Incorporating Cover Crops and Diversified Weed Management to Improve Cropping System Productivity

Open Access
Caswell, Katherine E
Graduate Program:
Master of Science
Document Type:
Master Thesis
Date of Defense:
February 28, 2017
Committee Members:
  • William Curran, Thesis Advisor
  • Heather Karsten, Committee Member
  • David Mortensen, Committee Member
  • Jeffery Hyde, Committee Member
  • Integrated Weed Management
  • Cover crops
  • agronomy
To address the need for diversified weed management and innovative methods of cover crop incorporation, two distinct experiments were performed. The first, was based in a diverse, no-till dairy cropping systems study was established in 2010 seeking to produce enough feed, forage, and fuel to supply a 65-cow, 97 hectare dairy farm in Pennsylvania while minimizing off farm inputs. A 6-year diverse crop rotation, the Pest Management rotation, evaluated strategies that attempted to reduce herbicide inputs and the risk of herbicide resistant weeds. The rotation was composed of a sequence of annual crops, cover crops, and a perennial hay crop. A Reduced Herbicide (RH) treatment was compared to a Standard Herbicide (SH) treatment that was more reliant on chemical weed control. Both treatments utilized Integrated Weed Management where the RH treatment incorporated more cultural and mechanical methods of control. Management was altered in 2013 to address challenges faced in the first three years and results of 2013-2015 are analyzed here. Weed management was evaluated for the corn silage and soybean portion of the rotation as this is where the most intensive weed management occurs. The RH and SH treatments were compared based on crop yield, weed biomass, and net return to the farm enterprise. Both the RH and SH treatments generally maintained adequate weed control during 2013-2015 but biomass was generally greater in RH. Soybean yield varied between the treatment in one year, but these differences were not attributed to weed biomass. A greater net return to the farm was seen under SH management in soybean and RH in corn silage. The second study sought to address cover crop adoption in the Northeast, that has been slow and limited due to a number of factors. Farmers are faced with a constricted time window for cover crop planting following harvest and before weather conditions prevent fall growth. Multiple methods have been evaluated to expand this restricted planting window including aerial seeding, underseeding and relay intercropping. All of these methods face additional challenges in no-till production systems. Researchers at Penn State developed an innovative cover crop interseeder to address establishment restrictions in no-till grain production. After design of the machine was completed, a number of successful intseeder cover crops needed to be selected. A successful interseeded cover crop may require traits that are not normally associated with post-harvest established cover crops. These species need to tolerate low light and moisture conditions while being able to establish. Annual ryegrass (Lolium multiflorum) has been shown to be a strong candidate for interseeding in earlier studies and a trial was conducted to test different varieties for interseeding ability. A Species Trial was conducted to evaluate different grass and legume species in either corn or soybean. These trials were conducted in Pennsylvania (PA), New York (NY), and Maryland (MD). Several species were shown to be better candidates for interseeding based on fall and spring biomass. These species were: Medium Red Clover (Trifolium pretense), Annual ryegrass, and Orchardgrass (Dactylis glomerata L.). The annual ryegrass trial showed similar performance across varieties with few performing better than others. A better understanding of appropriate cover crop selection can be used in conjunction with ongoing work with herbicide selection to create recommendations for farmers.