researchers will investigate the introduction and management of green manures. The roller-crimper technology will be tested as a termination strategy. With this technique, the green manure is pushed downward on the soil in its generative growing phase and bruised, after which direct drilling or planting happens in the vegetal mulch. The impact of the use of this technique on the development of the main crop, nutrient dynamics, soil quality, greenhouse gas emissions, weeds, pest and disease control and fuel consumption will be investigated in vegetable organic cropping system.
Search for a soil quality indicator
In the current CCBT project “Effects of soil management and fertilization on the soil microbiology. Search for a simple indicator for soil quality” different microbial detection methods (Rusch-test, phospholipids composition of the cell walls) and the molecular technique DGGE are evaluated as indicator for the general soil quality. This is done based on soil samples of treatments in (multiyear) field trials with soil management under certified organic growing circumstances held by different experimental stations (PCFruit, PCG, Inagro en PPK). Biological parameters as well as a number of chemical soil parameters will be determined.
Contact:
• Koen Willekens, [email protected] • Alex De Vliegher, [email protected] • Jane Debode, [email protected]
Funding: ILVO, CORE Organic II ERAnet (TILMAN-org) (2011 - 2014) and CORE Organic Plus ERAnet (SoilVeg) (2015 - 2017) (Department of Agriculture and Fisheries, Goverment of Flanders), CCBT-project (2014 - 2015) ‘Effecten van bodembeheer en bemesting op de bodemmicrobiologie. Zoektocht naar een eenvoudige indicator voor bodemkwaliteit’ (“Effects of soil management and fertilization on the soil microbiology. Search for a
Microbial activity plays an important role in many soil functions. Bacteria and fungi degrade organic matter and ensure the release and/or bonding of nutrients. In addition, a healthy and active microbial soil life improves soil structure and plays a role in the resilience of the soil.
Different objectives
Within this CCBT project, the partners Inagro, PCG, PPK, PCFruit, Organic Farmers’ networks and ILVO examine together whether the Rusch test can serve as a good indicator of soil quality and whether this simple test can provide interesting information to the grower regarding his cultivation practice. In addition, we want to gain insight into the relations between soil management and soil microbiology in various sectors within the Flemish organic farming sector.
The exchange between more fundamental research (ILVO) and more practical research (applied research stations) is also an important aspect of the project: what do these microbiological tests teach us about soil quality and soil management of organic soils?
In search of a simple indicator of soil quality
The first part of the project consists of determining the soil microbiology on different organic fields across Flanders. Existing fertilisation experiments as well as currently-farmed fields will be examined. This allows us to explore the state of the soil under practical conditions with land that has been managed in the same way for several years. Three methods will be used to measure the soil biology.
The first of the three is the Rusch test, a relatively inexpensive and simple test developed by German doctor and scientist Hans Peter Rusch, which has seen little application as yet. This test includes a microscopic counting of the number of bacteria present in a soil extract in two ways. For the first technique, the soil extract is untreated and for the second technique, sugars are added to mimic the release of exudates in the soil by the roots. This results in the activation of the rod-shaped bacteria which are useful for plant growth. The greater the difference between the two techniques,
Is soil microbiology a good indicator of soil
quality?
the better the soil quality in biological terms. The other two more complex techniques (PLFA and DGGE) will be compared to the results from the Rusch test to determine whether they all lead to similar conclusions.
The chosen fields/plots will be monitored for two years. During the first year, in addition to analysing the soil microbiology, a number of chemical indicators of soil quality will be measured. This may be partly explanatory for the observed differences in soil microbiology (TOC, HWC, pH KCl, Ntot). The second part consists of knowledge exchange on the possibilities to determine the soil microbiology by the different methods as well as on the possible relationships between the microbial life in the soil and the soil management in practice, as derived from the analyses.
Contact:
Carmen Landuyt, [email protected]
Partner: PCFruit vzw, Inagro vzw (Deparment of Organic Production) PCG vzw, PPK, Biobedrijfsnetwerken (Landwijzer, BioForum), ILVO
Location: various locations in Flanders
Funding: CCBT-project ‘Effecten van bodembeheer en bemesting op de bodemmicrobiologie - Zoektocht naar een eenvoudige indicator voor bodemkwaliteit’ (“Effects of soil management and fertilisation on soil microbiology – Search for a simple indicator for soil quality”)(Department of Agriculture and Fisheries, Government of Flanders) (1/4/14 - 31/12/15)
Sustainable soil management should optimise soil condition in order to improve soil workability, reduce pressure from weeds, disease and pests, increase nutrient use efficiency, optimise the air-to-water ratio, and sustain crop yield and quality.
ILVO investigates how sustainable soil management can be accomplished, with a focus on (non-inversion) tillage and organic matter management. ILVO investigates the effect of these practices on nutrient dynamics, physical and biological soil quality, weed and disease pressure and crop yield. The research on soil improving practices such as non-inversion tillage and biochar and compost applications is based on long-term field experiments (BOPACT, BIOCHAR).
Results for compost and non-inversion tillage
In 2010, ILVO established the BOPACT field trial in Merelbeke. The name BOPACT refers to ‘impact of compost and crop husbandry (tillage/ fertilisation) on soil and pathogens’. The trial combines three factors, i.e. non-inversion tillage vs. mouldboard ploughing, cattle slurry vs. pig slurry and farm compost (2 tonnes C/ha.year) vs. no compost. The crop rotation consists of silage maize, potato, summer barley and leek. Cover crops are grown during autumn and winter.
In the first 4-year rotation, we could already detect effects of the treatments on soil quality. Non-inversion tillage caused a redistribution of organic carbon in the soil. The concentration of organic carbon in the top layer increased microbial biomass and soil aggregate stability, which makes the soil more resistant to erosion. After two compost applications, the organic carbon content and microbial biomass were already higher in the compost treatments compared to the non-compost treatments. We have not yet found a clear effect on the plant parasitic nematode Pratylenchus penetrans. The occurrence of the nematode was strongly dependent on the crop grown. The proliferation of the inoculated bacterial disease Dickeya solani was lower in the pig slurry plots compared with the cattle slurry plots, what could be explained by the higher N content of the potato tubers or the higher application of calcium with the cattle slurry. We could not detect clear effects of the treatments on crop yield and nutrient uptake yet.