The Effects of Topdressing Organic Nitrogen on Hard Red Winter Wheat Yield and Quality: Part II

Final Report for ONE11-140

Project Type: Partnership
Funds awarded in 2011: $14,186.00
Projected End Date: 12/31/2012
Region: Northeast
State: Vermont
Project Leader:
Dr. Heather Darby
University of Vermont Extension
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Project Information


The demand for local organic food is steadily increasing throughout Vermont and New England. Consumers are asking for bread baked with locally grown wheat; however bakers have been slow to incorporate local wheat flour because of the challenges associated with obtaining grains that consistently meet bread-baking standards. Addressing the quality issue is essential for expanding the bread flour market in the northeast. One of the major quality factors facing Vermont grain producers is protein content. Much of the wheat currently produced in Vermont has protein levels below what most commercial mills would consider suitable for flour production. Assuring adequate available nitrogen (N) for grain yield and protein are the primary challenges of organic winter wheat production in New England. Topdressing N to increase protein quantity and quality is recommended for conventionally grown wheat, but the effectiveness of topdressing organic N sources needs evaluation. The objective of this study was to determine whether topdressing organic nitrogen (N) amendments, during key times of wheat development, would increase grain protein and yields.

In April of 2011 a trial was imposed within a winter wheat field at Gleason Grains in Bridport, VT. The experimental design was a randomized complete block design with four replicates. The treatments were three organic N amendments applied at the tillering stage (Feekes Growth Stage 5, F5), the flag leaf stage (Feekes Growth Stage 8, F8), or a split application with ½ the rate applied at both growth stages.. The amendments used were; ‘Cheep Cheep’ (4% N), Pro Booster (10% N), and Chilean Nitrate (16% N). Plots were sampled for soil nitrates prior to organic N application and at key developmental stages until the wheat reached physiological maturity. After harvest, yields were calculated and quality analyses performed.

The second year’s data indicate that topdressing wheat with organic N amendments can improve grain protein concentrations. The organic N source ‘Pro Booster’ with both soluble and slow release N sources and Chilean Nitrate applied at flag leaf or with a split application provided the most significant increase in wheat protein concentrations. Slow release N products such as composted poultry manure could increase protein but will need to have properly timed applications so that the N has enough time to be mineralized into plant available N sources. This may require applications prior to rapid uptake periods. This will allow the plant to access N at the critical stages hence resulting in potentially yield and protein increases. Based on a basic economic analysis the cost of organic N amendments may prohibit and economic benefit to topdressing wheat. A research report was written and disseminated through workshops and posted online. Three workshops were held during the summer that highlighted this project, there were about 90 in attendance. An episode of “Across the Fence” was filmed and aired on October 2, 2011. At the 8th Annual Northern Grain Growers Association’s (NGGA) conference a presentation on the 2011 trial results was given, there were 150 in attendances. Recently an article combining the 2010 and 2011 results was published in the NGGA’s quarterly newsletter.


The desire for local and organic food is on the rise throughout the Northeast. Consumers are asking for bread baked with locally grown wheat. Millers and bakers, however, cannot find enough locally grown organic wheat, and that which is available often does not meet the higher quality standards required bread production. Addressing the quality issue is essential for expanding the bread flour market in the northeast.

One of the major quality issues facing northern grain producers is low protein content of the wheat. Much of the hard red winter wheat currently produced in Vermont has protein levels consistently between 9 and 12%. Many of the commercial flour mills have target protein levels of 12-15%. In general, higher grain protein content results in improved bread baking characteristics of the flour.

Research suggests the amount of soil nitrogen (N) available to the plant during plant growth directly influences the quantity and quality of grain protein. It is relatively easy to obtain acceptable wheat protein levels if N is in a plant available form during periods of critical need. In a conventional system readily available synthetic fertilizers can be added to wheat during these times. However, in organic systems it is more difficult to manage N release rates. In Vermont, organic farmers rely solely on green and animal manures as the source of N for winter wheat crops. Since protein levels of winter wheat average 10% we assume that N is a limiting factor in both yield and quality. Farmers are interested to know if the addition of commercially available organic nitrogen sources during critical wheat development stages will improve the yield and protein content of the wheat crop.

