The company believes that the procedure, which was developed for food production in dry areas such as Australia, has also been shown to reduce pesticide use. Now Unilever Bestfoods Brazil has introduced the system to tomato farmers in the humid Cerrado region of the country.
Tomato plants need large volumes of water to produce strong yields and good quality fruit. Drip irrigation uses tubes to deliver small quantities of water and nutrients straight to the roots of plants. There is less wastage and evaporation compared with other watering systems, such as overhead sprayers, which Unilever claims reduces water use by up to 30 per cent.
Drip irrigation also helps to prevent mould because foliage remains dry. Five-year trials completed in 2002 at the Unilever Experimental Farm at Patos de Minas, Brazil show that fungicides (which control mould) can be reduced by 50 per cent. The use of pesticides can be cut by 25 per cent because they are delivered directly to the roots, reducing waste.
Because water is used more efficiently the soil does not become soaked, providing optimal growing conditions. If managed well, Unilever believes that the use of drip irrigation can increase tomato yields by up to 40 per cent. Higher yields per hectare make it possible to source greater volumes of fruit from fields closer to factories. This reduces haulage and fuel costs, and cuts emissions.
A major difficulty however is cost and complexity involved in the installation of the system. However, Unilever says that these expenses can be offset by increased yields and reduced chemical costs. In addition, there is also a long-term benefit to the environment from using less crop protection chemicals.
By the end of 2004, over 1,300 hectares (29 per cent) of tomato fields owned by Unilever growers in the Goiás State will be converted to drip irrigation. This is expected to rise to more than 50 per cent in 2006, leading to greater yields and further benefits for the environment.
The installation is part of Unilever's general move towards greener food production. The group accepts that increasing environmental and social pressures on agriculture - which threaten supply chains - and growing consumer concerns about the food chain - which threaten markets - demand a more radical attitude.
For example, Unilever Ice Cream recently committed itself to buying only HFC-free freezers from 2005. The freezers have already been introduced in Denmark, Greece, the Netherlands, Switzerland, and the UK, and the company claims it will have around 15,000 HFC-free cabinets in its fleet by the end of 2004.
The new freezers use the hydrocarbon, propane as refrigerant. Hydrocarbons are natural gases that do not harm the ozone layer and have virtually no impact on climate change. The HFC (hydrofluorocarbons) gases they replace are not ozone depletors like traditional refrigerants such as CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons), but do contribute to global warming.
Unilever says that laboratory trials suggest the hydrocarbon freezers are also more energy efficient, using up to 15 per cent less energy to keep ice cream at the right temperature, compared with other models. Longer-term trials in the Australian market showed a 9 per cent reduction in energy use compared with HFC cabinets. Although hydrocarbon refrigerants have been available in household freezers for some time, Unilever claims it is the first company to use them on a large scale for commercial freezer cabinets.