Life in the Soil: The Basis for Agriculture and Nutrition

Soil quality research using a soil sampler.

Tiny organisms in the soil perform important functions for society as a whole, especially for the agriculture and food sector. These organisms constitute a focal point of Agroscope’s research.

Incredible but true: There are more living organisms in a handful of soil than there are people on Earth! These organisms include bacteria, fungi and algae, but also larger soil dwellers such as worms, beetles and woodlice. One aim of Agroscope’s research is to better understand the diversity of and services performed by soil organisms, and to create the scientific bases to safeguard the fertility of soils for future generations.

Soil organisms as service providers

Intact soils are a prerequisite for producing high-quality food, simultaneously promoting groundwater filtering, flood protection, carbon storage, biological nitrogen fixation and the decomposition of organic matter. Such services performed by nature – so-called ecosystem services – are dependent upon the organisms that live in soils.

In a widely noted research project conducted in 2014, Agroscope demonstrated just how important soil organisms are for efficient plant production. In a model system, crops were grown on soils containing different populations and quantities of soil organisms. In the treatment with artificially limited biological soil activity, plant yield was markedly lower. At the same time, nitrogen loss through leaching increased. To better understand these mechanisms, Agroscope conducts field trials to investigate which agricultural practices influence soil life during soil management, and develops recommendations for resource-efficient plant-production systems.

Stephanie Pfister analyses the DNA of soil samples.

However, the natural resource ‘soil’ – the habitat of the soil organisms – is threatened both in quantitative and qualitative terms. On the one hand, fertile soils that have formed over centuries in Switzerland are being lost every second owing to soil sealing; on the other hand, incorrect soil management techniques can lead to humus loss, erosion and compaction. The passage of heavy agricultural machinery over wet soils causes soil compaction, leading to waterlogging and oxygen deficiency. Using newly developed probes, Agroscope investigates when the state of the soil structure becomes critical for soil organisms and plant roots owing to insufficient oxygen availability. We also analyse how an unfavourable soil structure influences the availability and mobility of nutrients and pollutants. Such findings are applied in Terranimo – a decision-making tool for farmers developed jointly by Agroscope, the School of Agricultural, Forest and Food Sciences (HAFL), and EU partners for the purpose of avoiding soil compaction.

Focus on soil quality

In the context of the Swiss Soil Monitoring Network (NABO), Agroscope measures – in addition to other soil properties and on behalf of the Federal Office for the Environment (FOEN) and the Federal Office for Agriculture (FOAG) – soil contamination by heavy metals and selected organic pollutants at regular intervals at about a hundred sites. In addition, soil microbiological parameters have been analysed at thirty of these sites since 2012 as part of the NABObio programme. For this purpose, mixed samples from hundred-square-metre observation plots are used to measure microbial biomass and soil respiration, and to analyse the genetic material of soil microorganisms. A finding of this research was, for example, that from 2012 to 2014 microbial biomass and activity in grassland soils were greater than in arable soils.

Moreover, soil organisms may serve as indicators, since they can point out harmful changes in their habitat at an early stage. The NABObio project makes use of the rapidly developing field of molecular genetics, which has recently enabled us to explore the diversity of microorganisms. Launched by Agroscope in 2014, the ‘Microbial Biodiversity’ research programme investigates the totality of microorganisms and the functions of their most important representatives in plants, fermented dairy products and the soil. In this context, microbial biodiversity is explored in various soils and systems that are representative for Switzerland and the agricultural sector, in order to better understand the interaction of soil type, soil management, and soil-dwelling microorganisms. This information will contribute to a more comprehensive assessment of soil quality.

Sustainable management

Agroscope develops measures for regenerating damaged soils. For this, the natural swelling and shrinkage behaviour of soils is studied in compacted soils, together with the formation of soil pores through the activity of roots and earthworms. In addition to an intact soil structure, humus content is important for the quality of an agricultural soil. In 2014, Agroscope used a new method to calculate the humus balance of various farm types throughout Switzerland, thereby providing indications regarding the sustainability of soil use. Leaving root and crop residues in the field and applying organic and recycled fertilisers such as farmyard manure and compost provides soil organisms with nutrition and improves soil structure. This is confirmed by analyses of the measurements in the DOK long-term trial, in which integrated and organic cultivation systems have undergone comparison for over thirty years. Similar advantages for soils are provided by green-manure crops in combination with no-till cultivation systems, which are developed and tested by Agroscope for resource-efficient arable agriculture.

Agroscope not only generates new knowledge, however – it is also concerned with the transfer of this knowledge to practice. In 2014, Agroscope employees delivered numerous technical papers at field and advisory meetings of cantonal institutions, and made important contributions in both the education and policy advisory sectors. Here, principles were provided for the understanding of life processes in soils, and how these processes can be used for sustainable agricultural production.

 

DNA Analysis in a soil sample

The soil sample is removed from the drill core.

The analysis also requires the soil sample at the plant roots.

After the DNA is extracted from the soil, it is prepared for the analysis.

The analysis of the results shows what organisms were in the soil.