Warm-Season Grass Binary Mixtures for Biomass in the Northeast

J.H. Cherney1, D.J.R. Cherney2, and M. Davis3
1Section of Soil & Crop Sciences, 2Dept. of Animal Science, Cornell University, and 3Farm Manager, Cornell Willsboro Research Farm, Willsboro, NY

Over five million acres of marginal agricultural land in the Northeast USA are no longer in use and have great opportunities for grass biomass production, although environmental or other supplemental compensation may be required for profitable production on low-yielding marginal land. Warm season grasses are considered a viable herbaceous second generation biofuel feedstock but are better suited to marginally productive cropland Future selection through breeding should have a significant focus on low-input types of environments.

Additional environmental benefits may accrue when mixtures are used instead of monocultures. Studies have suggested that polycultures sequester more carbon in the soil profile and have less N leaching compared to monocultures. Profitability in biomass production, however, is most strongly influenced by yield, and we focused on yield potential in this study.

Experimental layout

A long-term plot study was sown in 2010 in Ithaca (central NY, Williamson fine sandy loam soil) and Chazy (northern NY, Roundabout silt loam soil), and was completed in 2018. A goal was to determine if binary mixtures of warm-season grasses would result in increased yield over pure stands.

Three replicates of 12 treatments compared pure species with binary mixtures (Fig. 1). Binary mixtures had one species seeded in one direction, and the second species seeded perpendicular to the first. Pure species also were seeded twice, with one half the total seed sown perpendicular to the other half. Pure switchgrass and Atlantic coastal panic grass plots were seeded at 10 lbs pure live seed (PLS)/acre. Pure big bluestem plots were seeded at 12 lbs PLS/acre. Mixtures contained half the seeding rate of pure species plots for each species in a binary mixture. All entries were commercially available varieties, with the exception of RC Big Rock switchgrass, which was an experimental selection from Cave-In-Rock (REAP-Canada, Ste-Anne-de-Bellevue, QC). Insufficient seed was available of Timber switchgrass to seed at both sites.

Fig. 1. Plot layout at the two NY sites.

Plots (15’ x 15’) were fertilized with 50 lbs N fertilizer/acre at spring green up each year. Roundup was sprayed in the spring prior to warm season grass green up to control weeds after 2013. A few weeds were resistant to Roundup and remained, such as milkweed. Plots were well established by the 2013 growing season. Plots were harvested for yield determination each year in early October generally after first frost at a 4” stubble height using a flail harvester, harvesting 78 sq. ft. of plot area (3’ x 13’ twice per plot). Samples were collected for dry matter (DM) determination.


The more southern, generally wetter, Ithaca site averaged 22% greater yield across all years and species combinations. Ithaca long-term average precipitation is 4.5” per year more than Chazy (Plattsburgh, NY weather station), and Ithaca averaged 5.5” more per year during the experiment. Although Chazy is considerably farther north than Ithaca, long-term average heat units are very similar. Over the 2013-2017 period from May 1 to Oct. 1, both sites averaged 4916 GDD per growing season (base 32F). Warm season grass mixtures behaved differently on different sites. At Chazy, big bluestem (BB) tended to compete very well in mixtures with switchgrass (SW), while at the Ithaca site switchgrass tended to be the major component.

Big bluestem was the slowest species to become fully established, but Prairie View BB pure stands were the highest yielding at the Chazy site, averaged over five years. RC Big Rock switchgrass selection had the greatest yield in Ithaca for pure SW stands, averaging 6.6 tons DM/acre over 5 years. Cave-in-Rock SW (CAV) and the CAV-Prairie View BB mixture both yielded 13% less at Chazy than Ithaca, but pure Prairie View stands produced similar yields at both sites. Upland switchgrass mixed with Prairie View BB tended to produce the best overall results and was the most compatible mixture (Fig. 2). Other mixtures tended to become mostly monocultures over time.

Fig. 2. Average yields of pure switchgrasses (SW) vs. SW mixtures with big bluestem (BB).

Atlantic coastal panic grass (ACP) was promising the first year, but quickly deteriorated to a weak stand after the first year, and had significant weed invasion in later years, particularly at Chazy. BoMaster switchgrass struggled in pure stands and became a very minor component of mixtures. In later years, big bluestem and switchgrass tended to invade plots with weaker stands, as ripe seed was scattered each year during harvest with a flail harvester.


