Self watering containers increase lettuce yield

self watering containersA trial comparing the effectiveness of different irrigation methods has found that most crops grow best when cultivated in self watering planters. The study, carried by Nottingham Trent University, involved assessing four diverse irrigation methods in both raised wooden beds and plastic containers.

Lettuce, radishes and dwarf beans were planted and monitored over a six week period throughout June and July. These were chosen as examples of shallow rooted plants, root crops and legumes to offer the most effective evaluation. Some planters weren’t watered at all and some were watered manually, whilst sub irrigation self watering planters and automatic drip fed systems were also used.

The self watering container, known as the Harvester, was made from recyclable polyethylene with an integral water reservoir and Aquafeed™ capillary matting to keep soil moist which reduces the need for watering to once or twice weekly. The micro drip feed kit included a battery operated timer valve; plastic tubing and drip feed nozzles. The timer valve was programmed to open at intervals for set periods.

Each plant was sown from seed, with the manual beds watered twice daily. The automatic drip feed operated for 15 minutes twice daily whilst the Harvester was topped up only when the water level appeared low. On harvesting, the crops were weighed and then dried in ovens for 48 hours to record dry weight.

The results concluded that the manually maintained Harvester container produced the highest dry weights for lettuce as well as the highest average dry plant weight for radishes. The dwarf beans were discounted from the study due to extensive mollusc damage.

“The sub irrigation planter produced the largest weight yield of lettuces; 13% more than the next largest yield from the wooden raised bed with drip irrigation,” explains Dr Luke Harmer from NTU who set up and co-ordinated the trial. “This may be due to the fact that the Harvester system ensures the consistent provision of moist soil and the shallow root depth of the lettuces makes the Harvester particularly suitable for this application.”

The issue of maintenance was also reported on in the study. “Although the actual time spent on the planters which needed twice daily watering was minimal, it soon became a chore,” added Dr Harmer. “Care also needed to be taken to manually water to the soil condition, ensuring that the soil was moist and carried out with reference to the weather and the growth cycle of the plant.”

Developed in house by ecological horticultural suppliers Amberol, the Harvester range of self watering containers is used to grow a wide variety of fruit and vegetables with maximum cropping. “We are delighted with the results of the trial,” comments John Williamson, Marketing Manager at Amberol. ”We developed this horticultural technology as part of a push to encourage more people to grow their own fruit and vegetables and to conserve water. The Harvester has been designed specifically for smaller gardens where people are restricted for space, but still wish to grow their own.”

The Harvester planters come in a variety of sizes and can be used as a floor standing unit or converted to a raised bed on timber mounts.

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