Intensive cultivation of fruits and vegetables typically includes the use of polyethylene (PE) mulch (Lamont, 2005), partly because of its low cost and proven potential to increase yields and improve crop growth (Cirujeda et al., 2012). However, disposal of petroleum-based plastic mulches is a significant environmental concern that has led many growers to consider alternatives. Popular alternatives to PE mulches include organic mulches derived from agricultural or urban byproducts and waste [e.g., straw and newspaper mulches (Monks et al., 1997)], paper-based mulches (e.g., WeedGuardPlus; Sunshine Paper, Aurora, CO), or biodegradable plastic films and fabrics (Miles et al., 2012). Of these options, biofabrics and bioplastic films have demonstrated the greatest potential as commercial alternatives to PE mulch (Miles et al., 2012).
Bioplastic films have similar physical properties to PE and are typically effective in increasing soil temperatures relative to bare soil, which contributes to increased crop growth rate and yield (Cowan et al., 2014; Martin-Closas et al., 2008; Miles et al., 2012; Ngouajio et al., 2008). In contrast, most bioplastic films have lower tensile strength and mechanical resistance compared with PE (Martin-Closas et al., 2008). As a result, bioplastic films often degrade faster than PE during the growing season and are more susceptible to rips, tears, and holes during installation. Early deterioration of bioplastic films reduces their capacity for season-long weed suppression (Martin-Closas et al., 2008; Miles et al., 2012; Moreno and Moreno, 2008; Ngouajio et al., 2008; Waterer, 2010). Despite the potential shortcomings in season-long durability, fruit and vegetable crop yield is often similar between bioplastic and PE films (Martin-Closas et al., 2008; Miles et al., 2012; Moreno and Moreno, 2008; Weber, 2003).
Biofabrics are a relatively new concept and not yet commercially available. These mulches are typically spunbond, nonwoven fabrics composed of polylactic acid or polylactic acid in combination with polyhydroxyalkanoate (Cowan et al., 2014). One line of experimental biofabrics (SB-PLA-10/11/12; Natureworks, Blair, NE) was recently tested in vegetable cropping systems and some desirable characteristics were observed (Cowan et al., 2014; Miles et al., 2012). The fabrics were more durable than bioplastic films during the growing season (e.g., less visible deterioration and rips, tears, and holes) and the black biofabrics provided season-long weed suppression. By contrast, white translucent biofabrics did not provide acceptable weed control (Cowan et al., 2014). While bioplastic films tend to absorb and transfer solar radiation to the soil resulting in warmer temperatures, biofabrics, like organic mulches (e.g., straw), are less-effective conductors of heat and may even decrease soil temperatures (Larsson and Båth, 1996). As a result, crop yield increases, especially in cooler climates, are often greater for bioplastic films than for biofabrics (Cowan et al., 2014; Miles et al., 2012; Olsen and Gounder, 2001). In the absence of soil warming, the potential benefits of biofabrics are soil moisture retention and season-long durability and weed suppression. However, there is a concern that the more durable biofabrics may also be slow to decompose or biodegrade in the soil after the growing season (Cowan et al., 2013).
Decomposition of biodegradable mulch after the growing season is an important issue for growers. Slow degradation of a mulch (or any organic material) after soil incorporation can lead to accumulation of residue that may interfere with normal field operations (e.g., planting) or create an imbalance of carbon:nitrogen that contributes to nitrogen immobilization during subsequent growing seasons (Martens, 2001). Paper-based mulches decompose within 12 months of soil incorporation but are not durable enough to endure an entire field-based growing season (Li et al., 2014). Bioplastic films are slower to degrade than paper-based mulch, but certain products can be visibly degraded 13–24 months after soil incorporation, depending on local climatic conditions. A recently developed biofabric (i.e., SB-PLA-10) did not deteriorate during the growing season, but also showed little to no signs of biodegradation 13–24 months after soil incorporation (Cowan et al., 2013; Li et al., 2014). Thus, a balance is needed between durability during the growing season and rapid degradation after soil incorporation. Unfortunately, few biodegradable mulch products possess this necessary balance of properties.