At both sites, mixtures of Cave-in-Rock SW and ACP quickly became pure switchgrass stands. By the end of the trial, mixtures of Cave-in-Rock and Suther BB were pure switchgrass at Ithaca, and averaged 10% BB at Chazy. BoMaster SW and ACP, as well as mixtures of these two, tended to be weak stands at both sites, with up to 25% weeds observed in the summer of 2018. Prairie View BB and BoMaster SW mixtures were essentially pure big bluestem stands in 2018 at both sites. Suther BB and Cave-in-Rock SW mixtures were pure switchgrass in Ithaca, and averaged 10% big bluestem in Chazy. Prairie View BB and Cave-in-Rock SW mixtures averaged 15% bluestem in Ithaca and 35% bluestem in Chazy, at the end of the trial.

Ground cover

Plots in Ithaca were observed for ground cover in the spring of 2018 (Fig. 3). The three replicates were very consistent in ground cover. Switchgrass provided the most ground cover early in the season, with RC Big Rock SW appearing to have the greatest ground cover. BoMaster was the weakest switchgrass, typically with weed infestations. Approximately 50% of the ground area was bare in BB plots, but open areas were generally free of weeds. Even less surface area was covered by ACP, and open areas tended to be infested with weeds annually. With the exception of ACP at both sites, and BoMaster SW at Chazy, other species and species combinations developed into a closed canopy by mid to late summer, regardless of the ground cover observed in spring.


The only mixtures with a significant contribution from both species were Prairie View BB and Cave-in-Rock SW mixtures. These mixtures had considerably more switchgrass at the Ithaca site compared to the Chazy site. Our results agree with other studies suggesting that species mixtures will be largely influenced by environmental variation. Results from a single location may not be applicable to other environments. Mixtures can improve yields mainly in the establishing years, with the potential for better yield stability over the life of the stands. Farmers should consider planting adapted cultivar mixtures of big bluestem and upland switchgrass for enhanced yield and yield stability. Improving seedling establishment of big bluestem should be an important breeding priority for more widespread adoption of this crop.


This work was supported by the USDA National Institute of Food and Agriculture, Multistate project 218756. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the National Institute of Food and Agriculture (NIFA) or the United States Department of Agriculture (USDA).

Print Friendly, PDF & Email

2018 Corn Silage Hybrid Evaluation Results

Joe Lawrence, Allison Kerwin

The New York & Vermont Corn Silage Hybrid Evaluation Program continues to provide side by side evaluation of corn hybrids grown under a range of growing conditions representative of those experienced in the Northeast.  In 2018 the program evaluated 77 hybrids from 17 different seed brands.  Each hybrid was planted in replicated plots at 3 locations based on relative maturity (RM; Table 1).

The growing season was defined by below average precipitation and above average heat, measured as growing degree days (GDD) across trial locations (Figure 1). A defining difference between trial locations was the timing and amount of rainfall from late July to early September.  While all locations realized some level of improvement in growing conditions with more frequent rainfall in late July and August, its timing and impact on the crop varied. In general, rain arrived at all locations in time to facilitate normal pollination of the crop but ear development varied by location.

Figure 1. Rainfall and growing degree day accumulation by location and season for the NY & VT Corn Silage Hybrid Evaluation Program

The above average GDD accumulation throughout the season and particularly as the crop neared maturity resulted in fast dry down of the crop to target whole plant moisture content for silage harvest. A noticeable characteristic at harvest in many corn fields, including trial fields, was a healthy green plant with a dry ear.

While nutrient inputs at all locations met or exceeded crop needs, a lack of soil moisture may have compromised nutrient uptake at varying stages of crop development. Recognizing these real world influences and how a hybrid might perform under varying stressors is important to understand when evaluating this data.

The influence of growing conditions lead to location variability in hybrid performance in 2018 but overall better performance when compared to growing conditions experienced in 2017 (Figure 2).

Figure 2. Percentage of samples across all locations over a range of uNDF240 and starch levels by year for the NY & VT Corn Silage Hybrid Evaluation Program

The full report provides detailed data on individual hybrids entered into the program for 2018. The most significant parameters in the report vary by individual farm and that farms resources but some of the key data includes, yield, whole plant dry matter, starch content, measurements of fiber digestibility including neutral detergent fiber (NDF) digestibility at 30 hours (NDFD30) and undigested NDF at 240 hours (uNDF240), and predicted milk yields modeled in the Cornell Net Carbohydrate and Protein Synthesis (CNCPS) model.  The CNCPS model predicts the expected milk yield of different hybrids based on their inclusion into a high corn silage total mixed ration representative of the diets fed on many NY and Northeast dairy farms.

