Soil quality and tree status in a twelve-year-old apple orchard under three mulch-based floor management systems

Interest in abandoning herbicide fallow as the standard in-the-row orchard floor management system continues unabated. Despite research efforts, available relevant data remain insufficient to formulate reliable recommendations for individual site conditions. A long-term experiment was therefore initiated in a temperate climate area in south-western Poland. 'Ligol' and 'Pinova' cultivar apple trees were planted in an unirrigated orchard in 2004, with treatment plot tree-rows mulched and control plots maintained with herbicide fallow. In 2016, black woven polypropylene fabric and Agrostis vulgaris With. and Festuca ovina L. living mulches were compared with the herbicide fallow in terms of their effect on soil properties, tree nutrient status and yields. While the living mulches had a positive influence on soil porosity, humus content and pH, there were substantial yield reductions; arguably due to competition for water. It is therefore important that more intensive methods of understory vegetation suppression are explored and more competition-resilient rootstocks sought to counteract yield loss. The polypropylene cover was primarily associated with a decreased leaf K:Ca+Mg ratio. A synthetic mulch is a viable choice for certain rain-fed orchards.