Integrating weed and nutrient management in hop (Humulus lupulus) production using organic amendments

Since the times of prohibition, hop (Humulus lupulus) production has been regionally concentrated in the Northwestern U.S. However, consumer and industry interest in locally grown crops has presented an opportunity for Nebraska hop production. Nebraska produced 34,000 barrels of craft beer in 2014, yet there is limited commercial hop production. The increase in local beer manufacturing is ideal for the U.S. craft beer industry and specialty crop growers alike. With research in cultivar selection and breeding, sustainable management practices and harvest and drying methods, the Nebraska Hops Project is turning this vision of sustainable, locally grown hops into reality. Hop is a perennial herbaceous crop grown on a trellis system. It grows rapidly and has relatively high nitrogen requirements (150 to 200 lbs/acre). Because hop is a specialty crop, there are few herbicides registered for use, and organic or non-chemical approaches are typically limited to mulching, tillage, and hand-weeding. The combined challenges of providing sufficient crop nitrogen and managing weeds in hops, suggest there may be an opportunity for integrated weed and nutrient management using organic amendments like corn gluten meal and soybean meal. Both corn gluten meal (CGM) and soybean meal are labelled as organic fertilizers, and both have shown allelopathic effects on weed germination and growth at relatively low application rates. However, our recent research in annual vegetable crops suggests that relatively high rates of these organic seed meals (>25 lbs/acre) applied at the surface may inhibit weed seedling emergence via temporary ammonium toxicity without injuring the crop. The objective of this project is to test the potential for an organic seed meal to concurrently displace synthetic nitrogen fertilizer needs and reduce weed seedling emergence in hop production systems. To accomplish this objective, we will leverage an existing experimental commercial hop production facility at the University of Nebraska – a resource of the Nebraska Hops Project – where we will compare corn gluten meal with a weedy and weed-free control. We will collect data on soil nitrogen availability, weed emergence and biomass, and hop yield and quality. Results will be disseminated via extension and the Nebraska Hops Project team. Outcomes of this project include increased stakeholder awareness of hop production in Nebraska and increased efficiency and sustainability of hop production throughout the North Central Region through integrated weed and nutrient management using organic amendments.

The purpose of this research is to determine the capacity for integrated nutrient and weed management using organic amendments in hop production systems. Learning outcomes will be achieved through outreach with farmers and growers at a variety of scales ranging from commercial to small acreage market gardeners. Each stakeholder will increase his or her knowledge of sustainable agriculture through organic amendment application. The action outcomes of this project are that growers will apply this new knowledge into their own cropping systems. Growers who take action on this new knowledge will experience increased efficiency through the use of organic amendments as multi-functional inputs with fertilizer and weed control properties. This change in behavior will include changes in fertilizer source and application strategy and in approaches to weed management.

Specifically, growers will be less dependent on synthetic fertilizer, tillage, hand-weeding, and herbicides.