An ASABE Meeting Presentation Paper Number: 083512
Field Evaluation Of Emitter Clogging In Subsurface Drip Irrigation Systems Jiusheng Li, Ph.D, Professor, China Institute of Water Resources and Hydropower Research, 20 West Chegongzhuang Rd., Beijing 100044, China. E-mail:
[email protected].
Lei Chen Graduate student, China Agricultural University, Beijing 100083, China.
Yanfeng Li Ph.D,, Engineer, China Institute of Water Resources and Hydropower Research, 20 West Chegongzhuang Rd., Beijing 100044, China. E-mail:
[email protected].
Yuchun Liu Doctoral student, China Institute of Water Resources and Hydropower Research, 20 West Chegongzhuang Rd., Beijing 100044, China.
Written for presentation at the 2008 ASABE Annual International Meeting Sponsored by ASABE Rhode Island Convention Center Providence, Rhode Island June 29 – July 2, 2008 Abstract. Emitter clogging in subsurface drip irrigation (SDI) systems is affected by many physical, chemical, and biological factors, but field evaluation on emitter performance under varying clogging conditions is still lacking. Field evaluations were conducted on the SDI installations in a solar-heated greenhouse applied to tomato to investigate the effects of fertigation, dripline depth, and layeredtextural soil on emitter clogging. These installations, which had been operated for two years, included 33 experimental plots with dripline depths of 0, 15, and 30 cm, total number of fertigation events varied from 0 to 19, and total amount of urea fertigated varied from 0 to 1023 kg/hm2. Field evaluation demonstrated that, averaged for all the plots, 2.7% of the emitters can be declared to be clogged with discharge reduced more than 25%, and 2.1% of the emitters were completely clogged. No significant influence of total number of fertigation events and fertilizer applied as well as layered textural soil structure on emitter clogging was observed, but a slightly greater discharge reduction resulting from clogging was found for surface drip irrigation plots than for subsurface drip irrigation plots. No emitter clogging caused by root intrusion was detected. An investigation on the distributions The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily reflect the official position of the American Society of Agricultural and Biological Engineers (ASABE), and its printing and distribution does not constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review process by ASABE editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is from an ASABE meeting paper. EXAMPLE: Author's Last Name, Initials. 2008. Title of Presentation. ASABE Paper No. 08----. St. Joseph, Mich.: ASABE. For information about securing permission to reprint or reproduce a technical presentation, please contact ASABE at
[email protected] or 269-429-0300 (2950 Niles Road, St. Joseph, MI 49085-9659 USA).
of clogged emitters in the systems revealed that most clogged emitters occurred at the terminals of the laterals. To quantitatively evaluate the effects of emitter clogging on the uniformity of water application, the coefficient of variation for emitter discharge (CV) was related to discharge reduction percentage (Rq), showing that CV increased linearly with an increasing Rq resulting from clogging. Keywords. clogging, discharge, emitters, subsurface drip irrigation, uniformity.
The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily reflect the official position of the American Society of Agricultural and Biological Engineers (ASABE), and its printing and distribution does not constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review process by ASABE editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is from an ASABE meeting paper. EXAMPLE: Author's Last Name, Initials. 2008. Title of Presentation. ASABE Paper No. 08----. St. Joseph, Mich.: ASABE. For information about securing permission to reprint or reproduce a technical presentation, please contact ASABE at
[email protected] or 269-429-0300 (2950 Niles Road, St. Joseph, MI 49085-9659 USA).
引言写的不太到位，因时间关
Introduction
系 暂时就这样
Although recent research on emitter design and pretreatment has advanced the technology (Nakayama and Bucks, 1991; Ravina et al., 1997; Li et al., 2006), clogging remains one of the major problems in the management of drip irrigation systems. The factors causing clogging include particulate matter, biological growth, chemical precipitation, or combinations of these factors (Pitts et al., 1990). For subsurface drip irrigation (SDI) systems, emitter clogging may also be caused by root intrusion (Coelho and Faria, 2003) and the suction of solid particles by buried emitters from the surrounding soil when the system is turned off (Wang et al., 2005). Clogging caused by root intrusion can be prevented or greatly reduced by injecting trifluralin, a herbicide that is strongly absorbed to soil, to limit root growth in the immediate vicinity of the emitter (Suarez-Ray et al., 2006; Yu, 2007). Another method of treating such clogging is applying water at a high frequency (Suarez-Ray et al., 2006). Clogging could cause a great reduction in drip irrigation uniformity because the clogging of some emitters resulted in a higher discharge rate from non-clogged emitters (Bratls et al., 1982; Talozi and Hills, 2001). For SDI systems, clogging may impose a more serious influence on uniformity because it is more difficult to detect the clogging. The objectives of the work described in this article were to evaluate the effects of dripline depth, the amounts of water and fertilizers applied, and layered-textural soil on emitter clogging for SDI plots that had been operated for two years, and to quantify the relationship between uniformity and emitter clogging.
Materials and Methods SDI Installations Subsurface drip irrigation systems were installed in a solar-heated greenhouse located at the Experimental Station of National Center of Efficient Irrigation Engineering and Technology Research – Beijing (39°39´latitude and 116°15´ longitude) in March of 2006. The greenhouse was 50 m long and 8 m wide. Particle size composition, bulk density, saturated soil water content, and field capacity are summarized in table 1. The soil was classified as sandy loam. The SDI installations were used to investigate the effects of fertigation management practices on tomato quality and yield. As illustrated in fig. 1, the experimental field was divided into 33 equal plots with dimensions of 3.5 m by 2.4 m. In the experiments of both 2006 and 2007, three lateral depths of 0, 15, and 30 cm and three nitrogen levels of 0, 150, and 225 kgN/ha were used, resulting in nine treatments. These nine treatments (plots 7-33) were conducted on the original field soil. The profiles for plots 1-6 were reconstructed to investigate the effects of layered-textural soil on system performance of SDI installations and tomato growth. Two layered-textural soil treatments, a sandy over sandy loam soil (plots 1, 3, and 4) and a sandy loam-sandy-sandy loam soil (plots 2, 5, and 6), were considered. The properties for the refilled sandy soil are also indicated in table 1. For the sandy over sandy loam soil plots, the upper 20 cm of sandy loam soil was removed and the sandy soil was reconstructed with a bulk density of 1.5 g/cm3. The plots for the sandy loam-sandy-sandy loam soil were reconstructed with an upper 20 cm sandy loam soil with a bulk density of 1.33 g/cm3 followed by a layer of 10 cm sandy soil with a bulk density of 1.50 g/cm3. Thus, there were eleven treatments in total. For each treatment, an individual manifold (submain) was installed to ensure that the amount of water and fertilizers applied could be individually controlled. In the experiments, supply water was provided by a 1-m3 reservoir that had a pump with a capacity of 10 m3/h and a lift of 40 m. A disk filter (mesh no. 120, Arkal 1 1/2” Short Filter, Israel) was installed at the inlet of the mainline and a screen filter (mesh no. 200, Arkal 1 1/2” Short
3
Filter, Israel) was installed at the inlet of each sub-main to protect emitters from physical clogging. For all irrigation events, the pressure at the inlet of sub-main was fixed at 0.10 MPa. Table 1. Physical properties for the experimental soils. Soil
Undisturbed
Bulk density 3 (g/cm )
Contents (%)
Depth (cm) 2.0~0.02mm
0.02~0.002mm
