Short-term effects of changes in soil management and nitrogen fertilizer application on ‘Bramley’s Seedling’ apple trees.

Abstract

Nitrogen concentration of fruits was reduced and P and B concentrations increased by changing from an orchard system of herbicide tree rows and mown grass alleys (66% bare soil) to complete grass cover. There was a tendency for higher Ca concentrations in the generally smaller fruits from trees in complete grass plots and, in one year, these fruits developed less bitter pit during air and CA (9% Co2 + 12% O2) storage than those from trees in herbicide strips. Fruits from complete grass plots, particularly those which had received nil N fertilizer, were firmer, redder with a more yellow background colour at harvest than those from strip plots. After CA storage fruits from grass plots remained firmer and tended to be less green. Changing from herbicide strip to overall herbicide management reduced fruit P (in the third year of the experiment) and B, and tended to reduce fruit Ca concentration; the latter effect was due to small increases in mean fruit weight. Fruits from overall herbicide plots tended to develop more bitter pit during storage. Fruit from herbicide strips and overall herbicide were of similar red coloration, greenness and firmness both at harvest and after CA storage. Increases in fruit N which resulted from application of N fertilizer (62.5 kg ha-1) to herbicide strip or overall herbicide plots were small compared with those which occurred in complete grass. Nitrogen fertilizer application to complete grass and herbicide strip plots reduced fruit P more than when applied to overall herbicide. Fruit B concentrations were reduced by N application particularly in complete grass. Nitrogen fertilizer applied to complete grass plots reduced fruit red colour, firmness and increased greenness. There was little effect of N application on the quality of fruit from herbicide strip or overall herbicide plots.