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) Conduct partial budget analyses to determine effects of strip tillage and grain legume intercropping on overall cropping system profitability.
5) Monitor and compare Kernza, ACE-1, and field pea growth to inform planting schedules that allow for synchronous maturity and harvesting.
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 needs 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 rye cv ‘ACE-1’ (Secale cereale x 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 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.
Despite the potential to transform agriculture, there are still several agronomic issues to be addressed in Kernza 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). 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.
Based on preliminary research results from the 2017 field season the proposed research plan has been split into two separate experiments, one that will investigate intercropping field peas with two perennial small grain varieties, intermediate wheatgrass cv ‘Kernza’ and perennial rye cv ‘ACE-1’, and another that will investigate the effects of the timing of strip tillage on the renovation of established Kernza stands. In the fall of 2017 the intercropping experiment was planted and fall strip tillage was performed in the tillage experiment. Details on these two experiments and how they differ from the original proposal are provided below.
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. Intercrops were planted as a replacement series, with alternating rows of grain and peas at a 7.5 in row spacing. This experiment differs from the original proposal in several ways. Perennial rye is an additional perennial small grain crop that we are investigating. As we did not have established perennial rye stands available for this experiment, the perennial grain crops were newly planted, and thus tillage was uniform and is not a treatment. We also added the use of 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. Soybean was removed as a possible legume intercrop due to its late maturation relative to the perennial grains which caused significant harvest complications during our preliminary trial during the 2017 field season.
Due to our inability to examine the effects of strip tillage as a tool for stand renovation in the intercropping experiment described above, we have also begun a separate tillage experiment in the 3.5 year-old Kernza stand we had intended to use for the combined intercropping/tillage experiment as originally proposed. In the revised tillage experiment we will be investigating 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. This experiment differs from the original proposal in that we have added a fall tillage treatment based on our experiences using strip tillage in established Kernza stands in spring 2017. 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 may 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 in both experiments was begun in July and August 2018. In the intercropping experiment ACE-1 rye monoculture and polyculture, and field pea monoculture plots were sampled July 17 and 18, 2018. Kernza monoculture and polyculture, and field pea monoculture plots were sampled August 15 and 16, 2018. 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. In the strip tillage experiment Kernza plots were sampled August 27, 2018. All 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 by 40 ft strip was also harvested from each subplot with an Almaco plot combine after quadrat samples were collected. Combine samples were weighed before and after drying to calculate yield and grain moisture at harvest.
Data analysis for both of these projects will be conducted during spring 2019. Analysis of variance (ANOVA) will be used to identify any significant treatment effects or interactions. Response variables evaluated will 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. Land equivalent ratios will also be calculated for the grain/pea polycultures in the intercropping experiment.
Statistical results for both experiments are forthcoming. Preliminary analysis has identified a few trends that we will briefly mention here. In the intercropping experiment yields of ACE-1 did not appear to differ between monoculture and polyculture plots, while yields of Kernza were reduced in polyculture. Very few pea plants were observed in ACE-1 polyculture plots, however, while many were observed in Kernza polyculture plots, and this difference in crop compatibility will be important to understand if this type of intercropping is to be used more widely. Land equivalent ratios will help better quantify these trade-offs. The oat nurse crop appears to have little to no effect in the intercropping experiment. In the strip tillage experiment it appears that the fall applied tillage treatment improved Kernza yield to a small extent, while spring tillage had either no effect or a small negative effect on Kernza yield.
Education & Outreach Activities and Participation Summary
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).
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.