SOFTWARE FLOWDATA: Software for Analysis of Infiltration Data from Automated Infiltrometers M. D. Ankeny, M. A. Prieksat,* T. C. Kaspar, and K. M. Noh ABSTRACT Soil hydraulic properties are quite variable, and characterization of field sites usually requires many measurements. One way to collect thedata needed forfieldsite characterization is to use multiple infil- trometers with automated data collection capabilities. Automated in- filtrometers usepressure transducers connected to a dataiogger to measure cumulative infiltration overtime. The FLOWDATA soRware was developed to reformat, graphically display, and analyze the large well-structured data sets collected with automated infiltrometers. Pro- gram features include interactive editing, graphing, statistical sum- maries for each infiltration data set, and pooling of estimates from multiple data sets. Inputs required areidentification codes, times, transducer voltage readings, and transducer calibration files. Outputs areinfiltration rates, and saturated and unsaturated hydraulic con- ductivities. Program performance is demonstrated withdata from a typical field data file. S OIL HYDRAULIC CONDUCTIVITY is influenced by soil structure, porosity, and texture. Similarly, processes such as infiltration, erosion, runoff, ground- water recharge, soil aeration, and solute movement are affected by soil hydraulic conductivity. Thus, es- timates of soil hydraulic conductivity are needed to understand how management practices affect these processes. Several researchers have used ponded and tension infiltrometers to measure various soil hy- draulic properties in situ (Clothier and White, 1981; Ankeny et al., 1988, 1990; Elrick et al., 1988; White and Perroux, 1987, 1989; Smettem and Clothier, 1989). Ankeny et al. (1991) have proposed a method for cal- culating saturated and unsaturated hydraulic conduc- tivities from infiltration measurements madeat several tensions with ponded and tension infiltrometers. Soil hydraulic conductivity in the field varies be- cause of soil heterogeneity resulting from soil for- mation processes and landscape position. In addition, field hydraulic conductivities differ positionally in re- lation to wheel tracks, crop rows, or orientation of tillage implementsduring operation. As a result, char- acterization of the hydraulic conductivity of a field site requires measurements at many locations within the site. One way of collecting the data needed for field site characterization is to use multiple infiltro- meters with automated data collection capabilities. Ankeny et al. (1988) have developed an automated tension infiltrometer that measures in situ infiltration M.D. Ankeny, Daniel B. Stephens &Assoc., Inc., 4415Hawkins NE, Albuquerque,NM 87109; M.A.Prieksat, Dep. of Agron- omy, Iowa State Univ., Ames, IA 50011; T.C. Kaspar,Natl. Soil Tilth Lab., USDA-ARS, Ames,IA 50011; K.M.Noh, Dep. of Agric. Engineering, Keoukuk Univ., Chungju, Korea.Joint con- tribution from the USDA-ARS and Iowa State Univ. Journal Paper no. J-14575 of the Iowa Agric. and Home Econ. Exp. Stn., Ames, Project No.2878. Received 30 Jan. 1992. *Corresponding author. Published in Agron. J. 85:955-959 (1993). rates at preset tensions. Cumulative infiltration is mea- sured by pressure transducers that measure the pres- sure change caused by a decrease in water height in the infiltrometer reservoir. Transducer voltage output is stored as a function of time by a datalogger. The basic design and data collection system for the tension infiltrometer can also be used for a single-ring ponded infiltrometer (Prieksat et al., 1992). Manual calculations of saturated and unsaturated hydraulic conductivities from water flow measure- ments is time consuming and impractical for the analysis of multiple data sets from a field site. FLOWDATA software was developed to process and graphically display tension and ponded infiltrometer data sets col- lected by dataloggers. FLOWDATA also calculates infiltration rates and hydraulic conductivities from measurements of cumulative, steady-state infiltration over time at several tensions. SPECIFICATIONS Infiltration measurements are made with four-wire pressure transducers installed in the water reservoirs of tension (Ankeny et al., 1988) and ponded (Prieksat al., 1992) infiltrometers. Each infiltrometer has two pressure transducers. Output voltages from the pressure transducers are measured and stored by Campbell 1 21X dataloggers (Campbell Scientific, Logan,LIT). Data stored in the dataloggers can be transferred to a cassette tape or to a SM192 Campbell storage module for temporary storage. Data stored in a datalogger, on tape, or in a storage module are downloadedto a microcomputer hard disk or floppy disk using a CampbellPC201 Clock-Serial I/O tape read card and associated software. The FLOWDATA software for analysis of automated infiltrometer output was written and tested with SAS re- lease 6.03 for personal computers (SAS Institute, Cary, NC). Minimum requirements to use SAS 6.03 are a mi- crocomputer with an 80286 processor, a 30 Mb hard disk, 640 K of RAM, and a VGA monitor. A micro- computer with an 80386 processor, 2 Mb RAM, an 80 Mb hard drive, a VGA color monitor, a math coproces- sor, and DOS 3.3 operating system was used to execute the software for this demonstration. Hard disk space was used to store SAS program code, multiple graphic files, and SAS data files. OPERATION Ankenyet al. (1990) described procedures for mea- surements made with automated ponded and tension in- 1 Reference to a trade or company name is for specific infor- mationonly and does not imply approvalor recommendation of the company or product by the USDA or IowaState University to the exclusion of others that may be suitable. Abbreviations: ID, data line identification number; A, hydraulic conductivity divided by the matric flux potential. 955 Published July, 1993