US EPA

4550965 

Journal Article 

Within-Furrow Erosion and Deposition of Sediment and Phosphorus 

Brown, MJ 

1985 

Under present management systems, irrigation drainage streams continually load sediment into streams and rivers. This study sought to determine (1) the erosion and/or deposition pattern within the furrow of various furrow- irrigated crops; (2) the total sediment and P losses from the furrow during each irrigation throughout the irrigation season; and (3) how effective loose straw in furrows would be as an energy dissipator to reduce erosion and increase infiltration. The irrigation system studied was in southern Idaho where potato or bean were being cultivated. During the growing season on the potato plots, six irrigations yielded 13.7 t/ha of sediment and 5 irrigations yielded 7.9 kg/ha of total P. Water flow through the furrow ranged from 15.8 L/min to 6.4 L/min. During six irrigations, 59% of the total sediment loss occurred during the first two irrigations and 85% occurred during the first three irrigations. On a bean field with flat-end furrows, the area of erosion and deposition of sediment and P changed along the furrows from irrigation to irrigation during the season. The flow rate in the furrows for eight irrigations ranged from 14.2 to 22.6 L/min. The greatest erosion and some deposition occurred in the upper half of the furrows; further erosion and most of the sediment deposition occurred in the lower one-third of the furrows. Flow rates in wheel rows ranged from 14.2 to 18.4 L/min; rates in the nonwheel rows ranged from 15.2 to 22.6 L/min. During the first two irrigations on the flat-end bean field, 49% of the total sediment eroded left the furrows. Only 23% of the total eroded sediment was lost during the last four irrigations. On the bean field with convex-end furrows, erosion was greatest in the bottom one-third of the furrows. Erosion in the upper two-thirds of the furrows was similar to that in the upper two- thirds of the flat-end field. Loose straw in the furrows reduced sediment generated from erosion by 71%; entering stream sizes were 13.2 and 10.3 L/min for the straw and no-straw furrows, respectively. Straw also increased infiltration by 82% compared to no-straw furrows. Proper use of organic matter and better water management in the early part of the season could effectively increase infiltration and reduce soil and nutrient losses. (See also W91-03117) (Rochester-PTT) 

Furrow irrigation Idaho Irrigation practices Phosphorus; Sedimentation Soil erosion Infiltration Mulches Nutrients; Phosphorus losses