Managing the quality and quantity of global freshwater resources is one of the most imperative environmental challenges of the 21st century, with agriculture accounting for 70% of all global freshwater use (Fischer et al., 2007). Population growth and increasing urbanization worldwide have elevated competition for freshwater resources among domestic, industrial, and agricultural users, with agricultural water use deemed unsustainable in many parts of the world (Gleeson et al., 2012; Jury and Vaux, 2005). As a growing segment of agriculture in the United States, horticulture is not immune to water quality and quantity issues. Several U.S. states have regulations in place and/or are under federal mandates related to watershed-based agricultural irrigation withdrawals, including specialty crop intensive areas such as the Chesapeake Bay watershed (Lea-Cox and Ross, 2001) and Florida (Beeson and Brooks, 2008). Further restrictions are predicted by researchers and commercial nursery producers throughout the United States in the future (Beeson, 2004; Wilson and Albano, 2011). To meet the long-term freshwater needs of the world’s population, it is critical to increase the efficiency of agricultural water use (Howell, 2001; Knox et al., 2012). The use of moisture sensing technology is a promising avenue to address irrigation efficiency without compromising crop quality.
The use of technology has historically been the cornerstone of improving irrigation efficiencies, first in arid lands and modernized nations (Gleick, 2010) and more recently in developing nations (Wu et al., 2010). Examples of irrigation system components used to increase irrigation uniformity in specialty crops include drip, microirrigation nozzles, and matched precipitation sprinkler nozzles. These technologies have been incorporated into best management practices for the production of ornamental crops (Chappell et al., 2013), with the goal of reducing runoff of nutrient- and pesticide-laden water from production sites (Briggs et al., 1998; Lea-Cox and Ross, 2001; Tyler et al., 1996). However, good uniformity is only part of what is needed to achieve high efficiency, with the other component being application of the appropriate amount of water, based on crop water needs. Yet, the greenhouse and nursery industry has to date made little progress in the latter area.
Recently released commercial irrigation controllers that have improved irrigation efficiency in specialty crops include evapotranspiration (ET)-based controllers (Beeson, 2010) and ET plus daily light integral (DLI)-based controllers (Nautiyal et al., 2010). Although appropriate for homeowner applications, these controllers have proven to lack the accuracy required for many commercial agriculture applications, as data are frequently gathered for calculation of ET from weather reporting stations distant from the production facility using the controller technology (Crookston and Hattendorf, 2012). Additionally, if located on-site, instrumentation used to calculate ET and DLI can be inaccurate because of improper installation, calibration, and/or maintenance (van Iersel et al., 2013). For this reason, a simpler to operate and maintain irrigation control system, based on sensing of environmental conditions, is required for long-term adoption and use in commercial horticulture systems.
Jones (2007) concluded that monitoring of soil water content is the most valuable measure of plant or soil water status for the purpose of irrigation scheduling, as soil moisture monitoring consolidates all environmental conditions (e.g., temperature, light levels, humidity) into one measurement. For this reason, researchers over the last decade have initiated studies on the plausibility of using soil-moisture-based irrigation control to improve irrigation efficiency (Burnett and van Iersel, 2008; Garcia-Navarro et al., 2011; Miralles-Crespo and van Iersel, 2011; Warsaw et al., 2009). These studies indicate that using on-site, real-time sensing technology to monitor and control irrigation events serves three valuable purposes: 1) it reduces the number of environmental measures required to control irrigation to one, the volumetric water content of the soil or substrate; 2) it reduces the maintenance and calibration of sensors required to calculate an irrigation event to one, the capacitance-based soil moisture probe; 3) it uses on-farm data to determine soil moisture and therefore increases the precision and accuracy of environmental measurements compared with using measurements from off-site locations. Additionally, these data are easily integrated into existing, timer-based, irrigation systems and allows for easy automation (Jones, 2004). Despite this work, no automated irrigation control system based on soil moisture has been widely adopted by the greenhouse and nursery industry.
