prof.dr.ir. JW (Jan-Willem) van Groenigen
Postdoc project Simon Jeffrey: "Soil Amelioration with Biochar in a Natural Ecosystem (SABINE) and Biochar Application to Soil in a Natural Ecosystem (BASE)"
These projects investigate the effects of biochar application to semi-natural grasslands. Both projects utilise an experimental site which is set up on the Veluwe national park in the Netherlands.
The first project, SABINE, looks at the mid to long term effects of two biochars over four successive years. Biochar was produced from grass cuttings collected from the site and pyrolysed in two separate batches at 400°C or 600°C. This was applied to soil at a rate equivalent to 10 t ha-1. The effects on on above ground and below ground communities have been monitored over the past four growing seasons. This has been combined with a range of soil chemical and physical analyses and greenhouse experiments to investigate mechanisms behind observed effects.
The second project, BASE, investigates the effects of biochar applied at different application rates up to 50 t ha-1 equivalents, on above ground productivity, plant community and soil physical effects (e.g. field-saturated flow and soil water release curves). This is combined with cutting edge characterisation of the chemical and physical properties of biochars, including X-ray microtomography.
Postdoc project of Ingrid Lubbers: "Functional diversity of soil invertebrates: a potential tool to reduce N2O emission? "
Soil biota play a crucial role in the mineralization of nutrients from organic material. However, they can thereby increase emissions of the potent greenhouse gas nitrous oxide (N2O). Our current lack of understanding of the factors controlling N2O emissions is impeding the development of effective mitigation strategies. The challenge is to control N2O emissions from production systems without reducing crop yield. Diversity of soil fauna may play a key role: high functional diversity of soil invertebrates (FDSI) is known to stimulate nitrogen mineralisation and thereby plant growth. It is still unknown whether high FDSI can concurrently diminish N2O emissions. Experimental studies are contradictory, reporting both increasing and decreasing emissions by single faunal species. However, faunal species occur in communities of interacting species. We will therefore study the effect of FDSI on N2O emissions from agricultural soils. We hypothesize that increased FDSI decreases N2O emissions by facilitating more complete denitrification through 1) stimulating the activity of denitrifying microbes; and 2) affecting the distribution of micro and macro pores, creating more anaerobic reaction sites. To test this hypothesis, we will establish invertebrate food webs in soil microcosms with different levels of functional diversity. We will use state-of-the-art molecular analysis to quantify denitrifier gene expression, and X-ray tomography to analyse fine-scale changes in soil structure. This integration of soil biological and -physical impacts on N2O emissions will enable us to resolve whether FDSI can promote nitrogen mineralisation without increasing N2O emissions. This is essential for the development of effective mitigation strategies.
Postdoc project Diego Abalos: Plant ecology for nitrous oxide mitigation and sustainable productivity (ECONOMY)
Nitrogen (N) application to plants causes agriculture to be the dominant source of nitrous oxide (N2O), a potent greenhouse gas as well as a major threat to the ozone layer. Our recent paper (Abalos et al., 2014) shows that if N is applied to plant combinations with complementary root traits and high biomass productivity, N2O emissions can be diminished due to increased plant N uptake. Based on the current understanding of the microbiology behind soil N2O emissions and of plant-trait based ecology, the 'ECONOMY' project aims to build on these findings and develop a novel N2O mitigation strategy. We will use trait-based ecology to reveal how plants and plant interactions can be used to reduce N2O emissions in a context of climate change related disturbances. Employing an approach that ranges from the microcosm scale to regional simulation, the project will ultimately establish a mechanistic understanding of the plant traits affecting N2O emissions while taking into account the provision of other ecosystem services.
PhD project Jeffrey van Lent: The effect of land-use change on soil greenhouse gas emissions from tropical peat forest of the Peruvian Amazon
Tropical lowland peatlands are considered as high priorities in climate change adaptation and mitigation strategies worldwide, mainly due to their exceptionally high carbon stock in combination with high deforestation rates. However, even though large bodies of tropical peat have been found elsewhere, estimates of stocks and potential losses after land-use change are lacking outside Southeast Asia. This study is the first in its kind to intensively measure carbon and nitrogen dynamics for such a system in Peru, outside Southeast Asia. Additionally, current available studies on LUC and tropical peat tend to focus on deforestation and conversion of land uses, while carbon and nitrogen dynamics following degradation are less well known. I will intensively measure CO2, CH4, N2O fluxes and carbon stocks changes in intact and degraded sites in the Peruvian Amazon; performing experiments to unravel driving factors between temporal and spatial dynamics of GHG fluxes. Further, I will scale up results to the ecosystem level, and will quantify and predict the impact of tropical peat swamp degradation. This project is part of the Sustainable Wetlands Adaptation and Mitigation Project (SWAMP, www.cifor.org/swamp), a collaboration between the Center for International Forestry Research (CIFOR) and the USDA Forest Service (USFS).
PhD project Mart Ros: "Improving utilisation of soil phosphorus on dairy farms"
Phosphorus is an essential nutrient for the growth of plants. Due to its immobile character in soil, it frequently is a growth-limiting factor for agricultural crops. In Dutch agriculture, farmers used to apply large quantities of phosphorus in the form of animal manure and inorganic fertilisers to maintain the availability of phosphorus for plant uptake and thereby to ensure high crop yields. Due to environmental legislation and increasing fertiliser costs, phosphorus application levels have decreased. In this project I look, within the system of a dairy farm, for ways to increase phosphorus use efficiency and plant availability under a limited phosphorus input. I do experiments focussing on: selection of different grass species, earthworms and their effect on phosphorus availability, and the importance of manure quality for plant phosphorus uptake. I also work with advance surface complexation models to better understand the interactions between manure, soil and plants in relation to phosphorus.
PhD Project of Syed Faiz-ul Islam: Reduced greenhouse gas emissions from intensified rice production systems"
Rice (Oryza sativa) is one of the most important agricultural staples; it feeds more than half of the world population. Rice production systems are vulnerable to climate change impacts as well as being a major contributor to greenhouse gas (methane and nitrous oxide) emissions. The two main challenges for rice production systems are increasing production to accommodate the growing world population, while simultaneously reducing GHG emissions. In a series of lab, greenhouse and field experiment, I investigate the potential of a range of organic fertilizers (manure, straw, compost, digestate, biochar), mineral fertilizers in relation to water management strategies to improve yield-scaled GHG emissions. I also investigate the socio-economic drivers for farmers to adopt climate smart management options. My project is a cooperation between Wageningen University, The University of Copenhagen (Denmark) and the IRRI research institute in The Philippines.