22/11/2021
There's a long standing question when it comes to feeding plants, should one use inorganic granular or liquid fertilizer.
We will analyse this conundrum and by the end of this read, you should be able to discern which route is best for you.
Let's get started. What is fertilizer and why is it so vital to plant growth?
Fertilizer is a compound of elements or mixture thereof, see a plant requires a number of "things" in order to grow to it's fullest potential.
1. Granular or in most cases, Inorganic fertilizers are a compound of Macro Nutrients essential to plants, and although some plants require certain elements in larger quantities, all plants in general require three (3) Macro Nutrients, and these are;
a) Nitrogen (N). This element is important for plant growth. Without nitrogen, a plant can't synthesis or make its own food using the sun because of a lack of chlorophyll, causing yellowing of leaves, a direct result of nitrogen deficiency.
b) Phosphorus (P). This element is important in carrying genetics of plants from one generation to the other, plant vigor(overall health) and assists in most plant processes as it is present in every plant cell. A plant lacking (P) will not produce shoots and will have purple-red in it's leaves as a symptom.
c) Potassium. (K). This element assists in root formation and drought resistance and symptoms of deficiency are scorching (browning) of leaf tips, yellowing in between leaf veins and reduced plant growth and fruiting.
The pH of a soil affects nutrient uptake and may require either liming or application of gypsum to lower or raise the acidity of the soil respectively.
An important point to consider is to know the elements required by a crop and have a soil test done for a field before planting to i) get the best out of a crop and ii) eliminate resource wastage.
2. Liquid fertilizer is a compound of elements or micro nutrients also called trace elements in soluble form. These elements are required by the plant but only in very little quantities.
They are typically, but not only, applied to the foliage (leaves) of plants through which they are absorbed. The elements include; Copper, Boron, Zinc, Manganese and Molybdenum.
Different plants require certain micro nutrients in higher amounts such as Tomato which requires Boron for fruiting, without which, black spots at the base of the fruit is evidence of deficiency.
3. Compost/Manure. Compost is well rotted/ broken down organic matter. Manure is animal waste. Different animals live on different diets and as such produce manure rich in different elements. Cow manure for example, is high in organic materials and rich in nutrients that are slow released to plants. It contains about 3 percent nitrogen, 2 percent phosphorus, and 1 percent potassium (3-2-1 NPK). It is also important to note that cow manure contains high levels of ammonia and potentially dangerous pathogens, for this reason, it’s usually recommended that it be aged or composted before it's used as manure. It is for this reason that cow manure is ideal for tree crops.
Chicken manure has high amounts of nitrogen which is quickly released to the plants and is ideal for applying in seasonal crops and vegetables but care must be taken not to apply fresh chicken manure as it will burn and even kill the young plants.
Key Point: Free range animal manure usually has high amounts of weeds and grass seeds and will overrun a crop if not addressed early. It is also important to note that fully organic models require manure and/or compost or organic matter large quantities and therefore may be feasible at a small scale.
Organic matter (OM) is also a vital aspect of good soil health, especially in sandy soils as it prevents leaching or sipping down of nutrients, sandy soils may require higher or more frequent rates of application compared to clay or soil with high organic matter content.
Conclusion: There is no one size fits all model when it comes to fertilization, especially if growing a commercially viable crop, and though one aspect may be used, a good program is one that takes into account a) Knowledge of plant nutrients/element requirement b) soil element composition and availability of natural materials c) soil type
