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Improvements in sensor technology coupled with advances in knowledge about plant physiology have made it feasible to use real-time substrate volumetric water content sensors to accurately determine irrigation timing and application rates in soilless substrates in greenhouse and container production environments. Sensor-based irrigation uses up-front investments in equipment and system calibration in return for subsequent reductions in irrigation water use and associated costs of energy and labor, spending on fertilizer, and disease losses. It can also accelerate production time. We present formulas for assessing profitability when benefits and costs are separated in time and apply those formulas using data from an experiment on production of gardenia [Gardenia augusta ‘MADGA 1’ (Heaven Scent™)]. Sensor-controlled irrigation cuts production time and crop losses by more than half. Annualized profit under the wireless sensor system was over 1.5 more than under the nursery’s standard practice, with the bulk of the increase in profit due to the reduction in production time. These results indicate that controlling irrigation using wireless sensor systems is likely to increase profitability substantially, even if efficiency gains are not as high as those achieved under experimental conditions.

Irrigation management systems that use wireless transmission of substrate moisture data are beginning to become commercially available for ornamental growers, particularly for use in soilless substrates. These systems allow growers to precisely monitor and control irrigation in real time and are being shown to save time and other resources. On-farm evaluations indicate that these systems have potential benefits extending beyond reductions in water use and associated irrigation inputs: Some growing systems experience increases in plant growth rates, with corresponding reductions in production time, whereas some experience reductions in disease pressure and corresponding plant losses. We asked ornamental growers across the nation what they see as potential benefits and limitations of these systems as a means of assessing the likely state of acceptance of this technology at the time of its initial introduction. Grower perceptions were overwhelmingly positive, with the majority of respondents agreeing that wireless sensor systems can increase irrigation efficiency, improve product quality, reduce product losses, reduce irrigation management costs, reduce disease prevalence, increase ability to manage growth, reduce irrigation management costs, and reduce monitoring costs. System cost and reliability were major concerns. Grower perceptions of the benefits and drawbacks of irrigation sensor networks varied across size and type of operation as well as geographically and by the type of water source used. Making wireless sensor systems affordable and robust will likely be critical determinants of the speed and reach of adoption of these technologies.

Restoration efforts in the Chesapeake Bay recently intensified with the 2010 introduction of federal total maximum daily load (TMDL) limits for all 92 bay watershed segments. These regulations have specific, binding consequences if any of the six states or the District of Columbia fail to meet interim goals, including loss of federal dollars for various programs and increasing regulation of point sources, if non-point source (agricultural and urban) nutrient reduction goals are not met in the watershed. As part of the effort to better understand and account for non-point sources of pollution in the watershed, a team of agricultural experts from across the bay region was recently assembled, including the nursery industry. The goal of this panel was to inform stakeholders and policymakers about the inputs and management practices used across all Bay states. To increase both the precision and accuracy of loading rate estimates, more precise information should guide future iterations of the Chesapeake Bay model. A more accurate accounting of land area by operation type (e.g., greenhouse, container, and field) is a primary issue for the nursery and greenhouse industry, because the current Chesapeake Bay model relies on USDA agricultural census data, which does not separate container and field production, which have very different nutrient and irrigation practices. Field operations also typically account for a higher percentage of production area in each state, which may skew model results. This is very important because the type of operation (field, container-nursery, or greenhouse operation) has a significant impact on plant density, types of fertilizer used, and application rates, which combine with irrigation and water management practices to affect potential nutrient runoff. It is also important to represent a variety of implemented best management practices (BMPs) in the Chesapeake Bay model such as vegetated buffer strips, sediment ponds, controlled-release fertilizer, and accurately assess how these mitigate both nutrient and sediment runoff from individual operations. There may also be opportunities for growers who have implemented BMPs such as low-phosphorus slow-release fertilizers (SRF), precision irrigation, etc., to gain additional revenue through nutrient trading. Although there are currently some questions about how nutrient trading will work, this could provide additional incentives for further implementation of BMPs by both ornamental and other agricultural growers. It is possible that the TMDL process currently being implemented throughout the Chesapeake Bay will be used as a remediation process for other impaired estuarine water bodies, which have similar water-use regulations and issues. The lessons learned about the Chesapeake Bay model in general, and for the nursery and greenhouse industry in particular, will likely provide guidance for how we can be proactive in reducing environmental impacts and protect the economic viability of ornamental growers in the future.

