Developing Organic Quinoa Cropping Systems for Utah.

Developing Organic Quinoa Cropping Systems for Utah K.R. Buckland, J.R. Reeve, J.E. Creech Abstract Most of the Western United States faces increasing water shortages in the coming years which will prove a major challenge in maintaining sustainable farms. Quinoa may be an ideal alternative crop to meet the needs of the Intermountain West where drought and marginal soils with high salinity are common. Quinoa market prices are high and much of the demand is for organic grain. To evaluate the efficacy of different organic cropping systems for quinoa, a field trial was established as a random complete block (RCBD) with split plot and four replicates. The whole plot factor was cropping system [three levels: strip crop with hairy vetch + winter wheat mowed and blown into the crop row (SC), undersown clover (UC), and tillage only (T)]. The split plot factor was fertility [compost added (+C) or no compost added (-C)]. Steer manure compost was added prior to the first year of quinoa production at a rate sufficient to supply readily available phosphorous (P) for 2 years (11.2 Mg DM ha-1). While high summer temperatures resulted in poor seed set and no quantifiable yield in 2013, main effects of compost and cropping system were significant for above ground biomass and total panicle weight. Quinoa total biomass and panicle weight was greater in +C than -C treatments and T was greater than SC with UC intermediary. Readily mineralizable carbon, soil respiration and microbial biomass, as measured by substrate induced respiration, were greater in +C than –C and were unaffected by cropping system. In July, extractable soil nitrate (NO3-) was lower in SC+C than any other treatment combination, suggesting nitrogen immobilization. Results suggest compost increased quinoa growth and soil microbial activity while cropping system influence was mixed. It remains to be seen if adverse effects of high temperatures on seed set in quinoa can be resolved.