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Compiling a field manual from overhead photographs for estimating crop residue cover
Author(s) -
Molloy J. M.,
Moran C. J.
Publication year - 1991
Publication title -
soil use and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.709
H-Index - 81
eISSN - 1475-2743
pISSN - 0266-0032
DOI - 10.1111/j.1475-2743.1991.tb00871.x
Subject(s) - residue (chemistry) , computer science , agricultural engineering , crop residue , quadrat , environmental science , remote sensing , mathematics , agriculture , engineering , ecology , biochemistry , chemistry , botany , shrub , biology , geology
. A method is presented for compiling a manual for the estimation of crop residue cover in the field. The crop residue is a combination of standing stubble and the straw remaining on the ground after harvest. Field assessment of crop residue is important so that management decisions may be made in the field. Such decisions include selection of cultivation or sowing machinery, irrigation scheduling (for crusting materials), soil temperature control and grazing of crop residue. The manual consists of a graded set of colour photographs, taken from an overhead boom, and a sampling rate nomogram to determine the number of 1 m quadrats required in a given field to estimate the cover with a predetermined level of error. Two methods for calibration of the photographs are compared: (a) projection of slides onto a screen with manual counting, and (b) digital image analysis of the photographs. Image analysis is efficient, rapid and gives less error than counting from the projections because many more points are counted. The use of the manual in the field is described. It is an inexpensive piece of equipment for the field agronomist or farmer, and gives a reliable, rapid and semi‐quantitative estimate of residue cover.