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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Sustainable Agricultural Systems Laboratory » Research » Publications at this Location » Publication #333080
Title: Hairy vetch biomass across the eastern United States: Effects of latitude, seeding rate and date, and termination timing

Author
item Mirsky, Steven
item ACKROYD, VICTORIA - University Of Maryland
item CORDEAU, STEPHANE - Cornell University
item CURRAN, WILLIAM - Pennsylvania State University
item HASHEMI, MASOUD - University Of Massachusetts
item REBERG-HORTON, S. CHRIS - North Carolina State University
item RYAN, MATT - Cornell University
item SPARGO, JOHN - Pennsylvania State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2017
Publication Date: 4/20/2017
Citation: Mirsky, S.B., Ackroyd, V.J., Cordeau, S., Curran, W.S., Hashemi, M., Reberg-Horton, S., Ryan, M., Spargo, J.T. 2017. Hairy vetch biomass across the eastern United States: Effects of latitude, seeding rate and date, and termination timing. Agronomy Journal. 109:1510-1519.

Interpretive Summary: Cover crops are nonmarketable crops that provide a variety of benefits to cropping systems. Legume cover crops not only provide environmental benefits (e.g. erosion control, nutrient scavenging, water management), but decrease reliance on fertilizers by fixing nitrogen (N) from the atmosphere that can be used by a following cash crop. Hairy vetch is the most commonly grown legume cover crop in the Eastern US because of its hardiness and large N fixation and biomass production. While there has been a lot of research on management to improve hairy vetch performance, little has been done to examine seeding rates and how optimal rates might be influenced by timing of establishment and latitude. This topic is of particular importance given the relatively large cost of hairy vetch seed; planting hairy vetch at an optimal rate could considerably decrease farmer costs, simultaneously increasing both economic and environmental benefits of hairy vetch use. We conducted an experiment at sites in MA, NY, PA, MD, and NC across a range of seeding rates and dates and timings of termination to: 1) define the biomass production potential of hairy vetch; 2) determine minimum allowable seeding rates; and 3) quantify whether adjustments in seeding rate and timing of termination can compensate for late seeding dates. Hairy vetch was planted at two dates (optimal and late) at seeding rates ranging from 6 to 50 kg ha-1, and was terminated at early (vegetative), intermediate (10% flowering), and late (50% flowering) dates. The longer hairy vetch was allowed to grow between seeding and termination, the more biomass it accumulated. A biomass compensation was observed with increasing seeding rates when seeding was delayed; this effect being more pronounced with increasing latitude. Our results show significant variation in optimal seeding rates across a latitudinal gradient, and illustrate the advantages of using adaptive management for optimizing hairy vetch biomass production. These results will be of value to extension and ag-industry personnel when making recommendations about hairy vetch planting and management, and may help farmers to maximize the benefits accrued from hairy vetch use while minimizing production costs.

Technical Abstract: Hairy vetch (Vicia villosa Roth) is a winter annual legume cover crop that is often grown because it can provide a substantial amount of N to the following cash crop. Nitrogen accumulation is dependent on biomass production, which in turn is affected by climate, seeding rate and date, and timing of termination. The combined effect these factors have on biomass production has not previously been tested. Further, since legume cover crop seed is expensive, determining minimum allowable seeding rates could increase the use of legumes in cropping systems. We therefore conducted an experiment at sites in MA, NY, PA, MD, and NC across a range of seeding rates and dates and timings of termination to: 1) define the biomass production potential of hairy vetch; 2) determine minimum allowable seeding rates; and 3) quantify whether adjustments in seeding rate and timing of termination can compensate for late seeding dates. In a randomized complete block design, hairy vetch was planted at two dates (optimal and late) at seeding rates ranging from 6 to 50 kg ha-1. The hairy vetch cover crop was terminated at early (vegetative), intermediate (10% flowering), and late (50% flowering) dates the following spring and biomass was collected. The longer hairy vetch was allowed to grow between seeding and termination, the more biomass it accumulated. For every 100 GDD gained, hairy vetch biomass increased by an average of 530 kg ha-1. Estimated maximum biomass across seeding and termination dates and seeding rates ranged from 460.2 - 2815.3 kg ha-1 in MA, 22.8 - 9865.4 kg ha-1 in NY, 72.2 - 6883.9 kg ha-1 in PA, 770.6 - 7117.1 kg ha-1 in MD, and 4314.5 - 7759.1 kg ha-1 in NC. In MA, NY, and PA, hairy vetch reached maximum biomass production at seeding rates of 10-20 kg ha-1, at the low end of the currently recommended rate of 18-22 kg ha-1. In MD and NC, hairy vetch produced maximum biomass (> 6 Mg ha-1) when seeded at an optimal rate of 5-10 kg ha-1 (lower than the currently recommended rate). Increasing hairy vetch seeding rate generally increased biomass production and was proportional to latitude. A biomass compensation was observed with increasing seeding rates when seeding was delayed and this effect was more pronounced with increasing latitude. Our results show significant variation in optimal seeding rates across a latitudinal gradient, and illustrate the advantages of using adaptive management for optimizing hairy vetch biomass production.