Effect of field geometry on profitability of automatic section control for chemical application equipment

Abstract

Understanding how field geometry is related to over-application of inputs may help farmers make more informed decisions about investment in automatic section control (ASC) technology. The technology helps reduce input application overlap and therefore reduces input costs. The influence of field geometry on the profitability of ASC technology for chemical application was evaluated using overlap data estimated for 44 farm fields in Tennessee, USA. Reduction in overlap with ASC was defined as the difference in area sprayed controlling the entire boom as one section and area sprayed using seven-section ASC. Perimeter (m)-to-area (m²) ratio (P/A, m⁻¹) was used to categorize estimated chemical overlap by field size and shape. Estimated median reductions in overlap with ASC were 3.00 % for fields with P/A = 0.01, 9.65 % for fields with P/A = 0.02 and 13.50 % for fields with P/A ≥ 0.03. For a typical size cotton farm in Tennessee, investing in ASC was not likely to be profitable for fields with P/A = 0.01 but was generally profitable for fields with P/A ≥ 0.02. The low reduction in overlap for P/A = 0.01 with ASC resulted in chemical savings that were too small to pay back the investment in ASC within the useful life assumed for the technology and provide a minimum rate of return. Thus, P/A as a measure of field geometry may be useful for evaluating investments in ASC technologies.