf, they are unable to penetrate the plant and cause infections.

“We claim Ghana’s soil is rich in potassium, but that’s not the case. The farmers fail to apply fertilizer but they are always harvesting without restoring the lands with this essential nutrient,” Dr. Tetteh indicated.  

Nitrogen was however not found to be declining in the area.

“Because of the forest zone, nitrogen is not so critical because the leaves will fall and there will be decomposition and enrich the soil,” Dr. Tetteh said.

But there is a caution against the continuous use of lands which could result in declining nitrogen and organic matter contents.

Illegal miners thwart access to lands for testing

While the study was conducted for the cropping farmlands, illegal mining sites were not accessible to the researchers.

Illegal mining has become a bane to agriculture in the country: destroying many arable farmlands as they are found to use poisonous chemicals in extracting mineral ores like gold.

The three communities are known hubs for active illegal mining activities.

The researchers were prevented by the miners from assessing the quality of soils in these chemically-infested lands.

But it has become crucial for the country and its citizens to protect the once virgin land which served the agricultural needs of their ancestors. 

“Soil is a non-renewable natural resource. If you lose it, you will never get it again. So, what we have now, we need to protect the soil. Our great-grandfather left something nice for us, so we must protect and sustain it,” Dr. Tetteh said.

These conditions are discouraging youth participation in agriculture in the area.

“Because the soils are hardened and not yielding enough, the youth are not ready to go into farming as they are unable to make profits,” District Agric extension officer, Afia Asenso Owusu Ansah, revealed.

Lime to the rescue

But amidst this stark reality, scientists are proposing solutions to restore the declining soil fertility.

Since fertilizers are acidic in nature, the researchers are advising the use of lime - an inorganic compound of calcium oxides and hydroxides - and other regenerative agricultural techniques to restore the land.

Lime neutralizes soil acidity by raising the pH level, improves nutrient solubility, and provides essential nutrients such as calcium and magnesium. This generally improves the health of the plant and enhance root developments.

“Lime will correct this. But our farmers haven’t been well educated to apply it on their soils. So, they keep using fertilizers. Meanwhile, all fertilizers are acidic. So, as you use the fertilizer you must use the lime,” Dr. Tetteh advised. 

It has become now more than crucial for the country to take painstaking measures to save degrading soils, without which the very essence of life could be lost.