Feasibility of integrating annual feed grains into established organic pasture

Feasibility of integrating annual feed grains into established organic pasture

Summary

The purchase of feed grains represents a significant cost for dairy farmers in the Northeast and has led to increasing interest in on-farm production of grains. 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 dairy production and the need for purchased off-farm inputs. Additionally, intercropping into established pasture may reduce the need for full pasture renovation following the cessation of feed grain production. In 2012, six different management treatments, each replicated four times in a randomized complete block design, were established at the Organic Dairy Research Farm in Lee, NH. That experiment provided useful data on the weed and pasture community response to the treatments; however, due to several unanticipated personnel and technical challenges, we decided to move the study to a nearby UNH research farm for the 2013 iteration of the study. The 2013 study included several conventional herbicide-based treatments in addition to the six original organic-based treatments. In June 2013, nine management treatments were established at the University of New Hampshire Kingman Research Farm in Madbury, NH. The treatments included two controls, a pasture control (an established mixture of alfalfa and grass) (T9), and a full-tillage control with inter-row cultivation (not intercropped) (T1).  These were compared to seven intercropping treatments differing in disturbance intensity and glyphosate usage: Full tillage, with inter-row cultivation and a subsequent inter-seeding of crimson clover at final cultivation (T2); strip tillage (T3); strip tillage following a glyphosate burn-down (T4); minimal till (pasture undercut with a Yeoman’s plow following flail mowing) (T5); no till following a glyphosate burn-down (T6);  no till following a glyphosate burn-down and a subsequent inter-seeding of crimson clover at V6 (T7); and no till following flail mowing (T8). Corn was planted in all treatments except T9.

Objectives/Performance Targets

The results from our first season in 2012 informed our decision to include additional treatments that represent a broader range of conventional and organic-based approaches for farmers interested in on-farm feed grain production. By moving to Kingman Research Farm in Madbury, NH, we were able to include glyphosate-based approaches to reducing competition between the alfalfa and corn. However, our original objectives remain the same.

1.         Integrate a rotation of annual feed grains (corn-soybean) into a perennial legume pasture, and determine the optimal tillage system based upon crop yield, weed abundance, soil quality, and capital cost;

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;

3.         Calculate overall crop yield and weed abundance, and examine how pasture-to-crop ratios affect weed suppression and interspecific competition; and

4.         Perform a cost-benefit analysis for each cropping system treatment, and develop a grain production management plan for best practices within pasture-based dairy systems.

Accomplishments/Milestones

From the establishment of the first experiment at the Organic Dairy Research Farm we were able to assess late summer weed abundance and community composition in response to the tillage and intercropping treatments, and determine the extent of pasture recovery in each treatment in the following spring. Aboveground weed biomass was measured at peak biomass (mid-August, 2012), and again in May, 2013. Weeds were sorted to species, dried to constant biomass and weighed. We found that pasture recovery was highest in the minimally-tilled treatments compared to the conventionally-tilled treatments, which had a larger proportion of weed species, but lower total crop and weed biomass. Plant communities in the minimum-tillage treatments were more similar to the pasture control and were less temporally variable than were plant communities in the conventionally-tilled treatments.

Aboveground biomass (pasture and weed community composition) was collected in June 2013 to determine baseline conditions prior to the establishment of the treatments at the Kingman Research Farm. Soil samples were collected on June 18, 2013 and analyzed at the Cornell Soil Lab for an initial comprehensive soil health assessment. To evaluate differences in corn establishment and early season growth across the treatments, we measured corn populations and height and used a SPAD meter to measure leaf chlorophyll content. Moisture readings were taken regularly throughout the growing season and follow up soil health tests will be conducted by Cornell’s Soil Lab prior to the 2014 treatment establishment. The weed and pasture community was measured in mid-August 2013 and corn yield was measured in late fall. These data are currently being analyzed and will be combined with data from the upcoming 2014 field season in order to develop a grain production management plan for best practices for intercropping grains within pasture-based dairy systems.

Impacts and Contributions/Outcomes

Results from the first year of this experiment were presented at the Weed Science Society of America annual meeting in Baltimore, MD in February 2013, at the UNH Graduate Student Research Conference April 2013, and again at the Ecological Society of America (ESA) annual conference in Minneapolis, MN in August 2013. We plan to present the compiled results from years one and two at the 2014 Graduate Student Research Conference, as well as at the 2014 ESA conference in Sacramento, CA. We collected extensive video documentation of the treatments being established at the Kingman Research Farm and we will combine the video footage with data from the experiment into an educational video. 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. By sharing our research findings with other researchers and extension personnel, we hope to contribute valuable knowledge of how each management system functions. 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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