Final report for GNE17-156

Increasing the profitability of Kernza perennial wheat with intercropped grain legumes

Project Type: Graduate Student
Funds awarded in 2017: $15,000.00
Projected End Date: 12/31/2019
Grant Recipient: Cornell University
Region: Northeast
State: New York
Graduate Student:
Faculty Advisor:
Dr. Matthew Ryan
Cornell University
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Project Information

Summary:

Perennial grain cropping systems have the potential to improve agricultural sustainability by producing food and forage while also enhancing soil health, protecting water quality, and reducing the energy and labor required for field operations. Realizing these benefits requires development of agronomic management practices that improve perennial grain productivity to make them economically competitive with annual grain crops. Polycultures of small grains and legumes have been shown to be complementary, with overyielding often occurring due to resource partitioning and nitrogen fixation of the legumes. Perennial grains have also been found to have declining grain yields as stands age, possibly caused by interspecific (i.e. crop-weed) or intraspecific (i.e. crop-crop) competition. Managing competition through weed management and intentional disturbance (i.e. thinning) of older perennial grain stands has the potential to dramatically improve productivity but has yet to be seriously examined. In this project we evaluate management practices, including intercropping with grain legumes, strip-tillage renovation of older stands, and timing of weed removal, intended to improve the productivity and profitability of two promising perennial grain varieties, ‘Kernza’ intermediate wheatgrass (Thinopyrum intermedium) and ‘ACE-1’ perennial cereal rye (Secale cerealeS. strictum). Two field experiments were carried out at Cornell University’s Musgrave Research Farm in Aurora, New York between September 2017 and August 2019, one focusing on intercropping the two perennial grains with food-grade field peas (Pisum sativum) and the other on strip-tillage of a 3.5 year old Kernza stand. In the intercropping we found that field peas were not able to grow well below the relatively tall perennial grains, but the wider row spacing and lower seeding rate of the intercropped plots presented an opportunity to better understand how planting arrangement impacts perennial grain crop growth, productivity, and competitive ability. Kernza grain yields and biomass production were not impacted by the wider rows or lower seeding rate over the first two harvests; in fact the plants grown at a lower density trended towards higher productivity than those planted at the recommended rate in the second year. In contrast, ACE-1 productivity was greatly reduced at first harvest when grown at the lower ‘intercropped’ density, which we observed to be caused by a combination of less capacity for tillering and increased weed pressure in wider rows. Post-harvest weed removal improved yield of both perennial grains in the second growing season, with weed removal in both fall and spring having the greatest benefit but Kernza appearing to respond more strongly to weed removal in the fall and ACE-1 responding better to weed removal in the spring. The strip-tillage experiment found that fall tillage benefited Kernza grain yields at the following harvest, largely due to a increase in the number of fertile tillers per unit area. We attribute this result to reduced intraspecific competition in the older, very dense stand after tillage, leading to a flush of new growth. These results will both directly improve recommended management practices for these crops and have provided insights into these plants’ biology that will guide further research in their agronomic development. Ultimately, improving perennial grain crop production practices will move us closer to our goal of having these crops incorporated into agricultural systems in the Northeast United States so that their environmental benefits can be utilized.

Project Objectives:

To better understand the effects of strip tillage and intercropping grain legumes on the productivity and profitability of ‘Kernza’ intermediate wheatgrass and ‘ACE-1’ perennial cereal rye cropping systems we will pursue the following research objectives:

1) Quantify the effects of fall and spring strip tillage on Kernza yield components and vegetative biomass.

2) Quantify the effects of intercropping on Kernza, ACE-1, and ‘Mystique’ field pea biomass productivity and yield.

3) Quantify the effects of both strip tillage and intercropping on weed biomass and weed species composition in perennial grain cropping systems.

4) Monitor and compare Kernza, ACE-1, and field pea growth to inform planting schedules that allow for synchronous maturity and harvesting.

Introduction:

Agriculture faces many intractable problems in the near future that are unprecedented in their scale and global impact. Population growth, shifts in consumption and non-food uses of agricultural products, climate change, and degradation of natural capital threaten global food security. To meet greater demand without further compromising environmental integrity, farmers will need to increase production while regenerating and improving existing cropland (Foley et al. 2011). Perennial crops are a possible solution to some of these problems due to their reduced need for mechanical, material, and labor inputs, potential for production on marginal agricultural lands, and ability to provide ecosystem services that are not available from annuals, such as year-round erosion control (Asbjornsen et al. 2012; Zhang et al. 2011). Perennial grains are a key component in efforts to increase the proportion of perennial crops in agricultural production, as annual grain crops are grown on 70% of global agricultural land and make up 80% of the global food supply (Pimentel et al. 2012).

