REMOTE SENSING AND IN SITU DETERMINATION OF FORAGE QUALITY

Authors: Starks, Patrick; Coleman, Samuel; Phillips, William

Submitted to: Oklahoma Grazinglands Conservation Association Conference
Publication Type: Proceedings
Publication Acceptance Date: 8/16/2002
Publication Date: 8/16/2002
Citation: Starks, P.J., Coleman, S.W., Phillips, W.A. 2002. Remote sensing and in situ determination of forage quality. Oklahoma Grazinglands Conservation Association Conference. Paper No. 7.

Interpretive Summary: Matching of grazing animals to the forage resource base could improve profit margins of ranch enterprises by reducing expenditures for supplemental feeds. Our objective was to determine if it is feasible to estimate forage quality parameters directly in the field using hand-held remote sensing instruments with similar precision to that achieved using conventional bench-top near-infrared spectroscopy (NIRS) analysis of clipped, dried, and finely ground forages. Remotely sensed data were collected over live bermudagrass canopies at various times during the growing seasons of 1999, 2000, and 2001. Vegetation samples were clipped and reference values of percent nitrogen, acid detergent fiber, and neutral detergent fiber were determined by conventional wet chemistry methods. The ability to predict the reference values was then evaluated for both bench- top NIRS and hand-held radiometer techniques. Statistical analysis showed that the forage quality predictions from the hand-held method compared wel with the bench-top NIRS approach, indicating that it is feasible to estimate forage quality directly in the field. Measurements of forage quality from a hand-held radiometer approach could be coupled with estimates of forage quantity, thereby allowing near-real time mapping of the forage base enabling the rancher/livestock manager to assess fprage status and match the grazing animal to the forage base and improve management of grazing lands.

Technical Abstract: Matching of grazing animals to the forage resource base could improve profit margins by reducing expenditures for supplemental feeds. Our objective was to determine if it is feasible to estimate forage quality parameters directly in the field (i.e., in situ) using hand-held remote sensing instruments, and with similar precision to that achieved using conventional bench-top near-infrared spectroscopy (NIRS) analysis of clipped, dried, and finely ground forages. Remotely sensed data were collected over bermudagrass (Cynodon dactylon) canopies at various times during the growing seasons of 1999, 2000, and 2001. Vegetation samples were clipped and reference values of percent nitrogen, acid detergent fiber, and neutral detergent fiber were determined by conventional wet chemistry methods. The ability to predict the reference values was then evaluated for both bench-top NIRS and hand-held radiometer techniques. Statistical analysis of the forage quality predictions indicated that the hand-held method compared well with the bench-top NIRS approach, indicating that it is feasible to estimate forage quality in situ. Measurements of forage quality from a hand-held radiometer approach could be coupled with estimates of forage quantity, thereby allowing near-real time mapping of the forage base enabling the rancher/animal manager to assess forage status to better match the grazing animal to the forage base and improve management of grazing lands.