Yazar "Balendonck, J." seçeneğine göre listele

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    Measurement of Low Matric Potentials with Porous Matrix Sensors and Water-Filled Tensiometers
    (Soil Sci Soc Amer, 2009) Whalley, W. R.; Lock, G.; Jenkins, M.; Peloe, T.; Burek, K.; Balendonck, J.; Take, W. A.; Tuzel, I. H.; Tuzel, Y.
    Water-filled tensiometers are widely used to measure the matric potential of sod water. It is often assumed that, because these give a direct reading, they are accurate. With a series of laboratory tests with model laboratory systems of increasing complexity we show that the output of water-filled tensiometers can, particularly in drying sods, be in serious error. Specifically, we demonstrated that water-filled tensiometers can indicate a steady matric potential, typically between -60 and -90 kPa, when the sod is much drier. We demonstrate the use of water-filled tensiometers that can measure matric potentials smaller than -100 kPa in the laboratory and in the field. The physics of the failure of water-filled tensiometers is discussed. When the matric potential was greater than -60 kPa, in laboratory and field tests water-filled and porous matrix sensors were in good agreement. In the field environment the porous matrix sensor was useful because it allowed early detection of the failure of water-filled tensiometers. In dry soils (matric potential < -60 kPa) the porous matrix sensor was more reliable and accurate than the water-filled tensiometer.
  • Küçük Resim Yok
    Öğe
    Measurement of Low Matric Potentials with Porous Matrix Sensors and Water-Filled Tensiometers
    (Soil Sci Soc Amer, 2009) Whalley, W. R.; Lock, G.; Jenkins, M.; Peloe, T.; Burek, K.; Balendonck, J.; Take, W. A.; Tuzel, I. H.; Tuzel, Y.
    Water-filled tensiometers are widely used to measure the matric potential of sod water. It is often assumed that, because these give a direct reading, they are accurate. With a series of laboratory tests with model laboratory systems of increasing complexity we show that the output of water-filled tensiometers can, particularly in drying sods, be in serious error. Specifically, we demonstrated that water-filled tensiometers can indicate a steady matric potential, typically between -60 and -90 kPa, when the sod is much drier. We demonstrate the use of water-filled tensiometers that can measure matric potentials smaller than -100 kPa in the laboratory and in the field. The physics of the failure of water-filled tensiometers is discussed. When the matric potential was greater than -60 kPa, in laboratory and field tests water-filled and porous matrix sensors were in good agreement. In the field environment the porous matrix sensor was useful because it allowed early detection of the failure of water-filled tensiometers. In dry soils (matric potential < -60 kPa) the porous matrix sensor was more reliable and accurate than the water-filled tensiometer.
  • Küçük Resim Yok
    Öğe
    Use of a low-cost soil moisture sensor to reduce irrigation water usage in mild winter climate greenhouses
    (International Society for Horticultural Science, 2023) Tüzel, I.H.; Balendonck, J.; Tüzel, Y.; Öztekin, G.B.; Tunali, U.
    Fresh water sources are becoming scarce. Crop irrigation uses more than 70% of the world’s water, and thus, improving irrigation efficiency and saving water is key to sustaining the food demands of a fast-growing world population. Manually controlling irrigation often leads to over dosing and excess nutrients drain from the soil. Soil sensor activated irrigation is an important step in improving water use efficiency. By using sensors, irrigation water can be controlled more precisely to prevent excessive drainage and fertilizer leaching or even under dosing leading to yield reduction. Over the past decades, soil moisture sensor technology has been improved a lot, and meanwhile a large variety of TDR and FDR sensors with good performance are available. Water content may vary within an irrigated field. Since sensors only measure locally and existing sensors are relatively expensive, use of more sensors per field can become costly. The AquaTag is a prototype low-cost, wireless, near-field, passive, capacitance resonance type soil moisture sensor which can be read-out using a hand-held reading device. To help small-scale and low-tech farmers in saving water, we evaluated a simple irrigation support system making use of this sensor. The support system advises upon soil water activation levels and dosing taking crop stage and soil hydraulics into account, as well as the average water content of an irrigated plot obtained with the sensors. Its potential for useability was demonstrated in nine Turkish commercial farms with soil-grown vegetables. Farmers using the sensors were able to raise their irrigation water productivity on average with 22.9% as compared to farmers not using the sensors. The prototype performed well, but it should be further developed toward a sensor that can measure at rooting depth up to 30-60 cm. © 2023 International Society for Horticultural Science. All rights reserved.