While the benefits of perennial grain crops are attractive, development and adoption of perennial grain cropping systems relies on solving a number of agronomic issues that negatively impact their economic viability. Chief among these issues is significantly lower grain yields from perennial grains compared with annual analogs (Jaikumar et al. 2012). Substantial progress has been made in breeding higher-yielding cultivars of perennial wheat (DeHaan et al. 2014) and perennial rye (Acharya et al. 2004), but there has been less investigation of best practices for perennial grain crop management in the field. However, as little as 30% of yield increases in annual wheat can be attributed to genetic improvement over the past several decades (Anderson et al. 2005), suggesting that agronomic practices have a large effect on cropping system performance. Optimization of management strategies might also have a large impact on improving perennial grain productivity and thus profitability.

The purpose of this project is to investigate the impact of stand renovation via strip tillage and strip intercropping grain legumes on the productivity and profitability of intermediate wheatgrass cv ‘Kernza®’ (Thinopyrum intermedium) and perennial cereal rye cv ‘ACE-1’ (Secale cereale S. montanum) perennial grain crops in the Northeast. Kernza is a variety of intermediate wheatgrass domesticated for use as a grain crop by researchers at the Land Institute in Salina, KS. Breeding progress has recently reached a point where Kernza is beginning to enter small-scale commercial production through partnerships between researchers, growers, and processors interested in selling products made with Kernza to consumers interested in sustainably grown food (Karnowski 2017). As an example, Patagonia Provisions recently release Long Root Ale, a craft beer made from Kernza and marketed with the ecosystem services provided by Kernza as a key selling point (Lubofsky 2016). ACE-1 is a hybrid perennial cereal rye developed by researchers at the Agriculture and Agri-Food Canada Research Centre in Lethbridge, AB, Canada, originally intended as a forage crop but now also being utilized for food-grade grain production. We believe that Kernza and ACE-1 present opportunities for farmers in the Northeast to meet demands for local grain production and take advantage of the new market for perennial grain products while diversifying their cropping systems, decreasing costs through more efficient use of land, labor, and material inputs, and protecting their soils and the environment through reduced nutrient loss and enhanced soil carbon storage compared to annual grain crops (Jungers et al. 2019; Sprunger et al. 2019).

Despite the potential to transform agriculture, there are still several agronomic issues to be addressed in perennial grain cropping systems. One major issue is that yields tend to decrease in mature Kernza stands after two to three years of growth. This effect is believed to be caused by vigorous root growth that restricts tillering and reproductive capacity within a few years of planting (Jungers et al. 2017; Hunter et al. 2019). We are interested in how strip tillage might contribute to mitigating this problem via root pruning or other effects and subsequent stimulated growth of mature Kernza plants. In addition, grass-legume intercrops including intermediate wheatgrass have been shown to be more productive and weed suppressive than monocultures (Weik et al. 2002). We hypothesize that including grain legumes may provide similar benefits while also enhancing overall profitability of the system via sale of the legume crop. Finally, weed competition can reduce small grain yields by 50% or more (Murdoch 2018) and perennial crops have a wider range of potential critical periods of weed control than annuals due to their extended lifespan. By evaluating the impact of weed removal after perennial grain harvest on the following season’s productivity we hope to broadly identify targets for future research on timing of weed control in these systems.

Research

Materials and methods:

This project included two separate experiments, one that investigated intercropping field peas with two perennial small grains, intermediate wheatgrass cv ‘Kernza’ and perennial rye cv ‘ACE-1’, and another that investigated the effects of the timing of strip tillage on the productivity of established Kernza stands. In the fall of 2018 an additional, sub-project was initiated in the intercropping experiment investigating the impact of post-harvest weed control in the perennial grain plots. Details on both main experiments and the weed control sub-project including how they differ from the original proposal are provided below.

