INVESTIGATION OF THE EFFECTS OF SOIL COMPACTION IN COTTON

Soil compaction can cause yield reductions in cotton (Gossypium hirsutum). This study investigated the effect of soil compaction on canopy spectral reflectance, soil electrical conductivity (EC), and cotton yield. Field experiments were conducted during 2003-2005 using a completely randomized block design with four soil compaction treatments. The treatments were no subsoiling (control); subsoiled, disked, and bedded (conventional); subsoiled and compacted (compaction I); and compacted with no subsoiling (compaction II). Field data were collected on soil resistance, canopy reflectance, soil EC, and cotton yield. Comparison of means showed differences between treatments in reflectance in 2003 and 2004, soil compaction parameters in 2004 and 2005, and soil EC and yield in 2005. The depth and thickness of the hardpan were significantly correlated to green NDVI on 16 September (R-2 = 0.53) in 2003. Depth, average resistance of hard pan, and EC all showed relationships with yield in 2005. Their combination as independent variables could explain 65% of the variability in cotton yield in 2005. These results verified that compaction affected canopy reflectance and reduced cotton yield in Arkansas. The practical implications of the outcome of this study are the potential use of EC and canopy reflectance to infer crop yield and extent of soil compaction. However, a multi-site and multi-year study is necessary to confirm this possibility.