History of Controlled Environment Horticulture: Indoor Farming and Its Key Technologies

The most recent platform for protected horticultural crop production, with the shortest history to date, is located entirely indoors, lacking even the benefit of free, natural sunlight. Although this may not sound offhand like a good idea for commercial specialty-crop production, the concept of indoor controlled-environment plant growth started originally for the benefit of researchers—to systematically investigate effects of specific environmental factors on plant growth and development in isolation from environmental factors varying in uncontrolled ways that would confound or change experimental findings. In addition to its value for basic and applied research, it soon was discovered that providing nonlimiting plant-growth environments greatly enhanced crop yield and enabled manipulation of plant development in ways that were never previously possible. As supporting technology for indoor crop production has improved in capability and efficiency, energy requirements have declined substantially for growing crops through entire production cycles in completely controlled environments, and this combination has spawned a new sector of the controlled-environment crop-production industry. This article chronicles the evolution of events, enabling technologies, and entrepreneurial efforts that have brought local, year-round indoor crop production to the forefront of public visibility and the threshold of profitability for a growing number of specialty crops in locations with seasonal climates.

Inka Hydraulic Engineering at the Tipon Royal Compound (Peru)

The Inka site of Tipon had many unique hydraulic engineering features that have modern hydraulic theory counterparts. For example, the Tipon channel system providing water to the Principal Fountain had a channel contraction inducing critical flow as determined by CFD analysis- this feature designed to induce flow stability and preserve the aesthetic display of the downstream Waterfall. The Main Aqueduct channel sourced by the Pukara River had a given flow rate to limit channel overbank spillage induced by a hydraulic jump at the steep-mild slope transition channel location as determined by use of modern CFD methods- this flow rate corresponds to the duplication of the actual flow rate used in the modern restoration using flow blockage plates placed in the channel to limit over-bank spillage. Additional hydraulic features governing the water supply to agricultural terraces for specialty crops constitute further sophisticated water management control systems discussed in detail in the text.

Influence of Probable Precipitation Futures on Strawberries (Fragaria x ananassa): Results from a Simulated Rainfall Experiment

It is well established that the interacting effects of temperature and precipitation will alter agroecological systems on a global scale. These shifts will influence the fitness of specialty crops, specifically strawberries (Fragaria x ananassa), an important crop in the Northeastern United States. In this study, four precipitation scenarios were developed that are representative of current and probable-future growing season precipitation patterns. Using a precipitation simulator, we tested these scenarios on potted day neutral strawberries. This study generated four primary results: (1) though treatments received different amounts of precipitation, little difference was observed in soil volumetric water content or temperature. However, treatments designed to simulate future conditions were more likely those designed to simulate current conditions to have higher nitrate-in-leachate (N-leachate) concentrations; (2) neither total precipitation nor seasonable distribution were associated with foliar or root disease pressure; (3) while there was a slightly higher chance that photosynthetic potential and capacity would be higher in drier conditions, little difference was observed in the effects on chlorophyll concentration, and no water stress was detected in any treatment; and (4) leaf biomass was likely more affected by total rather than seasonal distribution of precipitation, but interaction between changing rainfall distribution and seasonal totals is likely to be an important driver of root biomass development in the future.

Farm Type and High Tunnel Management: Connections between Farm Characteristics and High Tunnel Outcomes in Indiana

High tunnels are a low-cost technology that can strengthen local and regional food systems and have been shown to help farmers extend the growing season and increase the yield and shelf life, and improve the quality of their crops. This study addresses a need for a better understanding of farmers’ experience with integrating high tunnels into their operations, to understand the human dimensions of high tunnel management. We present an analysis of survey and interview data to examine how farm characteristics affect the outcomes of growing specialty crops in high tunnels. Our findings show that farmers managing different types of farms have taken distinct approaches to integrating and managing high tunnels on their farms, with important implications for farm-level outcomes. We identify three types of farms commonly adopting high tunnels in Indiana: 1) alternative food and agriculture enterprises (AFAEs) are consumer-oriented, small-scale farms that sell their products directly to their customers in relationship-based market networks such as farmers’ markets and community-supported agriculture; 2) mixed enterprise farmers have larger operations and sell into both conventional commodity markets and direct markets; and 3) side enterprise farmers operate small-scale enterprises and their primary household income comes from off-farm employment or another business. Farm type is associated with divergent levels of time and labor investment, resulting in higher capacity use of high tunnels and greater financial return for AFAE farmers who make high tunnels central to their business, compared with mixed and side enterprise farmers who invest less time and labor into their high tunnels. We explain how farm characteristics and approaches to adopting the infrastructure shape farmers’ success and high-capacity use of high tunnels.

