New winter crops and rotations for the Pacific Northwest low‐precipitation drylands

Abstract

This article is an overview of recent advances in dryland cropping in the region of the Inland Pacific Northwest of the United States (PNW) that receives <300 mm annual precipitation. The climate of the region is Mediterranean-like with wet winters and dry summers. For the past 130 yr, monocrop 2-yr winter wheat (Triticum aestivum L.)-fallow (WW-F) has been the dominant rotation practiced on >90% of rainfed cropland throughout this region. Rapid advances in technology in the past several decades and the realities of dryland farm economics prompted most farmers to expand their land area and adopt conservation tillage and no-tillage practices. Three relatively new crops have gained some foothold in the past decade. These crops are winter pea (WP) (Pisum sativum L.), winter canola (WC) (Brassica napus L.), and winter triticale (WT) (X Triticosecale Wittmack). Like WW, all three of these "new" winter crops need to be planted in late August-early September into carryover soil moisture after a 13-to 14-mo fallow period to achieve optimum yield potential. Researchers and farmers have experimented with a multitude of spring-planted crops but, to date, all have shown high year-to-year variability in yield and none have been economically viable in the long term. The focus of this paper is to summarize major research conducted on WP, WC, and WT, as well as farmers' attitudes on the potential of these three winter crops for wheat-based rotations in the PNW drylands.

Increasing Biodiversity and Land-Use Efficiency Through Pea (Pisum aestivum)-Canola (Brassica napus) Intercropping (Peaola)

“…In the annual cropping zone, the spring legume part of the rotation is frequently replaced with spring canola due to price and herbicide options. The use of group 1 herbicides to control grassy weeds, which can be difficult in wheat production systems, is allowed for use in both winter and spring canola (5).…”

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

“…A 2‐yr winter wheat and summer fallow (WW‐SF) system is common to those areas of the inland Pacific Northwest (PNW) where winter‐dominant, annual precipitation is too low (<300 mm) for economical yearly crop production (Schillinger, 2020). Summer fallow stores soil water over a 14‐mo period for the following WW crop and thus reduces the frequency of crop failure and stabilizes total production compared to annual cropping (Young et al., 1999).…”

Winter Triticale: A Long-Term Cropping Systems Experiment in a Dry Mediterranean Climate

“…Annually, only 3% of land is planted to spring-sown crops (mostly spring wheat) [3]. A multitude of spring-sown crops so far tested by farmers and researchers in in the PNW drylands have not had stable yields nor been economically viable in the long term [4] because of heat and/or water stress encountered during their reproductive period [5]. Crop and climate models for the PNW predict future slight increases in winter precipitation but drier summers [2], which would put spring-sown crops at even further yield disadvantage compared to WW that matures earlier.…”

“…In the past 10-15 years, three relatively new winter crops have garnered interest in the region. These crops are winter triticale (WT), winter pea (Pisum sativum L.), and winter canola (Brassica napus L.) [5]. As with WW, these three new winter crops need to be planted in late August-early September into moisture accumulated in the soil after a 13-mo fallow to achieve optimum grain yield potential.…”