To investigate the effect of pyrolysis temperature on properties and nutrient values, biochars were produced from giant reed (Arundo donax L.) at 300-600 degrees C and their properties such as elemental and mineral compositions, release of N, P and K, and adsorption of N and P were determined. With increasing temperatures, more N was lost and residual N was transformed into heterocyclic-N, whereas no P and K losses were observed. P was transformed to less soluble minerals, resulting in a reduction in available-P in high-temperature biochars. A pH of <= 5 favored release of NH4+, PO43- and K+ into water. Low-temperature biochars <= 400 degrees C) showed appreciable NH4+ adsorption (2102 mg kg(-1)). These results indicate that low-temperatures may be optimal for producing biochar from giant reed to improve the nutrient availability. (C) 2012 Elsevier Ltd. All rights reserved.