UNal patents precision irrigation tensiometer
When and how much to irrigate are questions farmers perform frequently when turning on irrigation systems. The response will be in an agricultural tensiometer patented by the Universidad Nacional de Colombia (UNal).Bogotá D. C., 27 de septiembre de 2016 — Agencia de Noticias UN-
Field tests were carried out on an export flower glasshouse business in Madrid (Province of Cundinamarca).
According to the inventors most farmers feel more secure if they water their crops in excess, although excess moisture impacts crops and they need to be sprayed. This situation carries overruns and environmental impacts for the excessive use of agrochemicals.
“Use of these kinds of crop irrigation instruments in Colombia is very low as they are not very common in the market and they are expensive,” said Professor Roberto Villalobos, inventor and member of the Sustainable Development and Environmental Management Research Group.
However use of these types of tools is increasingly important because a global trend is to consolidate more accurate irrigation systems, independently of the soil type, if they are loamy (medium water storage capacity), clayey (more water storage capability) or sandy (low water storage capability.)
Part of the need lies in that according to FAO, food production should increase at least 70% for 2050. In 34 years the world will host close to 9,000 million people, most of which will live in cities in developed countries with climatic phenomena such as extensive and more varied drought periods.
Accuracy, the necessary goal
Precision irrigation uses available technology to program the moment, frequency and time according to crop characteristics, irrigation configuration, weather and soil of the land. Therefore it is possible to determine the amount of water needs at the adequate moment.
One of the purposes is to maintain crops at optimum moisture levels, also known as “field capacity” so the crop can also express its productive potential.
Through this capability plants have sufficient moisture and air capacity in soil pores and will invest minimum energy for their physiological and productive processes. Therefore farmers maximize their crops.
Irrigation means how to control humidity for optimal crop response. This monitors costs against benefits, expressed as indicators such as less energy consumption (linked to less water pump use) or fertilizer, labor and definitely water savings.
A conventional tensiometer, invented in the U.S. in 1959, works with a porous ceramic piece on the bottom. Once in the soil the tool captures the tension with which the soil retains water and expresses it in negative values in a vacuum gauge. Readings close or near zero suggests water excess. For instance 15 centibars indicates a crop is in field capacity and the farther from zero it will require more water. Furthermore a 30 centibar reading in sandy soil will indicate irrigation requirements but also will indicate the farmer has 2 or 3 days to irrigate.
Two in one
As opposed to a conventional tensiometer, the device invented at UNal has two ceramic pieces and it is about 30 cms long as soils may have different crops and root formation and extensions differ. For instance fruit trees can have up to 60 cm. (23.5 in.) of roots, while vegetable only 20 cm (7.8 in.).
The prototype has two vacuum gauges one on each end. Therefore measurement is expressed at medium root level and radical deepness.
Furthermore researchers discovered the best components for building the ceramics with the best porosity and required water conductivity. The blend of different portions of kaolin, clay, fire clay, calcium carbonate, feldspar, silica, alumina and talc offered the raw materials to build a suitable ceramic for the tensiometer.
The tensiometer was tested at different depths (15 and 30 cms) in glasshouse crops and compared to other conventional crops. On daily measurements carried out during 18 days they concluded that the UNal invention was equally efficient as other professional tensiometers and with the possibility of manufacturing it in Colombia to make it more accessible to farmers.
For instance in field tests carried out on an export flower glasshouse in Madrid (Province of Cundinamarca) cost reduction analysis showed less irrigation water needs which passed from 2.5 million liters per hectare to a million liters for the same chrysanthemum cycle which lasts for three months.
The efficiency of the prototype offers other added values in regards to its use. For example filling time was reduced to almost half (45 %), field installation was 42% and practically does need maintenance.(Por: Fin/HVC/DMH/APBL