Water: Elixir of life and of apples - A resource-saving approach to water (part 2)
Regulate water consumption
National regulations in Italy have already stipulated that farmers must log rainfall and irrigation quantities in a company folder. As affirmed by the South Tyrolean Advisory Service for Fruit Production and Winegrowing in their information brochure: “The aim of irrigation is to ensure an adequate water supply for fruit crops without unnecessary wastage of water and energy resources.” An orchard farmer can use two methods to control water usage effectively: By adapting consumption firstly to the environmental water balance, and, secondly, to the quantity of moisture within the soil.
The tensiometer measures the moisture in the soil (Photo: © Research Centre Laimburg).
Farmers can use an online program provided by the Advisory Service to calculate water balance. The program receives weather data from a number of weather stations, amongst other input variables. The objective of the program is to calculate evaporation at any given moment in an orchard by analysing a variety of parameters, thus enabling farmers to work out exactly how much water they need.
By employing a number of soil-measuring tools positioned throughout the orchards to gauge soil moisture, farmers obtain specific data which determines when and how much to irrigate and, thus, can carry out needs-based irrigation; this supplies sufficient water to meet the needs of the crops, prevent nutrients from being washed out into groundwater, and ensures that water is used in accordance with resource-saving principles.
Instruments used to measure water content of soil
Some measuring tools measure the water content of the soil indirectly and calculate soil moisture by volume, and others calculate the water tension in the soil or, rather, the force which the root must employ in order to draw water from the soil, irrespective of the nature of the soil. Tensiometers, as these instruments are known, have proven to be effective vineyard tools.
Tensiometer measurements are taken by inserting a water-filled plexiglass tube with a porous ceramic tip into the ground. When the soil surrounding the ceramic tip dries up, the water is drawn out of the plexiglass tube, resulting in a negative pressure within the tube; the pressure is displayed on a manometer attached to the upper end of the device, and can be read directly on site. An Advisory Service guide provides farmers with the optimum values required for effective irrigation control.
Needs-based irrigation helps to save water
Sustainability and efficient use of our planet’s resources are the burning issues of our times. The agricultural sector in South Tyrol has long been aware of the fact that the water supply available is sufficient for production purposes, but must only be used as and when needed. In other words: irrigation is all well and good, but only if and when necessary, and using water-saving, innovative technological resources.