It is important to evaluate this data in the context of your farm when selecting hybrids. The top performing hybrid at any one location or in any one category may not be a good fit for your feeding program. Factors that influence this vary by farm but include land base, soil resources, forage inventory, quality of available hay crops, access and cost of supplemental ingredients, and expectations of cow performance.

The trial results and location averages serve as a means to calibrate hybrid performance to a particular growing season and these averages can be used in conjunction with a company’s data on hybrids in their lineup, including hybrids not entered into these trials, to understand how a hybrid performed relative to what is realistic for that growing season. For example, in Figure 2 we see that over 50% of samples taken in 2018 had an uNDF240 value between 9 and 10 so this can be used to evaluate how close and far away from these values other hybrids performed in 2018.  However, due to the challenging growing conditions experienced in 2017 and the impact of growing conditions on fiber digestibility we see that the highest percentage of samples in 2017 had a uNDF240 value of 13-14 while a very small percentage (less than 10%) of 2017 samples were as digestible as the majority of 2018 samples.  Therefore it would not be fair to hold hybrid fiber digestibility or other performance indicators from 2017 to the same standards as 2018.

It is also important to recognize the companies that make these trials possible through their entry of hybrids.  The following companies participated in the 2018 trials:

Albert Lea – Viking, Augusta Seed, Channel, CROPLAN, Dairyland, Dekalb, Doebler’s, Dyna-Gro, Growmark FS, Hubner, Local Seed Company, Masters Choice, Mycogen, Pioneer, Seedway, Syngenta – NK, Wolf River Valley

The full report of 2018 can be found at the Cornell Soil and Crop Sciences website:

Additional trial information can be found in the following article and webinar:

Article: 2018 Corn Silage Overview

Webinar: 2018 Corn Silage Hybrid Test Results, New York and Vermont Corn Silage Hybrid Tests – 2018

Print Friendly, PDF & Email

What’s Cropping Up? Volume 28, Number 5 – November/December 2018

Feasibility Assessment of Dairy Biochar as a Value‐Added Potting Mix in Horticulture and Ornamental Gardening

Akio Enders a, John Gaunt a, b, Joshua Stone a, Leilah Krounbi a, Johannes Lehmann a, and Rajesh Chintala c

a Department of Soil and Crop Sciences, Cornell University, Ithaca, NY  14853

b GreenTree Garden Supply, Ithaca, NY  14850

c Innovation Center for U.S. Dairy

Total milk production in New York was 14,765 million pounds in 2016 (NYS Department of Agriculture and Markets, 2017). In 2018, New York State had the 3rd highest number of milk cows behind California and Wisconsin, with 625,000 cows (USDA NASS, 2018). Dairy manure excretion averages 12,821,616 tons per year in NY state alone (NYS Department of Agriculture and Markets, 2017; NRCS, 2018). This translates into 64,108 tons N, 38,465 tons P2O5, and 44,876 tons K2O (SARE, 2018) which can be recycled back for agricultural and horticultural use. In places where available manure nutrients exceed the needs of nearby field crops, the challenge becomes offsetting transportation costs. Unfortunately, these transportation costs can at times equal the manure’s value as a fertilizer (Pennington et al.).

Manure management generates 44% of total methane emissions on dairy farms (Wright et al., 2017). A more potent greenhouse gas than CO2 by 34-fold (Pronto et al., 2017), methane can be captured in anaerobic digesters for use as a fuel. Since 1998, 34 anaerobic digesters for dairy manure were installed and are operating across the state (EPA AGstar, 2018). These digesters facilitate a reduction in methane emissions by 1,502,327 MT CO2 equivalent units per year (EPA AGstar, 2018; Pronto et al., 2017).

Methane biogas is just one of the products generated in anaerobic digesters. The remaining digestate of wet reactors is comprised of partially-degraded biomass and nutrients, and contains up to 16% solids (Ward et al., 2008). Plant nutrients are concentrated by the microbial activity. Notably, ammonium nitrogen increases by up to 33% (Möller et al., 2008; Möller and Müller, 2012). The digestate slurry can screw-pressed to separate solids from liquids and recycled into useful products such as bedding or organic fertilizers. The solids can be further stabilized against decomposition through pyrolysis.

Heating under oxygen-free conditions, known as pyrolysis, converts biomass into a charcoal-like substance called biochar. During this process, carbon chains fuse into rings (McBeath et al., 2014). These substances resist decomposition in the soil, and can even slow the decomposition of non-biochar carbon (DeCiucies et al., 2018). As pyrolysis temperature increases, biochar surface area increases along with pH (Mukherjee et al., 2011). Generally speaking, pyrolysis concentrates plant nutrients when compared to the biomass feedstock (Enders et al., 2012).

