For hydroponic farming to be profitable, close attention must be paid to crop management and water-use efficiency. The good news is that tunnel farmers can improve these aspects of production without extensive capital outlay, according to Herbert Stolker, a consultant for Dutch hydroponic advisory company, Delphy.
Stolker, who specialises in tomato, pepper and cucumber production, was a speaker at the recent Undercover Farming Conference and Expo in Johannesburg.
Water availability is a concern for the undercover farming industry worldwide, and Stolker advises farmers to implement suitable water management strategies as soon as possible.
Water recirculating systems are cost-effective and efficient, and such a system can reduce water use in a greenhouse, as well as cut fertiliser bills by between 30% and 40%. Delphy conducted studies that showed that recirculation lowered water use to the extent that only 14l of water were required to grow 1kg of tomatoes.
Many growers construct their own low- cost harvesting equipment, such as this ladder on wheels, to make harvesting less labour-intensive.
In comparative trials in greenhouses without such technology, between 20l and 30l of water were required to grow 1kg of tomatoes. Open- field production was by far the most inefficient, with 1kg of tomatoes requiring 60l of water.
Growers should be aware of salt accumulation in recirculating systems, Stolker says. “Ensure that water supply – particularly if it’s from a borehole – and fertilisers have low sodium concentrations.” A biweekly water analysis will indicate if water:fertiliser ratios need to be adjusted.
Regular plant maintenance, such as pruning and trellising, extends the productive lifetime of a crop. Growers sometimes neglect this step, and this has a negative impact on the bottom line. “If a crop isn’t pruned, growth decreases and harvests decline,” Stolker stresses.
Deleafing is another essential aspect of pruning, helping to ensure that the plant achieves high productivity. “Many growers are afraid to deleaf in winter because they’re worried about the development of diseases, but with deleafing there’s enough air exchange to heal the open cut area around the stem,” he says.
Farmers should establish a schedule to ensure that all plants are trellised to make optimal use of greenhouse space. “Don’t fall behind schedule on this because spacing and equal distribution of plants in the greenhouse are essential for uniform growth,” Stolker urges. Fruit size and quality will be compromised if crops receive too much shade or too little sunlight.
Invest in equipment
A modest investment in the right equipment, such as knives for deleafing, will optimise the number of hours that workers dedicate to plant maintenance. Equipment should also be stored in the same place to avoid delays; searching for tools wastes production time.
According to Stolker, using a ladder wastes time. Climbing up and down it, and moving it between the rows, is cumbersome and increases labour costs. Growers should invest in modern alternatives that make it possible to increase the speed at which greenhouse tasks can be executed. He recommends rail pipe trolleys or lifts, and says that these are increasingly being used in South African greenhouses.
The rail pipe trolley is an internal transport system used for maintenance of plants and the greenhouse structure. The lift is used to transport containers of harvested produce out of the greenhouse. A cheaper alternative is simply to weld wheels to a ladder.
“This will help a picker to move through the rows in half the time it usually takes,” says Stolker. He encourages growers to phase out plastic buckets and crates used for harvesting. “I was fairly surprised when I saw this in South Africa, as it increases time spent on labour as well as wages,” he says.
If growers do not have rail pipe trolleys, they can make their own by securing two plastic crates on a lightweight surface and attaching rubber wheels. “This will speed up harvesting significantly, as pickers would no longer have to carry buckets between rows and outside. It’s all about thinking of clever solutions to get the job done quickly,” says Stolker.
Email Herbert Stolker at [email protected].