Management guidelines for efficient irrigation of vegetables using closed-end level furrows

Closed-end level furrows are commonly used to irrigate vegetables in the Lower Colorado River region (LCRR). The application efficiency of furrow irrigation in this area is often low. The objective of this study is to develop management tools and guidelines for the efficient irrigation of vegetables using closed-end level furrows. The study consisted of field experiment and modeling (model calibration, model verification, and the development of management tools by simulation). Field experiments were performed over a period of 27 months. Infiltration parameters were estimated for four soil textural groups (i.e., moderately coarse textured, medium textured, moderately fine textured, and fine textured soils) using a two-point method modified for closed-end level furrows. Model verification shows that the surface irrigation hydraulic model used in this study (SRFR) is capable of simulating the furrow irrigation process with acceptable levels of accuracy. Results of the study also indicate that adequate and efficient irrigations can be achieved using closed-end level furrows through the proper selection of unit inlet flow rate, Qo, and cutoff time, tco. However, given the soil and crop combinations in the LCRR, sometimes significant increases in irrigation efficiency, compared to present levels, can be attained only if furrow lengths are shorter than the typical size currently in use in the LCRR. Limitations of the proposed management tools and on-going research to address these limitations are briefly discussed.