This research project, sponsored by the U.S. Center for Dairy Innovation, enabled an assessment of upgrading anaerobically digested, screw-pressed dairy manure into a higher value biochar product. In summary, dairy manure biochar is an odor- and pathogen-free, nutrient-rich fertilizer with approximately twice the nutrient content of the original manure by mass, and more than three times that by volume. The nutrient value of the biochar as a substitute for other organic fertilizers was calculated as $240-340/ton. In addition, the carbon value as a substitute for commercially available biochar was calculated as $1580/ton. Analyses suggest that over half of the carbon in the resulting biochar is stabilized to benefit soil fertility and carbon sequestration for over a century after application.


Anaerobically digested, screw pressed, dairy manure was sourced from a 3000+ head New York dairy farm. Initial moisture content was 59%. After air drying to 12%, the feedstock was pyrolyzed at a highest temperature of 550 °C for 30 minute total residence time. Biochar yield was 38% of oven dry feedstock weight.

Biochar Basic Utility Properties and Toxicant Assessment were analyzed according to the International Biochar Initiative (IBI) Standard Product Testing Guidelines v 2.1. Total nutrient contents of feedstock and biochars were assessed to describe the effect of pyrolysis on plant nutrients. Transformations in nutrient availability of the manure and biochar were investigated with three extractants. Leachable nutrients were determined with a 0.01 M calcium chloride, available with a modified Morgan’s solution (ammonium acetate), and phosphorous with a fertilizer industry standard (2% citrate EDTA).

These data were used by our commercial partner, GreenTree Garden Supply, to substitute dairy manure biochar for all of the commercial biochar as well as a portion of fertilizer they use in three of their commercial growing media.

Basic Properties

The dairy manure biochar is 178% more dense than the manure at 503 lbs/cu yd, with ash content increased to 38%.

The IBI classification tool calculates the Carbon Storage Class of this biochar as 1, on a scale of 1-5 with 5 providing the highest carbon storage potential. This rating integrates both carbon quality and quantity. The high ash content of this biochar downplays the quality of the carbon present, hence the low rating. However, the quality of the carbon is such (i.e., low H/Corg ratio) that roughly half is expected to persist over 100 years, compared to practically 0% in the manure.

The pH of this biochar is 10.45. More importantly, it has a calcium carbonate equivalence of 3.30%. In other words, 100 pounds of biochar can neutralize acid as well as 3.30 pounds of lime. This falls under IBI Liming Class 1, rated on a scale of 0-3, with 3 relating to the highest lime equivalent. Therefore, this biochar is best suited for mildly acid soils that would benefit from increasing pH. Unlike biochar from biomass, this material possesses a moderate level of soluble salts with electrical conductivity (1:20 w:v) at 1.65 dS/m. For comparison, soil salinity begins to affect plant growth at levels over 2 dS/m.

The Fertilizer Class of this biochar, according to the IBI classification system, is 3 on a scale of 0-4. This is defined as providing adequate nutrition for corn at < 4.5 tons/acre provides for 3 out of 4 nutrients. Specifically, the calculation states that phosphorous, potassium, and magnesium requirements are met by application of 4.0, 1.3, and 1.3 tons/acre.

Toxicant Assessment

The IBI toxicant assessment is understandably quite stringent, screening for persistent organic pollutants:  polyaromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), dioxins (PCDD) and furans (PCDF); toxic heavy metals including:  arsenic, cadmium, chromium, lead, mercury; trace elements that become toxic at higher quantities including:  copper, molybdenum, nickel, selenium, and zinc; and phytotoxic elements including:  boron, chlorine, and sodium. The dairy manure biochar was non-toxic on all counts, and contained 30 times less than the threshold value for any single analyte. A germination trial also assessed biochar toxicity. Of the three species used (lettuce, ryegrass, and radish) germination in dairy manure biochar amended media was nearly identical to the control.

Total Nutrients

Biochar contained 4.1% P2O5, 2.2% K2O, and 4.4% MgO. Approximating from biochar yield, nutrient concentration in biochar could be as much 2.6x more than in manure. Gaseous losses during pyrolysis reduced the total content of plant nutrients in the biochar to 1.7x more than in manure feedstock. Sulfur is the most notable example where biochar contained 50% less than feedstock.

Available Nutrients

In addition to increasing total nutrient content, pyrolysis improved nutrient availability, exception for nitrogen and iron. The dairy manure biochar has a nitrogen content of 1.7%, however thermal treatment has converted this to plant unavailable forms and is therefore considered insignificant.

