Agronomic Potential of Narrow‐Leafed and White Lupins in the Inland Pacific Northwest

For economic and environmental reasons, there is need for alternative crops to rotate with winter wheat ( Triticum aestivum L.) in the inland Pacific Northwest (PNW). White ( Lupinus albus L.) and narrow‐leafed ( Lupinus angustifolius L.) lupins were evaluated as potential alternative grain crops under PNW conditions. Maximum grain yield of white lupin was 2128 kg ha −1 ; however, yields were unstable, and cultivars matured later and were more prone to disease than narrow‐leafed lupin. Narrow‐leafed lupin had a yield potential of >2000 kg ha −1 . Early sowing was the most important agronomic factor tested for maximizing yield of narrow‐leafed lupin, with greatest yields associated with sowing during the third week of March. Yield loss due to delayed sowing ranged from 5.8 kg ha −1 d −1 under dry conditions to as much as 60 kg ha −1 d −1 in more favorable conditions. In 2000, delaying sowing from 21 March to 17 April coincided with a reduction in soil water storage of 5.3 cm in the upper 1 m soil layer. Most of this evaporative loss occurred in the upper 50 cm layer, considerably reducing crop water availability. Crude protein content of grain also declined with delayed sowing. Maximum water use efficiency for grain production under our conditions was 6 kg ha −1 grain mm −1 water use. Mean harvest loss ranged from 24 to 62% of hand‐harvested yields, suggesting this will be a potential production constraint. Our results suggest good agronomic potential for narrow‐leafed lupin in the PNW. Agronomic challenges and market potential are discussed.