Hydroponics: an interview with Rosemary Nyamuh
What is hydroponics?
Hydroponics is the practice of growing plants without soil. The plants can be grown in a nutrient-rich solution, or in a disease-free substance such as sand, gravel or coconut fibre, watered with nutrient solution.
What are the benefits?
First of all, fertile land is not needed to grow crops hydroponically. Crops can be grown anywhere – inside and out – in a much smaller space than traditional farming. The environment is more controlled so there are fewer weeds and a lower risk of pests and diseases.
With the proper set-up, plants will grow and mature more quickly than if they are grown in soil. This is because the plants do not have to work as hard to obtain the nutrients they need to grow. Their exact needs are met so they can concentrate on leaf and stem growth instead of spending energy expanding their root systems. Fodder for livestock can also be grown quickly using hydroponics, reducing pressure on grazing land.
Water is recirculated so less is used and none is wasted. Where farmers have greenhouses, water can be collected and used from the roof.
Are there any disadvantages?
The biggest challenge is the cost. Quite a lot of equipment is needed to create a large-scale hydroponics system: containers, pumps, lighting, nutrients etc. However, there are small-scale, cheaper options.
For larger systems, a high level of knowledge is needed to manage the system well and avoid costly mistakes. The plants need to be closely monitored and the pH and nutrient levels in the system adjusted regularly.
As the plants are grown close together in an enclosed system, pests and diseases can spread rapidly. It is important to have a good disease management plan including the use of disease-free water and growing materials.
What advice would you give to someone new to hydroponics?
There are many different hydroponic systems to choose from, depending on the amount of money you want to spend and how complicated you want it to be. The wick hydroponic system is cheap and only requires a bucket, wicks, nutrient solution and something for the plants to grow in, such as sand.
The wicks draw the nutrient solution up from the bucket and release it into the growing medium, making it available to the plant roots. Wicks can be made out of any absorbent material including string, wool or cut-up bits of old clothes.
Ready-made nutrient solutions can now be bought in many places. To make your own, ask your local agricultural department for advice or speak to other hydroponic growers.
Find out as much as you can about the technology before you start. See if there are any local courses and, if you can, look at the many ‘how to’ guides available online. Joining a group of hydroponic growers can be very helpful as everyone can learn from each other. Forming a cooperative can also be a great way to spread the cost and share labour and other resources.
Which crops grow well in hydroponic systems?
Most vegetables and many other crops will thrive. Good examples include potatoes, tomatoes, strawberries, grapes, herbs, lettuce, cabbage and green beans. For a wick system, choose smaller, non-fruiting plants such as lettuce or herbs.
Rosemary Nyamu is Deputy Director of the Kenya School of Agriculture.
The Food and Agriculture Organization has produced several articles and manuals on hydroponics which can be accessed online: www.fao.org (search ‘hydroponics’).