Agro News - From Harvest to Roots: the Underground Journey!

You may have noticed that the harvest took place a few days ago. But while the fields might seem quiet, another story begins underground! To give you the inside scoop, Soil Capital went to the fields and conducted a spade test.

At Soil Capital, we support farmers in their transition to regenerative agriculture, which revitalises soil health and restores agroecosystems' natural fertility. It seeks to manage the land in harmony with nature, simultaneously creating ecosystemic and economic value.

As the harvest concludes, it is the perfect time to get our spades into the fields. This period offers an ideal opportunity to assess soil health and gather some insights for future plantings.

First of all, you may wonder, what is a spade test? As its name implies, it involves using a spade to dig into the soil and analyse it. Just as observing the stars helps you navigate through the night, studying the soil’s structure helps you plan and anticipate the next sowing periods - as long as you know how to interpret it, of course. Rest assured, this article aims to help you better decipher soil profiles.

Benefits of the spade test are numerous:

• Identify areas for improvement such as soil compaction, lack of organic matter, etc.
• Optimise the choice of plant cover based on the specific needs of each plot.
• Evaluate the possibility of reducing tillage for future plantings.

The picture below shows a spade test carried out on a plot of conventionally-managed Belgian loam soil.

We can observe a massive, closed structure on the first two surface horizons. There is little biological life, with no macroporosity and angular, geometrically-shaped aggregates.

?? A healthy soil tends to have more macropores, which are large pores facilitating water infiltration, root growth and a good aeration crucial for microbial activity. Moreover, angular, geometrically-shaped aggregates indicate soil disturbance and compaction, while healthier soil tends to display more rounded aggregates, allowing for more porosity.

In the third surface horizon, the presence of undecomposed straw in the ploughing furrow reflects a slowed-down biological life. The presence of carbon (=food), however, provides a better structure in the 15-25 cm horizon than in the surface horizons.?

?? Ploughing activities create a more compacted structure and turn straw residues within the soil. However, microorganisms responsible for decomposition need porosity and air to operate efficiently. In other words, ploughing disturbs the habitat of decomposers slowing down the decomposition process into organic matter, putting at risk the fertility of the soil.

Our aim will be to re-open the soil with a vertical tillage tool (such as a decompactor) to restore the natural verticality of the profile - previously disturbed by ploughing, turning the soil upside down. The installation of a cover crop with a wide diversity of roots will restore the structure of the horizons, with fasciculated roots on the surface to prepare the seedbed and tap roots to colonise the depths, feeding the biological life of the soil and refragmenting it.?

In the long term, the aim will be to raise organic matter levels to recover the soil's full fertility and exploit it at depth.?

By better understanding the processes that take place beneath our feet, we can put in place farming practices that are more respectful of the environment and more profitable in the long term.