By Gilbert Mwijuke
As hunger stalks millions of people in eastern Africa mainly due to a changing climate that has led to significant decline in food production in recent years, a new study has found that intensification of mineral fertilizer use in maize production can substantially improve food security in the region.
Towards the end of last year, the World Food Programme said that about 20 million people in eastern Africa were teetering on the brink of famine – and aid agencies have claimed that one person in the region is currently dying from hunger every 36 seconds.
In fact, despite recent improvements in living standards, studies have shown that food security remains a critical issue across most countries in sub-Saharan Africa, with more than a third of rural households across 17 countries in the region estimated to be food insecure.
The new study, which is titled Increased mineral fertilizer use on maize can improve both household food security and regional food production in East Africa and was published in December 2022 in the journal Agricultural Systems, estimated the effect of increasing the use of mineral fertilizer on maize yields and household food security and on regional maize supply.
Maize is one of the most consumed food commodities in eastern Africa, and the researchers used Uganda and Tanzania as case study countries because the two countries are in the top 10 maize producing countries in sub-Saharan Africa, with an average of 6.2 and 2.7 million tonnes per year, respectively.
“Our analysis showed that a substantial share of food insecure maize growers in Tanzania and Uganda could increase their household food availability in the short term with additional nitrogen fertilizer use on maize,” says the study, which was conducted by more than 10 researchers from across the world.
Exhausted soils
According to Geoffrey Ozuma, a crop scientist working with Uganda’s National Agricultural Research Organisation (Naro), the food insecurity that is currently ravaging eastern Africa can be largely blamed on the region’s exhausted soil due to increased pressure on the land as human populations rapidly increase.
The problem is compounded by lack of good agronomic practices among the region’s farmers, Mr Ozuma says, such as planting time and use of fertilizers. According to the new study, the average fertilizer use in the region is currently very low: 12 kilogrammes per hectare for nitrogen, two kilogrammes per hectare for potassium, and three kilogrammes per hectare for phosphorus.
“Farm inputs such as fertilizers are very expensive in Uganda. The government needs to provide these and machinery at subsidized prices,” Mr Ozuma said. “And farmers need to be sensitized about good agronomic practices and climate change.”
In the new study, the profit-maximizing nitrogen input was 82 kilogrammes per hectare in Tanzania, while in Uganda it was much lower, at 24 kilogrammes per hectare, mostly because of less favourable prices. A 50kg bag of nitrogen fertilizer costs Ush280,000 in Uganda, but prices are much lower in Tanzania.
“The profit-maximizing nitrogen input was above the reported nitrogen input for 95 per cent of the households in Tanzania and for 43 per cent of the households in Uganda. It was predicted to increase the food availability ratio of food insecure maize growers by 95 per cent in Tanzania, and by 25 per cent in Uganda,” the study says.
Could increase supply by 60%
With increased fertilization, the study says, food insecure maize growing households – which are estimated to be 35 in Tanzania and 42 per cent in Uganda – could increase overall maize supply by about 20 per cent whereas the 20-30 per cent food secure households that have a larger area planted with maize could increase maize supply in the region by an impressive 60 per cent.
The researchers estimated the response of maize yield to nitrogen fertilizer with a machine learning model trained on 15,952 observations and, with spatial price data, used this model to quantify the profit-maximizing fertilizer input for a sample of 4,188 households in Uganda and Tanzania.
“Households with relatively large per-capita maize area benefit most, as well as those located in areas where maize yields are low in the absence of fertilizer use and where yield responses to nutrients are high,” the study says.
According to Naro’s Ozuma, nitrogen is a very important nutrient for plants, without which they cannot do anything.
“All plants are green as a result of absorbing nitrogen, which helps them make their own food using carbon dioxide, water and sunlight. Yellowing of plants means a lack of food, and without food every living thing dies,” he said.
The study concludes: “Increasing staple food production on current agricultural land is necessary to improve household and national food security, while limiting biodiversity loss and carbon dioxide emissions associated with agricultural land expansion.”
