Are organic apples better for the soil? Study challenges assumptions.

An investigation into organic apple orchards in Australia has made a surprising discovery: their soils are remarkably similar to those of conventional orchards, where organic farming techniques aren’t used. This suggests that organic food labels don’t always indicate ecological conditions that are superior to the rest. The findings were based on soil samples taken from eight orchards in South Australia in 2023. Half of these were farmed conventionally, while the other half had been under certified organic management for seven years or more, involving a different approach to fertilizers and pesticides, among other things.

The researchers expected this to be reflected in the soil profiles, and they had two main assumptions here: that the organic orchards would have greater soil diversity and abundance than conventional orchards, and that organic soils would be closer to samples taken from unfarmed native soils in the surrounding area. On both counts, these assumptions proved to be wrong. The types of soil microbes did differ between organic and conventional plots—for instance organic plots had more dung saprotrophs, which are organisms like fungus that feed on decaying matter.

But that’s where the differences ended. When it came to the diversity and abundance of soil organisms, the two soil profiles were remarkably similar. The researchers go so far as to say that organic management had “no impact” on the diversity of soil microbes and fungi, compared to conventional plots.

.IRPP_ruby , .IRPP_ruby .postImageUrl , .IRPP_ruby .centered-text-area {height: auto;position: relative;}.IRPP_ruby , .IRPP_ruby:hover , .IRPP_ruby:visited , .IRPP_ruby:active {border:0!important;}.IRPP_ruby .clearfix:after {content: "";display: table;clear: both;}.IRPP_ruby {display: block;transition: background-color 250ms;webkit-transition: background-color 250ms;width: 100%;opacity: 1;transition: opacity 250ms;webkit-transition: opacity 250ms;background-color: #eaeaea;}.IRPP_ruby:active , .IRPP_ruby:hover {opacity: 1;transition: opacity 250ms;webkit-transition: opacity 250ms;background-color: inherit;}.IRPP_ruby .postImageUrl {background-position: center;background-size: cover;float: left;margin: 0;padding: 0;width: 31.59%;position: absolute;top: 0;bottom: 0;}.IRPP_ruby .centered-text-area {float: right;width: 65.65%;padding:0;margin:0;}.IRPP_ruby .centered-text {display: table;height: 130px;left: 0;top: 0;padding:0;margin:0;padding-top: 20px;padding-bottom: 20px;}.IRPP_ruby .IRPP_ruby-content {display: table-cell;margin: 0;padding: 0 74px 0 0px;position: relative;vertical-align: middle;width: 100%;}.IRPP_ruby .ctaText {border-bottom: 0 solid #fff;color: #0099cc;font-size: 14px;font-weight: bold;letter-spacing: normal;margin: 0;padding: 0;font-family:'Arial';}.IRPP_ruby .postTitle {color: #000000;font-size: 16px;font-weight: 600;letter-spacing: normal;margin: 0;padding: 0;font-family:'Arial';}.IRPP_ruby .ctaButton {background: url(https://www.anthropocenemagazine.org/wp-content/plugins/intelly-related-posts-pro/assets/images/next-arrow.png)no-repeat;background-color: #afb4b6;background-position: center;display: inline-block;height: 100%;width: 54px;margin-left: 10px;position: absolute;bottom:0;right: 0;top: 0;}.IRPP_ruby:after {content: "";display: block;clear: both;}Recommended Reading:Neither conventional nor GMO. What’s the place of ‘new genomic techniques’ in organic agriculture? The biggest differences were actually between farmed sites and native soils—though this difference did not go in the direction the researchers expected, because they found that native soils had significantly lower soil microbial and fungal biodiversity than the farmed land.

In fact overall, organic orchard soils were more similar to conventional soils than they were to native soils. What could explain this? The researchers think a main factor is that all plots including the organic ones were once farmed using conventional methods, which left a lasting legacy on the soil that organic methods haven’t yet managed to dispel.

What’s more, they found that farmers across both organic and conventional sites actually used several of the same techniques, such as mulching and ‘green manuring’, where crops like legumes are grown and incorporated into the soil to add nutrients. This complicates the binary organic/conventional divide—and might also explain the farms’ relative microbial richness compared to native soils. The study is small, and it considers just one food type in a specific location: by no means does it speak for all organic agriculture. But it does raise interesting questions about some of the assumptions we make when we see an organic label.

Instead of automatically assuming that organic produce indicates an ecologically superior system all round, the researchers suggest we need an approach that “moves beyond broad management labels” and also looks at the benefits of individual farming practices like green manuring to boost ecological health, whether on traditional or organic land. Matthews et. “Comparing apples and apples; evaluating the impact of conventional and organic management on the soil microbial communities of apple orchards.” Applied Soil Ecology.

Image: © Anthropocene. Made using AI.