Ps. Thenkabail et al., IMPACTS OF AGRICULTURAL MANAGEMENT-PRACTICES ON SOYBEAN AND CORN CROPS EVIDENT IN GROUND-TRUTH DATA AND THEMATIC MAPPER VEGETATION INDEXES, Transactions of the ASAE, 37(3), 1994, pp. 989-995
Vegetation indices from Landsat-5 Thematic Mapper (TM) observations on
single dates in August 1988, a drought year, and August 1989, a year
with wet early season conditions, were used to study the impact of agr
icultural management and cultural practices on soybean (Glycine max) a
nd corn (Zea mays) crop growth and yield. Management and cultural prac
tices studied included date of planting, tillage, soil association, dr
ainage, plant density, and stress factors. Crop ground-truth informati
on consisted of leaf area index, wet biomass, dry biomass, and grain y
ield. During both years ground-truth data were collected from at least
50 commercial farms every one to three weeks. Multispectral TM vegeta
tion indices were developed using the mid-infrared bands 5 and 7 as we
ll as the commonly used near-infrared and red bands. Two mid-infrared
vegetation indices proved to be particularly useful in identifying man
agement practice impacts on both crops. For both crops, yield and crop
growth measurements gave similar trends versus TM vegetation indices.
Planting date, plant density, an index of crop stress, and tillage si
gnificantly impacted on soybean and corn crop attributes.