OBWOGO: From Bill Gates, One More Reason to Invest in Fertiliser

Dr Subiri Obwogo • 11 June 2019

When I was growing up, things like fertiliser, water harvesting, mechanised farming or pesticides were unheard off. We were lucky that the soils were not denigrated and all that you needed to do was to drop a seed and come back six months later to a bumper harvest. We were assured of two rainy seasons— from February 28 to end of July and again from September to December. Not anymore.

I was therefore surprised to read that one of Bill Gates pet subjects is improving access to fertiliser in Africa as a way to boost agricultural productivity and lift millions from poverty.

You see, one of the reasons for low crop yields in Africa is poor adoption of relevant technologies in water use (irrigation), soil fertility (soil testing and amendment), pest and disease control, quality seed, access to finance and mechanisation and slow adoption of smart farming technologies, among others.

I wrote recently about low uptake of fertiliser in Africa and shared the graph below. The use of fertiliser per hectare in the USA, EU, India, China and Latin America (Brazil) is 132kg, 150kg, 157kg, 364kg and 175kg respectively, compared to average of 17 kg in sub-Saharan Africa.

Globally, the average use per hectare is 135kg. In Uganda and Kenya, the application rate is 2.5kg and 38.2kg per hectare respectively (Knoema 2016 data). (I’d argue that the only reason Uganda produces more than Kenya is abundant rainfall and access to virgin lands).


To quote Bill Gates article, “Farmers’ yields in many parts of Africa are just a fifth of those of U.S. farmers,” as depicted in the graph below.

Maize Bill

Let’s look at maize. Besides being a staple food for millions, it’s an important substrate in making animal feeds and edible oils. On average, Uganda produces three times per hectare what Kenya produces, although this is still below the global average of 12 tonnes per hectare (see graph below). As a matter of fact, maize production in Kenya has always lagged behind production.


But Gates has a warning on likely damage that can result from excessive use of fertiliser, “One of the consequences of the Green Revolution was excessive fertiliser use, leading to water pollution and other environmental impacts”.

He advocates training farmers how to apply fertiliser in the proper amounts that will increase yields while also promoting environmental sustainability. He also champions digital soil mapping and soil testing to provide farmers with valuable insights into how to improve the health of their soil so they can remain productive for generations to come.

In fact, one of the reasons for reduced maize productivity in Kenya is soil acidity resulting from excessive and reckless application of DAP fertiliser.  Studies have shown that in most cases, soil acidity ranges between 5 and 7 and farmers rarely use compost or animal manure during planting. 

Maize requires fertile, well-drained, well-aerated good textured soil. Soil PH determines availability of nutrients.  Maize grows best in soil PH of between 5.5 and 7.3, with an optimum of 6.0 to 6.5. In this range, nitrogen, potassium, phosphorus, calcium and magnesium are readily available.

Nitrogen helps to produce healthy leaves, phosphorus for root formation, potassium for fruiting, and secondary nutrients such as calcium and magnesium are important for physiological functions. 

As an aside, inorganic fertilisers are generally less expensive and have higher concentrations of nutrients than organic fertilisers. Also, since nitrogen, phosphorus and potassium generally must be in the inorganic forms to be taken up by plants, inorganic fertilisers are generally immediately bioavailable to plants without modification.

Here’s the sad part. Even as productivity dwindles and farmers confront high cost of inputs, including fertiliser, the Kenyan taxpayer was as at June 2011 paying a debt of Sh3 billion owed to foreign banks on account of the Ken-Ren Chemical and Fertilisers Company Limited that had been contracted to build a fertiliser factory in 1977 but which was never constructed

The then USA ambassador to Kenya, Wilbert John Lemelle wrote this, “It would seem at the moment that the highly placed Kenyans who are heavily involved in fertiliser import business, among them the President’s son and nephew, have carried the day against those who desire Kenya to have its own fertiliser capacity.”

Just as it happened with the infamous Sh7 billion Galana-Kulalu irrigation project that collapsed, the politically-correct fat cats with vested interest in importing fertiliser didn’t want to see fertiliser produced locally as this would cut off their money-minting schemes.

You might wonder whether it’s time to call out the heartless witch that cast a spell on Kenya’s development trajectory.