One reason for a lack of adoption of soil moisture-based sensor irrigation systems by the commercial nursery and floriculture industry has been a reluctance to implement any new irrigation technology without significant research, testing, and economic analysis; first in a controlled research setting and subsequently in on-farm settings. However, many soil moisture sensors have been developed in the last two decades (Blonquist et al., 2005) that can be used in specialty crop agriculture systems. This includes the widely adopted Acclima TDT control system (Acclima, Meridian, ID) developed for turfgrass applications (Blonquist et al., 2006). Yet, until recently, no soil-moisture-sensor-based control system (hardware) has been matched with a software package targeted to greenhouse and nursery producers.
Crops grown using WSNs in controlled research settings have included periwinkle [Catharanthus roseus (Kim and van Iersel, 2010; van Iersel et al., 2007)], lantana [Lantana camara (Kim and van Iersel, 2009)], ornamental cabbage [Brassica oleracea var. capitata (Miralles-Crespo and van Iersel, 2011)], hibiscus [Hibiscus acetosella (Bayer et al., 2013; Ferrarezi and van Iersel, 2011)], mophead hydrangea [Hydrangea macrophylla (O’Meara et al., 2011)], petunia [Petunia ×hybrid (Kim et al., 2011; Peter et al., 2011)], and snapdragon [Antirrhinum majus (Kim et al., 2012)]. These controlled research studies have demonstrated the utility of sensor-controlled irrigation. The subsequent step in facilitating adoption of this technology has been the on-farm implementation of soil-moisture-based irrigation hardware and software developed as part of the U.S. Department of Agriculture (USDA) Specialty Crops Research Initiative (SCRI) project (Kohanbash et al., 2013; Lea-Cox et al., 2013).
The objective of this manuscript is to describe the implementation and use of these WSNs at three commercial nursery and greenhouse operations in Georgia.
BayerA.MahbubI.ChappellM.RuterJ.van IerselM.W.2013Water use and growth of Hibiscus acetosella ‘Panama Red’ grown with a soil moisture sensor controlled irrigation systemHortScience48980987
BeesonR.C.Jr2004Modeling actual evapotranspiration of Ligustrum japonicum from rooted cuttings to commercially marketable plants in 12-liter black polyethylene containersActa Hort.6647177
BeesonR.C.Jr2010Modeling actual evapotranspiration of Viburnum odoratissimum during production from rooted cuttings to market size plants in 11.4-L containersHortScience4512601264
BeesonR.C.JrBrooksJ.2008Evaluation of a model based on ETo for precision irrigation using overhead sprinklers during nursery production of Ligustrum japonica grown in 11-L containersActa Hort.7928590
BlonquistJ.M.JrJonesS.B.RobinsonD.A.2005Standardizing characterization of electromagnetic water content sensors: Part 2. Evaluation of seven sensing systemsVadose Zone J.410591069
BlonquistJ.M.JrJonesS.B.RobinsonD.A.2006Precise irrigation scheduling for turfgrass using a subsurface electromagnetic soil moisture sensorAgr. Water Mgt.84153165
BriggsJ.WhitwellT.RileyM.B.LeeT.1998Cyclic irrigation and grass waterways combine to reduce isoxaben losses from container plant nurseriesJ. Environ. Hort.16235238
BurnettS.E.van IerselM.W.2008Morphology and irrigation efficiency of Gaura lindheimeri grown with capacitance-sensor controlled irrigationHortScience4315551560
ChappellM.OwenJ.WhiteS.Lea-CoxJ.2013Irrigation management practices. In: T. Yeager T. Bilderback D. Fare C. Gilliam J. Lea-Cox A. Niemiera J. Ruter K. Tilt S. Warren T. Whitwell and R. Wright (eds.). Best management practices: Guide for producing nursery crops. 3rd ed. 19 Sept. 2013 <http://contents.sna.org/bmpirrigation.html>
CrookstonM.A.HattendorfM.J.2012Two season comparison of nine smart irrigation controllers. Irr. Show Educ. Conf. Orlando FL 4–5 Nov. 2012. p. 381–384
FerrareziR.S.van IerselM.2011Monitoring and controlling subirrigation with soil moisture sensors: A case study with hibiscus. Proc. Southern Nursery Assn. Res. Conf. 56:187–191
