Economic returns from three-year crop rotations under low precipitation in Pacific Northwest

Authors: LONG, DANIEL - Retired ARS Employee; BARROSO, JUDIT - Oregon State University; PAINTER, KATHLEEN - University Of Idaho; Reardon, Catherine - Kate; WILLIAMS, JOHN - Former ARS Employee

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2022
Publication Date: 3/5/2022
Citation: Long, D.S., Barroso, J., Painter, K.M., Reardon, C.L., Williams, J.D. 2022. Economic returns from three-year crop rotations under low precipitation in Pacific Northwest. Agrosystems, Geosciences & Environment. 5(1). Article e20251. https://doi.org/10.1002/agg2.20251.
DOI: https://doi.org/10.1002/agg2.20251

Interpretive Summary: Growers in the Pacific Northwest are increasingly interested in oilseeds to diversify the traditional winter wheat-fallow rotation to lower disease and weed pressure, reduce herbicide resistance, and increase profitability. Interest is also increasing in response to rising consumer awareness of human nutritional benefits of food-grade vegetable oil made from canola and implementation of clean fuel policies that favor renewable fuels for the trucking and aviation industries. In this study, profit opportunities for producing Brassica oilseed crops in three-year rotations after either fallow or winter wheat were explored through a cropping systems experiment over five years under low precipitation in eastern Oregon. Dollar returns over total costs were negative with a traditional two-year rotation of winter wheat and fallow being least unprofitable. Three-year rotations with winter canola or spring carinata were less profitable, due to lower yield, than two-year rotations with winter wheat. Growers will likely not be motivated to grow oilseeds under low precipitation unless market demand for oilseeds shifts the relative price for these crops such that they provide a net economic return that is closer to that of winter wheat.

Technical Abstract: Winter wheat (Triticum aestivum L.)-summer fallow (WW-SF) remains the most economical cropping system in low precipitation (<300 mm) areas of the inland Pacific Northwest (PNW). Some producers are interested in diversifying this traditional two-year cropping sequence with oilseed crops to capture break crop effects and other rotation benefits. The objective of this study was to compare production costs and economic returns of two-year cropping sequences with those of intensified three-year sequences at a low-precipitation site where the long-term rotation has been WW-SF. A large-plot field experiment was conducted from 2014 through 2018 to compare costs and net returns from six crop rotations. Summer fallow with intensive tillage (SF) and reduced tillage (RTF) were included in two-year rotations with WW; and RTF in three-year rotations with WW, winter canola (WN, Brassica napus L.), or spring carinata (SC, B. carinata) as a primary crop and spring wheat (SW), spring barley (SB, Hordeum vulgare L.), or SC as a secondary crop. Yields of WW following RTF were higher than yields following conventional SF. Three-year rotations of WW-SC-RTF, WN-SW-RTF, and SC-SW-RTF were less profitable, on average, and had greater income variability than WW-SF and WW-RTF. However, a three-year rotation of WW-SB-RTF was as profitable as WW-SF. Including oilseeds in three-year rotations with fallow may be less profitable than WW in two-year rotation with fallow.