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.
Alef, K. 1998 Soil respiration, p. 217–224. In: Alef, K. and P. Nanniperi (eds.). Methods in applied soil microbiology and biochemistry. Academic Press, New York, NY
Atucha, A., Merwin, I. & Brown, M. 2011 Long-term effects of four groundcover management systems in an apple orchard HortScience 46 1176 1183
Atucha, A., Merwin, I.A., Brown, M.G., Gardiazabal, F., Mena, F., Adriazola, C., Goebel, M. & Bauerle, T. 2013 Root distribution and demography in an avocado (Persea americana) orchard under groundcover management systems Funct. Plant Biol. 40 507 515
Delate, K., McKern, A., Turnbull, R., Walker, J.T., Volz, R., White, A., Bus, V., Rogers, D., Cole, L., How, N., Guernsey, S. & Johnston, J. 2008 Organic apple systems: Constraints and opportunities for producers in local and global markets: Introduction to the colloquium HortScience 43 6 11
Glover, J., Reganold, J. & Andrews, P. 1999 Systematic method for rating soil quality of conventional, organic, and integrated apple orchards in Washington State Agr. Ecosyst. Environ. 80 29 45
Goh, K. & Ridgen, G. 1995 Understory biomass production and biological nitrogen fixation in an organic apple orchard in Canterbury, New Zealand Commun. Soil Sci. Plant Anal. 26 3261 3273
Granatstein, D. 2003 Organic 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>
Hansson, D. 1994 Acetic acid and Foraform (ammoniumtetraformiate) for weed control. Swedish University of Agricultural Sciences. Rapport 179. Alnarp. ISSN 0283-0086, ISRN SLU-LT-R-179-SE
Hansson, D. & Ascard, J. 2002 Influence of developmental stage and time of assessment on hot water weed control Weed Research Oxford 42 307 316
Hoagland, L., Carpenter-Boggs, L., Granatstein, D., Mazzola, M., Smith, J., Peryea, F. & Reganold, J. 2008 Orchard floor management effects on nitrogen fertility and soil biological activity in a newly established organic apple orchard Biol. Fertil. Soils 45 11 18
Johnson, E., Wolf, T., Caldwell, B., Barbour, R., Holm, R. & Sapsford, K. 2004 Efficacy 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>
Jordbruksverket 2014 23 Sept. 2014. <http://webbutiken.jordbruksverket.se/sv/artiklar/ovr228.html>
Markhart, A., Harr, M. & Burkhouse, P. 2005 Weed control in organic vegetable production: The use of sweet corn transplants and vinegar HortScience 40 1093
Marsh, K., Daly, M. & McCarthy, T. 1996 The effect of understory management on soil fertility, tree nutrition, fruit production and apple fruit quality Biol. Agr. Hort. 13 161 173
Melander, B. 1997 Optimization of the adjustment of a vertical axis rotary brush weeder for intra-row weed control in row crops J. Agr. Eng. Res. 68 39 50
Merwin, I. 2003 Orchard-floor management systems. In: Ferree, D.C. and I.J. Warrington (eds.). Apple—Botany, production and uses
Merwin, I., Rosenberger, D., Engle, C., Rist, D. & Fargione, M. 1995 Comparing mulches, herbicides, and cultivation as orchard groundcover management systems HortTechnology 5 151 158
Merwin, I., Ray, J. & Curtis, P. 1999 Orchard groundcover management systems affect meadow vole populations and damage to apple trees HortScience 34 271 274
Merwin, I. & Stiles, W. 1994 Orchard ground cover management impacts on apple tree growth and yield, and nutrient availability and uptake J. Amer. Soc. Hort. Sci. 119 209 215
Merwin, I., Stiles, W. & van Es, H. 1994 Orchard groundcover management impacts on soil physical properties J. Amer. Soc. Hort. Sci. 119 216 222
Neilsen, G. & Neilsen, D. 2003 Nutritional requirements of apple, p. 267–302. In: Ferree, D.C. and I.J. Warrington (eds.). Apples: Botany, production, and uses. CABI Publ., Cambridge, UK
