There are many conservation practices related to tillage that hold soil and water in crop fields. These include reduced tillage, mulch tillage, and direct seed. Each varies in how they reduce soil disturbances or leave crop residue. However, what are the effects on soil loss of adding such a practice to your field when compared with conventional tillage?
Ryan Boylan and his team at Palouse Conservation District are studying this question with two creeks near St John, WA. The Kamiache Creek watershed has 80% of its agricultural land mulch tilled and 20% conventionally tilled. They compared it with the Thorn Creek watershed where 80% of the agricultural land is conventionally tilled and 20% is mulch tilled.
Ryan monitors water quality and stream flow in both creeks and based on initial results from 2017-2018, they measured 5.5 times less sediment in Kamiache Creek than Thorn Creek. Or as Ryan puts it, the sediment leaving Thorn Creek (2,447 tons) would cover the entire Washington State University football field with 12 inches of soil. The sediment from Kamiache Creek (220 tons) would cover from the end zone to the 34-yard line at a depth of 3 inches.
These results make conservation tillage practices more appealing when compared to conventional tillage. However, these paired watersheds aren’t perfect mirrors of each other and results could also be effected by watershed size, precipitation, and soil type. Ryan continues this study to measure the influence of conservation tillage and other factors on soil erosion if you want to follow his progress at https://www.palousecd.org/.
If you are interested in trialing a direct seed system in your fields, contact Amanda Ward 509-888-6373. Foster Creek CD has a cost share program to assist you with the conversion for up to 750 acres over 3 rotations at $28/ac.