Downsizing an integrated crop management field study affects economic and biological results

In recent years, there has been increased interest in long-term, field-scal e cropping systems research to improve pest management, to protect air and soil quality, and to increase or maintain growers' profits. However, these studies require large tracts of land; sizeable labor forces, and substantia l inventories of equipment, which make them very expensive to conduct. Beca use of recent concerns about reducing field research casts, this study. com pares economic and biological results from an original complete 6-yr integr ated cropping management (ICM) systems field study to results from several downsized experiments, which were components of the :complete study. Compar ed with the original ICM study, the downsized experiments reduced the numbe r of treatment replications from four to three, reduced the number of crop rotation cycles from two to one (from 6 to 3 yr), or only grew one crop per rotation each year. The effect of downsizing on the profitability analysis and the statistical (biological) analysis were similar. Reducing replicati ons altered both profitability and biological conclusions less than reducin g the number of rotation cycles. Reducing crop rotation cycles markedly alt ered treatment profitability rankings compared with the complete study. Gro wing only one crop in a rotation per year was the most detrimental to biolo gical results and entirely precluded computing mean annual cropping system profitability. This empirical study supports the importance of replicating treatments fully over time, over space, and over crop rotational positions.