Field evaluation of furrow irrigation performance, sediment loss, and bromide transport in a highly erosive silt loam soil

Bean farms in southern Idaho are largely surface irrigated which adversely impact surface water quality due to improper design and management of the i rrigation systems. The objectives of this study were to evaluate a farmer's irrigation system performance and recommend alternative irrigation managem ent practices to improve its performance. Two sets of 14 furrows were locat ed in a 4-ha bean field at steep slope (2.74%) and relatively mild slope (1 .65%) sites for this study To investigate two dimensional coater and chemic al transport 200 kg ha(-1) bromide (Br) of KBr was applied to 12 plots esta blished within each site. Six furrow irrigations were monitored for inflows , outflows, and sediment lesser. Straw was applied at the rate of 934 kg ha (-1) to approximately half of furrows after the third irrigation to study i ts effect an irrigation performance and soil erosion. The farmer's irrigati on performance was poor with an estimated average application efficiency of 44%. Numerical simulations showed that by selecting proper irrigation dura tions and inflow rates, average application efficiency can be increased to 58%. Slope had a significant effect on irrigation performance as runoff vol ume was 52% larger and sediment lasses were eight times greater at the stee p site under non-straw conditions Application of straw mulch was effective in reducing sediment losses by 99 to 100%. Straw mulch was also effective i n enhancing lateral transport of chemicals as was demonstrated by Br mass t ransport analysis.