Abstract

GIANNINI, Ana Paula; ANDRIULO, Adrian Enrique; WYNGAARD, Nicolas  and  IRIZAR, Alicia Beatriz. PHOSPHORUS FRACTIONS UNDER DIFFERENT MANAGEMENTS. Cienc. suelo [online]. 2022, vol.40, n.2, pp.196-207.  Epub Apr 21, 2023. ISSN 1850-2067.

Phosphorus (P) is one of the nutrients that most limits agricultural production. Worldwide, the Pampas region has the highest edaphic P deficits. As its existence in the soil varies from ions in solution to very stable organic and inorganic compounds, it is necessary to carry out studies at different spatial-temporal scales to survey the most affected P fractions. The objectives of the present work were: a) to evaluate different P fractions before the agriculture introduction and the long-term changes in a typical Argiudol Pergamino series under two controlled situations with 35 and 105 years of continuous agriculture and, b) to evaluate long-term changes of these P fractions in the same soil series under the agriculture performed at regional level. The following P fractions were determined: total (PT), inorganic (Pi), organic (Po), and extractable P (Pe). The P reserves of the A horizon decreased 20 and 42% (PT), 20 and 58% (Pi) and 20% (Po) with 35 and 105 years of continuous agriculture, respectively, in relation to the reserves of PT, Pi and Po of the pseudo pristine situation. For its part, agriculture practiced at regional scale decreased by 29% (PT), 33% (Pi) and 20% (Po) compared to the pseudo-pristine situation. The Po declined in the first decades of agriculture. Subsequently, it would not contribute to crop nutrition. The PT reserve continued to decrease at inorganic fraction expense, visualized in the abrupt drop in Pe (92%), which was below the range of typical values reported for the rolling pampas sub region. The prevailing cropping system puts at risk the nutritional status of soils and the productivity of agroecosystems.

Keywords : organic phosphorus; inorganic phosphorus; extractable phosphorus; soil.

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