Cost-effective irrigation

Over-irrigating costs you money in terms of water and electricity, and may lower your crops’ potential. Under-irrigating is also detrimental. Learn to irrigate properly and at the optimal time, says Bill Kerr.

- Bill Kerr

All too often, I come across farmers who do not irrigate practically or economically. Applying too much water ends up wasting money, while watering too little can stress the plants.

Many farmers use a weekly irrigation schedule: that is, watering once a week for a set amount of hours. But they do this without determining how much water the crops actually need.

To begin with, you need to know how much water is delivered per hour through the irrigation system. The next step is to determine how deeply the water penetrates the soil. The rule of thumb is that 1mm of irrigation wets 1cm of soil. So, for example, 25mm of irrigation will wet the soil 25cm deep. But keep in mind that this is a very rough guide.