Soil analyses
Soil is our main working tool. It has physical, chemical and biological characteristics, in constant interaction, each influencing the others. The fuel of this system is carbon. This carbon is injected into the soil by the plant, notably through released exudates. These are sugars, of variable composition, derived from photosynthesis and released by the roots, feeding the soil. This means that the plant is an integral part of the soil, and must therefore be taken into account when thinking about “soil”.
Principle
In a functioning soil system, the interactions are such that biology makes available the nutrients present in the soil for the plant in the form, quantity, and timing it needs. The plant feeds the soil and the soil feeds the plant. The goal is to restore this virtuous circle in our agricultural systems.
We therefore work with a constantly moving environment, a complex ecosystem on which all our interventions have an impact, which we do not control. However, to better understand our influence and the evolution of this environment, we can rely on analyses to guide our future choices: understand to decide.
Different analyses
| Type of analysis | Objectives | Execution | Points of caution | Frequency | Examples |
|---|---|---|---|---|---|
| Spade test | Define soil structure, root establishment, decomposition of organic material, water infiltration… | In the field by the farmer | Compare what is comparable (weather…). | At least once a year | VESS |
| Soil chemical analysis | Long term: know the chemical elements in the soil and adjust them | In laboratory | Always work with the same laboratory. | Every 2 - 3 years | Kinsey - Albrecht |
| Sap analysis | Short term: more precise than dry leaf analysis. Correct imbalanced elements during the year | In laboratory | Sampling before 9 a.m. to get precise results on nitrogen and sugar. Send immediately after sampling.
Do not only do analyses at the “field edge”. |
Several times a year | Novacrop |
| Leaf analysis |
Determine nutrient imbalances in the plant |
In laboratory | Samples must be well dried. Less precise than sap analyses: imbalances are visible only after yield has been affected. | Several times a year | Waypoint |
| Soil biological analysis | Enter a virtuous circle: know the quality and biological functioning of your soil and monitor its evolution | In laboratory | Choose the analysis that suits you best. Do not change laboratories. | Every 2 - 3 years: always choose the same period in terms of climate | Chromatography
Microbial biomass Nematodes (Elisol) Microscopy |
| Field plant analysis | Visually identify plant imbalances | In open field | Master visual signs well.
Warning, once the imbalance is visible on the plant, yield has already been impacted. |
Regularly throughout the year | |
| Sap analysis at field edge | To measure pH, conductivity, nitrates and Brix | At field edge with portable measuring device | Information can be biased: a phosphorus deficiency can cause high Brix
Gives limited information depending on the device. |
Useful if measured before/after foliar applications in biology and/or nutrients | Horiba tools |
Source
This article was written with the kind contribution of Marie-Thérèse Gässler from Gässler SAS.
