Apple trees are relatively poor competitors with other vegetation because of their low root density per unit of soil, 1 to 10 cm root per cm3 compared with 103 cm per cm3 for grasses (Neilsen and Neilsen, 2003). Therefore, high tree productivity depends on low weed competition (Granatstein, 2003; Weibel and Häseli, 2003). In organic apple orchards, floor vegetative cover can be used to improve soil fertility and moisture retention, control soil erosion, increase yield, and develop fruit quality and storage potential, as well as reducing weed competition (Granatstein and Mullinix, 2008; Stefanelli et al., 2009; Zoppolo et al., 2011).
Herbicides are recognized as being a highly effective and relatively inexpensive method for limiting weed competition (Merwin, 2003). However, use of herbicides is very restricted in integrated apple production and they cannot be used in organic orchards as a result of potential adverse effects on the environment, human health, soil microbial activities, and groundwater quality (Atucha et al., 2011; Glover et al., 1999; Merwin et al., 1995).
Tillage within the tree row is a widely used weed control strategy in organic orchards. New equipment for weed control, which permits tillage between adjacent tree trunks, improves tree vegetative growth efficiency (TerAvest et al., 2010). However, tillage can have negative effects on the growth of young trees (Hogue and Neilsen, 1987) and on soil quality (Hoagland et al., 2008). It also increases nitrogen leaching from the root zone (Weidenfeld et al., 1999), impedes internal water drainage (Merwin and Stiles, 1994), disrupts surface roots (Cockroft and Wallbrink, 1996), and lowers soil cation exchange capacity and soil organic matter content (Wooldridge and Harris, 1991). To avoid these negative impacts, mechanical tillage should be replaced with new floor management systems that are productive under the constraints of organic fruit growing (Delate et al., 2008).
Acetic acid (vinegar) has been shown to be effective as a non-selective herbicide in controlling some weeds (Johnson et al., 2004). It is used as weed killer in organic orchards in the United States and it is authorized in several European countries such as Belgium, Denmark, France, Sweden, and the United Kingdom, where concentrations of up to 240 g·L−1 are used (Delate et al., 2005; SANCO, 2013). However, acetic acid may show poor suppression at low doses, damage low-hanging leaves on apple trees, and decrease soil pH (Markhart et al., 2005).
Although different natural and artificial mulches (such as legume biomass, wood chips, aluminum, bark, propylene) suppress weeds, maintain soil moisture, affect soil temperature, increase organic matter, and enhance soil microbial activities, their use is still restricted because they are expensive and labor-intensive (Sanchez et al., 2003; Tahir et al., 2005; Yao et al., 2005). They may also increase the populations of rodents and other pests (Granatstein and Mullinix, 2008; Merwin et al., 1999).
Establishment of one or more crops in the tree row (living mulch) to prevent weed competition can produce conflicting effects. In some studies it improved soil fertility and water-holding capacity (Merwin et al., 1994), but in others, it decreased root and shoot growth (Atucha et al., 2013; Merwin and Stiles, 1994), delayed fruit maturity, and reduced yield as a result of competition with the fruit trees (Goh and Ridgen, 1995; Marsh et al., 1996).
The “sandwich” system has been developed in Switzerland as a new method of living mulch combined with modified tillage. Annual or perennial crops are sown in a narrow strip (40 to 50 cm wide) within the tree row, whereas the soil to each side of this strip is tilled (Weibel et al., 2007). Weed control around the tree trunks can be avoided by having a low-growing vegetated strip and the narrow cultivated strip at each side of the tree row can provide a competition-free zone for tree roots (Schmid and Weibel, 2000; Weibel and Häseli, 2003). This method is reported to show the lowest costs for practical weed control without any negative effect on tree performance and yield (Stefanelli et al., 2009). The sandwich system can also decrease pests and diseases and increase biodiversity (Schmid and Weibel, 2000), improve soil conditions, and enhance nutrient cycling (Stork and Jerie, 2003; Yao et al., 2005). However, several challenges to sandwich systems must be resolved such as choosing living mulch mixtures that have minimal competition, avoiding rodent problems, and adjusting vegetation growth without any negative effects on apple yield, fruit quality, and storability.
