Sustainable cropping systems for dairy farms in the Northeastern US

Sustainable cropping systems for dairy farms in the Northeastern US

Summary

In spring 2010 we established the Sustainable Dairy Cropping Systems farm designed to produce all of the feed, forage, and tractor fuel needs for an average-sized dairy farm in Pennsylvania. Two diverse crop rotations were initiated on 12 acres at the Pennsylvania State University Agronomy Research Farm near University Park, PA. Cropping system strategies include no till, manure injection, cover crops, a cover crop roller, perennial legumes, green manure crops, cover crops, winter canola, and a straight vegetable oil tractor. Within each crop rotation we are evaluating a different innovative management strategy; the forage rotation compares injecting manure to surface application while the grain rotation compares a combination of weed management strategies designed to reduce herbicide use relative to a “standard” herbicide weed management program. To examine the effect of diverse rotations managed and IPM practices on insect pests and beneficial insect populations, a simple corn-soybean grain rotation was also included for comparison purposes (see Fig. 1).

Twelve original project members, a post-doctoral researcher, six graduate students, six undergraduate students, numerous staff research assistants, and the Agronomy research farm staff contributed to the field activities as well as data collection and processing. Members of the USDA ARS team established monolith lysimeter plots at the site to compare total nutrient losses among manure management strategies. We met with the nine member Advisory panel at the project site to update them on our progress and gather input, and followed up with the USDA ARS Beltsville Agriculture Research Center and Rodale Institute members about how they manage long-term farming systems projects. We obtained support for a MS Agronomy graduate student to study weed management in the project; she will begin in January 2011. We launched a project website: http://cropsoil.psu.edu/research/cropping-systems, and are analyzing results of the first year.

• Figure 1: Summary of each crop entry in the three crop rotations and the cropping system strategies that we are evaluating within each rotation

Objectives/Performance Targets

The Sustainable Cropping System farm focused on dairy production and will be based on ecological principles and processes, and test the hypothesis that a farm can minimize off-farm inputs and rely primarily on natural processes to be both productive and profitable. The design will be based on the following agroecological principles: i) minimize nutrient and soil loss, and build soil organic matter and nutrient pools (via no-till, cover crops, manure injection, legumes) and promote biological processes for nutrient acquisition (legumes, soil biological activity, mycorrhizae), ii) enhance biological diversity and ecological interactions to optimize crop yields and minimize pest outbreaks (ex. crop rotation with diverse crop species and lifecycles, intercrops, and cover crops for weed suppression, disruption of insect movement, and promotion of beneficial insect populations), iii) be energetically efficient and productive (produce oilseed crops for farm fuels, use ecological principles to minimize the off-farm inputs of energy, nutrients, & pest control). The sustainable cropping systems were developed by July 2009.

Several strategies that meet the above agroecological system principles will be evaluated, including: no-tillage or rotational no-till, manure injection, crop rotations and intercrops of perennials, annuals, cover crops, and legumes, a roller-crimper, and a locally produced (New Holland) Straight Vegetable Oil (SVO)-powered tractor. Research indicates that in a well-designed cropping system, these practices can contribute multiple agroecosystem benefits. A number of variations and combinations of these strategies have not however been fully evaluated within a long-term farming systems experiment. Therefore, for some of the strategies, we will evaluate two variations of the strategies within the crop rotation in a split-plot (ex. inject vs. broadcast manure in the forage rotation; or reduced herbicide vs. standard herbicide, Fig. 1) or split-split plot design (ex. red clover versus hairy vetch nested within manure comparisons in forage rotation or canola vs canola and oats nested in the weed management rotation; Fig. 1). All of the above scientific comparisons will enable us to document system impacts of a broader range of options available to farmers. These comparisons will also enable the team to more fully understand the fundamental agroecological processes, to share our findings through scientific publications, and to contribute to advancing the science and adoption of sustainable agriculture. We established and began evaluating these cropping system strategies in March 2010.

