Soil management is looked at as applying chemical fertilisers to the soil every year to increase crop yield. That is true of course. But soil management should be looked at beyond that.
Apart from increasing crop yield, there are other parameters that are important in crop harvests in addition to quantity. Issues such as quality of crop yield are also important.
Sometimes the nutrients available in the soil influence the quality of the yield. Some studies have shown that tomato storability is influenced by the nutrients that were available in the soil but have been taken up by the crop. Issues of storability are critical, especially here in Malawi where electricity is a big problem. Crop yield quality includes nutrient content of the crop and flavour for crops such as onion and garlic among others.
Quantity as the only parameter of yield has been overemphasised. In most of our agricultural shows, we talk of a big onion, a big cob of maize or a big root of cassava without necessarily talking about other quality parameters such as storability and the nutrient content that the crop contains. Such a big tomato may have a thin skin that makes it difficult to transport and have a very short shelf life.
Availability of soil nutrients also affect mineral composition of the food we take. The mineral composition of food is influenced by what the plant took from the soil. If the soil was deficient of iron, the crop from such soil will be deficient of iron.
Soil nutrients that are required in large amounts are called macronutrients and those that are required in small amounts are called micronutrients. Nutrients such as nitrogen, phosphorus, potassium, calcium, magnesium and sulphur are macronutrients. Soil nutrients such as chlorine, copper, manganese, boron, zinc, molybdenum and others are examples of micronutrients. Plants need both macro- and micronutrients for growth and production.
Unfortunately, fertilisers supply only nitrogen, phosphorus, sulphur and potassium, which are macronutrients. This means that fertilisers do not supply the much-needed micronutrients to crops. It also means that ways have to be found to supply the much-needed micronutrients to these crops.
Time and again, farmers have been told that chemical fertilisers are not a substitute for organic fertilisers. In the absence of fertilisers that contain micronutrients in our markets, this makes manure-making a must. As scientists are still working on other methods that will help farmers supply the macronutrients to the soil, farmers should intensify manure-making and application to supply these soil nutrients. This will be an answer to crop yield quality improvement and an improvement in nutrition as well.
Here we are talking about serious manure-making and use and not just for showing off. Farmers have to be guided on how to make manure and also best materials that should be used in manure-making. It is a given fact that the type of nutrients the manure will release in the soil is what was in the materials for making manure. Therefore, quality of materials for manure-making should be seriously considered before embarking on the manure-making mission.
Farmers should understand the importance of applying manure in their gardens. Many are the times farmers have jokingly made manure along the roads just to show off. Most of those farmers do not even apply this manure in their gardens. They are doing it simply because they are told to.
It is an interesting story to see some commercial farmers buying manure from poultry farms and apply them in their farms. No one pushes them but they have realised the importance of manure applying in their fields.
Malawi economy is dependent on agriculture; therefore, agriculture must be taken seriously. Soil management should not be taken lightly since it is a key to agriculture development in the country. Proper soil management can be an input in the health sector where high-quality food is an answer to some of our health problems in addition to high crop yield we talk about.
The author is an agriculture expert and also a Malawi Assemblies of God pastor but writes personal capacity.
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