Soil type affects biological phosphorus cycling more than soil management.

GILI, ADRIANA; ALBERTO QUIROGA; ELKE NOELLEMEYER; FRASIER, ILEANA; M. UHALDEGARAY; FLORENCIA GÓMEZ; LUCILA ÁLVAREZ; ROMINA FERNÁNDEZ

GEODERMA

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2022 vol. 426

0016-7061

There is a need for more sustainable management of phosphorus (P) fertilization including reutilization of wastesand taking more advantage of the biological cycling of P in the crop-livestock-soil system to comply with theSustainable Development Goals. The objective of the present study was to evaluate the effect of soil type andmanagement on microbial carbon (C) and P transformations (mineralization-immobilization processes) and theirseasonal fluctuations throughout the year to assess the feasibility of enhancing biological P cycling by changingcrop rotations. A sandy loam petrocalcic Paleustoll with a calcium carbonate hardpan at approximately 0.8 mdepth, and a sandy typic Ustipsamment were selected in the Argentinean semiarid Pampa. Soil managementtreatments were a 50-year-old Weeping Lovegrass pasture (PP) and three agricultural plots belonging to longtermtrials with and without cover crops under no-till: maize monoculture (M􀀀 M), maize-rye (M􀀀 R), andmaize-vetch (M􀀀 V). Soil microbial biomass C and P (MBC, MBP), soil respiration, metabolic quotient, Pmineralization rate, and anion exchange membrane extractable P (solution P) were determined during winterand spring of 2017, and summer and autumn of 2018 at 0?0.05 and 0.05?0.10 m depth. Results indicated thatdifferences in the relationships between MBP and MBC were mostly influenced by soil type. In the Paleustoll, thisrelationship showed a threshold value of 94.7 μg MBC g􀀀 1 where soil microbial biomass P reached a maximumvalue of 6.6 ug MBP g􀀀 1. No relationship between P mineralization rate and MBP was observed in this soilindicating P limitation explained by the negative relationship between exchangeable calcium and solution P. Oncontrary, a positive and linear relationship between MBP and MBC was found in the Ustipsamment, which wasaffected by the season of the year. A nonlinear relationship between metabolic quotient and MBP was found inthe Ustipsamment but not in the Paleustoll. Soil management was more related to microbe-plant P competitionduring periods of active growth in the Paleustoll, while in the non-P limited soil (Ustipsamment), environmentalconditions and the presence of active rhizosphere stimulate microbial activity, shown by seasonal variations,increasing P mineralization rates to sustain microbial and plant P demand.