• Figure 1: Summary of each crop entry in the three crop rotations and the cropping system strategies that we are evaluating within each rotation

Accomplishments/Milestones

Our interdisciplinary team including 19 researchers, educators, and graduate students by fall 2010, met monthly to plan field research and outreach activities, and share results; subcommittees also met as needed. In March, we decided that in order to make statistical comparisons and draw rigorous conclusions about the impact of our diverse grain crop rotations and IPM on pest and beneficial insect populations, we needed to include a comparison rotation at our project site: a corn-soybean grain crop rotation with pre-emptive insect control (Bt corn and prophylactic insecticides) (see Fig. 1). Soon after, we began field operations to layout field scale plots for the 3 crop rotations (see Figs. 1 and 2) with each crop entry present every year. Crop entries of each rotation are blocked and all rotations are replicated four times for a total of 56 main crop entry plots (120’ x 90’) (ex. corn silage after green manure crop). Each crop entry was divided into the manure or weed management split-plot treatments (60’x 90’) and then into the green manure or the canola management split-split plot treatments (30’x 90’) for a total of 112 main management plots and 224 split-split plots (see Fig.2). We collected soil samples from each split-split plot to characterize the soil fertility and carbon prior to initiating the rotations. Soil samples were also collected from the grain rotation plots for water stable aggregate and glomalin analysis.

The winter rye cover crop that had been planted on most of the project site in November 2009 served to represent rye and “winter wheat” in this 2010 season. In April, spring canola was planted to represent winter canola, and all of the alfalfa and alfalfa and orchardgrass plots were planted (Table 1). All of the other crops were planted according to the crop rotation design. Crop management details (crop variety, planting date, seeding rate/plant population, seeding depth, row spacing) are provided for each rotation and crop entry in Table 1. Nutrient (manure and inorganic fertilizer) application dates and rates for each crop are summarized in Table 2. Scouting for insect pests was conducted throughout the growing season to guide management decisions. The pest management practices employed (eg. cultivation, insecticide and herbicide applications, early harvests, and seed treatments) are listed in Table 3, with the exception of the Bt traits of the corn in the corn-soybean rotation, which is described in Table 1.

To monitor the performance of the cropping system strategies, soil fertility, weed populations, crop yield, and crop feed/forage quality were sampled in all crop entries. Crop yield and feed/forage quality data is being prepared for the virtual dairy herd model this winter. To identify strategies that might improve establishment of our small-seeded crops in no-till systems, we quantified winter canola and fall and spring alfalfa seedling populations in the cropping systems, as well as residue and slug activity in alfalfa. Mycorrhizal populations were compared with bioassay corn plants in the alfalfa vs. alfalfa and orchardgrass and pea and triticale crop entries in the grain rotation, and the non-transgenic and transgenic corn grain crop entries of the grain and corn-soybean rotations.

We accomplished several goals for assessing pest and beneficial invertebrate populations in the Sustainable Dairy Cropping Systems Trial. Scouting protocols were established for key pests including slugs, potato leafhoppers, soybean aphids, wireworms/grubs, and European corn borer. To monitor beneficial invertebrates, we established 160 pitfall traps in corn and alfalfa plots, deployed on eight sample dates throughout the season. The resulting pitfall samples will provide baseline data to measure the influence of the diverse rotations and conservation practices on beneficial invertebrates, particularly ground-dwelling predators. In addition, we developed a protocol for using sentinel prey to measure in the experiment the ecosystem services provided by predators.

Weed biomass was collected prior to cash crop harvest in all reduced herbicide (RH) and standard herbicide (SH) treatments in 2010. In 2010 we relied on the background weed seed bank to assess weed control success. A number of weed species infested our experimental site including common lambsquarters, velvetleaf, fall panicum, some foxtail species and more scattered populations of Canada thistle and burdock. Weed seedbank subplots that included common ragweed, giant foxtail, and smooth pigweed were established in late fall 2010 in selected treatments and will be used to measure treatment success in 2011 and beyond.

In spring 2010, the farm energy analysis tool and whole farm computer simulation models were used to conduct an energetic analysis and predict greenhouse gas emissions of the USDA ARS BARC farming systems trial. Energy use was quantified at our Penn State sustainable dairy cropping systems farm for many of the crop operations in large fields typical of farms in PA. This was done to remove the frequent turning required at the end of our 90’ plots. We have made plans for more detailed quantification of energy use by a diesel tractor and the canola-powered straight vegetable oil tractor on farm scale fields in 2011.