Experimental Design

In order to investigate the potential benefits of intercropping grain legumes with perennial small grains we established a new field experiment in fall 2017 using a split-plot, spatially balanced complete block design. Perennial grain and field pea monocultures and intercrops are the whole plot treatments and oats planted as a winter-killed nurse crop is the split-plot treatment (PGP Plot Map). The two perennial grains and the oat nurse crop were planted September 19, 2017, and field peas were planted April 20, 2018. Monoculture seeding rates were 15 lb/ac for Kernza, 71 lb/ac for ACE-1, and 120 lb/ac for ‘Mystique’ field peas (Pisum sativum). Intercrops were planted as a replacement series, with alternating rows of grain and peas at a 7.5 in row spacing, and thus seeding rates for each species were half of the monoculture rate. We also included oats as a winter-killed nurse crop for the perennial grains as a split-plot treatment in order to determine whether it can improve the perennial grains’ ability to compete with weeds during the establishment year. This additional research question was developed based on results of our other perennial grain field experiments and information provided by collaborators at the University of Minnesota and the University of Wisconsin.

We began a secondary project to investigate the impacts of post-harvest weed competition nested within this intercropping experiment after the first grain harvest in 2018. Four 5 ft by 5 ft subplots were delineated in each monoculture and polyculture perennial grain plot that did not receive the oat nurse crop treatment two weeks after grain harvest and crop biomass removal (i.e. early August in ACE-1 plots and early September in Kernza plots).  Each subplot was randomly assigned one of four weed control treatments: Fall weed removal, Spring weed removal, Fall and Spring weed removal, and No weed removal (control). Subplots were hand weeded every two weeks between plot establishment and the first major frost in late October 2018  and/or between spring green-up in early April 2019 and crop anthesis in early to mid June 2019; depending on treatment. These treatment levels were selected to determine whether weed competition during the Fall post-harvest regrowth period or Spring tillering period has a greater impact on crop performance for either of the perennial grain crops.

We also conducted a separate tillage experiment in a 3.5 year-old Kernza stand that had exhibited significant grain yield decline over time. In the tillage experiment we investigated the effects of the timing of strip-tillage on Kernza productivity using a randomized complete block design with fall tillage, spring tillage, and a no-till control as treatments (STROKE Plot Map). The fall tillage treatment was applied October 23, 2017 and the spring tillage treatment was applied May 9, 2018 just prior to Kernza jointing. Spring tillage must be done prior to Kernza jointing to avoid excessive damage to the plant that inhibits grain production, but timing of spring tillage is complicated by wet field conditions that have become more common and problematic in the northeast in recent years. Fall tillage was expected to have similar renovation effects as spring tillage, while avoiding these potential timing issues and also reducing workload on farmers during the busy spring planting season.

Data Collection

Data were collected in both experiments in July and August of 2018 and 2019. The intercropping experiment was sampled at different times for each perennial grain species to coincide with each species reaching physiological grain maturity. ACE-1 rye monoculture and polyculture, and field pea monoculture plots were sampled July 17 and 18, 2018 and July 18, 2019. Kernza monoculture and polyculture, and field pea monoculture plots were sampled August 15 and 16, 2018 and August 13, 2019. Field pea monoculture plots were sampled twice to provide better estimates of land equivalent ratios for the polycultures, due to the different harvest dates of the two perennial grains. The post-harvest weed competition plots were sampled at the same time and using the same methods as quadrat sampling of perennial grain plots in the larger experiment. The strip-tillage experiment Kernza plots were sampled August 27, 2018.

In both the intercropping and strip-tillage experiments aboveground crop and weed biomass was collected from two 0.5 m2 quadrats in each subplot of each experiment, then combined to form one composite sample for each subplot. In the intercropping experiment a total of 40 subplots were sampled (5 whole plot treatments x 2 subplot treatments x 4 replicates) and in the strip tillage experiment a total of 15 subplots were sampled (3 whole plot treatments x 5 replicates). Biomass samples were first separated by crop and weed species. Crop biomass was then further separated into seedheads (Kernza and ACE-1) or pods (field pea), and vegetative biomass. A 20 seedhead subsample was randomly selected from each subplot in the strip tillage experiment for quantification of yield components to better understand the physiological impacts of any tillage effects: seedhead weight, seedhead length, spikelet count, floret count, seed count, and seed weight. All biomass was dried at 65C for a minimum of five days before dry weights were recorded. Seedheads and pods were counted and threshed before grain was reweighed. A single 5 ft strip was also harvested from each plot with an Almaco plot combine. In the strip-tillage experiment the combine harvest occurred one week prior to quadrat sampling, while in the intercropping experiment combine harvest occurred within one week after quadrat samples were collected. Combine-harvested samples were weighed before and after drying and dehulling to calculate yield and grain moisture at harvest.

