Agronomist notebook: You farm small? Intercropping is the way to go

Many farmers practise intercropping, which involves growing different crops on the same piece of land at the same time.

Intercropping aims at maximising the utilisation of nutrients in the soil as well as resources and providing support to the crops with weak stems if planted together with those having strong stems (secondary crops).

It also aids in suppressing weeds through provision of a good ground cover.

The practice leads to increased yield, easier field management, and control of pest and diseases.

There are three main intercropping systems namely strip/row intercropping, mixed intercropping, and relay cropping.

In strip intercropping, two or more crops are grown in rows on the same piece of land while alternating them.

Examples of crops produced in this manner are pigeon peas and maize.

Mixed intercropping system entails planting several seeded plants together at the same time through the placement method. Crops that should be grown using this method include cotton with legumes.

Lastly, in relay cropping, one plants a fast-growing crop on top of an already existing standing crop. Often, the second crop is sowed during the growth, more frequently near the onset of the reproductive development and fruiting of the first crop.

Examples are planting maize and sweet potatoes, with the latter acting as a cover crop reducing the impact of soil erosion and maintaining moisture.

Over the years, maize and beans have been the most strip intercropped crops, which have an adverse benefit to both crops if well planted.

Beans have root nodules that help fix free nitrogen from the atmosphere into the soil. Nitrogen is a primary macro-fertiliser element and it’s needed by several plants in large quantities for vegetative growth.

EXTERNAL MECHANICAL SUPPORT

On the other hand, some bean varieties require external mechanical support, which is provided by the maize plant, resulting in increased yields. This implies that farmers should plant bean seeds next to the maize crop.

Intercropping with compatible crops increases biodiversity by providing a habitat for a variety of insects and soil organisms. This helps in decomposition and improvement of the soil structure.

To control pests, one may intercrop a repellent crop with another. The system involves masking the smell of the production crop to keep pests away from it.

For instance, planting coriander as an intercrop helps control pests such as aphids, whiteflies and mites. The coriander plant attracts ladybirds, which feed on the pests. To achieve the best result, the coriander plant should be planted before the main crop.

In maize production, the push and pull strategy works to control the stem borer. Planting napier or Brachiaria grasses, with desmodium as a legume plant and maize works best. Desmodium is planted in between rows of maize and produces a smell that stem borer moths do not like.

This pushes the pest away from the maize crop. The napier grass should planted around the maize as a trap crop, which attracts the pest to lay eggs on it.

This, therefore, ensures the larva does not develop since it produces a sticky substance that traps and kills the pest reducing the impact of stalk borers on the maize plant.

Intercropping desmodium with maize also helps to reduce the impact of striga weeds due to the chemicals produced by the roots of plant.

This strategy has also helped the farmers to control the fall armyworm.

This form of intercropping helps farmers increase their maize yields, have fodder for their livestock, improve the soil structure by providing a cover crop and improve soil fertility since desmodium fixes.