Land degradation usually leads to a reduction in soil fertility, decline of plant productivity, and loss of biodiversity. Introducing beneficial microbial inoculants to degraded lands represents a promising and sustainable strategy. The aim of this project is to reveal the ecological roles of microbial inoculants and soil-resident microbial community in restoring both belowground biodiversity and aboveground productivity in the degraded land.

Unsustainable agricultural management practices such as non-conservationist tillage and overuse of fertilizers result in soil acidity and, in turn, soil degradation due to reduced carbon (C) concentrations and nutrient availability and increased aluminum toxicity. Application of lime (L) and phosphogypsum (PG) can overcome these constraints and improve soil quality, but the long-term effects of these amendments on both abiotic and biotic soil properties are not known, particularly when applied in combination. Here, we evaluate the effects of L (acidity corrective), PG (soil conditioner), and their combination (LPG) on soil organic matter (SOM) transformations, soil chemical and physical properties, microbiome assembly, N uptake by intercropped plants, maize yield, archaeal and bacterial abundances, and N cycle genes in the maize and ruzigrass rhizospheres in a long-term field experiment in tropical soil with a no-till maize and forage ruzigrass intercropping system. 

Soil phosphorus (P) availability may limit plant growth and alter root-soil interactions and rhizosphere microbial community composition. The composition of the rhizosphere microbial community can also be shaped by plant genotype. In this project we examine the rhizosphere bacterial and fungal including Arbuscular Mycorhizal Fungi (AMF) communities of young plants of 24 species of eucalypts (22 Eucalyptus and two Corymbia species) under low or sufficient soil P availability.

The aim of this research is to understand how cover crop species combined with different times of N application affect the cover crop straw, nutrition and productivity of cash crop, soil chemical properties and soil microbial composition and function in a holistic approach of the entire agricultural system under tropical no-till system. Focus is on microbiome that immediately respond to the N application disturbances and in a long period to the plant cultivation, N inputs and soil properties changes. We use 3-year field experiment with palisade grass and ruzigrass cover crops and subsequent maize cash crop combined with different N management strategies to quantify the microbial genes of the N cycle and the bacterial and fungal communities’ structure and composition in the agricultural system.

The goal of this project is to decipher the role of fungal denitrifiers in N2O production from soils under sustainable management practices. Here we apply mesocosms experiments combined with SIP and meta-omics approaches targeting the functional genes of N cycle. In addition, we design primers for fungal denitrifiers based on complete fungal genomes and soil metagenomics data.  

The aim of this project is to determine the ecological relationship between bacteria and soil aggregates. We inoculate individual beneficial bacteria and different microbial communities from different natural soils in simulated Mars soil, attempting to explain their improvement in soil aggregate stability by bacterial exudates (EPS), necromass and microbial functional traits.

Sufficient Phosphorus (P) and Iron (Fe) supply is essential for crop production. Most of the P and Fe in soil is not readily available for the plant, making agriculture depending on inorganic fertilizers mainly derived from depletable resources. An alternative to this unsustainable practice is to use recycled compounds recovered during wastewater treatment. This project focuses on the use of the two recycled compounds struvite (MgNH4PO4·6H2O) and vivianite (Fe3(PO4)2·8H2O) which are both insoluble and hard to synchronize with the nutrient needs during early plant development. To increase efficient nutrient release of these recycled sources, we propose the use of microbes that can solubilize P and release siderophore, both recognized traits of plant growth promoting microbes. Several plant growth-promoting microbes have been isolated, but their transfer to agriculture, so far, resulted in an inconsistent success, due to competition or resistance of the resident soil microbiome to inoculants. This project will circumvent this challenge by steering the local microbiome with the addition of recycled nutrients and will further optimize the microbiome by microbial community breeding. Overall, this project will focus on identifying microbial community members with struvite and vivianite solubilizing function, optimizing these communities, determining the role of these communities on increasing the nutrient release as well as monitoring the recruitment of these beneficial microbes in the rhizosphere and the effect on plant growth.

The Maasheggen area is a unique cultivated landscape in the Netherlands (near Boxmeer, province Noord-Brabant) and has been designated as a UNESCO biosphere reserve (https://www.maasheggenunesco.com/en/). Its mosaic of hedgerows, small arable fields and meadows make this a very interesting area to study the effects of land use and landscape elements on functional biodiversity and ecosystem services.