Determining the utility of an unmanned ground vehicle for weed control in specialty crop systems

Specialty crop herbicides are not a target for herbicide discovery programs and many of these crops do not have access to relevant herbicides. High‐value fruit and vegetable crops represent high potential liability in the case of herbicide‐induced crop damage and low acres for revenue. Labor shortages and higher manual weeding costs are an issue for both conventional and organic specialty crop growers. Robotic weeders are promising new weed control tools for specialty crops, because they are cheaper to develop and, with fewer environmental and human health risks, are less regulated than herbicides. However, many of the robotic weeders are too expensive for small growers to use. In the future greater investment into robotic weeders for small scale growers will be important. The Clearpath robotics platform Husky may provide a cheap and autonomous way to control weeds in small diversified specialty crop farms. Being able to work autonomously in multiple soil moisture environments is the driving factor behind optimizing the Husky platform for weed control. Research has been conducted to evaluate the impact of soil moisture and mechanical actuator on mobility and weed control. Though weed control was not commercially acceptable in these studies, future optimizations to the Husky robotics platform have the potential to achieve commercial success.

Recent Field Implementation of Contemporary and Smart Farming Technologies at the University of Maryland Eastern Shore

Smart farming experiential learning and research endeavors have been ongoing at the University of Maryland Eastern Shore (UMES) for the past several years. Recent field implementation of contemporary technologies for variable rate fertilizer application based on multispectral drone imagery; deployment of wireless solar powered soil moisture sensor network on a field with subsurface drip and fertigation capability; and development of a sustainable platform integrated with a Cartesian robotic device powered by solar and wind energy that can seed, weed, irrigate, and capture time-lapse photography while servicing a small raised bed for specialty crops and vegetables will be described in this paper. Results from the initial phase of implementation efforts and future goals will also be highlighted.

Agricultural Meteorology/Climatology

Agricultural meteorology (also referred to as agrometeorology) is the study of the effects of weather on agriculture, while agricultural climatology (alternatively, agroclimatology) is concerned with the effects of climate on agriculture. These fields of study share many of the same goals, philosophies, approaches, and methods. As a consequence, disciplinary boundaries are indistinct, and the terms “agricultural meteorology” and “agrometeorology” are increasingly used interchangeably with “agricultural climatology” and “agroclimatology.” Agricultural meteorology/climatology is oftentimes considered a bridge between the physical and biological sciences, although this interdisciplinarity increasingly includes the social sciences. While most research has focused on the production of food staples (e.g., maize, rice, and wheat), agricultural meteorologists and climatologists also address the influence of weather and climate on specialty crops, animal husbandry, commercial forestry, and aquaculture. Management of agricultural pests and diseases is another major focus. Atmospheric and biophysical processes operating at a wide range of temporal and spatial scales—from seconds to centuries and from an individual leaf to a global agricultural system—are explored. Agricultural meteorologists and climatologists promote the sustainable management of agricultural resources and strive to improve the livelihoods of agricultural stakeholders. Both basic and applied research are conducted to further these goals, and agricultural meteorologists and climatologists are often involved in the development, delivery, and evaluation of agricultural services. These services range from decision support tools for daily agricultural operations to services focused on seasonal or longer-term planning. Observations of the atmosphere-plant-soil environment are central to research and applications in agricultural meteorology/climatology, as are empirical and process-based models. Agriculture is highly vulnerable to climate variability and change, and potential adaptation strategies are widely investigated. Mitigation is also a concern as many agriculture activities emit greenhouse gases or contribute to land cover change. As other entries in Oxford Bibliographies address the theoretical aspects of atmosphere-plant-soil interactions (see “Land-Atmosphere Interactions” by Geoffrey M. Henebry, Nathan J. Moore, and Jiquan Chen), this entry primarily focuses on the applications-based literature in agricultural meteorology/climatology. The intent is to draw on both classic and recent literature to illustrate the nature of the research questions and applications of concern to agricultural meteorologists and climatologists, the approaches they use to address these questions and concerns, and the types of agricultural services they provide.

Imaging analysis method to quantify leaf deformation in response to sub-lethal rates of dicamba

Dicamba is a synthetic auxin herbicide that is prone to off-target movement, including drift and volatilization. Due to the increased acreage of dicamba-resistant soybean to control glyphosate-resistant weeds, dicamba drift injury to neighboring vegetable crops is of concern. A method to quantify leaf deformation (often referred to as leaf cupping) caused by dicamba injury was developed and compared to visual rating techniques to determine its accuracy and suitability. A second objective was to determine the relative dicamba sensitivity of several economically important vegetable crops. Soybean, snap bean, tomato, and cucumber were grown in the greenhouse and exposed to dicamba at 0, 56, 112, 280, 560, 1120, and 2240 mg ae ha−1, which is respectively 0, 1/10000, 1/5000, 1/2000, 1/1000, 1/500, and 1/250 of the maximum recommended label rate for soybean application (560 g ae ha−1). Plants were evaluated visually and using an imaging analysis technique where leaf deformation index (LDI) was measured using a leaf area scanner. LDI is calculated by dividing the two-dimensional projection of the area of the leaf in its natural configuration by the area of the flattened leaf. Across all four crops, log-logistic regression analysis indicated the LDI method had lower I50 values with lower standard error, demonstrating the LDI method gives more precise estimates of sensitivity. This novel method provides an objective, quantitative method to measure dicamba drift injury and determine relative sensitivities of valuable specialty crops.