Data Analysis

Data from both experiments were analyzed using mixed effects analysis of variance (ANOVA) models implemented in R version 3.5.3 (R Core Team 2019). Response variables evaluated include hand-harvested and plot combine crop yield estimates, total crop biomass, crop harvest index, total weed biomass, and the various yield components measured in the strip tillage experiment (Table 4). Initial models for the intercropping experiment included the cropping system (i.e. the three species monocultures and the two polycultures as individual treatments), the nurse crop split-plot treatment, and year as fixed effects, and block and split-plots as random effects. Due to inherent differences in growth and life history characteristics that caused many species interactions separate models were created for the two perennial grain species, as is summarized in this report (Table 1). The oat nurse crop split-plot treatment was not significant for all crop productivity variables and was therefore removed from those models. Nurse crop treatment effects were observed for weed biomass sampled in Kernza plots but are not reported here. Land equivalent ratios (LERs) were calculated for the grain/pea polycultures in the intercropping experiment but are excluded from this report as the low yield of peas in polyculture in both years, and in monoculture in year two, caused the LERs to be unreliable indicators of polyculture productivity. Models for the strip-tillage experiment included tillage treatment as the sole fixed effect and block as a random effect.

 

Research results and discussion:

Intercropping Experiment

In reporting the results of the intercropping experiment, it should first be stated that growing field peas and perennial cereals together does not appear to be viable. In both years of the experiment peas had difficulty growing under the shade of 5 ft to 6 ft tall perennial grasses, and harvesting was complicated due to differences in both the height and time to maturity of the intercrops. This incompatibility might be solved by altering planting arrangements (e.g. growing a climbing pea variety within perennial grain rows) or timing (e.g. planting peas earlier to increase their early vigor and competitive ability) but at this time we do not recommend intercropping perennial cereals and grain legumes.

Despite the difficulties with growing a successful intercrop we can draw some conclusions from the comparison of the two perennial grain crops in monoculture and “intercropped” plots due to the wider row spacing and lower seeding rate used when planting alternate rows in the intercropping treatment. There was no consistent pattern in Kernza response to these treatments across the four response variables measured (Table 2). Kernza grain yields were similar between the two planting treatments in the first year of the experiment, but interestingly yield increased in the intercropped plots with wider rows in the second year while remaining constant in monoculture.  Kernza crop biomass was similar between intercropping treatments in both years, but increased dramatically from the first to second years, and on an absolute basis crop biomass increased more in plots grown in wider rows over time. While there was no statistical difference in seedhead counts between treatments or years there were also opposite trends between monoculture and intercropped treatments, with seedhead counts appearing to decrease in narrower rows and increase in wider rows over time. This suggests that intraspecific competition that appears to reduce Kernza yield over time may be occurring as early as the first growing season when stands are planted at the current recommended seeding rate and row spacing. We also observed a steep decline in total weed biomass over time in the intercropping treatment, suggesting that despite relatively high weed pressure during establishment Kernza is capable of quickly outcompeting annual weeds. We are currently working on analyzing weed species data from the full experiment to determine the effects of these treatments on weed community composition, as well as analyzing data from the weed competition subplots to determine when weed control after the first harvest might be most effective.

Table 1: Summary of ANOVA and model fitting statistics for all crop productivity response variables measured in intercropping experiment.

   

Intercrop

Year

Intercrop x Year

Crop Species

Response Variable

F1,25

Pr(>F)

F1,25

Pr(>F)

F1,25

Pr(>F)

Kernza

Grain Yield

0.107

0.746

4.040

0.054

6.006

0.021

 

Crop Biomass

0.013

0.909

35.688

<0.001

1.260

0.271

 

Seedhead Count

0.669

0.420

2.354

0.136

3.933

0.057

ACE-1

Grain Yield

12.075

0.002

289.315

<0.001

3.846

0.060

 

Crop Biomass

15.243

<0.001

151.051

<0.001

2.416

0.133

 

Seedhead Count

17.755

<0.001

18.087

<0.001

0.244

0.626

a Nagelkerke method

           

 

Table 2: Mean (SE) values for hand-harvested yield, crop biomass, weed biomass, and seedhead counts from first and second year Kernza® intermediate wheatgrass grown in monoculture (MC) or intercropped (IC) with field peas. Treatment means within each response variable sharing the same letter are not significantly different at α = 0.05.

