Net Revenue of Pea Cover Crop – Wheat Compared to Fallow-, Pea Grain- and Wheat-Wheat Systems across Time and Space.

Net revenue from pea cover crop (hayed or sprayed) – wheat systems were equal to fallow-wheat systems, but much less than from a pea grain-wheat system, in a long-term study in southwestern Montana (Bozeman, 2003 - 2016). Economic assessments were conducted under scenarios of full and half rates of recommended N fertilizer and sharp vs flat wheat protein discount. Net returns from wheat in rotation with pea cover crops at Bozeman were equal to fallow, especially at low N rates and sharp protein discounts, but occurred only after multiple cycles (years 7-10). Long-term annual precipitation is 414 mm at Bozeman, approximately 100 mm wetter than the major dryland wheat producing regions of northern Montana. The objective of this study was to assess whether economic comparisons of similar cropping system alternatives would differ in the drier climate of northern Montana. A study comparing chem fallow, pea cover crop, pea harvested for grain, and spring wheat (continuous wheat) in 2-yr rotations with winter wheat, and managed with four N fertilizer rates, was conducted near Big Sandy and Dutton, MT (2011-2017). Although optimal N rates differed among cropping systems, net revenue was much greater for the pea-wheat system than the other three systems across all N rates. Pea cover crops were very effective at increasing N uptake in subsequent wheat but net revenues tended to be lower than the chem fallow system, due largely to pea seed, fertilizer, and herbicide costs. We are committed to carrying the Big Sandy site forward to see if cover crop economics improve in the long run.