³¹P‐NMR‐spectroscopic investigations of NaOH‐extracts from soils with different land use in Yucatan (Mexico)

In aqueous NaOH‐extracts of top‐soils (0‐10 cm) from typic chromuderts, phosphorus was determined by NMR‐spectroscopy. In addition to inorganic orthophosphate, orthophosphate monoesters and diesters were detected. Pyrophosphate was only found in traces after clear‐cutting and burning of the forests. The result of clear‐cutting and agricultural land use is an increase of inorganic P from 19% (forest) to 33% (maize field). Compost gardens and mature tree gardens contain only 9‐13% inorganic P in the NaOH‐extract. The organic P‐fraction consists mainly of orthophosphate monoesters (57‐72%). The orthophosphate diester content is only 10–21%. It could be shown, that the increase of inorganic P in the course of clear‐cutting and ploughing is correlated with a decrease of orthophosphate mono‐ and diesters.