   

Kernza MC

Kernza IC

Response Variable

Units

2018

2019

2018

2019

Grain Yield

kg ha-1

406.8 (40.4) ab

389.3 (45.9) ab

322.6 (42.2) a

499.4 (27.6) b

Crop Biomass

kg ha-1

3668.7 (244.6) a

6622.1 (1001.6) b

3055.5 (306.0) a

7375.4 (570.8) b

Weed Biomass

kg ha-1

1052.9 (149.3) ab

627.3 (234.7) a

1719.3 (229.9) b

438.8 (145.3) a

Seedhead Count

m-2

241.0 (18.8) a

228.6 (37.7) a

208.9 (20.6) a

305.9 (29.1) a

 

In contrast with results observed with Kernza, ACE-1 perennial cereal rye exhibited a very different response to the wider row spacing and lower seeding rates of the intercropping treatment. ACE-1 grain yields and crop biomass were both lower for the intercropping treatment in the first year of the experiment and dropped precipitously in both treatments in the second year (Table 5). Seedhead counts were highest in the monoculture treatment in the first year and were similar between the 2018 intercropping treatments and both treatments in 2019. It is interesting to note that while the number of seedheads per unit area were very similar between 2018 intercropped plots and 2019 monoculture plots, grain yield in 2018 intercropped plots was more than five times higher. While we did not measure components of yield in this experiment, these data indicate that each individual seedhead was much less productive in the second-year ACE-1 stand. This is consistent with our field observations that many ACE-1 rye plants seemed stunted with underdeveloped seedheads at harvest. Weed biomass increased dramatically between 2018 and 2019 in both monoculture and intercropped ACE-1 plots, which in conjunction with the large decreases in crop productivity suggests that ACE-1 struggles with inter-specific (i.e. weed) competition after the first harvest. This conclusion is further supported by data from the weed competition sub-project conducted in 2019, which show significantly higher grain yields and crop biomass production from ACE-1 when weeds are controlled in the spring, or both fall and spring, after the first harvest (Figures 2 and 3).

 

Table 3: Mean (SE) values for hand-harvested yield, crop biomass, weed biomass, and seedhead counts  from first and second year ACE-1 perennial cereal rye grown in monoculture (MC) or intercropped (IC) with field peas. Treatment means within each response variable sharing the same letter are not significantly different at α = 0.05.

   

ACE-1 MC

ACE-1 IC

Response Variable

Units

2018

2019

2018

2019

Grain Yield

kg ha-1

3082.4 (145.5) c

438.8 (115.4) a

2324.9 (200.2) b

227.8 (55.8) a

Crop Biomass

kg ha-1

9621.3 (526.9) c

2863.7 (622.5) a

6956.9 (494.7) b

1716.8 (400.0) a

Weed Biomass

kg ha-1

57.9 (19.7) a

3538.3 (349.6) b

202.6 (62.3) a

3755.0 (295.7) b

Seedhead Count

m-2

414 (20.4) b

262.6 (50.7) a

263.9 (19.1) a

144.0 (32.2) a

 

Figure 1: Grain yields of ACE-1 perennial cereal rye and Kernza intermediate wheatgrass subjected to varying levels of weed control during the fall and spring seasons between the first and second harvests. Error bars represent standard error of the mean. Treatments sharing a letter within a crop species are not significantly different from each other at α = 0.05.
Figure 1: Grain yields of ACE-1 perennial cereal rye and Kernza intermediate wheatgrass subjected to varying levels of weed control during the fall and spring seasons between the first and second harvests. Error bars represent standard error of the mean. Treatments sharing a letter within a crop species are not significantly different from each other at α = 0.05.
Figure 2: Crop biomass productivity of ACE-1 perennial cereal rye and Kernza intermediate wheatgrass subjected to varying levels of weed control during the fall and spring seasons between the first and second harvests. Error bars represent standard error of the mean. Treatments sharing a letter within a crop species are not significantly different from each other at α = 0.05.
Figure 2: Crop biomass productivity of ACE-1 perennial cereal rye and Kernza intermediate wheatgrass subjected to varying levels of weed control during the fall and spring seasons between the first and second harvests. Error bars represent standard error of the mean. Treatments sharing a letter within a crop species are not significantly different from each other at α = 0.05.

