Nitrogen competition in the rhizosphere
Professor Davey Jones, Environment Centre Wales, Bangor University, UK
Wednesday 24 March 2010, 1600-1700
Furness Lecture Theatre 2
Centre for Sustainable Agriculture Seminar
Although we generally consider nutrients to be taken up by plants and microbes in an inorganic form (e.g. phosphate, nitrate, ammonium, sulphate), dissolved organic nutrients also constitute a significant resource in many terrestrial and marine ecosystems. In many cases, they also represent one of the major nutrient loss pathways (e.g., in streamwater) although rarely are they included in ecosystem models. The importance of nutrients held in an organic form is becoming increasingly apparent as we start to understand the role they play in plant and microbial nutrition and plant-microbial signaling. One area of great uncertainty surrounds the cycling of dissolved organic N (DON) at the root-soil interface. While we understand little about the processes involved in this cycling, this has not stopped many researchers advocating it as one of the primary factors driving ecosystem development. Clearly we need to substantiate such claims, hence the nature of my talk. During the talk I will focus on DON. This will show how important it is as a source of N across global latitudinal gradients. I will also show how we have been investigating microbial-root competition for DON at the soil root interface using a range of isotopic tracking techniques. The talk will also present new data on recent analytical advances (i.e. NanoSIMS) which allow the visualization of stable isotopes (e.g. 15N) in plant-soil systems at the cellular and sub-cellular level.