Fertilisers: How to grow and maintain a healthy maize crop
At this time of the year, nearly all maize-growing areas in Kenya have planted and the crop is at the vital stage where nutrition will determine the quality and the size of the harvest.
At this stage, farmers need to ensure that their maize crop receives the right amount of nutrition to see it through the flowering and seed formation stages.
A healthy maize crop is able to withstand different challenges like pests and diseases.
How to ensure the right nutrition at this stage?
There are different ways of providing the right nutrients for maximum yield. A farmer can choose to use the following two main ways;
- Organic manures
- Inorganic fertilizers
It is important to control other factors like weeds, soil moisture (water), plant spacing and pests and diseases. For best performance always keep your farm weed-free as weeds are unwanted plants that bring unfavourable conditions like hiding and hosting pests, consuming water and nutrients in the soil meant for the crop and introducing diseases.
Organic manures are plant or animal waste or a combination of both that are used to provide crop nutrients through natural decomposition. The types under this are:
- Farmyard manure- such as cow dung, chicken droppings all mixed with the beddings from the cow boma or chicken house and allowed to decompose.
- Compost Manure- decomposed plant waste mixed with other substances like ash, animal dung, kitchen waste to improve nutrient content.
- Green manure - This is directly mixing a green crop into the soil. As an example most farmers during weeding, uproot weeds cut them up then mix the cut pieces with soil. This is basic green manure. However, one can grow a cover crop, usually, a legume like beans or cowpeas to later cut it up and bury it in the soil. As it rots and decomposes, the legume releases nutrients for use by our maize crop.
If you plan to use organic manure as your main nutrient source, apply your well-rotted manure during planting. The most common issue with farmers is identifying well-rotted manure, it should be like dark soil and no plant or animal matter should be visible. Well-rotted manure ensures that any diseases or weed seeds present are eliminated by the high temperatures during decomposition.
This method is by far the most commonly used because of the direct impact on maize growth.
Topdressing schedule for maize
Farmers are always advised to carry out a soil test which provides detailed information on nutrients needs for the specified crop.
The most common topdressing splits using CAN or urea in Kenya are:
- Initial topdressing. Done at the stage when the plant has four leaves to around 10 or more leaves. This is generally the vegetative stage of the crop. This has led to the advice that we should ensure we top-dress our crop when the maize height reaches the knee of an adult.
- Second and possibly last topdressing is done when the crop is starting to tassel. A tassel is the male flower of the maize crop formed at the top of the crop.
The above split has resulted in an effort to minimize labour costs. However, farmers can split the nutrient needs, especially when using inorganic fertilizers to a maximum of 6 splits if it makes economic sense to them. It is important that farmers apply the right amount of fertilizers to the crop. To understand the calculations behind the fertilizer amounts, watch out for our next article.