Submitted to: Soil Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 28, 1994
Publication Date: N/A
Interpretive Summary: To better predict furrow erosion and manage irrigation, we should know the changes that occur over time in furrow erosion and in other soil properties that may affect erosion, one being wet aggregate stability, a measure of soil aggregate resistance to breakdown when sieved in water. Changes in furrow erosion and aggregate stability of an irrigated southern Idaho soil were monitored over the 1988 and 1989 irrigation seasons. Some of the changes seen in furrow erosion could have been caused by biological activity, that may have changed some soil physical properties. Trends of furrow erosion and aggregate stability from 1988 to 1989 were dissimilar, probably due, in part, to slight differences in the water content of the soil in the furrow when each irrigation began. These findings are important because they indicate that, for SCS scientists or erosion control specialists to minimize erosion, control efforts should be maximized when the erosion potential is highest, generally the first third of the irrigation season. Erosion can be better controlled by farmers or producers if, when a soil's stability is low, irrigation is delayed a few days. Knowledge of temporal changes in furrow erosion and aggregate stability, and the processes that cause change, can be used in these ways to minimize erosion from irrigated land as well as increase a soil's resistance to furrow erosion.
Technical Abstract: Numerous soil factors, including aggregate stability, affect erosion rates from irrigated furrows. Since aggregate stability varies within growing seasons, furrow erosion may vary as well. The study objectives were to (1) measure furrow erosion and aggregate stability periodically over two growing seasons, (2) statistically characterize the temporal variation in furrow erosion and aggregate stability, and (3) relate variation in erosion rates to changes in aggregate stability and other soil properties. Erosion rates from replicated, previously unirrigated furrows in fallow plots on a Portneuf silt loam (coarse-silty, mixed, mesic Durixerollic Calciorthid) at Kimberly, Idaho, USA, were measured every two to three weeks from mid-May through mid-August, 1988, and from late-April to late-August, 1989. During each 6.5-h irrigation, three furrows in 1988 and four furrows in 1989 were irrigated at an inflow rate of 11.3 Lmin-1 At each irrigation, soil samples were taken to a depth of 5 cm from the bottom of furrows adjacent to or near those irrigated. From these samples, soil gravimetric water content was measured and aggregate stability was determined by wet sieving. Erosion from furrows not previously irrigated varied greatly when measured throughout two growing seasons. For both years, erosion rates were significantly lower later in the growing season than earlier. For a 4.0% slope area in 1988, furrow erosion rates varied over the entire season by a factor of six or more while aggregate stability varied (increased) by only 17%. Thus, aggregate stability was not significantly correlated with furrow erosion rates.