Field performance (e.g., weed suppression and soil moisture retention) and soil decomposition of biodegradable mulches will also be influenced by the production environment. High tunnel production of fruits and vegetables is increasingly common. High tunnels create a microclimate that is markedly different from the field environment. In high tunnels, air and soil temperatures are warmer, wind speed is reduced or eliminated, direct solar radiation is reduced, and precipitation is eliminated (Miles et al., 2012; Wien, 2009). Moreover, reduced surface soil moisture throughout the high tunnel contributes to reduced weed emergence and growth, which may reduce the need for weed suppression from a given mulch product (Cowan et al., 2014). However, weed emergence within high tunnels will be greatest within the crop row where irrigation water is delivered from drip tape; thus, weed suppressive characteristics of biomulch are still important in high tunnels. Deterioration of biodegradable mulches in high tunnels is slowed during the growing season (Miles et al., 2012); however, the rate of decomposition of the mulch after soil incorporation was not different between field and high tunnel environments (Li et al., 2014). The latter result is somewhat surprising given the typical differences in soil moisture and temperature between field and high tunnel environments (e.g., warmer but drier in the high tunnel).
The objective of this study was to evaluate the field performance, durability, and decomposition following soil incorporation of four experimental spunbond, nonwoven biofabrics in comparison with two commercially available bioplastic mulch films and a bare soil control across field and high tunnel cucumber cropping systems.
CirujedaA.AibarJ.AnzaloneÁ.Martín-ClosasL.MecoR.MorenoM.M.PardoA.PelachoA.M.RojoF.Royo-EsnalA.SusoM.L.ZaragozaC.2012Biodegradable mulch instead of polyethylene for weed control of processing tomato productionAgron. Sustain. Dev.32889897
CowanJ.S.InglisD.A.MilesC.A.2013Deterioration of three potentially biodegradable plastic mulches before and after soil incorporation in a broccoli field production system in northwestern WashingtonHortTechnology23849858
CowanJ.S.MilesC.A.AndrewsP.K.InglisD.A.2014Biodegradable mulch performed comparably to polyethylene in high tunnel tomato (Solanum lycopersicum L.) productionJ. Sci. Food Agr.9418541864
Díaz-PérezJ.C.BatalK.D.2002Colored plastic film mulches affect tomato growth and yield via changes in root-zone temperatureJ. Amer. Soc. Hort. Sci.127127136
JenniS.D.BreultD.StewartK.A.2004Degradable mulches as an alternative for weed control in lettuce produced on organic soilsActa Hort.638111118
LarssonL.BåthA.1996Evaluation of soil temperature moderating and moisture conserving effects of various mulches during a growing seasonActa Agriculturae Scandinavica Section B Soil Plant Sci.46153160
LiC.Moore-KuceraJ.MilesC.LeonasK.LeeJ.CorbinA.InglisD.2014Degradation of potentially biodegradable plastic mulch films at three diverse U.S. locations. AgroecolSustainable Food Systems.38861889
Martin-ClosasL.PelachoA.M.PicunoP.RodriguezD.2008Properties of new biodegradable plastics for mulching, and characterization of their degradation in the laboratory and in the fieldActa Hort.801275282
MilesC.WallaceR.WszelakiA.MartinJ.CowanJ.WaltersT.InglisD.2012Deterioration of potentially biodegradable alternatives to black plastic mulch in three tomato production regionsHortScience4712701277
MonksC.D.MonksD.W.BasdenT.SeldersA.PolandS.RayburnE.1997Soil temperature, soil moisture, weed control, and tomato (Lycopersicon esculentum) response to mulchingWeed Technol.11561566
MorenoM.M.MorenoA.2008Effect of different biodegradable and polyethylene mulches on soil properties and production in a tomato cropSci. Hort.116256263
NgouajioM.AurasR.FernandezR.T.RubinoM.CountsJ.W.KijchavengkulT.2008Field performance of aliphatic-aromatic copolyester biodegradable mulch films in a fresh market tomato production systemHortTechnology18605610
OlsenJ.K.GounderR.K.2001Alternatives to polyethylene mulch film—A field assessment of transported materials in capsicum (Capsicum annuum L.)Austral. J. Expt. Agr.4193103
WortmanS.E.KadomaI.CrandallM.D.2015Assessing the potential for spunbond, nonwoven biodegradable fabric as mulches for tomato and pepper cropsSci. Hort.193209217
WortmanS.E.LindquistJ.L.HaarM.J.FrancisC.A.2010Increased weed diversity, density and above-ground biomass in long-term organic crop rotationsRenew. Agr. Food Syst.25281295