|Lascano, R - TEXAS AG EXP STN, LUBBOCK|
|Hicks, S - TEXAS AG EXP STN, LUBBOCK|
|Landivar, J - TEXAS AG EXP STN, CORPUS|
Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 20, 1998
Publication Date: N/A
Interpretive Summary: The surface (2") soil-water content of a 100 acre field planted with cotton was measured 3 times during the growing season with electronic sensors. Calibration of the electronic sensor showed that measurements require only 5 seconds and are independent of soil type. The sensor was mounted on a 5 ft long staff and the recording data-logger with power supply were packaged in a small back-pack. Using this equipment, two people could sample the 100 acre field every 60 ft (about 800 measurements) in <3 hours. Measurements were also done on a grid pattern with spacing determined from semi-variogram analysis to be >100 yards. A contour map of surface water content was developed using Kriging techniques from 48 measurements distributed over the field. Future work will test the hypothesis that, remote sensing of the surface water content could be used to calculate the field water balance.
Technical Abstract: The surface (0.0 - 0.06 m) volumetric soil-water content (SWTR) of a 36-ha field planted with cotton was measured 3 times during the growing season with sensors that measure SWTR in the frequency-domain. The sensor, data-logger, and power supply were mounted on a back-pack allowing two people to sample the 36-ha field in <3 hours. Measurements were done on a grid pattern with spacing determined from semi-variogram analysis. For example, SWTR measured every 3 m along 700 m transects indicated that the sampling range varied between 100 - 160 m. By determining the spatial structure for SWTR a contour map was developed using Kriging techniques. Our hypothesis, that needs testing, is that a time-series of these measurements would define the surface boundary and could then be used as input to a simulation model to calculate the field water balance.