The aims of the present study were to investigate different OFMS in an organic apple orchard adapted to a cool climate and evaluate their effects on weed management, soil nutrient content, and soil physical conditions as well as apple yield, quality, and storability to replace standard tillage with new floor management systems.
AlefK.1998Soil respiration p. 217–224. In: Alef K. and P. Nanniperi (eds.). Methods in applied soil microbiology and biochemistry. Academic Press New York NY
AtuchaA.MerwinI.A.BrownM.G.GardiazabalF.MenaF.AdriazolaC.GoebelM.BauerleT.2013Root distribution and demography in an avocado (Persea americana) orchard under groundcover management systemsFunct. Plant Biol.40507515
DelateK.McKernA.TurnbullR.WalkerJ.T.VolzR.WhiteA.BusV.RogersD.ColeL.HowN.GuernseyS.JohnstonJ.2008Organic apple systems: Constraints and opportunities for producers in local and global markets: Introduction to the colloquiumHortScience43611
GloverJ.ReganoldJ.AndrewsP.1999Systematic method for rating soil quality of conventional, organic, and integrated apple orchards in Washington StateAgr. Ecosyst. Environ.802945
GohK.RidgenG.1995Understory biomass production and biological nitrogen fixation in an organic apple orchard in Canterbury, New ZealandCommun. Soil Sci. Plant Anal.2632613273
GranatsteinD.2003Organic tree fruit research needs for Washington state. Center for Sustaining Agriculture and Natural Resources Washington State University Wenatchee WA. 24 Apr. 2007. <http://organic.tfrec.wsu.edu/OrganicIFP/OrganicFruitProduction/Organic%20TF%20Research%20Summary%20Sept03.pdf>
HanssonD.1994Acetic acid and Foraform (ammoniumtetraformiate) for weed control. Swedish University of Agricultural Sciences. Rapport 179. Alnarp. ISSN 0283-0086 ISRN SLU-LT-R-179-SE
HoaglandL.Carpenter-BoggsL.GranatsteinD.MazzolaM.SmithJ.PeryeaF.ReganoldJ.2008Orchard floor management effects on nitrogen fertility and soil biological activity in a newly established organic apple orchardBiol. Fertil. Soils451118
JohnsonE.WolfT.CaldwellB.BarbourR.HolmR.SapsfordK.2004Efficacy of vinegar (acetic acid) as an organic herbicide. Agriculture Development Fund (ADF) Project No. 20020202 and Agriculture and Agri-Food Canada (AAFC) Project A03637 Final report. University of Saskatchewan Saskatoon. 15 Oct. 2008. <http://www.agr.gov.sk.ca/apps/adf/adf_admin/reports/20020202.pdf>
Jordbruksverket201423 Sept. 2014. <http://webbutiken.jordbruksverket.se/sv/artiklar/ovr228.html>
MarkhartA.HarrM.BurkhouseP.2005Weed control in organic vegetable production: The use of sweet corn transplants and vinegarHortScience401093
MarshK.DalyM.McCarthyT.1996The effect of understory management on soil fertility, tree nutrition, fruit production and apple fruit qualityBiol. Agr. Hort.13161173
MelanderB.1997Optimization of the adjustment of a vertical axis rotary brush weeder for intra-row weed control in row cropsJ. Agr. Eng. Res.683950
MerwinI.2003Orchard-floor management systems. In: Ferree D.C. and I.J. Warrington (eds.). Apple—Botany production and uses
MerwinI.RosenbergerD.EngleC.RistD.FargioneM.1995Comparing mulches, herbicides, and cultivation as orchard groundcover management systemsHortTechnology5151158
MerwinI.RayJ.CurtisP.1999Orchard groundcover management systems affect meadow vole populations and damage to apple treesHortScience34271274