We describe and estimate the potential environmental benefits associated with the adoption of wireless sensor irrigation networks (WSIN) in United States ornamental crop production. Benefit estimates are based on results from on-farm research conducted during the previous three years, using both conservative and optimistic assumptions about the levels of WSIN technology adoption. We project reductions in water use and air and water emissions for six U.S. agricultural regions, the U.S. overall, and the six states that make up the Chesapeake Bay watershed. Based on these analyses, an average nationwide WSIN adoption rate of 50% in ornamental operations would result in annual water use savings of ≈223 billion liters (enough for 400,000 U.S. households annually) or a 25% reduction in total water use for all ornamental production. Reductions in annual carbon dioxide emissions, assuming only the reduced energy use from pumping less water was 36,232 Mg (equivalent to removing 7500 cars annually). Reduced fertilizer applications and more efficient irrigation resulted in reductions of 282,000 kg nitrogen and 182,000 kg phosphorous. These efficiency gains and nutrient discharge reductions have been shown to generate significant profits for growers, but would cost hundreds of thousands of dollars to achieve using conventional urban or agricultural best management practices (BMPs). If WSIN technologies are adopted in other areas of specialty horticulture (e.g., fruit, vegetable, and nut production) or in agronomic crops [e.g., corn (Zea mays) and wheat (Triticum sp.)], the indirect and induced private and environmental benefits will likely be much higher. Since the environmental benefits of WSIN technologies depend critically on adoption rates, we also briefly describe potential pathways to increase WSIN adoption such as providing technical assistance or offering financing or loan guarantees.

Quantifying the range of fertilizer and irrigation application rates applied by the ornamental nursery and greenhouse industry is challenging as a result of the variety of species, production systems, and cultural management techniques that are used. To gain a better understanding of nutrient and water use by the ornamental industry in Maryland, 491 potential operations (including multiple addresses and contacts) in the state were mailed a packet of information asking for their voluntary participation. Of the 491 potential operations, it was determined that 348 operations were currently in operation. Of those 348 operations, 48 (14% of the operations in the state) participated in a site visit and an in-depth interview, and a detailed site analysis of the water and nutrient management practices was performed on a production management unit (MU) basis. The authors define an MU as a group of plants that is managed similarly, particularly in regard to nutrient and irrigation application. Greenhouse operations reported, on average, 198, 122, and 196 kg/ha/year of nitrogen (N), phosphorus (P, as P₂O₅), and potassium (K, as K₂O) fertilizer used, respectively, for 27 operations, representing 188 MUs. Twenty-seven outdoor container nursery operations had a total of 162 MUs, with an average of 964, 390, and 556 kg/ha/year of N, P₂O₅, and K₂O fertilizer used, respectively. Field nursery (soil-based) operations were represented by 17 operations, producing 96 MUs, with an average of 67, 20, and 25 kg/ha/year of N, P₂O₅, and K₂O fertilizer used, respectively. Irrigation volume per application was greatest in container nursery operations, followed by greenhouse and field nursery operations. Data were also analyzed by creating quartiles, which represent the median of the lowest 25%, the middle 50%, and highest 75% of values. It is likely that the greatest quartile application rates reported by growers could be substantially reduced with little to no effect on plant production time or quality. These data also provide baseline information to determine changes in fertilization practices over time. They were also used as inputs for water and nutrient management models developed as part of this study. These data may also be useful for informing nutrient application rates used in the Chesapeake Bay nutrient modeling process.

This experiment measured plant growth of a halophyte (species adapted to saline conditions) confetti tree (M aytenus senegalensis) using runoff from kneeholy plants (R uscus aculeatus). Three irrigation treatments were used, a standard nutrient solution or control (T₀), runoff water collected from kneeholy plants irrigated with the standard nutrient solution blended 50:50 with tap water (T₁), and 100% runoff water collected from kneeholy plants irrigated with the standard nutrient solution (T₂), in which the nutrient concentrations were analyzed by high-performance liquid chromatography. Growth, photosynthetic parameters, and mineral composition were measured at the end of the experiment. Electrical conductivity and pH increased with increasing runoff application (decreased blending). Treatment 2 had significantly higher plant height, number of branches, number of leaves, leaf area index, and dry weight. Treatments 1 and 2 had significantly lower root lengths compared with the control. Chlorophyll concentration and green index color in leaves were greater in T₂ and T₁ than T₀. The mineral composition of roots and leaves was affected by irrigation treatment, resulting in an increase of sodium and chloride concentration and a decline of nitrogen and phosphorous concentration compared with the control. The reuse of runoff water was beneficial for growing this commercially important halophytic species in Spain, a consideration that is particularly relevant in locations with water quality, quantity issues, or both.