Strip-tillage Experiment

Kernza grain yields estimated from both combined strips and hand-harvested quadrat samples were higher at harvest following fall tillage than after spring tillage or the untilled control (Table 4; Figure 3). Tillage effects on crop stand density (stem count) and tiller fertility (seedhead count and fertile tiller percentage) contributed to this yield improvement. Components of yield within individual seedheads (i.e. spikelet, floret, and seed counts and thousand kernel weight) did not differ between tillage treatments. It appears that the disturbance caused by strip-tillage in the fall reduces intra-specific competition by thinning the stand, and that the remaining plants respond by producing more seed-bearing tillers in the following growing season. Spring tillage caused a greater reduction in overall stand density when compared to the untilled control, but was apparently unable to respond to reduced competition enough for a similar yield increase in the time between tillage and harvest. We were unfortunately unable to collect data from this experiment in 2019 so we are cautious in drawing broad conclusions about the efficacy of these strip-tillage treatments without additional evidence. We also cannot comment on whether the fall tillage effect would carry over into a second growing season, or whether the stand-thinning effect of spring tillage could stimulate yield a season later but are curious about investigating these questions as well. Nevertheless, these results provide additional evidence that yield decline in mature Kernza stands is at least partially caused by intraspecific competition effects, and that targeted disturbance regimes should be further investigated to identify management tools to maintain Kernza yield over time.

 

Table 4: Mean (Standard Error) components of yield from fourth year Kernza® intermediate wheatgrass harvested in the season following fall, spring, or no (control) management disturbance from strip-tillage. Treatment means within each yield component sharing the same letter are not significantly different at α = 0.05.

Yield Components

Units

Control

Fall

Spring

p-value

Combine-harvested Yield

kg ha-1

182.8 (10.8) a

235.9 (6.6) b

166.2 (19.3) a

0.008

Hand-harvested Yield

kg ha-1

136.4 (4.4) a

219.4 (34.0) b

134.3 (26.9) a

0.036

Crop Biomass

kg ha-1

7290 (220) a

6775 (475) a

5300 (375) b

0.007

Harvest Index

kg kg-1

0.018 (0.001) a

0.032 (0.005) b

0.024 (0.004) ab

0.038

Stem Count

m-2

1004.0 (110.8) a

763.0 (47.5) ab

716.2 (56.8) b

0.046

Seedhead Count

m-2

182.2 (12.6) a

261.2 (23.5) b

140.2 (29.8) a

0.013

Fertile Tillers

%

18.8 (1.7) a

34.7 (4.0) b

19.2 (3.1) a

0.005

Spikelet Count

m-2

16.6 (0.5) a

17.1 (0.6) a

16.9 (0.6) a

0.842

Floret Count

m-2

50.6 (2.0) a

56.0 (5.3) a

56.5 (4.0) a

0.461

Seed Count

m-2

28.4 (1.9) a

29.6 (3.6) a

31.0 (2.7) a

0.740

Thousand Kernel Wt.

g

5.07 (0.16) a

5.09 (0.16) a

5.05 (0.03) a

0.975

Figure 3: Comparison of Kernza intermediate wheatgrass grain yields subjected to strip-tillage at different times between the third and fourth harvests.  Error bars represent standard error of the mean. Treatments sharing a letter are not significantly different from each other at α = 0.05.
Figure 3: Comparison of Kernza intermediate wheatgrass grain yields subjected to strip-tillage at different times between the third and fourth harvests.  Error bars represent standard error of the mean. Treatments sharing a letter are not significantly different from each other at α = 0.05.
Research conclusions:

Intercropping Experiment

As stated above, we encountered several difficulties that negatively impacted the viability of a perennial grain/field pea intercropping system and thus we do not recommend implementing the type of system that we initially proposed. Field peas struggled to grow in polyculture with taller perennial grains, and pea yields and biomass production were low. In addition, asynchronicity in crop development and stature complicated harvesting of the intercrops. Based on our observations there was a contrast between how the two perennial grain species performed in polyculture with peas, with ACE-1 being more compatible from a harvesting perspective but being much more competitive with peas in the first year, and vice-versa for Kernza. 

The intercropping experiment did provide insight into the effects of planting density and row spacing on the two perennial grains, however, with Kernza generally performing similar or better in the wider rows of the intercropped plots, while ACE-1 performed poorly with wider rows and lower seeding rate. This leads us to believe that there are opportunities to improve planting recommendations for these crops and we intend to look more closely at seeding rate, row spacing, and planting date in the future.

Data from the weed competition sub-project in the intercropping experiment have yet to be fully analyzed but preliminary results confirm our observations that ACE-1 rye is more strongly impacted by weed pressure, but that managing weed competition can improve productivity of both crops. We expect that this project will help us narrow our focus for further weed management research with the ultimate goal of providing perennial grain growers with integrated weed management strategies that enhance the productivity, profitability, and sustainability of their operations.

