Effect of Nitrogen Sources, Rates, and Application Time on Spring Wheat Yield and Grain Protein

1. Effect of Nitrogen Sources, Rates, and Application Time • on Spring Wheat Yield and Grain Protein bc cd Olga S. Walsh, Western Triangle Agricultural Research Center, Conrad, Montana JUSTIFICATION RESULTS • Nitrogen (N) - the most common nutrient • limiting yield of spring wheat in Montana • (Engel, 1993) • Spring wheat - key cereal crop grown in Montana • Wheat production represents ~ 25% of Montana’s agricultural revenue (stuffaboutstates.com, 2010) • Protein content - base for established market adjustments for spring wheat, with premiums paid for increase above the baseline levels • Leaf burn apparent in spring wheat following application of UAN at 90 kg N ha-1 rate before flowering at WTARC • Spring wheat grain yields were not impacted by foliar UAN application before flowering at WTARC • Foliar application of UAN at 90 kg N ha-1 rate negatively impacted yields at Patton; plots topdressed at 45 kg N ha-1 rate yielded significantly higher, independent of application time. Figure 1a OBJECTIVE a • To determine the most efficient N fertilizer source, N rate, and N fertilizer application time combination for optimizing Montana spring wheat yield while maximizing grain protein ab ab ab ab ab ab b a a b b b EVALUATED FACTORS cd cd • Fertilizer Timing: PreplantvsTopdress • Preplant • Supplies N to establish crop stand • Better soil/weather conditions (Randall and Schmitt, 1998) • Risk of N loss (immobilization, volatilization) (Fowler and Brydon, 1989; Wuest and Cassman, 1992) • Topdress • Supplies N at maximum plant uptake – higher NUE (Walsh et al., in press) • N fertilization after Feekes 5 – crop can catch up (Morris et. al., 2005) • Enables fertilization based on crop need/yield potential • Fertilizer Sources: Granular vs Liquid • Granular N (urea) • Up to 30% N loss as ammonia for • broadcasted urea (Engel, personal communication) • Urea applied with the seed – seed damage, drying out of seed bed – affects germination • Liquid N (urea ammonium nitrate = UAN) • Plants absorb water and nutrients through leaves (Wittwer and Teubner, 1959) • Efficiency of foliar fertilizers is higher • (Mosali et al., 2006) • Crop injury/leaf burn (Wesley et al., 1998) e Figure 1b Figures 1a and 1b. Effect of fertilizer N rate, source and application time on spring wheat grain yield at WTARC (1a) and Patton (1b), 2011. MATERIALS AND METHODS DISCUSSION • 3 dryland experimental sites: Western Triangle Research Center, Conrad, MT, 2 on-farm studies (Jack Patton, Knees, Chouteau County, MT and Pat Wheeler, Valier, Pondera County, MT) • Choteau spring wheat variety • 4 preplant N rates (0, 40, 80, and 120 lbs N ac) • 3 topdress N rates (0, 40, and 80 lb N ac) • 2 topdress N fertilizer sources (granual – urea, 46-0-0, and liquid – urea ammonium nitrate (UAN) , 28-0-0) • 2 topdress application times (before flowering and after flowering) • Data from WTARC and Patton are evaluated for 2011 • Spring wheat mean grain yield was higher at WTARC (1735 kg ha-1) compared to Patton (1544 kg ha-1) • Yields ranged from 618 to 2047 kg ha-1 at WTARC and from 1262 to 2004 kg ha-1 at Patton • Greater response to fertilizer N observed at WTARC; unfertilized check yielded twice as high at Patton, compared to WTARC • Preplant N rate and topdress application time significantly effected yield at both sites (p<0.05) • At WTARC, fertilization before flowering resulted in greater mean spring wheat yield (1432 kg ha-1) compared to after flowering (1274 kg ha-1) • Fertilizer N source had no significant effect on spring wheat yields CONTACT INFORMATION Dr. Olga S. Walsh, WTARC, MSU telephone: (406)278-7707 e-mail: olga.walsh@montana.edu web: http://ag.montana.edu/wtarc/ • AKNOWLEDGEMENTS: We are grateful to: Mr. Jack Patton and Mr. Pat Wheeler for support and cooperation, • Mr. Clint Rouns and Mr. John Miller (WTARC, MSU), and Dan Picard (Pondera County Extension Agent, MSU), for their expertise and support • We are grateful to Montana Fertilizer Advisory Committee for funding this project