La fitotecnia en la Argentina

Una mirada retrospectiva hacia el rol de la fitotecnia en la Argentina permite identificar distintas etapas, que pueden ser caracterizadas por el perfil predominante en cada una, siendo en cada caso este perfil el motor de los adelantos que permitieron avanzar hacia la siguiente.Academia Nacional de Agronomía y Veterinari

La fitotecnia en la Argentina

Una mirada retrospectiva hacia el rol de la fitotecnia en la Argentina permite identificar distintas etapas, que pueden ser caracterizadas por el perfil predominante en cada una, siendo en cada caso este perfil el motor de los adelantos que permitieron avanzar hacia la siguiente.Academia Nacional de Agronomía y Veterinari

Contribution to characterisation of biochar to estimate the labile fraction of carbon

Different analytical techniques were used to find the most reliable and economic method for determining the labile fraction of C in biochar. Biochar was produced from pine, poplar and willow (PI, PO and WI, respectively) at two temperatures (400 and 550°C) and characterised using spectroscopic techniques [solid state 13C nuclear magnetic resonance spectroscopy (NMR)], molecular markers [pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS)], thermogravimetry (TG), elemental composition and wet oxidation (potassium permanganate and potassium dichromate). Short term incubation (110h) of an A horizon from an Umbrisol amended with the biochar samples at two doses (7.5 and 15tha-1) was also carried out to provide supplementary information on the influence of biochar-soil interaction on CO2 evolution. Spectroscopic analysis demonstrated that the degree of biochar carbonisation was influenced by the type of feedstock and heating conditions and followed the order WI-400<PI-400~WI-550~PO-400<PO-550<PI-550. The thermo-labile fraction of the biochar samples, estimated from TG, ranged between 21% and 49%. The fraction of total C oxidised with potassium permanganate (Cper/Ctotal) was <50gkg-1 in all cases, whereas potassium dichromate (Cdichro/Ctotal) oxidation efficiency ranged between 180 and 545gkg-1. For each type of feedstock, the highest values of either chemically or thermally degradable C corresponded to the biochar produced at low temperature. Results indicate that low cost methodologies, such as dichromate oxidation and TG, reflected the degree of biochar carbonisation, and could therefore be used to estimate the labile fraction of C in biochar. © 2011 Elsevier Ltd.The authors acknowledge financial support from the Ministry of Agriculture and Forestry of New Zealand. They would like to thank the staff of the Departmento Edafología y Química Agrícola, USC – Campus de Lugo, for the pressure plate measurements, and F. Jackson (Nutrition Laboratory, Massey University) for cellulose, hemicellulose and lignin content determination. R.C.P. was partly funded by the NZAGRC. J.A.M.-A. thanks the Spanish MCyT via the award of a Juan de la Cierva contract.Peer Reviewe