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Title: Solute transport in a loamy soil under subsurface porous clay pipe irrigation

Author
item SIYAL, A - Sindh Agricultural University
item VAN GENUCHTEN, M - Universidade Federal Do Rio De Janeiro
item Skaggs, Todd

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2013
Publication Date: 4/1/2013
Citation: Siyal, A.A., Van Genuchten, M.T., Skaggs, T.H. 2013. Solute transport in a loamy soil under subsurface porous clay pipe irrigation. Agricultural Water Management. 121(2013):73-80.

Interpretive Summary: Many less-developed regions of the world lack adequate water resources and would benefit from the implementation of water-saving agricultural practices such as drip irrigation. However, modern drip irrigation technology is typically cost-prohibitive in these areas. A low-cost alternative is to irrigate with buried baked-clay pipes. With this technique, water seeps through buried porous pipes and into the soil. Applying the water below the soil surface helps minimize evaporative water losses. A key to sustaining production with these systems is managing the accumulation of salts in the soils; increasing soil salinity is a frequent cause of reduced productivity and food yields. In this research, we combined field data with computer simulations to study the movement and accumulation of salts in an agricultural field irrigated with buried clay pipes. The information provided by this study will be helpful for determining sustainable, cost-effective management practices for clay pipe systems. This research will assist irrigation engineers and other workers trying to develop and implement water-saving irrigation methods for less-developed parts of the world.

Technical Abstract: Subsurface porous clay pipe irrigation is widely considered to be a very promising method for small scale irrigation in arid regions. Unfortunately, salt accumulation at and near the soil surface using this method may affect the germination of direct-seeded crops. Predicting salt movement and accumulation with clay pipe irrigation will allow producers to anticipate the need for leaching to control salinity in the soil root zone. The HYDRUS-2D model was used to simulate the accumulation of salt from a subsurface clay pipe irrigation system, installed at 30 cm depth, during the growing season of an okra (Abelmoschus esculentus) crop irrigated with water having a salinity of 1.1 dS m-1. The loamy soil profile had an initial salinity of 2.3 dS m-1. Predicted electrical conductivity (ECe) values at the end of the growing season correlated significantly (R2 = 0.92-0.94) with measured saturated paste ECe data obtained at the end of the field experiments. Salinity was found to be relatively low around the pipes, but increased with distance away from the pipes. Measured and predicted soil salinity levels were especially higher above the clay pipes. Our results indicate that proper management of salt accumulation is vital for sustainable crop production whenever subsurface irrigation systems are being implemented.