Statement of Issues

Agriculture is threatened by its sensitivity to climate change and irregular weather patterns. Accurate projection of yields and harvest time are essential to pair production with market demands and forecast financial margins. In controlled environment agriculture (CEA), farmers can closely control most aspects of the growing environment and adjust production to weather and market fluctuations. The ability to control environmental and agricultural inputs results in increased resource efficiency per production area and reduced shrinkage compared with outdoor field production. Hence optimized efficiency and use of low–cost alternative resources is fundamental for the successful future of CEA operations. Adaptation to climate change to overcome potential risks demands strategies that match current and projected conditions.

CEA is an economically important sector in agriculture in the U.S. Despite the economic crisis in 2008, the USDA Census reported that the number of operations and sales in specialty crops increased by 7.5% and 17%, respectively, from 2009 to 2014. IBISWorld reported that the hydroponic industry is on the growth stage in the market, which is characterized by many new companies entering the market, rapid technology change, growing acceptance by consumers, and rapid introduction of products and brands. CEA is particularly important in northern climates where year–round production is only possible in protected agriculture, and in urban areas where space is limited.

While we have advanced the understanding of energy, light, and water utilization in CEA, we still must further understand the potential of emerging technologies on energy and water optimization. The results of our previous project expanded knowledge on (1) the effect of irrigation practices and nutrient management on plant health, (2) the energy footprint and efficiency of different type of lights and production systems, and (3) sensors to monitor energy use. For the next project, we propose evaluating new greenhouse lamps, wavelengths of light, and layout designs and their effect on plant growth. We also aim to evaluate and design low energy alternatives to ventilate high tunnels, cool and heat greenhouses, and sensors to monitoring environmental conditions and plant growth. We will evaluate organic fertilizers for production of edible crops and test alternative growing media for container production. Finally, we will evaluate alternative irrigation methods and water sources to reduce the amount of fresh water for crop production. We will evaluate non-chemical alternatives to control diseases. Ultimately, we aim to measure energy and water consumption and develop saving strategies. We will deliver recommendations to commercial growers.

Our team consists of 24 members who represent 18 different experiment stations. Four members (FL, NH, IN, IL), are representatives of three new stations, who joined our group in the 2016–2017 period. Five new members (2 OH, IA, NC, MI) joined our group in this upcoming period. Our team has produced a total of 158 scholarly outputs which include 11 dissertations/theses, 1 book, 10 book chapters, 45 refereed journal articles, 20 symposium proceedings, and 71 presentation papers. Our team has also dedicated to translate research outcomes to stakeholders via 170 outputs, including 72 popular articles, 28 sponsored-workshops, 28 participations in workshops, and 42 other creative works. We have a long standing history of collaboration and productivity and the continuous enrollment of new and young faculty reflects the steady growth of our field of research.

The environmental conditions in each of our stations vary by location, nonetheless by conducting research as a multistate group we are able to develop robust models and then tailor research projects and recommendations to our local stakeholders. Moreover, our team brings together a complementary knowledge base that is essential for optimizing resource management in CEA. Members include greenhouse engineers, plant scientists, and an economist, all with practical experience in solving problems in multidisciplinary environments and direct contact with stakeholders.

Justification

A major benefit of growing plants in CEA operations is the ability to use sensors to monitor the production environment to make informed decisions about fertilization, irrigation, heating, cooling, and lighting. Over the last decade, new technologies have emerged in the industry with the potential to provide growers with alternatives to improve production efficiency and profit margins. However, science–based guidelines are needed for growers to make informed–decisions about the feasibility of implementing these technologies in their operations. Growers can achieve consistent production (i.e. increase crop cycles per year, reduce time from seed to harvest, and improve flowering regulation) by reducing temporal and spatial variation in the greenhouse environment. Our team believes that sensors and control strategies are essential for efficient production in CEA operations. CEA production systems range in technological complexity from high tunnels to highly controlled environments (e.g. plant factories). Strategies to control fertilization, irrigation, heating, cooling, and lighting will vary by CEA production systems. We aim to work with the whole range of CEA operations.

Heating, cooling and lighting options determine energy consumption and are strongly correlated with plant growth rate. Therefore, the efficiency of heating, cooling, and lighting have a direct impact in the bottom–line of businesses. Fan performance and ventilation alternatives to achieve homogeneous temperatures and humidity, temperature prediction models using thermal environment in high tunnels and greenhouses, and alternative lighting wavelengths, intensity and duration can be used to regulate plant growth and maximize outputs (production) per input (energy).

Water management is closely tied to nutrient management, particularly in greenhouse production where plants receive nutrients via fertigation. Automated–irrigation scheduling using sensor–based set–point irrigation has the potential to reduce water volume significantly. Despite the low–cost of water, we anticipate that economic benefits may result in terms of reduced labor, fertilizer injection, and disease incidence. Fertilizer reduction can also lower the environmental impact related to fertilizer runoff into natural habitats, and fertilizer mining and processing. CEA facilities can be designed or easily retrofitted to maximize water use efficiency, while at the same time minimize or eliminate leachate from contaminating the outdoor environment (e.g., recirculating ebb and flood irrigation). We propose to determine set–point irrigation control of different irrigation species in propagation and evaluate how alternatives substrates and water sources impact water use in container production.

In 2017, the National Organic Standard Board voted to allow USDA Organic certification of hydroponic production systems. This news provides CEA operations a gateway to a growing market. However, high efficiency in organic greenhouse production in not possible yet. Matching nutrient availability with crop demand is a major challenge in organic greenhouse production, which can have negative effects in plant quality and productivity. Nutrient release from organic compounds is linked to microbial activity, hence associated with environmental conditions and cultural practices that affect microbiological processes. We propose to develop nutrient release curves of organic–sources of fertilizer under multiple environmental conditions and provide recommendations on how to improve predictability of nutrient release.

Even though the U.S. is a pioneer in CEA, there is still a lot of room for resource optimization. For example, the water footprint global average (gal per pound) for tomato production is 25.6, the average in the U.S. is 15.2 which is 15 times more than the average in the Netherlands where the majority of crops are grown in greenhouses. Our team believes that optimization of resources used in CEA can result in significant reduction of agricultural inputs (water, fertilizer, and energy), increased production efficiency (days to harvest, crops per year, yields per square foot greenhouse), and lowered production costs.