Chemical characterization and agronomic effectiveness of phosphorus applied as a polyphosphate-chitosan complex

abonos chitin chitine clay soils engrais espectroscopia rmn fertilizers fosforo loam soils lolium perenne nmr spectroscopy phosphore phosphorus pirofosfatos polifosfatos polyphosphate polyphosphates pyrophosphate pyrophosphates quitina sol argileux sol sablolimoneux spectroscopie rmn suelo arcilloso suelo franco technique des traceurs tracer techniques