Preferences for different nitrogen forms by co-existing plant species and soil microbes: reply

The comment of von Felten et al. (2008) raises a number of interesting and valid points concerning the measurement of direct uptake of amino acids by plants. But, as they highlight, none invalidate our main finding that all plant species tested were able to take up the full range of amino acids presented to them, but that all preferred inorganic over organic N forms (Harrison et al. 2007).