Harvesting rainwater offers many benefits for agriculture

Rainwater harvesting is nothing new and to design and construct a simple harvesting system is quick, easy and doesn’t have to cost the earth. But using it for spraying is becoming more popular with some growers even seeing benefits with efficacy of some actives.
“Making use of rainwater that falls on your buildings can save you money,” says Ian Barker, head of water at the Environmental Agency.

“It could mean potentially less storage for waste, and reduce the likelihood of contaminated run-off from yards entering streams and rivers.

Rainwater harvesting might not be suitable for everyone, but even if it cannot supply all your needs it’s still worth thinking about. It can help reduce costs and reduce your environmental impact.”

One such grower is Martin Hamilton, a Farmers Weekly Barometer Farmer in Co Down, Northern Ireland, who collects water to use in and around the Mash Direct business. Predominately its uses are to clean down areas inside and outside the buildings, but the real benefit he believes is in the application of crop protection chemicals.

The water is collected from four sheds measuring 36x30m and piped to a 15000 litre water tank which sits behind the spray store. There is a basic filtering system that ensures leaves and any other debris are intercepted before entering the tank.

“I think everybody should be doing it, it’s so simple and straightforward. Even in an area of high rainfall like here, we have a responsibility to use water wisely. Many of the big retailers that we supply have a water management policy to ensure we use water responsibly.

“It is something I feel very bullish about because we know how severe the blight problem was last season. In a seriously difficult year, we believe that some of the success in controlling it had been down to using soft water,” says Mr Hamilton.

Lincolnshire grower Mark Pettit of WB Pettit & Son, Ferry Farm, Gainsborough, Lincolnshire, designed and built his own system to reduce water costs and his reliance on mains water. There are two farms in his village and if both farms are spraying simultaneously, the water pressure in the village can drop to an unacceptable level by 4pm.

So this March, Mr Pettit added an additional 20000 litre water tank to bolster his existing 8000 litre capacity. The new system collects rainwater from one half of his 24x20m grain store. “In a wet season like we have just had, we have collected just about enough water for all my spraying needs.

“The whole project took me about a week to install. I redirected the down pipes to feed the new water tank and then dug a 50m long trench to connect the new tank with the existing tank. I fill my sprayer from the existing tank and when I need more water I just open a valve and the tank automatically fills up, it looks after itself.

Phase two at Ferry Farm, will be to install a similar water tank to harvest rainwater from the other side of his grain store and then link the two water tanks together. The water is not filtered going in to the tank and any sediment tends to sink to the bottom.

Tom Robinson, Syngenta application specialist, says most crop protection formulations can be used in a wide variety of “waters” with or without other substances without giving rise to much practical difficulty. However, occasionally problems can arise and when choosing water quality for spray mixes a number of factors need to be considered.

Cleanliness

Dirty water contaminated by particles of soil or organic matter should be avoided. Not only will the particles cause blockages within the sprayer, but these can deactivate some actives such as diquat.

pH

Acid waters are associated with upland areas on hard rock with peat, or localised lowland peat soils. Growers should be aware that pH can even change during the day depending on the methods used by the water companies to adjust pH and manage water quality. Some actives are considerably less stable in slightly alkaline solutions than slightly acidic ones and this is why some manufacturers have in the past sold buffering agents to maintain the pH at 5.0.

Hardness

This is a measure of mineral load, mostly affected by the presence of calcium or magnesium. However, the presence of manganese or iron can also affect water hardness. It varies around the country with limestone and chalk areas proving to be the hardest.

Calcium and iron in the water can deactivate certain pesticides, especially glyphosate and sulfonylureas. In very hard areas simply add ammonium sulphate such as AS Elite.

“As a general rule harvested rainwater will be the best choice for applying crop protection products, with but there are always a few instances where this is not the case,” says Mr Robinson.

Source: Farmers Weekly (By Gus Hartley Russell)

Farmers often have large barns of sheds that have ideal roof surfaces for collecting rainwater and in some cases, assuming there are enough water tanks for storage, harvested rainwater could supply a large percentage of a farm’s irrigation requirements.  Rainwater harvesting is simple for homeowners too – at the one end of the scale, a rain barrel with a downpipe from a gutter may be all that is required.  On the other end of the scale, more sophisticated rainwater systems with multiple above ground or underground water tanks can supply a home or business with most, if not all of its water requirements.  In South Africa, we recommend JoJo Tanks products.  JoJo Vertical & Horizontal Tanks are the first and ONLY tanks in South Africa to be tested and approved as “fit-for-purpose” by CSIR’s Agrément SA (Certificate no 2011/385) and have an FDA-approved, food-grade black interior lining.  Click on the links below to find the right jojo water tank, jojo rainwater tank, jojo tank stand or other JoJo Tanks product according to your needs and budget.

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