Grow Your Own Fertilizer -Plant Cover Crops with Maize

Backgrounder

Many farmers in different parts of the world are growing their own fertilizers. Commercial fertilizers are becoming more and more expensive and they often fail to keep the soil fertile. So farmers are growing cover crops which are available, inexpensive, and help to keep the soil fertile for many years.

Cover crops protect the soil from rain and sun by keeping the soil covered, they help to control weeds, and they add organic matter and nutrients, including nitrogen, to the soil. Today we are going to talk about three different cover crops to grow with maize. They are velvet beans (Mucuna pruriens), which are grown by farmers in Honduras, lablab beans (Dolichos lablab), grown by farmers in South Africa, and sunnhemp (Crotalaria ochroleuca) grown by farmers in Tanzania.

Let’s start by talking about velvet beans. In the North Coast area of Honduras, farmers get double the maize yields that farmers in the rest of the country get. This is because farmers on the North Coast grow velvet beans with their maize. They plant velvet beans between the rows of maize about two weeks after the maize is planted. When the maize is about 1/2 metre tall, farmers cut the velvet beans back with a sharp hand tool so that the velvet beans do not overtake the maize. The bean crop protects the soil. Even if the rains stop for 2 or 3 weeks moisture stays in the soil because the bean crop keeps the soil covered. After the maize is harvested, the beans grow rapidly, and cover the maize stalks left on the ground. This makes a thick mulch which protects the soil from the sun and wind and prevents weeds from growing. Farmers chop the mulch with a machete and plant next year’s maize crop directly into the bean mulch. They just separate the mulch a bit, make holes in the soil, and place the maize seeds in the holes. If they leave the velvet beans in the field like this they will reseed themselves. Or they plow the velvet bean plants into the soil for added fertility. Some farmers let their animals graze the bean mulch.

In Southern Africa farmers grow lablab beans with maize in a similar way. They plant the maize first. Two to four weeks later they plant lablab beans between the maize seedlings. By planting the lablab beans later than the maize, the maize has time to mature without being overrun by the beans. Lablab beans have the advantage of being good eating as well as being a fertilizer crop.

Farmers in Tanzania use a different fertilizer crop called sunnhemp. They plant one row of sunnhemp for every two rows of maize. With this system they have fewer weeds in the field. They leave the sunnhemp standing in the field until it is completely dry and then harvest the seeds. Then they cut down the sunnhemp and use it as a mulch for the maize. This mulch fertilizes the soil and keeps the weeds down.

Cover crops such as velvet beans, lablab beans, and sunnhemp are becoming popular fertilizer crops. These crops protect the soil from rain and sun by keeping the soil covered, they help to control weeds, and they add nutrients to the soil. By growing these crops with maize, farmers increase their yields at little or no extra cost.