In 2011, we continued to explore the relationship between topdressing organic nitrogen amendments, the application times, and how these two factors influence the quality and quantity of grain protein for a second year.

Project Objectives:

In March 2011 the University of Vermont Extension was awarded a SARE Partnership grant to establish a trial at Gleason Grains in Bridport, VT. The purpose of this project was to collect a second year of results to determine whether topdressing organic nitrogen (N) amendments, during key times of wheat development, would increase grain protein and yields.


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  • Erica Cummings
  • Ben Gleason


Materials and methods:

The seedbed at the Bridport location was prepared by conventional tillage methods. All plots were managed with practices similar to those used by producers in the surrounding areas (Table 1). The plots were seeded with winter wheat (var ‘Redeemer’) on September 18, 2010. Prior crop in 2010 was clover. In addition to clover, the trial area had chickens pasturing on it throughout the 2010 growing season.

In early April of 2011 the experiment was imposed within the winter wheat field on the Gleason Farm (Image 1). The experimental design was a randomized complete block design. Treatments were replicated four times. The treatments were three organic N amendments applied at 3 different application times. The amendments used were; ‘Cheep Cheep’ (4% N), Pro-Booster (10% N), and Natural Nitrate of Soda (16% N). The product ‘Cheep Cheep’ is an OMRI approved and widely available dehydrated poultry litter product. It has a guaranteed analysis of 4-3-3. The OMRI approved ‘Pro Booster’ is a fertilizer manufactured for North Country Organics in Bradford, VT. The blended fertilizer is composed of vegetable and animal meals and natural nitrate of soda. It has a guaranteed analysis of 10-0-0. The OMRI approved Natural Nitrate of Soda is more commonly known as ‘Chilean Nitrate’. It is mined from Northern Chile. It has a guaranteed analysis of 16-0-0. The use of Natural Nitrate of Soda is allowed, however, it is limited to supplying no more than 20% of the crops total N requirements.

In the case of wheat it was assumed that an average yield of 4000 lbs would uptake approximately 100 lbs of N per acre. Therefore the allowed application rate of N from ‘Chilean Nitrate’ would be 20 lbs per acre. The goal was to supply the wheat with 20 lbs of N from each fertilizer source. The organic fertility sources (‘Cheep Cheep’ and ‘Pro Booster’) contain mostly organic-N and therefore the amount of N available to the plants would be only a percentage of the total applied. Based on past data collection and information from the companies it was assumed that 50% of the total N from the ‘Cheep Cheep’ would be available and 30% from the ‘Pro Booster’. The topdress amendments were broadcast applied by hand at the required time. Hence the ‘Chilean Nitrate’ was applied at a rate of 125 lbs per acre, the ‘Cheep Cheep’ at 1000 lbs per acre, and the 'ProBooster’ at 600 lbs per acre. An unfertilized treatment served as a control.

The application timing of the N fertilizer was at the tillering stage (Feekes Growth Stage 5, F5), the flag leaf stage (Feekes Growth Stage 8, F8), or a split application with ½ the rate at both growth stages. On April 19, 2011, the tillering (F5) amendments were applied and the flag leaf (F8) application was on May 19, 2011.

Plots were sampled for soil nitrates prior to organic N application and at key developmental stages until the wheat reached physiological maturity. From each plot a composite of 10 soil cores (1 inch dia., 12 inch depth) was taken, placed on ice, and transported to the testing laboratory on the day of sampling. Soil nitrates were measured using flow injection analysis. In addition, plant samples were taken to determine total nitrogen concentration by combustion analysis at the same time as soil sampling. The tissue samples consisted of 2 rows of wheat top growth, 12 inches in length, and replicated twice per plot. Samples were put into clean paper bags, placed on ice, and transported directly to the laboratory for analysis. All soil was analyzed at University of Vermont’s Agricultural and Environmental testing laboratory in Burlington, VT. Plant samples were sent to Cumberland Valley Analytical Services in Hagerstown, MD for analysis.

Plots were harvested with an Almaco SP50 plot combine on July 20th, 2011; the harvest area was 5’ x 20’. Following harvest, seed was cleaned with a small Clipper cleaner. Once cleaned the sample was weighed to determine yield. An approximate one pound subsample was collected to determine quality.

Quality measurements included standard testing parameters used by commercial mills. Test weight was measured by the weighing of a known volume of grain. Generally the heavier the wheat is per bushel, the higher baking quality. The acceptable test weight for bread wheat is 56-60 lbs per bushel. Once test weight was determined, the samples were then ground into flour using the Perten LM3100 Laboratory Mill. At this time flour was evaluated for its protein content, falling number, and mycotoxin levels. Grains were analyzed for protein content using the Perten Inframatic 8600 Flour Analyzer. Grain protein affects gluten strength and loaf volume. Most commercial mills target 14-15% protein. The determination of falling number (AACC Method 56-81B, AACC Intl., 2000) was measured on the Perten FN 1500 Falling Number Machine. The falling number is related to the level of sprout damage that has occurred in the grain. It is measured by the time it takes, in seconds, for a stirrer to fall through a slurry of flour and water to the bottom of the tube. Falling numbers greater than 350 indicate low enzymatic activity and sound quality wheat. A falling number lower than 200 indicates high enzymatic activity and poor quality wheat. Deoxynivalenol (DON) analysis was analyzed using Veratox DON 5/5 Quantitative test from the NEOGEN Corp. This test has a detection range of 0.5 to 5 ppm. Samples with DON values greater than 1 ppm are considered unsuitable for human consumption.

Mixed-model analysis was calculated using PROC MIXED procedure of SAS. Mean separation among treatments involving fertilizer source and timing of application were obtained using the LSMEANS procedure when the F-test was significant (P< 0.10). Soil nitrate and plant nitrogen were analyzed using the PROC MIXED procedure in SAS using the Tukey-Kramer adjustment, which means that each application time and amendment type was analyzed with a pairwise comparison .

Research results and discussion:
Weather Data

Seasonal precipitation and temperature recorded at weather stations in close proximity to the 2011 sites are shown in Table 2. This growing season brought extreme weather conditions. Between April and May 16 inches of rain fell, 10 inches above normal rainfall amounts. The increased moisture delayed wheat growth, especially in clay or compacted areas where water pooled and stayed wet for extended amounts of time. In addition, the heavy rainfall increased nutrient leaching. From one extreme to the other; in June and July, there were several weeks with very little rain and higher than normal temperatures causing drought like conditions and putting further stress on the wheat. Just prior to harvest a violent thunderstorm with high winds caused severe lodging of several plots in the first rep which impacted yields. From planting to harvest in Bridport there was an accumulation of 5016 Growing Degree Days (GDD), 217 GDDs higher than the 30 year average.

Soil & Plant Nitrogen

The treatments differed significantly in soil nitrate-N concentration at the June 1st sampling date (Table 3). Pro Booster applied at flag leaf had the highest soil nitrate-N level, 19.1 ppm. Other treatments did not differ from each other in soil nitrate-N concentrations. There were no significant differences soil nitrate-N concentrations at the July 5th sampling date. The June 1st sampling of plant N differed significantly among treatments. With the exception of Cheep Cheep, all organic N amendments applied at flag leaf or as split applications had higher plant N concentrations than the control or amendments applied at tillering. Pro Booster applied in split applications had the highest percent plant N, 2.27%. There were no significant differences in the plant nitrogen content at the July 5th sampling.

Wheat Yield and Quality

Wheat Yield and Quality
The treatments did not differ significantly in winter wheat yield (Table 3 and Figure 1). When ‘Cheep Cheep’, Pro Booster or Chilean Nitrate were applied at any of the different application times; tillering, flag leaf, or a split application at both growth stages, this resulted in higher yields than the unamended Control plots. The split application of ‘Chilean Nitrate’ treatment yielded the highest with 2855 lbs ac-1; the Control was the lowest yielding with 2138 lbs ac-1.

The treatments did differ significantly in winter wheat crude protein concentration (Table 4 and Figure 2). ‘Pro Booster’ applied at either the flag leaf or both (tillering and flag leaf) growth stages had the highest protein level at 12.9%. ‘Pro Booster’ applied at the flag leaf or both growth stages had significantly higher protein levels than all of the ‘Cheep Cheep’ application times; tillering, flag leaf, or both. ‘Cheep Cheep’ applied at the tillering stage had the lowest protein level with 11.6%. Interestingly, the control plot did not differ significantly from any of the other treatments. Overall, the application of ‘Pro Booster’ or ‘Chilean Nitrate’ at the flag leaf or both (tillering and flag leaf) growth stages resulted in the best chance to improve both wheat protein levels and yields. While ‘Cheep Cheep’, applied at the same stages did improved protein levels it did not improve yields. ‘Cheep Cheep’ applied at tillering resulted in the highest yield of the three application times; this is possibly due to the slow N release nature of this product. The other grain quality tests measured were; test weight, falling number and DON levels. None of these additional tests differed significantly among treatments.

Research conclusions:

The second year results demonstrated that topdressing can increase protein concentration by 3 percentage points. This was demonstrated across two years of research. The information and outreach we have disseminated has aided producers in making more informed decisions on wheat fertility practices. This can be observed through a 100% increase of grain samples submitted to the UVM Cereal Testing Laboratory, Burlington, VT for protein and other quality analysis. Producers are also seeking out and cultivating varieties know to have higher protein concentrations. Evaluations conducted at the 2012 Annual Grain Growing Conference indicated that outreach events have helped 57% of participants improve grain quality, 43% improve grain yield, and 52% increase soil health and fertility.

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

Producing High Quality Organic Bread Wheat, an on-farm workshop was held June 9, 2011 at Gleason Grains in Bridport, VT. The workshop highlighted the NE SARE funded organic fertility experiment. In addition, Ben Gleason discussed crop rotation and weed control in wheat grown for human consumption. We viewed Ben’s wheat processing facility including his seed cleaning, meadows mill, and sifting operation. This event had 40 attendees consisting of farmers, Extension, and other agricultural professionals. Many of the farmers were anxious to view project results.

Production & Processing of Organic Grain: Getting to the Nitty Gritty, an on-farm workshop was held June 21, 2011 at Aurora Farms in Charlotte, VT. The workshop highlighted the Kenyon family’s grain production and processing techniques. They discussed their attempt to conduct large scale organic N topdressing trials which results in a very stuck tractor. However, they do plan to establish the trial again next year. This event had 50 attendees consisting of farmers, Extension, and other agricultural professionals.

UVM Crop and Soils Field Day, an on-farm workshop was held August 6, 2011 at Borderview Farm in Alburgh, VT. The workshop highlighted all UVM Northwest Crop and Soil research projects. A presentation was given as part of the day. This event had 250 attendees consisting of farmers, Extension, and other agricultural professionals.
We produced a video documenting the project, that aired on October 7, 2011 an episode of “Across the Fence”; This video was posted on YouTube and linked to both the UVM Extension North West Crops and Soils Program and Northern Grain Growers Association (NGGA) websites.

A research report was written on the results from this topdressing; hard copies were handed out at 4 winter conferences and workshops and a pdf version was posted on both the UVM Extension Northwest Crops and Soils Program and Northern Grain Growers Association (NGGA) websites.

The Effects of Topdressing Organic Nitrogen on Hard Red Winter Wheat- Part 2, a PowerPoint presentation, describing the project and trial results was given at the 8th annual Northern Grain Growers Association conference held on March 15th at the Essex Resort and Spa in Essex, VT. This annual gathering had four concurrent sessions and covered topics including, on seed security, equipment innovations, and grain processing. There were 150 attendees consisting of farmers, bakers, millers, Extension, and other agricultural professionals from around the Northeast and Canada.

