Greenhouse Engineering:

A.J. Both, Rutgers University

Richard Gates, University of Illinois

Gene Giacomelli, University of Arizona

Murat Kacira, University of Arizona

Peter Ling, Ohio State University

George Meyer, University of Nebraska

Plant Production and Physiology:

Stephanie Burnett, University of Maine

Martin Gent, Connecticut Agricultural Experiment, New Haven

Meriam Karlsson, University of Alaska

Chieri Kubota, University of Arizona

Joyce Latimer, Virginia Tech

Richard McAvoy, University of Connecticut, Storrs

Neil Mattson, Cornell University

George Wulster, Rutgers University

Economics:

Robin Brumfield, Rutgers University

Statement of Issues and Justification

Statement of Issues:

Horticulture, including greenhouse production, is a vibrant and economically important sector of agriculture. The wholesale value of horticulture specialty crops (defined as greenhouse, nursery, and related crops such as seeds and vegetable transplants) was $11.7 billion in 2009, the last year such comprehensive data was available (USDA NASS, 2010). The members of our group serve growers in several states (AK, AZ, CT, ME, NE, NJ, NY, OH, PA, and VA) that encompass a large range of climate and growing conditions. Greenhouse and nursery production is ranked as the top grossing agricultural commodity in two member states: CT and NJ (USDA NASS, 2007). Greenhouse production, a.k.a. controlled environment agriculture (CEA), is particularly important for growers faced with temperate and colder climates that make structures such as greenhouses and high tunnels vital for season extension and year-round production of flowers and edibles.

Over the last decade, growers have been faced with resource management issues, particularly related to fuels for heat and water for irrigation, that have significantly impacted their livelihoods. Energy prices (oil in particular) have risen dramatically and as a result of shortages in some parts of the country, water (used mainly for crop irrigation) has not always been available in sufficient quantities to grow horticultural crops using traditional production practices. While year-round crop production in greenhouse facilities often requires significant amounts of water and energy, the fact that all aspects of the growing environment can be accurately controlled typically results in much higher resource use efficiencies per unit produced compared to outdoor field production. Hence the optimized resource management is vital for the successful future of CEA operations.

Greenhouse and nursery facilities are high input systems using vast amounts of water, fertilizers, chemicals, plastics, and labor to produce crops. Consumers are exhibiting greater degrees of environmental awareness, mass marketers are adopting strict purchasing guidelines that encourage environmental sustainability, and government policies to reduce carbon emissions have resulted in a demand for crops that not only meet aesthetic expectations but are also produced, distributed, and marketed using sustainable methods. The use of renewable and biodegradable inputs while growing an aesthetically pleasing and healthy plant will meet these demands. Green industry stakeholders have identified production practices which reduce plastic and water use as a major focus to increase sustainability even though the environmental and economic costs associated with these specific practices are undetermined.

The members of our team represent a complementary knowledge base that is absolutely essential for solving the resource management challenges facing the greenhouse industry. Members include greenhouse engineers, plant scientists and an economist with diverse areas of expertise and all have experience solving problems in multidisciplinary environments. Team members have frequent interactions with a wide variety of industry stakeholders and communicate regularly through presentations at regional and national meetings, trade publications, onsite grower visits, and informal contacts resulting from grower questions. In addition, they work closely with a large number of Extension agents in their respective states.

Our team proposes to address resource management issues related to water and nutrient applications, as well as to energy use. We propose to use sensors to collect improved information about the plant status, the growing environment and outdoor conditions. Thus, the whole continuum in the greenhouse and crop system is considered, evaluated, and decisions are made for optimized resource use. We want to develop and implement environmental control strategies that optimize resource management and maximize crop quality and yield, while also maximizing the economic return to the grower.

Justification:

The increased severity and duration of water shortages throughout many parts of the United States have revealed the importance of water management for crop production, including crops grown in CEA facilities. Climate change has, and will continue to, create prolonged drought that will make water an even more important issue for CEA in the future (IPCC, 2008). In some parts of the United States, water is limited not only in quantity (Ackerman and Stanton, 2011), but also in quality (e.g., hardness, acidity level, high or low concentrations of specific nutrients, contamination with undesirable constituents). Water management is closely tied to nutrient management, particularly in greenhouse production where plants typically receive nutrients along with every irrigation event (termed fertigation). When crops are fertigated, careful attention to watering practices such as the use of sensor-based irrigation or water capture and reuse are thereby also important to reduce the quantity of fertilizer applied (Burnett and van Iersel, 2008; Rose and White, 1994). A reduction in fertilizer inputs can directly reduce the environmental impact related to fertilizer mining and production. In addition, nutrients readily leach from root substrates and this can cause environmental problems on site and in neighboring soils and/or bodies of water (Bilderback, 2002). CEA facilities can be outfitted with systems that 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). However, only a limited number of greenhouse operations use the latest water and nutrient management technologies. Our team believes that further reductions in water and nutrient use can result in improved economics for CEA operations and enhance their environmental sustainability.

At the same time, significant increases in oil prices over the last decade have had a major impact on the greenhouse industry (Brumfield et al., 2009). In order to stay in business, growers have been looking for ways to reduce their fuel consumption (Mears et al., 2009; Both and Mears, 2008). They have implemented strategies to reduce greenhouse heat loss (Both et al., 2007b), installed more energy efficient equipment (Reiss et al., 2007) and investigated alternative energy sources (Both et al., 2011, Mears et al., 2009). While natural gas prices have not seen such a dramatic increase compared to oil prices, growers using natural gas have also been impacted because many supplies and most transportation depends on oil. Reductions in energy consumption per unit growing area also reduce the carbon footprint of greenhouse operations and this is becoming an important issue as consumers are increasingly concerned about sustainable production practices. Our team believes that additional energy savings are feasible and that they can improve the bottom line for CEA operations.

One of the major benefits of growing plants in a greenhouse is the ability to use environmental sensors to monitor the production environment and plant responses so as to make informed decisions about production processes such as fertilization, irrigation, heating, cooling, and lighting (Kacira and Ling, 2001; Kacira et al., 2002a, b; Nemali and van Iersel, 2006; Meyer and Camargo, 2008; Meyer et al., 2009; Story et al., 2010; Streimer et al., 2011, Kim et al., 2011; Li et al., 2012). Advanced growers utilize computer control systems and a variety of sensors and senor networks to accurately manage the greenhouse environment. The benefit of these systems is that they reduce temporal and spatial variation in the greenhouse environment, thus improving the conditions for uniform and predictable plant production. In addition, accurate climate control and proper control strategies can help reduce waste of resources and improve resource use efficiency. A variety of sensors are available in the market, but the challenge is to convince more growers of their value and teach them their proper use. Our team believes that sensors and control strategies are indispensible tools for efficient resource management in greenhouse operations.