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An experimental assessment of the long-term effects of applying different forms of organic matter

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An experimental assessment of the long-term effects of applying different forms of organic matter on soil quality.

Lead scientist
Dr Paul Alexander, RHS
Partners
Reading University
Start date
2007
End date
2017
Keywords

Soil, Organic Matter, Carbon, Cultivation, RHS

Benefits to gardeners

The project results will enable the gardener to make an informed decision on whether it is necessary to apply organic matter annually, how it will affect their soil and which type of organic matter will suit their needs best.

With the results from this experiment, gardeners will be also able to better appreciate how they can potentially help mitigate climate change.

There are the additional benefits of engaging current and future RHS members, informing policy and contributing to the scientific community worldwide.
 

The problem

In agriculture and horticulture organic matter has long been seen as a useful method of managing soil and plant fertility. Focus is increasingly on the role soil management can play in climate change mitigation (through carbon sequestration) and this project will examine the role individual gardeners can play through the use of different forms of organic matter. However, long-term repeated annual applications of the same form of organic matter may also have detrimental affects on soil quality and subsequently plant health.

Approach

A 10-year field experiment has been set up at our trials site at Deers Farm, Wisley. This is a randomised and replicated (10 replicates) experiment where different forms of organic matter are applied annually to the same 3x3m plots. The forms of organic matter are double-chop mushroom compost, horse manure, bark/wood chip, Wisley green compost (at two application rates) and composted bracken. One replicate is also left bare.

An annual ‘crop’ of plants are grown on the plots to reproduce the nutrient ‘sink’ effect of plants in garden borders and best replicates gardening practices.

On an annual basis, soil analysis, plant nutritional analysis and general plant health are assessed.
 

Advisory information

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