Phosphorus fractions and dynamics as affected by land-use changes in the Central Mexican highlands |
| |
| Authors: | Jeannette S Bayuelo-Jiménez Takashi Muraoka Eulogio de la Cruz-Torres Esperanza Quintero-Ponce Lydia C Paredes-Gutiérrez Mohammad Zaman |
| |
| Institution: | 1. Instituto de Investigaciones Agropecuarias y Forestales, Universidad Michoacana de San Nicolás de Hidalgo, Tarímbaro, Mexico;2. Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, Brazil;3. Instituto Nacional de Investigaciones Nucleares, Ocoyoacac, Mexico;4. Soil and Water Management & Crop Nutrition Subprogramme, Department of Nuclear Sciences and Applications, Joint FAO/IAEA Division International Atomic Energy Agency, Vienna, Austria |
| |
| Abstract: | Land-use change from forest to agriculture in the volcanic ash-derived soils of Mexico has increased over recent decades. It is likely that land uses and management practices, particularly fertilizer use have affected phosphorus (P) distribution and availability. The objective of this study was to evaluate the effects of land-use types (native forest and maize mono-cropping), and the related P addition, on the forms and distribution of soil P and their isotopic exchangeability. An Andisol, sampled from a cropping site, along with the contiguous area under native forest was treated with 32P-labelled potassium phosphate (KH232PO4). The soil samples were extracted after incubation times of 7, 21, 35 and 49 days. Phosphorus content and 32P recovery in fractions sequentially extracted were assessed for each incubation time. Total soil P was dominated by inorganic fractions (79 to 86%) in both land-use types. Resin-Pi, bicarbonate extractable inorganic P (Bic-Pi) and sodium hydroxide extractable inorganic P (NaOH0.1-Pi) were all raised with P addition. However, the proportion of organic P fraction was reduced under cropped soil. The recovery of 32P in soils with P addition indicates that resin-Pi, Bic-Pi and NaOH0.1-Pi comprised nearly all the exchangeable P. In native soils with no P addition, more than 19% of the 32P was recovered in Bic-Po and NaOH0.1-Po forms. This finding indicates that organic P cycling is crucial when soil Pi reserves are presented in an inadequate amount. Ecologically based management has to be designed for replenishment and succeeding maintenance of soil organic P compounds to increase sustainable agricultural production. |
| |
| Keywords: | Andisol Hedley fractionation land use P exchangeability radioisotopic tracer |
|
|