Nutrient use in the cropping systems was quantified (Table 2) and available crop nutrient summaries are in preparation. We also initiated spatially- stratified soil sampling to calibrate soil sampling methods for the corn pre-sidedress nitrogen test (PSNT) with shallow disk manure injection. To conduct a complete nutrient balance, 12 large (90 x 50′) field “lysimeter” areas were installed, where we will begin measuring all nutrient inputs and outputs in 2011, including water (rainfall, evapotranspiration, surface runoff, subsurface leaching). The lysimeters will be used to quantify nutrient use efficiency of crop entries in the forage rotation to determine the environmental trade-offs of new manure management approaches (shallow disk injection, surface broadcast and aeration) in comparison with conventional approaches. Through these lysimeters, improvements in the conservation of nitrogen, phosphorus and soil will be documented, as well as differences in atmospheric emissions (ammonia, greenhouse gases). Results will be used to adjust cropping system components as the project evolves and validate regional modeling efforts related to the Chesapeake Bay.

Incorporation of manure into soil with a shallow disk injector was tested in the current study because it has been previously been shown to drastically reduce ammonia and odor emissions and nutrient runoff. However, belowground bands of manure have the potential to lead to increased emissions of the greenhouse gas nitrous oxide (N20). With injected manures, high rates of concentrated microbial activity in response to the addition of readily-metabolized manure organic matter can result in the anaerobic conditions needed for the denitrification of soil and manure nitrates (largest source of nitrous oxide).

Nitrous oxide emissions were measured periodically for approximately one month after manure injection and broadcast application just prior to canola planting in September 2010. Narrow flux chambers were used to measure emissions from directly over injection slots, from unamended soil between injection slots, and from broadcast applied manures. For injected plots, weighted means were then calculated reflecting the combined emissions from both the injection slots and the unamended areas between slots.

The project team met with our Advisory panel to update them on the project goals, our progress, and to show them the farm fields, equipment and lysimeters. Based on feedback from the Advisory panel, we decided to drill the red clover into the winter wheat, rather than frost seed it. In addition, to reduce volunteer canola seed germination in the crop following canola, after canola harvest we rotary harrowed the field to stimulate seed germination and sprayed the seedlings with glyphosate prior to alfalfa, and glyphoste with 2,4-D prior to planting rye.

We also visited some of the Advisory panel members at their project site at the USDA ARS Beltsville Agriculture Research Center and consulted with Rita Seidel at the Rodale Institute about how they manage their long-term farming systems trials. We discussed their: i) tools for data management and record keeping, ii) protocols for delineating undisturbed treatment areas for yield, feed/forage quality monitoring and field areas for sampling that causes disturbance; and iii) procedures for reviewing new research proposals in their project. We also hosted a visit of two members of the NESARE Advisory Council.

In July 2010, Kristin Haider, a Masters graduate student in Ecology joined the project team to study mycorrhizae. In August, Emily Duncan a doctoral student in Soil Science joined the project. She will compare the nutrient budgets of the manure management treatments. In fall 2010, we recruited and obtained financial support from the Dept. of Crop and Soil Sciences for a MS Agronomy graduate student to study the weed management systems in the project; she will begin in January 2011.

In August, the project website was launched: http://cropsoil.psu.edu/research/cropping-systems. In September, we were invited to present at our project site to the Penn State University Legislator’s tour; this involved presenting to six groups of invited attendees (~100 people). Other outreach activities included presenting the project to three student groups; as well as to journalist Rona Kobell who wrote an article about the project in the Bay Journal, September 2010 issue: http://www.bayjournal.com/article.cfm?article=3907.

With funding from a NRCS Conservation Innovation Grant that we were awarded in fall 2009, some team members worked with four county educators to promote adoption of some of the innovative conservation practices. With the NRCS CIG grant, we purchased two roller crimpers that are on two farms in northern and southern PA counties, and shallow disk manure injection equipment for four commercial manure haulers in different counties to use on multiple farms. Members of the project participated in demonstrations at three extension education events: i) the 2010 Manure Expo at University Park, ii) the PSU “Farming for Success” field day at Landisville in Lancaster, PA, and iii) Steve Groff’s Cover Crop Field Days in Lancaster, PA.

