Why Nigerian soils cannot produce crops without fertilizer – Prof Amapu

Can we know your specific interest in the field of soil science?My specific interest in soil science is to see how the soil can provide the required nutrients needed by plants; the plants that produce the food we eat. The soil has to be properly fed. The plant needs to be fed to produce the […]

Can we know your specific interest in the field of soil science?
My specific interest in soil science is to see how the soil can provide the required nutrients needed by plants; the plants that produce the food we eat. The soil has to be properly fed. The plant needs to be fed to produce the food that we need from them.
What do you mean by ‘the soil needs to be fed before it can produce the food we need?
Plant is a living thing, just like the human being. Plants possess the characteristics of living things that include eating. We call their food nutrient. Seventeen elements of nutrients out of the over 100 we have are essential for plants. They are essential because of three basic reasons.
One: without them the plant would die prematurely – right from seedling – without completing its circling.
Two: the nutrient has its function and no other thing can replace that function.
Three: it helps in metabolism that is the development processes; the building and breaking down process that takes place in plants. This is just like what happens in the human body.
For example, the human body doesn’t eat garri or tuwo but such food are broken down and the body makes use of the nutrient it requires and throws away the parts that are not needed, and this is why we go to toilet.
In addition to the 17 nutrients, there are those that we call the beneficial. They are beneficial to specific needs of the plant but they are not essential. This is to say these 17 nutrients are required by all the plants but the beneficial are required by certain plants under certain conditions.
The soil actually provides these 17 elements that I have mentioned. There are some other elements that come in from the water or the air. So, the soil is actually the medium through which these nutrients are given to the plants. So, fertilizer comes in when the soil fails to provide these nutrients.
Are you saying that Nigeria’s soil cannot provide these nutrients as such we must use fertilizer?
You have given the answer. If your soil provides these nutrients, you don’t need to apply fertilizer.
What is responsible for the deficiency?
Up to the 1960s, a farmer would just open a new farmland and plant his crops and they would do very well. However, after two to three years, you would find that the yields are going down because those nutrients in the soil are going down by the day.
It is just like you keeping your bags of grains in your store. The moment you begin to pick the bags for certain needs like eating or selling, they would begin to go down; that is how nutrients are to the soil. The continuous usage of our land requires that we must apply fertilizer.
When soil lacks nutrients, it shows hunger sign where you see the plant looking yellowish instead of green. This is telling the farmer that his plant is hungry because those nutrients, especially nitrogen, are lacking.
The system of abandoning land, like land rotation, helps but the problem is the impossibility of the practice now.
We should also know that soils are differently endowed. This is because these soils are formed from rocks and there are different types of rocks. I don’t want us to go deep into science. But each of the three types of rocks that we have, have different quantity of nutrients in them. So, it depends on where your soil is formed. If your soil is formed from the rock that has many of these nutrients, it means your soil is naturally endowed.
Apart from the type of rock, there are other things that affect the formation of soil, which enables it to store enough of these nutrients or not. Water is needed; temperature and organisms in the soil also matter. One very important constituent of the soil is what we call organic matter. If the organic matter of your soil is low, nutrients would also be low, particularly nitrogen phosphorous.
An environment where the temperature is high, there is the likelihood that the organic matter content would breakdown and the nutrients would be low. In Nigeria our temperature is high unlike in Europe where the temperature is low. So, the organic matter of their soil would be high because they are not broken-down and lost. This is our situation. Immediately you open up our soil for agriculture, they begin to loss their nutrients and become poor and this makes the use of fertilizer inevitable.
Now, we have different types of fertilizers. Traditionally, we don’t know the mineral fertilizers. We only knew the organic fertilizers, that is, manures that come from plants or animals.
The problem of the manures is that the concentration of these nutrients that we are talking about is low. For example, the farm yard manure, research conducted here in IAR has shown that if you want to cultivate a crop of maize of one hectare you need about five tonnes of such fertilizer, that is 50 bags of 100 kilogrammes but you need just about eight bags of mineral fertilizer in such area. From here you can see the difference.
This is why when people keep talking of organic farming, personally I feel that it is lack of proper knowledge or they are just trying to deceive us. In Europe, they can go for organic farming because their soils are already rich and they have enough of these organic fertilizers. For example, how many animals do we have here? With our condition here, it is very difficult to survive on organic farming.
However, combining organic and mineral fertilizers can be the best option for us, and it can even help in curtailing the negative effects of mineral fertilizer. Anybody that is saying we should stop using mineral fertilizer is not being honest with us because the fertility status of our soils now cannot support the production of crops without the mineral fertilizer.
Some experts say mineral fertilizers destroy soils?
People accuse mineral fertilizer as having bad sides but this arises from wrong use. It is like when you go to the hospital and a doctor prescribes a drug for you and you decide to take the drugs contrary to the doctor’s prescription, you can imagine the effects.
Organic matter is referred to as the lifeblood of soil because of its importance and, yes, nitrogen fertilizer affects that; like acidity of crops. This largely comes in from wrong use. Most farmers don’t balance their fertilizer application with the right fertilizer combination.