This archive report was first published on 25 July 2019.
Kenya's maize yields have been a cause for concern, with most regions recording between 9 to 11 bags per acre, a far cry from the target yield of 30 to 40 bags.
According to experts, poor farming practices, including incorrect application of nitrogen fertilizers, are partly to blame. Top dressing, which involves applying nitrogen in granular fertilizer form to crops, is a crucial aspect of maize cultivation.
However, top dressing and weeding go hand-in-hand. Weeds compete with maize plants for nutrients, and if not removed, can limit yields during times of high nitrogen demand. Urea, or CAN, is the cheapest form of nitrogen, but it should only be used when rain is guaranteed to prevent it from hydrolyzing and being lost as gases to the atmosphere.
Experts recommend applying nitrogen at the knee-high stage of maize growth, which is around 18 inches tall. This allows the plants to absorb the nutrients effectively. Weeding between rows of maize should continue until the plants achieve their natural canopy, which suppresses further weed growth.
It's also essential to note that weeding during dry spells can have a negative impact, as it removes soil moisture. Therefore, it's best to weed when the rain is around and leave the weed trash in the lines to act as an umbrella during drier periods.
While embracing good farming practices, it's also crucial to weed before the maize flowers so that they can't seed and regrow. Mechanical weeding is possible, but it must be done with GPS guidance to avoid uplifting the planted maize through human error.
Most subsistence farmers intercrop maize with beans or other leguminous crops, which has advantages such as reducing crop failure risk and providing a cover crop within the rows. However, in the long term, crop rotation is a better practice to achieve good natural soil nutrient balance and maximize yields.
