Changes in Phosphorus Status of 'Cripps' Pink' Apple Trees After Application of Mulches

Abstract

The effect of four different mulches on fruit quality was quantified, either directly via mineral nutrient contributions or indirectly, by increasing nutrient uptake efficiency in the soil. We hypothesised that fruit nutrient levels would increase more when an organic mulch, containing nutrients, was applied to the soil, with smaller/no increases when an inorganic mulch was applied to the tree row.In this paper, we concentrate on changes in fruit phosphorus (P) concentrations after application of five treatments: a clean cultivated control, an inorganic woven geotextile fabric, and organic mulches -compost, wood chips and a vermi-castings/ wood chips combination. The trial was conducted on a commercial farm, Lourensford Estate, South Africa, from October 2008 to April 2012 -on an adjacent light, sandy and heavier, sandy-silt soil.Mineral nutrient analyses of the soil, leaves, mulches and fruit were performed. Yield and fruit size were determined. Soil temperatures and soil water status were recorded hourly during the last two seasons. P concentrations did increase chronologically from the soil, then into leaves and then into the fruit after application of mulches that provided additional P to the soil. Sporadic increases in both leaves and fruit occurred, but could not always be related to treatment effects. The significant consistent increase of P levels of the vermi-castings treatment in the heavy soil is likely to be a combination of reduced irrigation volumes, as well as a treatment effect.All mulches resulted in the well-established buffering of soil temperatures, soil water content and percentage soil carbon. Based on results from this study, it is not feasible to apply mulches for the sole purpose to increase P levels in the soil, leaves or fruit of established trees -although increases were noticed from time to time. In addition to water and temperature modifying effects of mulches that would differ between soil textures and depend on the mulch source, increases in P concentrations may result. As yield efficiency is still the primary factor determining income per hectare for the producer, the decrease in yield that resulted from mulching under these conditions, will still outweigh any positive contributions of mulches. It is therefore of utmost importance to first adjust irrigation volumes to a mulch treatment before the advantageous properties of mulching will be of value.

THE EFFECT OF SOIL MULCHING ON THE YIELDING OF HARDY KIWIFRUIT CULTIVARS (Actinidia arguta) IN CENTRAL POLAND

“…'Gold Millenium' did not affect significantly the tree growth and did not have positive effect on the total soluble solids of the fruit. Although Kotze et al (2015) proved that yield of mulched apple trees generally was higher in the lighter then heavier site. Very good growth of ornamental shrubs in containers, was also achieved when cut-rye straw was used for mulching, however in some species and cultivars vegetative growth reduction was also observed (Marosz 2012).…”

“…Some authors reported that mulching generally improves the root and shoot growth of plants (Harris et al 2004). Mulching improved the vegetative growth of apple trees in orchards (Szewczuk et al 2011;Kotze 2015), had a positive impact on the assimilation of some strawberry plant macroelements (Kęsik and Maskaleniec 2004), and positively affected the yielding of lingonberries (Laszlovszky Zmarlicka 2015). Mulches positively affected the pH and organic matter content of soil in the experiment with apple cv.…”