Furrow irrigation erosion and sedimentation: On-field distribution

Erosion created by furrow irrigation is a serious problem in some states and has resulted in reduced crop yields. Most furrow erosion assessments have been based on measured sediment discharge from the field, which results in an average erosion rate for the whole field. However, erosion theory predicts that the erosion rate should decrease with distance from the head (inflow) end of the furrow. The purpose of this study was to quantify soil erosion and deposition distribution within furrow irrigated fields. Within field sediment discharge measurements on two silt loam fields in southern Idaho showed that over half of the soil that eroded from the head end of the furrows deposited on the lower portions of the field as furrow flow rates decreased. Erosion rates on the upper quarter of uniformly-sloped furrows were 6-20 times greater than average rates from the field. The measurements demonstrate the need to measure erosion rates on the head ends as well as for the whole field, and explain visible erosion damage from head ends where field average erosion rates are not high