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COMPARING DRIPPERS FOR ROOT INTRUSION IN SUBSURFACE DRIP IRRIGATION APPLIED TO CITRUS AND COFFEE CROPS

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Paper number  032095,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.13777) @2003
Authors:   Prof. Rubens Duarte Coelho, Eng. Luis Fernando Faria
Keywords:   Physical barrier, drippers , clogging

This work aimed to quantify drippers performance as physical barrier in subsurface drip irrigation (SDI), regarding the flow variation due to root intrusion in citrus and coffee crops. The experiment was carried out inside a greenhouse during the years of 2001 and 2002, at the University of Sao Paulo (ESALQ) in Brazil. Coffee seedlings and orange scions were planted in vases with 100 liters of capacity, irrigated by fourteen different models of commercial drippers (selfcompensated and regular devices) from Plastro, Netafim, Drip-in, Carborundum, Rainbird, Naan- Dann and Irrimont companies, in two depths (15 and 30 centimeters) and in two soil water depletion levels (dry and humid conditions), resulting a total of 1400 drippers monitored. It was accomplished six determinations of individual flow rate during 18 months, using a very sensitive low flow magnetic meter. The flow data of the emitters were analyzed for each reading, though the parameters: a) relative flow (QR%), having as reference the initial flow rate measured and b) Flow coefficient of variation (CVQ%) of the analyzed sample. It was concluded that some emitter models are more resistant than others to root intrusion. The irrigation levels resulted some interesting observations regarding the root intrusion; flow variations were more evident for emitters at 30 centimeters depth under dry conditions for coffee crop. Self-compensated emitters tended to be more unstable, initially increasing the average flow rate with root and soil particles presence. Regular emitters tended to be more stable, decreasing the average flow rate with root and soil particles presence.