FischerG.TubielloF.N.van VelthuizenH.WibergD.A.2007Climate change impacts on irrigation water requirements: Effects on mitigation, 1990-2080Technol. Forecast. Soc. Change7410831107
GleesonT.AlleyW.M.AllenD.M.SophocleousM.A.ZhouY.TaniguchiM.VanderSteenJ.2012Towards sustainable groundwater use: Setting long-term goals, backcasting, and managing adaptivelyGround Water501926
JonesH.G.2007Monitoring plant and soil water status: Established and novel methods revisited and their relevance to studies of drought toleranceJ. Expt. Bot.58119130
KohanbashD.KantorG.MartinT.CrawfordL.2013Wireless sensor network design for monitoring and irrigation control: User-centric hardware and software developmentHortTechnology23725734
KimJ.van IerselM.2009Daily water use of abutilon and lantana at various substrate water contents. Proc. Southern Nursery Assn. Res. Conf. 54:12–16
KimJ.van IerselM.2010Photosynthesis and water use of vinca (Catharanthus roseus) during drought: The effect of different drying rates. Proc. Southern Nursery Assn. Res. Conf. 55:114–120
KimJ.MalladiA.van IerselM.2011Physiological responses of petunia to different levels of drought stress. Proc. Southern Nursery Assn. Res. Conf. 56:46–51
KimJ.BelaynehB.Lea-CoxJ.2012Estimating daily water use of snapdragon in a hydroponic production system. Proc. Southern Nursery Assn. Res. Conf. 57:336–340
KnoxJ.W.KayM.G.WeatherheadE.K.2012Water regulation, crop production, and agricultural water management: Understanding farmer perspectives on irrigation efficiencyAgr. Water Mgt.10838
Lea-CoxJ.D.RossD.S.2001A review of the federal clean water act and the Maryland water quality improvement act: The rational for developing a water and nutrient management planning process for container nursery and greenhouse operationsJ. Environ. Hort.19226229
Lea-CoxJ.D.BauerleW.L.van IerselM.W.KantorG.F.BauerleT.L.LichtenbergE.KingD.M.CrawfordL.2013Advancing wireless sensor networks for irrigation management of ornamental crops: An overviewHortTechnology23717724
Miralles-CrespoJ.van IerselM.2011A calibrated time domain transmissiometry soil moisture sensor can be used for precise automated irrigation of container-grown plantsHortScience46889894
NautiyalM.GrabowG.MillerG.HuffmanR.L.2010Evaluation of two smart irrigation technologies in Cary North Carolina. Proc. Amer. Soc. Agr. Biol. Eng. Conf. Paper No. 1009581
O’MearaL.ChappellM.van IerselM.2011Water consumption of Hydrangea macrophylla as affected by environmental factors. Proc. Southern Nursery Assn. Res. Conf. 56:162–166
PeterA.O.ThomasP.A.van IerselM.2011Growth of petunia as affected by substrate moisture content and fertilizer rate. Proc. Southern Nursery Assn. Res. Conf. 56:167–172
TylerH.H.WarrenS.L.BilderbackT.E.1996Cyclic irrigation increases irrigation application efficiency and decreases ammonium lossesJ. Environ. Hort.14194198
van IerselM.KangJ.BurnettS.2007Making greenhouse irrigation more efficient: Effects of substrate water content on the growth and physiology of vinca (Catharanthus roseus). Proc. Southern Nursery Assn. Res. Conf. 52:92–96
van IerselM.SeymourR.M.ChappellM.WatsonF.DoveS.2009Soil moisture sensor-based irrigation reduces water use and nutrient leaching in a commercial nursery. Proc. Southern Nursery Assn. Res. Conf. 54:17–21
van IerselM.W.ChappellM.Lea-CoxJ.D.2013Sensors for improved efficiency of irrigation in greenhouse and nursery productionHortTechnology23735746
WarsawA.L.FernandezR.T.CreggB.M.AndresenJ.A.2009Water conservation, growth, and water use efficiency of container-grown woody ornamentals irrigated based on daily water useHortScience4413081318
WilsonP.C.AlbanoJ.P.2011Impact of fertigation versus controlled-release fertilizer formulations on nitrate concentrations in nursery drainage waterHortTechnology21176180
WuP.JinJ.ZhaoX.2010Impact of climate change and irrigation technology advancement on agricultural water use in China: A letterClim. Change100797805