Researchers have gathered science based information from different Nordic countries in a manual on how to check out the health of soil with low-tech methods, readily available and easy to use for farmers and others. The researchers also provide strategies for improving soil health.
During 2021-2022 researchers gathered in the network “Nordic Network on soil health” (NetSH). They shared research, knowledge and experiences on how to improve and sustain soil health in Nordic agricultural soils. They shared the most relevant low-tech methods for evaluating soil health with each other and in workshops.
Healthy soil functions are important for healthy soil-plant ecosystems on the farms, so strategies for farmers to improve and sustain soil functions, soil structure and soil biology have been in focus.
NetSH also held an open webinar, “Soil health in the Nordic region”, that gained a lot of attention with 130 participants. In addition to this, there were two online meetings and one on-soil workshop arranged by the network.
Photo: Reidun Pommeresche, NORSØK
MANUALS: How to check your soil?
Methods to evaluate soil health on farms has been demonstrated to make them available to as many as possible. Assessment of soil structure, soil compaction, root growth and soil biology has been discussed in the network and knowledge has been exchanged.
The most important tool is the spade combined with sensory evaluations, including pressing soil clumps between your fingers to evaluate how easily they brake and checking the smell of the soil in different depths.
The manuals are available in four Nordic languages:
• Danish: Tjek jordens sundhed
• Finnish: MARA Maan rakenteen aistinvarainen arviointi (2019) – Avointen oppimateriaalien kirjasto (aoe.fi) and Peltomaan laatutesti, Microsoft Word – Peltomaan_laatutesti_Havainto_ohjeet2.doc (proagria.fi)
These methods give a high score to soils with good structure with raisin shaped (rounded and porous) soil aggregates, deep and well growing plant roots, how easily the soil clumps brake, not to hard soil pans and the presence of several pink (inside) root noodles on legume roots and some earthworms in the soil. A healthy soil should relatively fast decompose organic matter, have some dark brown to black color due to organic matter content and have a smell of different fungi, like forest soils. All these methods include focus on comparing soil samples taken with a spade and to visualize and discuss soil functions and soil health with the farmers.
Compacted soil – a common Nordic problem
In the Nordic region we all experience the most severe soil problems in vegetable and cereal production. Much of this can be linked to soil compaction, with a very hard pan (zone) just below the tillage depth. But also in grass production there are soil structural and drainage challenges. In many cereal fields and some grass fields the straw and plant residues decompose very slowly or almost not at all.
In the Nordic region the soil types range from organic (peat) agricultural soils with more than 40 % soil organic matter to different mineral soils with low content of organic matter. In some areas the content of soil organic carbon (SOC) is creeping under 1,5 % (= 3 % soil organic matter SOM) which often is highlighted as a critical lower limit to several soil functions. In our Nordic cool conditions, we discussed that the content have to be higher than this for the soil to function well.
Some strategies to improve soil health
A selection of strategies to improve soil health in the Nordic region as discussed in the Network-meetings and on the workshop is listed here. The order of the key words is not ranked.
Mineral soil:
How to improve soil biology? Input of plant residues and other organic material, better crop rotations and plant diversity, enough water and oxygen in the soil, increase the content of SOM if it is very low.
How to improve aggregate stability? Ley (grass/clover) in the crop rotation, green plants most of the year, use of animal manure and compost, and liming with limestone or natural gypsum.
How to avoid soil compaction and improve soil structure? Lowering tire load and tire pressure and not driving on wet soil. Use a mixture of cover crops, sub crop in cereal and when deep tillage is used, sow plants immediately.
How to improve the decomposition rate of straw and plant residues in the soil? Cover crops, cut the material before incorporation, check for drainage problems. Oxygen and gas exchange very important for decomposition. Improve soil structure.
How to loosen a hard ploughing pan? Crop rotation + mechanically subsoiling, alfa alfa 2 years and animal manure/sludge.
Peaty soil:
In agricultural organic (peat) soil the aim should be to reduce carbon losses, instead of trying to increase the carbon content. Improve the soil structure from above, not plowing organic material to deep.
Let the spade become your friend
The Nordic farmer should use the spade to check their soils and a more diverse crop rotation as a start to improve soil health. Focus on soil structure and year around green plant cover will be useful in a future with a more unstable climate, with more heavy rains and droughts.
Contact
Sustain Nordic soil health (NetSH)
Reidun Pommeresche, Norwegian Centre for Organic Agriculture (NORSØK)