Florida is one of the leading states for the commercial production of ornamental horticulture in the United States, producing $1.8 billion in crop value per year (U.S. Department of Agriculture, 2015). About 46% of the production area is used for container production (Hodges et al., 2016). In a survey of Florida nurseries, 76% of growers produced plants in containers, which represented 86% of all products sold (Hodges, 2011). In the United States, 65% of ornamental plants sold were grown in containers. Container production is resource intensive (hand labor, fertilizer, herbicide, etc.) and commonly occurs with overhead irrigation that inefficiently applies large volumes of water (Yeager et al., 2010). Although inefficient with regard to plant water use, overhead irrigation is the least expensive and most flexible method of applying water to container crops because spacing configurations change frequently as plants grow in size or are sold. The population of Florida is estimated to increase by 3 million residents by 2025 (University of Florida, 2017). Population growth in Florida will intensify the demand for water in the future. As water becomes more limited because of increased demand and/or periodic drought, container growers may need to justify their use of water.
Ornamental plants have been grown in a multipot box system with a significant reduction of inputs (water and energy) and increased growth parameters (Irmak et al., 2004). This system captures irrigation and rain water into an irrigation reservoir and shields the external sides of containers from solar radiation. However, the multipot box system does not address other factors such as the lack of weed control, the lack of ability to use existing nursery infrastructure, and the possibly prohibitive cost for large-scale adoption. A similar method could be used, without the reservoir, using a plastic mulch system. A plastic mulch system could improve favorably on some of the aforementioned limitations.
Horticultural crops, such as cucumber (Cucumis sativus), eggplant (Solanum melongena), melon (Cucumis melo), pepper (Capsicum annuum), potato (Solanum tuberosum), radish (Raphanus raphanistrum ssp. sativus), squash (Cucurbita pepo), and tomato (Solanum lycopersicum), have benefited from plastic mulch in field production, through water and fertilizer savings, yield increases, earlier fruiting, weed reductions, improved fruit quality, and soil temperature modulation (Lamont, 2005; Locascio et al., 1985; Ramakrishna et al., 2006; Ruidisch et al., 2013; Zhao et al., 2012). We believed that by using a novel method of placing low-density polyethylene mulch over the top of nonspaced (container-tight or pot-to-pot) containers during the beginning phase of the production cycle, similar to vegetable field–grown crops, similar benefits might be attained. The effectiveness of mulch in reducing water loss in container production varies by the study. Altland and Lanthier (2007) demonstrated production with a variety of organic and nonorganic mulch types. Hydrangea (Hydrangea macrophylla) grown with overhead irrigation in a primarily bark substrate had similar water demand to nonmulched control plants. Amoroso et al. (2010) similarly reported water loss from 3-L containers was mainly driven by transpiration of giant arborvitae (Thuja plicata) when mulches were used. By contrast, Argo and Biernbaum (1994) showed in subirrigated easter lily (Lilium longiflorum) grown in peat substrates, covering the surface with a plastic evaporation barrier resulted in 35% fewer irrigation events and 22% to 50% reduction in the amount of water applied compared with nonmulched control plants. Lohr and Pearson-Mims (2001) reported a reduction in frequency of irrigation of 34% with sphagnum moss mulch and a 13% reduction with pine bark (0.2- to 0.4-inch particle size) mulch.
We also believed, similar to other studies, that mulching might cause beneficial temperature modulation (Snyder et al., 2015), which might enhance growth, provide beneficial environmental impacts such as reducing fertilizer leaching (Argo and Biernbaum, 1994), and reduce the need for herbicides (Marble et al., 2017). The mulch might also minimize hand labor to remove weeds and pick up containers that blow over. An important consideration in our study and the use of a mulching method is that growers would have to make minimal costly changes to existing overhead irrigation infrastructure, and there would be no need to buy specialized equipment. The goal of our study was to determine if plastic mulch used over nonspaced containers would provide sustainable benefits (economic, environmental, and quality enhancement) to growers without additional production costs.
AmorosoG.FrangiP.PiattiR.FiniA.FerriniF.2010Effect of mulching on plant and weed growth, substrate water content, and temperature in container-grown giant arborvitaeHortTechnology20957962
ArgoW.R.BiernbaumJ.A.1994Irrigation requirements, root-medium pH, and nutrient concentrations of easter lilies grown in five peat-based media with and without an evaporation barrierJ. Amer. Soc. Hort. Sci.11911511156
Delta-T Devices2010User manual for the SM300 soil moisture sensor. SM300-UM-1.1. Delta-T Devices Cambridge UK
GilliamC.H.FareD.C.BeasleyA.1992Nontarget herbicide losses from application of granular Ronstar to container nurseriesJ. Environ. Hort.10175176
HodgesA.2011Production and marketing practices in the Florida nursery industry 2008. Univ. Florida Inst. Food Agr. Sci. FE894
HodgesA.KhachatryanH.RahmaniM.CourtC.2016Economic contributions of the environmental horticulture industry in Florida in 2015. Sponsored project report to Florida Nursery Growers and Landscape Assn. Univ. Florida Inst. Food Agr. Sci. Gainesville/Apopka FL
IrmakS.HamanD.IrmakA.JonesJ.CampbellK.CrismanT.2004Measurement and analyses of growth and stress parameters of Viburnum odoratissimum (Ker-gawl) grown in a multi-pot box systemHortScience3914451455
LiakatasA.ClarkJ.A.MonteithJ.L.1986Measurements of the heat balance under plastic mulches. Part. I. Radiation balance and soil heat fluxAgr. For. Meteorol.36227239
LocascioS.J.FiskellJ.G.A.GraetzD.A.HawkR.D.1985Nitrogen accumulation by peppers as influenced by mulch and time of fertilizer applicationJ. Amer. Soc. Hort. Sci.110325328
MarbleS.C.KoeserA.K.HasingG.McCleanD.ChandlerA.2017Efficacy and estimated annual cost of common weed control methods in landscape planting bedsHortTechnolgy27199211
RamakrishnaA.TamH.M.WaniS.P.LongT.D.2006Effect of mulch on soil temperature, moisture, weed infestation and yield of groundnut in northern VietnamField Crops Res.95115125
RuidischM.BartschS.KetteringJ.HuweB.FreiS.2013The effect of fertilizer best management practices on nitrate leaching in a plastic mulched ridge cultivation systemAgr. Ecosystems and Environ.1692123
SnyderK.GrantA.MurrayC.WolffB.2015The effects of plastic mulch systems on soil temperature and moisture in central OntarioHortTechnology25162170
U.S. Department of Agriculture20152012 census of agriculture: Census of horticulture specialties (2014). Vol. 3 Spec. Studies Part 3. AC-12-SS-3. U.S. Dept. Agr. Natl. Agr. Stat. Serv. Washington DC
University of Florida2017Population studies program. 14 June 2017. <https://www.bebr.ufl.edu/population>
YeagerT.H.WrightR.D.DonohueS.J.1983Comparison of pour through and saturated pine bark extract N, P, K, and pH levelsJ. Amer. Soc. Hort. Sci.108112114
ZhaoH.XiongY.LiF.WangR.QiangS.YaoT.MoF.2012Plastic film mulch for half growing-season maximized WUE and yield of potato via moisture-temperature improvement in a semi-arid agroecosystemAgr. Water Mgt.1046878