Although increased and earlier yields were observed, the long-term effects needed to be determined, so HDC project TF 177 was set up to extend the trials for a further five years.
A Braeburn and a Cox orchard in Kent planted in 2004 have been included in the trial comparing trees mulched with composted green waste and trees growing in a bare herbicide-treated strip. Mulch was applied in 2004 and a second application was made to treated trees in 2007 with 30 tonnes/ha applied each time.
During the season, fruit diameter for each variety was recorded weekly and at harvest and fruit size, weight, yield and maturity measurements were recorded. Leaf and fruit analyses were carried out and storage potential was calculated. Soil moisture was also monitored at 10cm intervals down to 90cm.
For both varieties, fruit size and weight increased and overall yield increases were found in the Cox orchard. Water retention improved and increased vegetative growth occurred. Fruit starch, sugar and firmness measurements indicated that maturity was advanced by mulching.
Higher levels of nitrogen, potassium and magnesium were noted in leaf analyses. In soil analysis, potassium in particular increased dramatically where mulch was applied. A cautionary note is the observed increased uptake of potassium into the fruit leading to a decrease in phosphorus and calcium. This could have an adverse effect on storage potential.
Horticultural Development Company
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