IMPACT OF SOIL-MANAGEMENT SYSTEMS ON ORGANIC DWARF APPLE ORCHARDS ANDSOIL AGGREGATE STABILITY, BULK-DENSITY, TEMPERATURE AND WATER-CONTENT

With growing pressure to reduce pesticide use, fruit growers require a n alternative to herbicidal control of weeds. One option is the use of mulches or permanent vegetative ground covers, which in turn may have advantages in promoting soil physical properties and improving growth . This study examined the short-term effects of ground cover managemen t in two newly established dwarf apple orchards in Quebec. Effects of cultivation, composted manure mulch, straw mulch, grass cover crops, a cover crop mixture of lupin and wild carrot (mixed flora) and geotext ile were determined, comparing soil aggregate stability, bulk density, temperature, volumetric water content and tree growth. Straw and geot extile mulches resulted in higher soil water contents and tree growth relative to soil under grass or mixed flora ground cover. Ground cover maintained soil aggregate stability. Soil temperatures were highest u nder cultivation and geotextile treatments in spring and summer months , and apple yields and growth rates were greater than for ground cover treatments. Straw mulch buffered soil from temperature variation. Lit tle effect of mulch treatments on soil bulk density was observed. Give n that soil water content was the primary factor related to optimum or chard production, straw and geotextile mulches promoted soil water ret ention and could be considered superior management options for growers , depending on costs of establishment and maintenance of the mulches.