Fernandez, Adria L.2012-02-242012-02-242012-01https://hdl.handle.net/11299/121059University of Minnesota M.S. thesis. January 2012. Major: Applied plant sciences. Advisors: Dr. Craig Sheaffer, Dr. Donald Wyse. 1 computer file (PDF); vi, 56 pages, appendix p. 56.Two field experiments using organic methods were conducted at Rosemount, Becker, and Lamberton, MN in 2009 and 2010. The first experiment investigated the effect of intercropping on field pea (Pisum sativum L.) and lentil (Lens culinaris Medik.) yields. Intercrop treatments used were wheat (Triticum aestivum L.), oat (Avena sativa L.), oilseed radish (Raphanus sativus L.), winter rye (Secale cereale L.), rapid-cycling brassica (Brassica campestris L.), and unweeded and hand-weeded sole crop controls. Grain was harvested from wheat, oat, and oilseed radish, while winter rye and rapid-cycling brassica served as unharvested “living mulch” crops. Lentil and pea yields in all intercrop treatments were lower than or equal to both weeded and unweeded sole crop controls at all locations and years. Pea and lentil yields of sole crop controls equaled or exceeded total (legume plus intercrop) yields of all intercrop treatments in nearly all cases. In pea and lentil, winter rye and rapid-cycling brassica intercropping decreased weed biomass compared to the unweeded control in some treatments; however, this reduction in weed biomass did not result in improved pea or lentil yields. The second experiment investigated the effects of variety selection, delayed sowing, and weed removal on yield and weediness of spring-planted field peas and lentils. Treatments in this experiment were two lentil varieties (Crimson and Pennell) and four yellow field pea varieties (DS Admiral, Commander, Yellow, and Miami), complete manual weed removal or no weed control, and three planting dates between April 14 and May 15. Yield differences among cultivars were observed in lentils but not in peas. Yields of Crimson lentil were 66% higher on average than those of Pennell lentil. Weed removal improved pea yields by an average of 63% and lentil yields by an average of 87%, although interactions with location occurred. Average yields of peas planted at the early date were 23% and 71% greater than yields at the middle and late dates, respectively. In lentils, average yields at the early date were 50% and 120% greater than those at the middle and late dates, respectively. Delayed planting was ineffective in reducing weed biomass. Field pea reliably produced yields sufficient to offset estimated production costs in both low-price commodity and high-price direct marketing scenarios. Lentil yields did not consistently exceed economic break-even levels in most environments.en-USApplied plant sciencesThesis or Dissertation