Site-specific crop management (SSCM) is a farming method which takes advantage of field variability to optimize the management of a site. Application of SSCM techniques requires knowledge of the spatial variability present in the field and equipment which is capable of applying production inputs in such a way as to address those spatially variable needs. A cotton height sensor was developed and evaluated to provide knowledge of spatially variable cotton heights in an actively growing field. A GPS-controlled direct injection sprayer was assembled from commercially available components and tested by applying growth regulatory chemicals to a cotton crop.

A cotton height sensor was developed and evaluated to determine its ability to measure and record cotton heights across a field. Geo-referenced position was recorded with the height sensor output to provide a means by which a map of the cotton height across the field could be made. The cotton height sensor utilized two separate sensing methods for cotton height determination. An infrared light curtain was used to obtain height values within ±33 mm (1.3 in.) of hand measured values. A bank of limit switches with arms contacting the plants was used on the same implement, but the resolution was only ±46 mm (1.8 in.). Both methods were evaluated for damage to the growing crop, and damage was within 10% of what a normal cultivation pass might cause. The prototype sensor was found to be capable of farm scale use on a daily basis.