Evaluation of the portable furrow infiltrometer
Abstract Twenty infiltrometer tests were conducted to compare infiltration rates estimated by the recirculating infiltrometer (RIF) and the newly developed portable infiltrometer (PIF). Two types of furrows commonly used in the western United States; small and steep, and large and less steep; were considered in high and low infiltration soils. Comparison of the PIF and RIF infiltration rate measurements indicated that PIF was most accurate in estimating steady infiltration rates. Use of the PIF for predicting infiltration rate functions was not recommended because of the need for collecting accurate measurements early during the infiltration process. Considering ease of installation, accuracy in measuring steady infiltration rates, and ability to collect data during irrigation, the PIF is a promising device for use in surface irrigation management.
The Effects of Three Furrow Shapes on Water Advance Characteristics, Application Efficiency, Deep Percolation and Tail Water Run-off
— Furrow irrigation is considered to be inefficient when compared to most pressurized irrigation systems. The objective of this research was to determine if different furrow shapes have different impacts on water management practices such as application efficiency, deep percolation ratio and tail water runoff. Three furrow shapes, a triangular (V-shaped), rectangular (R) and trapezoidal (T p ) shaped were evaluated and the results were compared with output from SIRMOD II. The parameters calculated from field data were not very different from those determined by the model. This indicated that the model predicted the volume balance of the field data with reasonable accuracy. It was observed that the time of advance was shorter for the triangular shaped furrow and much longer for the rectangular shaped furrow. Performance efficiency parameters were good for the trapezoidal and triangular shaped furrows and very poor for the rectangular furrow. Tail water ratio (TWR) was much higher in the triangular furrow and lower in the rectangular furrow. Where there was no deep percolation ratio, the model failed to return a reasonable value. parameters; application efficiency (AE), requirement efficiency (RE), requirement distribution efficiency (RDE), and total distribution efficiency (TDE) and the design or management variables for furrow irrigation. The analysis of performance indices by Assefa et al, (2017), on furrow irrigation in sugarcane indicated that the effect of slope was not statistically significant except distribution uniformity and uniformity coefficient; furrow length and flow rate were highly significant on all performance indicators. All indices except deep percolation ratio and storage efficiency had shown an increasing trend as flow rate increases. In furrow irrigation in clayey soil, Eldeiry et al . (2004) found that furrow length and application discharge are the main management and design parameters affecting application efficiency. Alazba (1999) noted that furrow performance relies on many irrigation parameters that include furrow geometry (shape, size, length, and slope); soil characteristics (infiltration and roughness); and management parameters (flow rate, application time, and required depth).
Factors Which Affect Furrow Intake Rates
To apply irrigation water efficiently, the water must be absorbed evenly 
across the field. In surface irrigation systems, this requires either that 
the water be spread quickly across the soil surface so that each portion of 
the field has a nearly equal time to absorb water, and that all portions of 
the field absorb water at the same rate; or that water intake rate varies 
across the field to compensate for differences in intake opportunity time. 
 
Water distribution in surface irrigation systems is determined by: 1) the 
water application system capabilities and management, and 2) the infiltration 
characteristics of the field soils. Improved application systems and design 
procedures for surface irrigation are being developed. But unless soil 
infiltration rates can be managed to achieve uniform water intake at desireable 
rates, high surface irrigation application efficiencies cannot be achieved. 
Although the problem of nonuniform soil water intake can be solved by applying 
the water through sprinkler or trickle systems at rates lower than the 
lowest intake rates, with the present high energy costs, this option is often 
not economical. 
 
The objective of this study is to evaluate several farmer manageable factors 
which can affect water intake rates into irrigated furrows. The long term 
research goal is to quantify the effects of farmer practices which decrease 
intake uniformity, practices he can apply to improve uniformity, and practices 
which can change intake rates. Intake rate modification can be useful to 
accelerate advance (thus decreasing variations in intake opportunity times), 
counteract the effects of variations in intake opportunity times, or better - 
adapt a field to a fixed or desireable water application system or schedule. 
The manageable factors which will be discussed are: 
1) wheel compaction of furrows 
2) surface soil water content 
3) flow rates, and 
4) intermittent application, such as "surge" irrigation.