The strip-tillage experiment produced the most directly applicable result of this research, showing strong evidence for the benefits of fall strip-tillage in an older Kernza stand. As yield decline over time has been a major challenge to the profitability of Kernza production this result is expected to inform management practices in the near future. We do want to be cautious with our recommendations at this time, as this result came from one type of strip-tillage at a single site and year, and other attempts to stimulate Kernza yield using disturbance have been unsuccessful, likely due to variation in the type, intensity, and timing of the disturbance. However, we do see this as a promising technique for perennial grain management and hope to replicate and improve upon these results in the future.

Participation Summary
5 Farmers participating in research

Education & Outreach Activities and Participation Summary

3 Curricula, factsheets or educational tools
2 Tours
6 Webinars / talks / presentations
4 Workshop field days
1 Approximately 200 consumers learned about Kernza and the environmental benefits of perennial grains by participating in a consumer preference study that built off of this work. A more detailed description is provided below.

Participation Summary

500 Farmers
400 Number of agricultural educator or service providers reached through education and outreach activities
Education/outreach description:

On January 16, 2018 we held a meeting with an advisory board of four organic grain farmers local to the Finger Lakes region of New York, all of whom have participated in other perennial grain research done at Cornell. At the meeting we discussed both of the experiments in this project and received feedback on our objectives and experimental design.

On June 7, 2018 we gave a presentation focusing on ACE-1 perennial cereal rye at the Cornell Small Grains Management Field Day at the Musgrave Research Farm in Aurora, New York. Approximately 80 farmers were in attendance and received a fact sheet on ACE-1 (Small Grains Management Field Day Handout). 

On June 28, 2018 we presented updates on this project to a group of 50 researchers and food industry representatives at the 3rd Annual Kernza Conference in Lindsborg, Kansas.

On July 13, 2018 we held a workshop on perennial grains at the Cornell Musgrave Research Farm Field Day in Aurora, New York. This workshop included visits to our Kernza intermediate wheatgrass and ACE-1 perennial cereal rye field experiments and discussion of intercropping, planting and harvest timing and techniques, yields, and post-harvest processing such as Kernza dehulling. Approximately 160 farmers were in attendance and received a fact sheet about Kernza and ACE-1 (Musgrave Field Day Handout 2018).

On August 9, 2018 we held an on-farm meeting with our four advisory board members and a few of their colleagues. This was an opportunity for them to see our research plots, update them on research progress and preliminary results, and discuss research goals going forward.

On July 1, 2019 we presented results from the strip-tillage experiment at the 4th Annual International Kernza Conference in Madison, WI. Approximately 100 stakeholders were in attendance representing academic collaborators, food industry partners, and Midwestern farmers with experience growing Kernza.

On July 11, 2019 we held an extension presentation and field tour titled “Kernza: The First Perennial Grain” focused on agronomic management and ecosystem services of Kernza at the Musgrave Research Farm Aurora Farm Field Days. Approximately 100 attendees from academia, industry, and local New York farms participated and received a fact sheet (Musgrave Field Day Handout 2019).

Between September 6th and 27th, 2019 approximately 200 people from the Ithaca, NY community participated in a consumer preference study titled “Assessing Willingness to Pay for Bread Made with Kernza Using a BDM Auction” through the Cornell University Lab for Experimental Economics and Decision Research (LEEDR). The study was conducted in collaboration with Cornell Applied Economics & Management faculty member Dr. Miguel Gomez and M.Sc. student Nima Homami, and developed in partnership with and funded by Lead Scientist Dr. Lee DeHaan of The Land Institute, Salina, KS. Participants learned about Kernza’s environmental benefits and tasted bread made with Kernza flour and organic wheat flour, then indicated their economic valuation of the products via surveys developed using stated preference methods. Results of this experiment are forthcoming.

On November 12, 2019 investigator E. Law won 2nd place in the Perennial Grains student poster contest at the ASA-CSSA-SSSA Annual Meeting in San Antonio, TX for a poster titled “Strip-tillage as a Tool for Maintaining Yield in Mature Intermediate Wheatgrass Stands”(ASA 2019 Poster). Approximately 4000 people from industry and academia attended the conference and had the opportunity to view the poster while it was displayed; we personally interacted with about 200 attendees during the two-hour dedicated poster session.