• Figure 1: Summary of each crop entry in the three crop rotations and the cropping system strategies that we are evaluating within each rotation
• Table 2: Nutrient management for each crop entry
• Table 3: Pest management practices for each crop entry
• Table 2: Nutrient management for each crop entry
• Figure 2: Schematic of crop rotation-crop entry plot layouts for Block 1
• Table 1: Crop production practices for each crop entry

Impacts and Contributions/Outcomes

The feedback from our Advisory panel meeting in July 2010 was positive and the farmers informed us that a website would be an effective way to communicate results to many farmers. We are currently analyzing results from the 2010 field season. Crop yields did not differ between the manure and weed management strategies and in general met or exceeded crop yield expectations for our particular location and soil type. The only exception was spring canola that yielded less than half of what was anticipated for winter canola. We are exploring possible reasons and strategies to reduce canola seed loss during harvesting with other canola researchers at Penn State.

As expected for a predominantly no-till system, slugs were an important pest in most crops and we used their abundance as an opportunity to build knowledge for field crop growers in the region. For instance, slug activity-densities under simple shelter traps were highly correlated with damage to corn and alfalfa. Therefore, shelter traps may provide an economical method for farmers to predict the likelihood of slug damage to their crops. Data from 2010 also suggest that spring alfalfa seedings are less vulnerable to slug damage than fall seedings, a result of practical importance for alfalfa growers.

In coming years, we predict that the complex rotations will foster increased predator abundance and diversity, leading to enhanced predation services. Taking advantage of our network of pitfall traps, we collected live predators for laboratory experiments to screen predators for their ability to eat slugs. Very little research of this sort appears to have been conducted previously in the Northeast or mid-Atlantic regions; therefore our experiments are vital to understanding the control potential of resident natural enemy communities. Our efforts have identified at least two potentially important slug predators in our region, the ground beetles Pterostichus melanarius and Chlaenius tricolor. In future experiments, we hope to gauge the control potential of these predaceous beetles under field conditions.

European corn borer damage was significant in the corn grain plots that were planted with transgenic non-Bt corn (8 % lodging), while corn borer damage was absent in the Bt corn grain plots in the corn-soybean rotation. However, initial yield data suggest that this damage probably did not translate into reduced yield. This finding is consistent with our hypothesis that reduced input systems can compete with higher input, transgenic-based systems, achieving similar yields at lower cost. As expected for the first year, predation measured using sentinel prey was similar in the three rotations.

As anticipated, the highest rates of nitrous oxide emissions were directly from the injection slots. Peak emission rates from injection slots (about 10 days after manure application) ranged from 103 to 615 g N2O ha-1 day-1, while emissions from sampling locations between slots ranged from 9 to 18 g N2O ha-1 day-1. Peak weighted mean emissions for injected plots ranged from 33 to 120 g N2O ha-1 day-1. Nitrous oxide emissions from broadcast manure were low on all sampling dates (<10 g ha-1 day-1).

Even the highest emission rates observed were a very small portion of the plant available nitrogen provided by the manure application (about 150 kg N ha-1), however the agronomic and environmental benefits of reducing ammonia emissions and nutrient runoff provided by injection must be weighed against the potential cost of greater nitrous oxide emissions. Further testing is needed to determine if the greater nitrous oxide emission seen in the preliminary study were simply a result of a greater pool of nitrate remaining in the soil due to lower losses of nitrogen as ammonia with injection or if the physical conditions created by manure injection led to greater denitrification than when manure is evenly incorporated into soil by tillage.

Through the NRCS CIG grant, six farmers compared manure injection to surface application in replicated side-by-side, field scale strips on their no-till fields. Two farmers used the roller crimper to roll down their wheat cover crop or green manure hairy vetch crop prior. In 2011, additional farmers plan to participate in the on-farm shallow disk manure injection evaluation and we anticipate that the commercial manure haulers will promote it with additional farmers.

Members of our team (Heather Karsten and Ron Hoover) are co-PIs with Sjoerd Duiker and Charlie White on a successful 2010 NRCS CIG grant proposal to promote cover crops and manure injection in 10 counties in Pennsylvania. The grant leveraged previous on-farm cover crop demonstrations as well as our 2009 NRCS CIG grant award and this NESARE Agroecosystems project. Activities include cover crop mixture demonstrations on 10 farms, additional on-farm manure injection demonstrations, and the production of on-farm videos with farmers explaining how and why they adopted cover crops and manure injection on their farms.

Collaborators: