Reduced Growth of Pea Following Cool-Season Oilseeds.

Reduced yield of pea following brassicaceae bioenergy feedstocks could be related to reduced root nodulation of pea from alleleopathy associated with crucifer residues.  Increasing the rate of inoculum and/or starter fertilizer at seeding could help pea overcome impacts of alleopathy.  A greenhouse experiment in 2012 investigated the impact of pea grown on soil collected from the surface 20 cm of no-till research fields of brassica napus, camelina, flax (non brassicaceae) and durum harvested in Fall 2011, either with or without seed-applied inoculum, and with or without starter fertilizer applied at planting.  Seed yield of pea was 27% greater following durum than following canola, while pea yield following flax and camelina was similar to durum and canola.  Parallel trends were also observed for shoot biomass, root biomass, plant height, pods per plant, and barren pods per plant.  Inoculum treatment resulted in 13% more pods per plant, while starter fertilizer resulted in 15% more pods per plant but a 22% reduction in seed weight.  Overall results suggest that pea yield is greater following durum than canola, and that inoculum and starter fertilizer applied at planting did not increase yield, in spite of increasing the number of pods per plant.