On January 7 and 8, 2020 we gave two presentations related to this grant at the Northeast Plant, Pest, and Soils Conference in Philadelphia, PA. Investigator E. Law presented the major findings of the intercropping experiment an oral presentation titled “Intercropping Perennial Grains and Peas: Opportunities and Challenges”. Undergraduate research assistant M. Spoth presented a poster titled “Post-Harvest Weed Competition in Perennial Grain Crops: A New Critical Period of Weed Control?” (NEPPSC 2020 Poster) pertaining to the weed competition sub-project described above and funded by a Schmittau-Novak Integrative Plant Science Grant awarded by Cornell University. Approximately 200 stakeholders from academia and industry attended the conference.

On January 18, 2020 we conducted a workshop titled “Perennial Grains in Sustainable Cropping Systems” at the NOFA-NY 2020 Winter Conference in Syracuse, NY. Approximately 30 local organic farmers participated in the workshop.

On February 19, 2020 we were invited to give a keynote presentation titled “Growing Perennial Small Grains as Dual-Purpose Grain and Forage Crops” at the 2020 Pennsylvania Forage Conference in Dauphin, PA. Approximately 50 local farmers were in attendance.

We are currently working on two manuscripts for submission to peer-reviewed journals based on this work, one pertaining to the intercropping experiment and one for the strip-tillage experiment. We anticipate submitting both papers to the journal Renewable Agriculture and Food Systems within the next year.

Project Outcomes

50 Farmers reporting change in knowledge, attitudes, skills and/or awareness
2 Grants applied for that built upon this project
2 Grants received that built upon this project
$17,787.00 Dollar amount of grants received that built upon this project
2 New working collaborations
Project outcomes:

As part of this project, new knowledge was generated on how to manage perennial grain crops in the field, which we hope to build on with future research that will help us realize the tremendous potential for sustainable food and forage production from these crops. Other work has demonstrated the environmental benefits of perennial crops such as Kernza, but there are substantial economic (e.g. lower grain yields than annual grains) and practical barriers (e.g. differences in planting and harvesting operations) to widespread adoption of these crops (and thus actual improvement in cropping system sustainability) that can be lowered by identifying best management practices for their production. These management practices will include factors such as seeding rates, row spacing, and weed management that are also necessary for annual crops, but also novel management strategies such as renovation of mature stands as we investigated in this project. We are confident that our continued research in perennial grain cropping systems will eventually result in more diversified grain cropping systems in the Northeast that protect our water resources, build soil health, provide multiple revenue streams for growers through dual-purpose grain and forage production, and contribute to local food value chains that build stronger connections between consumers and the people that produce their food.

Knowledge Gained:

This project has greatly increased our understanding of agronomic management of the two perennial grain crops that we investigated, which will be incorporated into future research and extension activities as we make progress towards incorporating perennial grains into sustainable cropping systems. I am currently planning on pursuing an academic career in sustainable agriculture/agroecology and I expect that I will continue to conduct research on perennial grain crops in the future.

This research funded by this grant contributed to the development of two other research projects that were described above: the weed competition sub-project that was conducted in the intercropping experiment during its second year, and the consumer preference study that extended our research past the farm to start exploring how perennial grains might fit into a local food value chain. The weed competition experiment was developed in response to our observations of the contrasting responses of the two perennial grain species to weed competition during establishment and after harvest, taking advantage of the established perennial grain plots. The consumer preference study leveraged our network of local organic grain farmers and their connections to grain processing facilities and a local bakery to take Kernza grain grown at our research farm, turn it into locally produced bread, and evaluate consumers’ willingness to pay for the bread itself and also the potential environmental benefits of growing Kernza instead of annual grains.

Assessment of Project Approach and Areas of Further Study:

One of the main challenges and opportunities in working with perennial grain crops is the lack of information about management practices. This is challenging in that we did not always know what to expect and some of our research objectives simply did not work out. However, in many cases, we were still able to learn something new about how to grow and manage these crops. A key example of this is that our original proposal incorporated strip-tillage and legume intercropping into the same experiment, which was a complete failure in a preliminary trial we conducted in 2017. As a result, we split our objectives into two separate experiments that asked similar questions and generated both interesting results and further questions to pursue.

A key factor in the success of this project was our ability to work with a variety of stakeholders to develop our research objectives and adapt our experiments to keep up with newly emerging questions in perennial grain cropping system development. We communicated regularly with collaborators at other institutions, including researchers at The Land Institute that developed Kernza breeding lines and  have considerable experience growing it, to better understand the challenges and opportunities that these systems present. We also have worked closely with an advisory board of local organic grain farmers, millers, and bakers to obtain ideas and feedback about our research program. These relationships are invaluable to our research program and we fully intend to maintain and grow them in the future.

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.