MerwinI.StilesW.1994Orchard ground cover management impacts on apple tree growth and yield, and nutrient availability and uptakeJ. Amer. Soc. Hort. Sci.119209215
NeilsenG.NeilsenD.2003Nutritional requirements of apple p. 267–302. In: Ferree D.C. and I.J. Warrington (eds.). Apples: Botany production and uses. CABI Publ. Cambridge UK
OliveiraM.T.MerwinI.A.2001Soil physical conditions in a New York orchard after eight years under different groundcover management systemsPlant Soil234233237
PageA.L.MillerR.H.KeeneyD.R.1982Methods of soil analysis. Part 2. 2nd Ed. American Society of Agronomy and Soil Science Society of America Madison WI
RoperT.R.KellerJ.D.LoescherW.H.RomC.R.1988Photosynthesis and carbohydrate partitioning in sweet cherry: Fruiting effectsPhysiol. Plant.724247
SanchezE.E.GiayettoA.CichonL.FernandezD.AruaniM.C.CurettiM.2007Cover crops influence soil properties and tree performance in an organic apple (Malus domestica Borkh) orchard in northern PatagoniaPlant Soil292193203
SanchezJ.EdsonC.BirdG.WhalonM.WillsonT.HarwoodR.KizilkayaK.NugentJ.KleinW.MiddletonA.LoudonT.MutchD.ScrimgerJ.2003Orchard floor and nitrogen management influences soil and water quality and tart cherry yieldsJ. Amer. Soc. Hort. Sci.128277284
SandskärB.2005Pests in fruit (Skadegörare i frukt). The Swedish Board of Agriculture (SJV) Jönköping Sweden
SANCO2013Final review: Report for the active substance acetic acid. Rev. 4 /2602/08 6 July 2013
SchmidA.WeibelF.2000Das Sandwich-System—ein Verfahren zur herbizidfreien Baumstreifenbe- wirtschaftung?[The Sandwich System a procedure for herbicide free in-row weed control?]. Obstbau25214217
StefanelliD.ZoppoloR.PerryR.WeibelF.2009Organic orchard floor management systems for apple effect on rootstock performance in the midwestern United StatesHortScience44263267
StorkP.JerieP.2003Initial studies of the growth, nitrogen sequestering, and dewatering potential of perennial grass selections for use as nitrogen catch crops in orchardsAustral. J. Agr. Res.542737
TahirI.2006Prediction of optimum harvesting date for some apple cultivars p. 1–10. In: Control of pre- and postharvest factors to improve apple quality and storability. Diss. SLU
TerAvestD.SmithJ.Carpenter-BoggsL.HoaglandL.GranatsteinD.ReganoldJ.P.2010Influence of orchard floor management and compost application timing on nitrogen partitioning in apple treesHortScience45637642
TesicD.KellerM.HuttonR.J.2007Influence of vineyard floor management practices on grapevine vegetative growth, yield, and fruit compositionAmer. J. Enol. Viticult.58111
VarelaP.SalvadorA.FiszmanS.2005Shelf-life estimation of ‘Fuji’ apples: Sensory characteristics and consumer acceptabilityPostharvest Biol. Technol.381824
WeibelF.HäseliA.2003Organic apple production—With emphasis on European systems. In: Ferree D.C. and I.J. Warrington (eds.). The CABI apple book. CABI Publishing Wallingford Oxon UK
WeibelF.TammL.WyssE.DanielC.HäseliA.SuterF.2007Organic fruit production in Europe: Successes in production and marketing in the last decade, perspectives and challenges for the future developmentActa Hort.737163172
YaoS.MerwinI.BirdG.AbawiG.ThiesJ.2005Orchard floor management practices that maintain vegetative or biomass groundcover stimulate soil microbial activity and alter soil microbial community compositionPlant Soil271377389
ZoppoloR.J.StefanelliD.BirdG.W.PerryR.L.2011Soil properties under different orchard floor management systems for organic apple productionOrg. Agr.1231246