Oliveira, M.T. & Merwin, I.A. 2001 Soil physical conditions in a New York orchard after eight years under different groundcover management systems Plant Soil 234 233 237
Page, A.L., Miller, R.H. & Keeney, D.R. 1982 Methods of soil analysis. Part 2. 2nd Ed. American Society of Agronomy and Soil Science Society of America, Madison, WI
Roper, T.R., Keller, J.D., Loescher, W.H. & Rom, C.R. 1988 Photosynthesis and carbohydrate partitioning in sweet cherry: Fruiting effects Physiol. Plant. 72 42 47
Sanchez, E.E., Giayetto, A., Cichon, L., Fernandez, D., Aruani, M.C. & Curetti, M. 2007 Cover crops influence soil properties and tree performance in an organic apple (Malus domestica Borkh) orchard in northern Patagonia Plant Soil 292 193 203
Sanchez, J., Edson, C., Bird, G., Whalon, M., Willson, T., Harwood, R., Kizilkaya, K., Nugent, J., Klein, W., Middleton, A., Loudon, T., Mutch, D. & Scrimger, J. 2003 Orchard floor and nitrogen management influences soil and water quality and tart cherry yields J. Amer. Soc. Hort. Sci. 128 277 284
Sandskär, B. 2005 Pests in fruit (Skadegörare i frukt). The Swedish Board of Agriculture (SJV), Jönköping, Sweden
SANCO 2013 Final review: Report for the active substance acetic acid. Rev. 4, /2602/08, 6 July 2013
Schmid, A. & Weibel, F. 2000 Das Sandwich-System—ein Verfahren zur herbizidfreien Baumstreifenbe- wirtschaftung? [The Sandwich System, a procedure for herbicide free in-row weed control?]. Obstbau 25 214 217
Stefanelli, D., Zoppolo, R., Perry, R. & Weibel, F. 2009 Organic orchard floor management systems for apple effect on rootstock performance in the midwestern United States HortScience 44 263 267
Stork, P. & Jerie, P. 2003 Initial studies of the growth, nitrogen sequestering, and dewatering potential of perennial grass selections for use as nitrogen catch crops in orchards Austral. J. Agr. Res. 54 27 37
Tahir, I. 2006 Prediction 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
Tahir, I., Johansson, E. & Olsson, M.E. 2005 Groundcover materials improve quality and storability of ‘Aroma’ apples HortScience 40 1416 1420
TerAvest, D., Smith, J., Carpenter-Boggs, L., Hoagland, L., Granatstein, D. & Reganold, J.P. 2010 Influence of orchard floor management and compost application timing on nitrogen partitioning in apple trees HortScience 45 637 642
Tesic, D., Keller, M. & Hutton, R.J. 2007 Influence of vineyard floor management practices on grapevine vegetative growth, yield, and fruit composition Amer. J. Enol. Viticult. 58 1 11
Varela, P., Salvador, A. & Fiszman, S. 2005 Shelf-life estimation of ‘Fuji’ apples: Sensory characteristics and consumer acceptability Postharvest Biol. Technol. 38 18 24
Weibel, F. & Häseli, A. 2003 Organic 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
Weibel, F., Tamm, L., Wyss, E., Daniel, C., Häseli, A. & Suter, F. 2007 Organic fruit production in Europe: Successes in production and marketing in the last decade, perspectives and challenges for the future development Acta Hort. 737 163 172
Weidenfeld, B., Fenn, L.B., Miyamoto, S., Swietlik, D. & Marlene, C. 1999 Using sod to manage nitrogen in orchard floors Commun. Soil Sci. Plant Anal. 30 353 363
Yao, S., Merwin, I., Bird, G., Abawi, G. & Thies, J. 2005 Orchard floor management practices that maintain vegetative or biomass groundcover stimulate soil microbial activity and alter soil microbial community composition Plant Soil 271 377 389
Zoppolo, R.J., Stefanelli, D., Bird, G.W. & Perry, R.L. 2011 Soil properties under different orchard floor management systems for organic apple production Org. Agr. 1 231 246