Feasibility of integrating annual feed grains into established organic pasture

Feasibility of integrating annual feed grains into established organic pasture

Summary

The purchase of organic feed grains represents a significant cost for organic dairy farmers in the Northeast and has led to increasing interest in on-farm production of grains. Organic feed grain production, however, often relies on intensive tillage for seed bed preparation and weed control, which can negatively impact soil quality. Intercropping annual feed grains with perennial pasture could reduce the need for intensive tillage, and may lessen the environmental impacts of organic dairy production and the need for purchased off-farm inputs. Six different management treatments, each replicated four times in a randomized complete block design, were established in 2012 at the University of New Hampshire Organic Dairy Research Farm in Lee, NH. Two control treatments, a pasture control (an established mixture of alfalfa and grass) (T1), and a full-tillage conventional organic feed-grain control (not intercropped) (T2), were compared to four intercropping system treatments differing in disturbance intensity: full-tillage with annual legume (crimson clover) inter-seeded following feed grain emergence (T3); strip-tillage establishment into living pasture (T4); minimum-till establishment into pasture following mowing and undercutting (T5); and minimum-till establishment following mowing only (T6). Aboveground weed biomass was measured at peak biomass (mid-August).Weeds were sorted to species, dried to constant biomass and weighed. Annual weed abundance increased with tillage intensity, with higher weed abundance in conventionally tilled treatments compared to the minimally tilled intercrop treatments. Weed community composition also differed across treatments. In contrast, corn biomass was highest in the conventionally tilled treatments and lowest in the minimally tilled treatments. At the community-level, total plant biomass (corn, pasture, and weeds) was highest in T2 and T3. These results suggest that intercropping into established pasture using conservation tillage methods can decrease weed abundance; however trade-offs exist between disturbance intensity, maintenance of desirable pasture species, and corn yield. As the project continues, we hope to learn strategies for better addressing these trade-offs.

Objectives/Performance Targets

Producing organic feed grains within certified organic pastureland presents unique challenges, which will require the development equally unique solutions. Through the accomplishment of the following strategic objectives, our aim is to assess the benefits and limitations of the intercropping systems, and seek to mitigate potential obstacles that New England dairy farmers may encounter.
In order to meet our overall objectives we:
1. Established a rotation of annual feed grains into a perennial pasture, and have begun to evaluate the optimal tillage system based upon crop yield, weed abundance, and capital cost; and
2. Measured overall crop yield, pasture composition, and weed abundance in the first year of the rotation in all treatments.
Over the next year, we also plan to:
1. Determine how crop yield and weed abundance in the second year of the rotation are affected by our tillage and intercropping treatments;
2. Assess soil quality in response to the treatments, by using standard soil quality indicators, to determine how intercropping intensity affects soil properties—nitrogen availability, soil carbon, moisture, and organic matter—and microbial activity along the gradient of management intensity; and
3. Perform a cost-benefit analysis for each cropping system treatment, and develop a grain production management plan for best practices within organic pasture-based dairy forage systems.

Accomplishments/Milestones

Aboveground biomass (pasture and weed community composition) was collected on June 14, 2012 to determine baseline conditions prior to treatment establishment. Soil samples were collected on July 18 for an initial assessment of total carbon and nitrogen. These soil samples have been prepped and are currently being prepared for analysis on the Gas Chromatography-Mass Spectrometer (GC-MS). In mid-June, the soil was prepped for the six different management treatments, using conventional till (moldboard plow), strip-till, and minimal till methods. Treatments were then seeded with corn, and crimson clover was broadcast in the inter-seeded treatment (T3) three weeks later. To assess differences in corn establishment and early season growth across the treatments, we measured plant populations and height and used a SPAD meter to measure leaf chlorophyll content. Plant community biomass was measured in mid-August and crop biomass was measured in late fall. Results from this first year of the study are currently being analyzed. We are also in the process of performing a cost-benefit analysis for each cropping system treatment for year one. These data will be combined with data from the 2013 field season in order to develop a grain production management plan for best practices within organic pasture-based dairy forage systems.
Due to issues with equipment and labor, the project started later than we had hoped. Additionally, immediately after the corn was seeded, we experienced extremely hot, dry weather. Both the late start date and drought conditions contributed to relatively low corn growth and production in all treatments. In order to avoid some of the equipment issues, we will purchase a new grain seeder this winter, to be used for the 2013 planting. We plan to seed (soybean) as early as possible and perform secondary cultivation for weed management, which we hope will result in better yields across all treatments.

Impacts and Contributions/Outcomes

We will be presenting the results from this summer’s research at the Weed Science Society of America Annual Meeting in Baltimore, MD in February 2013. By sharing our research findings with other researchers and extension personnel, we hope to contribute valuable knowledge of how weed communities respond across a gradient of increasingly integrated tillage and intercropping, so as to identify the most useful combination of both approaches.
We have also begun discussions with local farmers in anticipation of working with UNH Video Production Services to film an educational outreach video this spring. This video is intended to assist farmers in making informed decisions about pasture management strategies and reduced tillage implements, and will be targeted to dairy farmers in the Northeast. It is also our intention to conduct this experiment so that farmers do not have to take the financial risk experimenting with different tillage methods themselves; they can learn from our efforts.

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