Biochar provided 13% more available phosphorous than the manure feedstock with 1.2% of biochar mass as P2O5, i.e. as would be printed on a fertilizer label. Interestingly, increased available phosphorous was coupled with a 10-fold decrease in leachable phosphorous.

The biochar also demonstrated 59% more available potassium than the manure with 1.6% of biochar mass as K2O.

Commercial Value

When all nutrient and carbon content is accounted for, the dairy manure biochar has a value between $0.91 – $0.96/lb (or $1,828-$1,912). This is calculation is based on the weighted average wholesale price for individual components in commercially available organic fertilizers as below. The majority of value, $0.79/lb, arises from the biochar carbon.

The product evaluation performed by GreenTree Garden Supply substituted all of the commercial biochar (80% C) with dairy manure biochar (43% C) on a carbon basis. The additional nutrient content in the dairy manure biochar reduced wholesale material cost for two products by 2.26% and 0.19%.

Future Outlook

A practical challenge to biochar production from manure is its moisture content. Waste heat from biogas combustion could fulfill this requirement, given the proper infrastructure. Additionally, pyrolysis coproduct gases could be upgraded and then co-fired alongside biogas for electricity generation to power on-farm pyrolysis. Biochar application to fields would increase fertility and offset nutrient inputs.

Organic farming is a feasible commercial application for dairy manure biochar. The biochar is cost competitive with other organic phosphorous sources and organic farmers are accustomed to spreading the larger bulk quantities as fertilizer. Additional fertilizer (especially N) would be blended with the biochar to achieve a desired nutrient balance and concentration and the final product would contain biochar to benefit soil fertility in the long term.

Ammonia gas lost from leachate ponds is another resource that can be utilized when biochar is introduced to the system. Biochar has proven effective in adsorbing both ammonium in solution and ammonia gas (Wang et al., 2016). This nitrogen loading can be enhanced with repeated exposure to CO2 to precipitate ammonium bicarbonate (Van Humbeck et al., 2014). Ammonium bicarbonate-biochar fertilizer has demonstrated greater efficiency than synthetic nitrogen alone (Mandal et al., 2016), however commercial production has not yet been achieved.


New York State Department of Agriculture and Markets. 2017. New York State Dairy Statistics 2017 annual summary. NYS Agricultural Statistics Service, NYS Department of Agriculture and Markets, Division of Milk Control and Dairy Services, Albany, New York, pp.2.

United States Department of Agriculture, National Agricultural Statistics Service.
https://www.nass.usda.gov/Publications/Todays_Reports/reports/mkpr0718.pdf (last accessed Nov 27, 2018)

Natural Resource Conservation Service. https://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/null/?cid=nrcs143_014154 (last accessed Oct 26, 2018)

Sustainable Agriculture Research and Education. https://www.sare.org/Learning-Center/Books/Building-Soils-for-Better-Crops-3rd-Edition/Text-Version/Animal-Manures-for-Increasing-Organic-Matter-and-Supplying-Nutrients/Chemical-Characteristics-of-Manures (last accessed Oct 26, 2018)

Pennington, J.A., VanDevender, K., and Jennings, J.A., Nutrient and Fertilizer Value of Dairy Manure. University of Arkansas Division of Agriculture, Cooperative Extension Service, Agriculture and Natural Resources bulletin FSA4017.

Wright, P., Gooch, C. and Oliver, J.P., 2017. Estimating the Economic Value of the Greenhouse Gas Emission Reductions Associated with on-farm Dairy Manure Anaerobic Digestion Systems in New York State. In 2017 ASABE Annual International Meeting (pp. 1). American Society of Agricultural and Biological Engineers.

Pronto, J., Gooch, C., and Wright, P. 2017. Meeting New York State’s Energy, Environmental and Economic Goals While Strengthening Dairy Farms Through the Widespread Adoption of Manure‐Based Anaerobic Digestion Technology- Working Paper. Pro-Dairy program, Cornell University, Ithaca, NY p. 4. https://prodairy.cals.cornell.edu/sites/prodairy.cals.cornell.edu/files/shared/documents/ADworking_paper_Oct17.pdf (last accessed Oct 28, 2018)

Environmental Protection Agency. 2018. AgSTAR Livestock anaerobic digestor database. https://www.epa.gov/agstar/livestock-anaerobic-digester-database (last accessed Oct 28, 2018)

Ward, A.J., Hobbs, P.J., Holliman, P.J. and Jones, D.L., 2008. Optimisation of the anaerobic digestion of agricultural resources. Bioresource technology, 99(17), pp.7928-7940.

Möller, K., Stinner, W., Deuker, A. and Leithold, G., 2008. Effects of different manuring systems with and without biogas digestion on nitrogen cycle and crop yield in mixed organic dairy farming systems. Nutrient cycling in agroecosystems, 82(3), pp.209-232.

Möller, K. and Müller, T., 2012. Effects of anaerobic digestion on digestate nutrient availability and crop growth: a review. Engineering in Life Sciences, 12(3), pp.242-257.

McBeath, A.V., Smernik, R.J., Krull, E.S. and Lehmann, J., 2014. The influence of feedstock and production temperature on biochar carbon chemistry: a solid-state 13C NMR study. Biomass and Bioenergy, 60, pp.121-129.

DeCiucies, S., Whitman, T., Woolf, D., Enders, A. and Lehmann, J., 2018. Priming mechanisms with additions of pyrogenic organic matter to soil. Geochimica et Cosmochimica Acta, 238, pp.329-342.

Mukherjee, A., Zimmerman, A.R. and Harris, W., 2011. Surface chemistry variations among a series of laboratory-produced biochars. Geoderma, 163(3-4), pp.247-255.

Enders, A., Hanley, K., Whitman, T., Joseph, S., Lehmann, J., 2012. Characterization of biochars to evaluate recalcitrance and agronomic performance. Bioresource Technology, 114, pp.644-653.

Wang, B., Lehmann, J., Hanley, K., Hestrin, R. and Enders, A. (2016) Ammonium retention by oxidized biochars produced at different pyrolysis temperatures and residence times. Royal Society of Chemistry Advances, 6, pp.41907-41913.

Van Humbeck, J.F., McDonald, T.M., Jing, X., Wiers, B.M., Zhu, G. and Long, J.R., 2014. Ammonia capture in porous organic polymers densely functionalized with brønsted acid groups. Journal of the American Chemical Society, 136, pp.2432-2440.

Mandal, S., Thangarajan, R., Bolan, N.S., Sarkar, B., Khan, N., Ok, Y.S. and Naidu, R. (2016) Biochar-induced concomitant decrease in ammonia volatilization and increase in nitrogen use efficiency by wheat. Chemosphere, 142, pp.120-127.

Print Friendly, PDF & Email

Another Shocker: Organic Wheat with High Inputs 86 Bu/Acre Vs.79 Bu/Acre for Conventional Wheat (both yield 80 bushels/acre with recommended inputs)

Bill Cox, Eric Sandsted, and Phil Atkins

Conventional wheat with recommended inputs (on the right), despite more yellowing of the leaves in the lower canopy in mid-June, yielded similarly (~80 bushels/acre) as high input conventional wheat (on the left).

We initiated a 4-year study at the Aurora Research Farm in 2015 to compare the corn, soybean, and wheat/red clover rotation with different crop sequences in conventional and organic cropping systems during the 36-month transition and early certification period to an organic cropping system. One of the many objectives of the study was to determine if corn, soybean, and wheat respond similarly to management inputs (high and recommended) in conventional and organic cropping systems. This article will discuss the agronomic performance of organic wheat and conventional wheat with recommended and high inputs in the 4th year of the study (red clover-corn-soybean-wheat/red clover).

We no-tilled a treated (insecticide/fungicide seed treatment) Pioneer soft red wheat variety, 25R46, in the conventional cropping system; and the untreated 25R46 in the organic cropping system at two seeding rates, ~1.2 million seeds/acre (recommended input) and ~1.7 million seeds/acre (high input treatment) with a John Deere 1590 No-Till Grain Drill (7.5 inch spacing between drills) on September 27, the day after soybean harvest. We applied about 200 lbs. /acre of 10-20-20 as a starter fertilizer to wheat in both conventional treatments. We also applied Harmony Extra (~0.75 oz. /acre) to the high input conventional treatment at early tillering or GS 2 stage in the fall (October 27) for control of winter perennials (dandelion in particular).

Organic compared with conventional wheat yielded similarly (recommended inputs) or 9% higher (high inputs) at the Aurora Research Farm in 2018.

We applied the maximum amount of Kreher’s composted chicken manure (5-4-3 analysis) that would flow through the drill as a starter fertilizer (~150 lbs. of material/acre) in both organic treatments. We also broadcast Kreher’s composted manure the day after planting  to provide ~50 lbs. of actual N /acre (assuming 50% available N from the composted manure) in the high input treatment of the organic cropping system. In addition, we also added Sabrex, an organic seed treatment with Tricoderma strains, to the seed hopper of 25R46 in the high input treatment in the organic cropping system.