The article ‘The Impact of Topdressing Organic Nitrogen on Winter Wheat Protein, Year 2, was published in the spring edition of the Northern Grain Growers Association’s newsletter. This article combined the 2010 and 2011 research results on protein and yields.

We are currently working on a manuscript for submission to a peer reviewed journal to be published in 2013.

Project Outcomes

Project outcomes:

A simple economic analysis of the amendment costs was performed to get a sense of benefit to applying additional N to wheat. The goal would be to see increased yield and quality so that the farmer would be able to justify the cost of the amendment as well receive a higher return on the crop. The most expensive amendment was Chilean Nitrate. However, since it is readily available it actually cost less per unit of plant available nitrogen (PAN) than the other amendments. To apply 20 lbs of PAN the lowest cost was $90.6 per acre. Would a farmer make back the initial investment of the fertilizer plus additional income on increased yields and quality? Commercial mills often pay a $5 per ton premium for every ½ percent protein over the base of 12% CP. A current price for organic wheat is $450 per ton. Across years there was a maximum yield increase of 30% (approximately 1000 lbs per acre) when additional N was applied to wheat as compared to the control. This could mean an increase of $225 per acre for yield increases. There was also as much as 3% CP concentration increase in wheat when topdressed with organic N sources. This could translate into a $30 premium per ton on protein. If a farm has an average yield of 2 ton per acre for winter wheat this would be a $60 premium. However, given this scenario it is assumed that the farm met the 12% minimum CP level for the mill. In the experiment only some of the treatments met and exceeded the 12% minimum CP level. Therefore topdressing may also help the farmer from receiving dockages at the mill. Overall during the project period we observed a maximum financial gain of $285 per acre as a result of topdressing with Pro Booster at the flag leaf stage. This would barely cover the cost of the amendment. More cost effective amendments with similar yield and quality increases would make topdressing economically viable for the farmer.

Amendment Costs:

Cheep Cheep (50% available N): = $558.00 per bulk ton t
= $6.98 per lb N
= $13.95 per lb PAN
20 lbs = $279.00 per acre

Pro-Booster (30% available N): = $968.00 per bulk ton
= $4.84 per lb N
= $14.67 per lb PAN
20 lbs = $293.33 per acre

Chilean Nitrate (100% available N): = $1474.00 per bulk ton
= $4.60 per lb PAN
20 lbs = $ 92.13 per acre

Farmer Adoption

Farmers are excited to implement practices that will improve wheat quality on their farms. This was obvious based on the turnout at the on-farm field day events over the last two years. The second year results demonstrated that topdressing can increase grain protein. There have been numerous farms that were anxious to experiment with topdress applications of nitrogen in organic wheat. At least 15 farmers followed up with additional questions after reading or listening to a presentation on the research. In 2011, another on-farm trial was planned to record plant loss from topdress of N at flowering. However due to the weather the application could not be performed. In 2012, there were 3 farmers that topdressed winter wheat at the tillering stage. Further verification of results and development of mineralization rates of organic N materials will definitely lead to adoption of this practice by several farmers in New England.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

This research project was conducted across two difficult growing seasons. Several years of research will be required to continue to develop results across a number of years, environments, and weather conditions. At this time it appears as though further research will be needed to evaluate mineralization rates of various organic amendments. It was obvious from the data that organic amendments released nitrogen (N) at a slower rate compared to the Chilean Nitrate. It is well documented that N based fertilizer sources should be added at the critical stages such as tillering and flowering. However, given the lag time for N release of the organic materials new standard recommendations will need to be developed. Interestingly during the time of this project, the National Organic Program has planned to phase out the product Chilean Nitrate. Therefore there is even a more immediate need to determine the N mineralization rates of other organic N sources. Lastly, farmers have asked how much of the wheat in their fields would be damaged from applications at tillering or flowering? Will the wheat be killed or will there be reduced yields? This question will be answered through further on-farm studies.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.