Growing high quality organic fruit and vegetables

In organic systems soil fertility and soil organic matter (SOM) levels in particular, depend on good balanced rotations and efficient use of manures and composts.

SOM has many roles, including providing food for soil organisms; providing nutrients for the crop; maintaining good structure and optimum moisture levels and generally promoting healthy, vigorous crop growth.

Recent research has also shown that organic approaches to soil fertility can bring benefits for consumers including higher levels of ‘healthy’ phytochemicals such as antioxidants and vitamins on the one hand, and lower levels of undesirable compounds such as heavy metals and glycoalkaloids in potatoes on the other.

In addition, improvements in taste and shelf-life can be attributed to slower delivery of nutrients to the plant and a better match between nutrient supply and crop demand at key stages of plant growth.

Non-chemical approaches to pest, disease and weed management and the prohibition of GM varieties in organic systems also have implications for quality.

Results from the Quality Low Input Food (QLIF) project also identified more subtle effects such as higher levels of vitamins in organic compared to conventional lettuce, attributed to the absence of pesticides in one study.

However, the same project showed that using insectproof netting on brassicas reduced levels of certain antioxidants, so the picture is still unclear.

Drought can influence the taste of some crops; for example lettuce that has been water stressed tastes bitter. Variety has a major influence on many aspects of quality and the trick is to work in partnership with your customers to find ones that suit both your growing system and their taste. Research in Switzerland found that taste descriptions at the point of sale helped get customers interested in, and become more accepting of, new varieties.

Organic Centre Wales has produced a series of factsheets covering the issues raised in this article in more detail. We will also be running a series of training days over the summer. Details on our website: www.organiccentrewales.org.uk.