ABSTRACT:
Photographic color slides of crop residue covering soil surfaces were projected onto screens with 100, 200, and 300 randomly located dots and visually evaluated for the number of dots that were coincident with images of residue. Specially prepared simulated residue slides were also projected onto the screens. Accuracy was improved by using at least three screen replications. There was not a consistent trend in improvement of accuracy between the 100-, 200-, and 300-dot screens. The observed residue cover was considerably higher than the calibration values. The dot-screen procedure appears to be consistent enough to obtain relative comparisons among tillage practices with three replications of observations of the same photographic slide.
Footnotes
John E. Morrison, Jr., is an agricultural engineer and F. Wesley Chichester is a soil scientist at the Grassland Soil and Water Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, 808 East Blackland Road, Temple, Texas 76502; David E. Escobar is a remote sensing specialist at the Subtropical Agricultural Research Laboratory, ARS, USDA, 2413 East Highway 83, Weslaco, Texas 78596. Dot-screen procedures were conducted by L. A. Bartek, engineering technician, Temple, Texas. This article is a contribution from ARS, USDA.
- Copyright 1989 by the Soil and Water Conservation Society
This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.