PNW 578-Updated

PNW 578 Nitrogen Management for Hard Wheat Protein Enhancement Brad Brown, Mal Westcott, Neil Christensen, Bill Pan, Jeff Stark anaging nitrogen (N) to produce both high yields and acceptable protein of Contents M hard winter or spring wheat, especially in Page high rainfall and irrigated systems, has been frus- Key Points .........................................................2 trating for Pacific Northwest (PNW) growers and Wheat Nitrogen Utilization...................................4 those who serve them in an advisory capacity.A N Uptake........................................................4 better understanding of the principles of wheat Yield and Protein Relationships...........................5 nitrogen utilization, the relationships of protein to Satisfying the N Requirements for Yield ..............6 yield and available N, and N management for hard Nitrogen and Wheat Protein ................................6 wheat should enable fieldmen, consultants, advis- Late Season N for Increasing Protein ..................7 Rate and Timing .............................................7 ers, and growers to produce high yields of hard Yield Effects...................................................8 wheat with acceptable protein more consistently. N Use Efficiency .............................................8 Land-grant programs in the Pacific Northwest Application and Irrigation Method ....................8 have conducted considerable research on N man- Planting Dates and Varieties............................9 agement for irrigated wheat protein enhance- Late Season Moisture.....................................9 ment.The research answers many questions relat- Economics ...................................................10 ed to wheat protein enhancement in irrigated Deep Soil N and N Mineralization ..................10 PNW production systems. Baking Quality ..............................................11 Predicting Protein for Protein Enhancement .......11 Land-grant soil scientists in the PNW have Plant Analysis...............................................11 written this publication to share information and Chlorophyll Meter..........................................13 to relate in-depth the wheat and N management Spectral Assessment....................................13 issues related to grain protein enhancement.The Summary.........................................................13 focus is on irrigated wheat, but many of the prin- Further Reading ...............................................14 ciples will apply to rain-fed wheat as well. A Pacific Northwest Extension Publication • University of Idaho • Oregon State University • Washington State University Key Points Wheat N Utilization Nitrogen and Wheat Protein • Most of the N used by wheat is taken up before • Available N is the most critical factor affecting grain flowering and later moved to the developing kernel protein. during grain fill. • Increasing available N during vegetative growth • Photosynthesis that occurs during grain fill largely increases both yield and protein, except under con- determines kernel starch contents. ditions where available N is extremely deficient or • Conditions that affect plant stored N at flowering or excessive. photosynthesis during grain fill appreciably affect • The N required for acceptable protein may exceed grain protein at harvest. that required to maximize yield by 0.4 pound N per Yield and Protein bushel. • Growing conditions that affect yield have correspon- Late Season N ding effects on grain protein. • Applying all the fertilizer N required in irrigated situ- • Increasing yield from optimal cultural practices or ations, for both maximum yield and acceptable pro- correcting nutrient shortages can reduce protein if tein, during vegetative growth can cause excessive no additional N is provided. vegetative growth and reduce yield. • Inclement growing conditions, such as drought and • Nitrogen applied after vegetative growth is used pri- high temperature, which reduce yield, frequently marily to increase protein. increase grain protein. • The protein increase from late N depends on the N • Stressing wheat during late grain fill and sacrificing rate and the wheat plant N content. yield should not be necessary to produce hard • The protein increase from late N is little affected by wheat with acceptable protein. N sources, wheat variety,or planting dates. Satisfying N Requirements for Yield • Late N induced protein increases in most irrigated field trials have led to improved baking quality. • Yield potential is affected mostly by N available during vegetative growth stages. • The economic return from late applied N depends on N fertilization costs, yield, the protein increase, • Total available N required per bushel to maximize and the protein discount or premium. production ranges from less than 2 pounds to more than 3 pounds depending on the production system. Estimating Protein • The more productive the system, the less N required • Flag leaf N testing can be useful for estimating grain per bushel for maximizing yield. protein and the protein increase from late N. • Use of soil testing to measure residual N is essential • Protein may not increase much if flag leaf N concen- for the most accurate estimates of N requirements to trations at heading exceed 4.2 to 4.3 percent. maximize yield. heat grain protein is an important quality factor The difference in gross returns for irrigated or high that influences the marketability of all wheat rainfall soft whites and hard reds can be calculated using W market classes in the United States. High pro- annual market prices in Portland, OR, for soft whites and tein is desirable for all hard and durum wheat market hard reds at 13, 14, and 15 percent since 1982. Hard red classes, and in some soft wheat markets, when soft wheat spring or winter wheat was assumed to be 95 percent as is used for specific noodle or bread products. Otherwise, productive as soft white spring or winter wheat.Yields lower protein is desired for many soft wheat uses. Higher for soft white winter (SWW) of 120 bushels/acre protein is associated with increased kernel hardness, (bu/acre) and soft white spring (SWS) wheat of 96 gluten strength, and loaf volume. bu/acre were used for the comparison. Hard wheat with higher protein frequently is marketed The average difference in gross returns for hard red at a premium compared to lower protein wheat of the spring at 13, 14 or 15 percent protein as compared to same market class.When high protein wheat is limited in SWS wheat were $24, $47, and $61 per acre, respectively. supply,the high protein premium may represent as much Avoiding the discount below 14 percent was more criti- as 50 percent or more of the market price in low price cal than gaining the premium above 14 percent. years.When expected hard wheat prices or high protein Discounts per bushel (for protein <14%) can be as much premiums appreciably exceed soft wheat prices, some as three times the premium (for protein >14%). producers shift their soft wheat acreage to hard wheat For HRW wheat, the gross return over SWW wheat was classes. only 21 cents/acre for 11 percent protein HRW,$12/acre While some rain-fed production areas, such as the for 12 percent protein, and $31/acre for 13 percent pro- Northern Plains, have climates that allow the routine protein. Historically,the gross return for HRW over SWW duction of high protein hard wheat or durum classes, wheat is considerably less than the gross return for HRS other rain-fed areas produce high protein wheat less fre- vs. SWS.Also, the discount for lower protein HRW has quently depending on available moisture, temperature, been less than the discount for low protein HRS. For the and greater fluctuations in yields. Given highly productive gross return comparisons, additional N application and wheat in high rainfall or irrigated systems, low protein fertilizer costs were not considered. levels are the general rule unless growers make a deter- Producer interest in HRS fluctuates with the price dif- mined effort to effectively manage available nitrogen ferential between the soft and hard wheat market classes. resources for high protein. Even then, intensive N man- There would be greater production of HRS were it not for agement involving higher N or late season N applications grower concerns about producing HRS with acceptable can fail to produce the desired result of high grain pro- protein. Understanding the issues related to wheat protein. tein is critical if producers are to avoid or minimize low protein discounts and maximize their economic returns. LEGEND: This bulletin reviews many factors that govern wheat protein and mentions selected PNW research that addresses HRS = hard red spring wheat HRW = hard red winter wheat Fig. 1. Average annual wheat prices in Portland, OR, for hard red spring SW = soft white wheat (a) and hard red winter (b) wheat market classes at different protein as compared to common soft white wheat. SWS = soft white spring wheat (a) SWW = soft white winter wheat HRS 15% 6 HRS 14% VPR = volume to protein ratio HRS 13% SW 5 Failure to consistently produce high protein wheat despite greater expenditures of resources is frustrating for 4 hard wheat growers throughout the western U.S.The situ- ation is exacerbated under some irrigation systems. In a Market price ($/bu) 3 1999 survey in western Idaho, hard red spring wheat (HRS) from furrow irrigated fields averaged 2.2 percent (b) HRW 13% lower protein than wheat from sprinkler

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