B. Brown

Biofumigant Biomass, Nutrient Content, and Glucosinolate Response to Phosphorus

ABSTRACT Information on biofumigant-green manure vegetative biomass, nutrient, and glucosinolate content sensitivity to phosphorus (P) is lacking for species used in potato and sugarbeet production. Therefore, available P effects on field-grown condiment yellow mustard (Sinapis alba, cv. IdaGold) and oilseed radish (Raphanus sativa, cv. Colonel) were evaluated (2001–03). Low soil P was generally more limiting to radish foliage P concentrations or uptake than to the mustard, suggesting inherent differences in their ability to access and accumulate P. While radish P and S concentrations increased with higher P, concentrations in mustard were either unaffected or reduced. Foliage P concentrations were more closely related to biomass of radish (r2 = 0.46) than mustard (r2 = 0.11). Mustard exceeded radish in biomass and S accumulation. Phosphorus effects on glucosinolates producing ionic or isothiocyanates were relatively insignificant. These biofumigants differ appreciably in their ability to access and accumulate P, but P effects on nutrient content or glucosinolates were minor.

Winter Wheat Yield, Quality, and Nitrogen Removal Following Compost- or Manure-Fertilized Sugarbeet

ABSTRACT To efficiently use nitrogen (N) while protecting water quality, one must know how a second-year crop, without further N fertilization, responds in years following a manure application. In an Idaho field study of winter wheat (Triticum aestivum L.) following organically fertilized sugarbeet (Beta vulgaris L.), we determined the residual (second-year) effects of fall-applied solid dairy manure, either stockpiled or composted, on wheat yield, biomass N, protein, and grain N removal. Along with a no-N control and urea (202 kg N ha−1), first-year treatments included compost (218 and 435 kg estimated available N ha−1) and manure (140 and 280 kg available N ha−1). All materials were incorporated into a Greenleaf silt loam (Xeric Calciargid) at Parma in fall 2002 and 2003 prior to planting first-year sugarbeet. Second-year wheat grain yield was similar among urea and organic N sources that applied optimal amounts of plant-available N to the preceding year’s sugarbeet, thus revealing no measurable second-year advantage for organic over conventional N sources. Both organic amendments applied at high rates to the preceding year’s sugarbeet produced greater wheat yields (compost in 2004 and manure in 2005) than urea applied at optimal N rates. On average, second-year wheat biomass took up 49% of the inorganic N remaining in organically fertilized soil after sugarbeet harvest. Applying compost or manure at greater than optimum rates for sugarbeet may increase second-year wheat yield but increase N losses as well. Abbreviations CNS, carbon–nitrogen–sulfur

Nitrogen Timing for Boot Stage Triticale Forage Yield and Phosphorus Uptake

Optimal N timing for boot stage winter triticale forage production and phosphorus (P) removal is not well established. Irrigated winter triticale in low and relatively high Olsen P soil was treated with six rates of fall pre-plant N and two rates of late winter N at Parma in 2006 and 2007. Triticale boot stage biomass, protein, nitrate-N, P concentrations, and P uptake and were determined. Fall preplant N increased forage production and frequently produced more boot stage triticale biomass. It also tended to increase P uptake, but reduced P and forage protein concentrations likely due to plant dilution. Higher N increased forage P concentrations in high P soil in one of two years. Available soil P did not affect forage protein. Forage protein in the range of 10.5 to 11.0% was necessary for maximum forage production. It appears that more N is required for maximizing P removal than is required for maximizing production.