Less toil blog April 23 2018

Picture: Paul Flynn with field lab attendees                                   Credit: Neil Ferguson

By market gardener and attendee Max Johnson

With the wind battering down at Locavore’s Left Field farm in Neilston, this was a suitable day to blow out the cobwebs and get back to the elementals.

Perfect then, that today’s Field Lab was focused on one of the most fundamental topics: soil. Growers and farmers across the range of professionalism, experience and scale gathered to hear Paul Flynn, the Soil Association’s Crops and Soils Advisor, take a closer look at soil and how we can get the most out of it in the short- and long-term. This was combined with a visit to Left Field to learn some practical ways to get to know our own soils.

We learned to listen to your soils rather than the market pressures pushing you to work your ground early or too hard. For example, if fields are worked with machinery while the soil is too damp it can result in compaction, which in turn means worse drainage, reduced ability of plants to access nutrients, and can even result in denitrification. Of course, this risk is not as severe with no-till/no-dig approaches in which use of compaction-causing machinery is minimal or non-existent. In remedying damp soils, Paul urged the use of green manures, which stop rainwater from reaching the ground and allow lots of water to leave the soil through transpiration. On the practical side, we learned how to carry out a basic water infiltration test (see notes for details).

Picture: Locavore market gardeners Louis, Floortje and Beth

We then looked at soil structure and life, which are key not only to drainage issues but also to plant health and productivity. While quick fixes for a poor soil structure, such as lime and gypsum, were recommended, in the medium- to long-term Paul outlined how soil life such as earthworms, bacteria and fungi are vital in soil structure and nutrient availability. A good tip for gaining healthy soil life populations was to ensure there is always organic matter on the soil and to minimise rotavator use (which kills fungi and two thirds of earthworms with every pass!).  At Left Field, Paul then demonstrated practical tests for gauging soil composition, compaction, structure, and life (see notes for details).

Next up, we looked at soil pH and nutrient levels. The key issue here is that pH affects the ability of plants to absorb various nutrients, and that different crops prefer different pH levels. The pH can normally be adjusted within a year or two and here Paul proposed the use of lime, especially for those renting land, due to its cheapness and easiness to apply. With regards to nutrient levels, rock phosphates and compost were recommended and, again, green manures were brought up - this time as a means of resting and re-fertilising fields. To test pH, Paul recommended splashing out for a proper laboratory soil test, which he said was well worth the small investment to have certainty about what’s going on in your soil.

Despite us all hailing from fairly diverse farming and growing backgrounds, there was a sense that we all took a lot from the day, whether in theoretical knowledge or practical techniques. There was also a sense of respectful awe for the enormity of the topic at hand. The message, though, was simple and humbling: look after your soil and it will look after you.