Effects of different ground vegetation management systems on soil quality, growth and fruit quality of culinary apple trees

Abstract

SummaryContact and residual herbicide, polypropylene woven (plastic) and straw mulches were compared as ground vegetation management systems in a newly planted Bramley/M.9 apple orchard at HRI-East Malling, UK over an eight year period. The effects of these treatments on weed control, soil quality, tree nutrition, tree growth, crop yield and fruit quality were measured. Contact herbicide gave the poorest weed control, followed by residual herbicide.Very little weed intrusion occurred in the plastic and straw mulch treatments. The concentrations of soil biomass C, biomass N and respiration rates were consistently greatest under the straw mulch and contact herbicide, suggesting that C and N was incorporated into the soil biomass most efficiently under these treatments. Soil solution nitrate concentrations also were lowest under straw mulch and contact herbicide. The straw mulch increased the concentration of K in the surface soil (0–15 cm) compared with the other treatments, and this was reflected by consistently higher concentrations in the leaves of trees. The contact herbicide treatment had lower leaf concentrations of N in most years. Fruit mineral concentrations reflected leaf mineral concentrations. Trees growing in the straw mulch had the greatest shoot growth and those in the contact herbicide treated soil had the least. These increases are ascribed to the greater conservation of moisture within the profile during the shoot extension period. Differences in harvest yield between treatments were generally small in individual years, however cumulative differences occurred over six crops. Trees in the straw mulch had the greatest yields and mean fruit weights. The ground vegetation management systems did not influence fruit quality except in the second harvest, when yields were low and the individual fruit were large.