We frost-seeded red clover into all the wheat treatments on March 22. We applied ~70 lbs. of actual N/acre (33-0-0, ammonium nitrate) in the recommended input treatment of conventional wheat on March 23, about a week before green-up. In the high input conventional treatment, we applied ~50 lbs. of actual N/acre (33-0-0) on March 23 and then applied another 50 lbs. of actual N/acre on April 26 about 10 days before the jointing stage (GS 6). We also applied a fungicide (Prosaro at 4 oz. /acre) to the high input treatment on May 30.

We applied Kreher’s composted chicken manure to provide ~70 lbs. of available N/acre to organic wheat in the recommended input treatment on March 21. Also, we applied an additional ~50 lbs. of available N/acre to organic wheat in the high input treatment on March 21. All the plots were harvested with an Almaco plot combine on July 10. We collected a 1000 gram from each plot to determine kernel moisture and grain N% in the laboratory.

We presented data on wheat emergence as well as wheat densities and weed densities in the fall (http://blogs.cornell.edu/whatscroppingup/2017/12/01/organic-compared-with-conventional-wheat-once-again-has-more-rapid-emergence-greater-early-season-plant-densities-and-fewer-fall-weeds-when-following-soybean-in-no-till-conditions/) and weed densities in the early spring (http://blogs.cornell.edu/whatscroppingup/2018/05/25/no-till-organic-wheat-continues-to-have-low-weed-densities-in-early-spring-april-9-at-the-tillering-stage-gs-2-3/) in previous news articles. Briefly, organic wheat had more plants/acre, and similar weed densities in the fall and spring (Table 1). This is the second time that organic compared to conventional wheat no-tilled into soybean stubble had better stands and very low weed densities. Organic growers who harvest soybean fields with low winter weed pressure (dandelion, mallow, chickweed, henbit, mayweed, etc.) should consider no-tilling organic wheat, especially if the soybean field had been moldboard plowed. If soybeans were no-tilled into roller-crimped rye in early June, the rye residue could harbor significant slug/snail populations during the cool and damp fall mornings, which could impact wheat stands.

A cropping system x management input interaction was observed for wheat yield in 2018 (Table 2). Organic and conventional wheat yielded 80 bushels/acre with recommended inputs in 2018. Organic wheat showed a 6 bushel/acre response to high input management (500,000 more seeds/acre and an additional 30 lbs. of N/acre). In contrast, conventional wheat did not respond to high input management, despite 500,000 more seeds/acre, a fall herbicide application, 30 lbs. more N/acre, and a fungicide application. Once again, conventional wheat did not respond to the “new way” of managing wheat, high input wheat, which is similar to results that we have observed in all years with dry springs when we compared high and recommended input wheat in the 1980s and 2000s. Obviously, there is no need to apply additional N or apply a fungicide to wheat during dry springs because fertilizer N applied in late March or early April will not be lost to the environment via leaching or denitrification and disease pressure is low.

In 2016, a year with very similar precipitation patterns to 2018 (5.88 inches vs. 6.5 inches of precipitation, respectively, from April 1 through June 30), organic wheat yielded ~7.5% lower than conventional wheat when averaged across input treatments with no response to high input treatments in either cropping system(http://blogs.cornell.edu/whatscroppingup/2016/09/26/organic-wheat-looked-great-but-yielded-7-5-less-than-conventional-wheat-in-20152016/). Temperatures in May when N demand by wheat is the highest, averaged 62.0o in 2018 but only 56.5o in 2016. Cool temperatures limit N mineralization from organic sources so in 2016 we speculated that the use of an organic N source may have resulted in less available N to the organic wheat crop. Indeed, grain N% concentration in organic (1.66%) vs. conventional wheat (2.03%) was much lower in 2016 lending credence to the lack of available N as the major factor in the lower organic wheat yields. In 2018, conventional compared with organic wheat once again had greater grain N% concentration (1.99% vs. 1.77%, respectively, Table 2) but the difference was not as vast. Evidently, the warm May conditions allowed for release of adequate N from Kreher’s composted manure to maximize yields. May of 2018, however, was the second warmest on record in central and western NY. In years with cool late April and May conditions, organic wheat production may face N availability challenges because of low mineralization rates of organic N sources.

