Assessment of microirrigation for sugarbeet production

Sugarbeet (SB) is a major value-crop in many furrow (Fu) irrigated areas of Wyoming where nitrate (NO3) contamination prevails. Microirrigation (M) ma y be an option for managing such pollution while sustaining SB production. With the goal of evaluating efficacy of M for SB production, in comparison to Fu practice, studies were conducted through field experiments, computer simulations, and economic assessments. The field study with SB consisted of a Fu and three M treatments (M1, M2, and M3 representing a management allo wable depletion factor of 0.20, 0.35, and 0.50, respectively) and three Fer tilizer doses. Water use, post-harvest soil NO3 concentrations, SB yields, and water percolation were measured. Computer simulations were performed us ing a transport and irrigation model to predict soil NO3 concentrations and the results were compared with the experimental data. The economic feasibi lity of adopting M for 10 to 40 ha area was evaluated using a capital budge ting analysis. Results of field studies indicated lower water use, higher s oil NO3 levels, less water percolation and greater SB yields with M than un der Fu practice. The yields increased as management allowable depletion fac tor and fertilizer rate augmented. Computer simulations predicted that post -harvest soil NO3 concentrations were higher when SB were irrigated with M rather than Fu practice. Simulation results were comparable with the field data. The economic analysis indicated that irrigation costs decreased and S B returns increased with M practice. Results of capital budgeting showed th at adoption of M in Wyoming was feasible for small-scale SB production. The profitability of the M system was dependent on the irrigation regime and t he conversion area.