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

ABSTRACT:

Bean farms in southern Idaho are largely surface irrigated, which adversely impact surface water quality due to improper design and management of the irrigation systems. The objectives of this study were to evaluate a farmer's irrigation system performance and recommend alternative irrigation management practices to improve its performance. Two sets of 14 furrows were located 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 water and chemical transport, 200 kg ha⁻¹ bromide (Br) of KBr was applied to 12 plots established within each site. Six furrow irrigations were monitored for inflows, outflows, and sediment losses. Straw was applied at the rate of 934 kg ha’ to approximately half of furrows after the third irrigation to study its effect on irrigation performance and soil erosion. The farmer's irrigation performance was poor with an estimated average application efficiency of 44% Numerical simulations showed that by selecting proper irrigation durations and inflow rates, average application efficiency can be increased to 58%. Slope had a significant effect on irrigation performance as runoff volume was 52% larger and sediment losses were eight times greater at the steep site under non-straw conditions. Application of straw mulch was effective in reducing sediment losses by 99 to 100%. Straw mulch was also effective in enhancing lateral transport of chemicals as was demonstrated by Br mass transport analysis.