In conclusion, organic wheat yielded the same as conventional wheat with recommended inputs and yielded 9% greater than conventional wheat with high inputs. Kreher’s composted chicken manure, however, is very expensive (~$300/ton with only 5% N analysis of which we assumed only 50% N availability) so N costs approximated $6/lb. of N or ~12x higher than the ammonium nitrate source for conventional wheat. Consequently, organic compared with conventional wheat with recommended inputs probably had lower returns in 2018, despite being eligible for the organic price premium in the 4th year of this study (we will conduct a complete economic analysis of this 4-year study in late fall or spring of next year). Organic wheat with high inputs probably had similar economic returns as conventional wheat with high inputs, a common practice among some NY wheat growers, because the 12x higher cost for N in organic wheat would be offset by the higher cost for treated seed, fall herbicide application, the second N application, and late spring fungicide application in high input conventional wheat. Most organic wheat growers, however, probably use a dry solid manure source that is far less expensive than Kreher’s composted chicken manure so the economic analyses in this study will be slanted against organic wheat. On the other hand, the use of dry solid manure is far more difficult to apply precisely and at the correct time to insure availability to the wheat crop in May during stem elongation so the yield data may be slanted towards wheat in this study.

Print Friendly, PDF & Email

NYCSGA Precision Ag Research Update: Year One of Model Validation

Savanna Crossman, Precision Agriculture Research Coordinator
New York Corn and Soybean Growers Association

The 2016 field season marked the first year of testing for the variable rate planting model that is being developed by the Precision Ag Research Project. Growers across New York State know the challenges that the severe summer drought brought to our region.  Crop yields were impacted across the state and the research was no exception.  While unfortunate, it is advantageous to be able to test the model during a dry year and learn from how the crops reacts to the stress.

Across the board, the mid-to-lower seeding rates fared the best in the corn and soybean trials.  The model was tested on five fields this year and only four made it to grain harvest due to severe drought stress.  The results revealed that in three of the fields, there was not a significant difference in the profit produced by the model.  While the average yield of the model was significantly less, the model was able to achieve similar profit per acre by using lower seeding rates. (Table 1) 

Figure 1. 2016 Beach 2 model design. The left image displays the planting rate map and the right image displays the hybrid map.

A variation of the model design was planted on one field, Beach 2, in a split planter fashion with two contrasting hybrids.  This varied design was used as it allowed for of multiple points of comparison, including hybrid comparison.  Check strips were integrated every two passes to allows direct comparison of how the model performed to the typical grower practice rate.  From there, the design becomes more complicated.  The first pass would be planted at the model optimized rate for hybrid A, which meant hybrid B was also being planted at that same rate.  Then the next pass would plant at the rate optimized for hybrid B while hybrid A was being planted at that rate as well.  This allows us to examine the hybrid response to population in more depth. (Figure 1)

The hybrids P0216 and P0533 were selected due to their differences in plant architecture and responses to stress.  In years of excellent growing conditions, the tight leaf structure and short stature of P0533 will produce aggressive yields.  The hybrid P0216 will produce average yields in years of stress as well as in excellent conditions.

A 4,000 foot view of this field would show that there was not a significant yield difference between the model and the grower’s flat rate.  The model yielded about 2 bu/ac more than the flat rate, but that difference was not statistically significant.  When we separate the results out by hybrid, we see a much more telling story.

These hybrids resulted in a wonderful side-by-side comparison this year.   When compared to the flat rate, P0533, regardless of optimization, yielded significantly more per acre and yielded an astounding $64/ac more.  Conversely, P0216, regardless of optimization, yielded less than the flat rate and produced a profit $22/ac less than the flat rate.

Figure 2. P0216 optimized yield versus P0533 optimized yield.

A deeper look into the results showed that that when both hybrids were planted optimally, P0216 yielded almost 18 bu/acre higher than P0533 (Figure 2).   It also demonstrated that P0533 exhibited a statistical significant response to model optimization.  Meaning, when it was optimized the yield significantly improved over not being optimized (Figure 3).  This is likely due to the fact that in a stressful year, P0216’s yields will not fall apart due to seeding rate while P0533 benefited from precise placement.

Figure 3. P0533 exhibited a hybrid response to population.

These same hybrids in Beach 2, however, exhibited the exact opposite hybrid response in 2014 which was a normal year in terms of weather conditions.  Knowing this emphasizes the importance of multiple years of testing and data collection to create a robust algorithm.  The biggest gain from the 2016 season has been the strong design and analysis process that has been developed.  What the project has accomplished in these terms, is at the leading edge of the scientific community.

In order to build upon what the project has already accomplished, the project is still looking to get more producers involved and participating.  The project aims to get fields in the research that have a large amount of variation and are fifty acres or greater.  Any interested growers are highly encouraged to get in touch with the Project Coordinator, Savanna Crossman, at 802-393-0709 or savanna@nycornsoy.com.


Print Friendly, PDF & Email