Phosphorus fertilization modify soil P fractions differing in availability, but little is known about bioavailability of these pools for the crops when increasing P fertilizer rates in the medium term. Our objectives were to evaluate: i) changes in Bray - 1 P content (extracted with 0,03 M NH4F and 0,1 M HCl) and soil P fractions as estimated by physical (Cambardella and Elliot method, POM-P) and chemical fractionation (Hedley method), ii) the relationship between these fractions and P bioavailability quantified in a test crop, and iii) the interaction with sulfur (S) fertilization after 10 years of continuous P and S fertilization. Soil samples were taken after 10 years in an experiment that followed a maize - full season-soybean - double-cropped wheat /soybean sequence that received P and S fertilization when cereals were sown. Treatments consisted of a factorial combination of three P rates (0, 20, and 40 kg P ha − 1) and four S rates (0, 12, 24, and 36 kg S ha − 1) applied to cereals from 2000 to 2010. After that, a maize used as a test crop was sown and P uptake was considered as bioavailable P. Soil samples were taken before sowing the test crop, and P in soil was fractionated chemically by the Hedley method and physically by wet sieving. After 10 years, when P fertilizer was not applied, soil Bray -1 P decreased 50 % respect to the initial P values, and increased up to 2.3 times when evaluating the highest P fertilizer rate. P fertilization did not change in POM - P. P soil labile (NaHCO3-Pi) and moderately labile (NaOH- Pi and HCl 1 M Pi) inorganic fractions increased 83 %, 50 %, and 22 % in response to P addition, representing an increase of 4.2, 4.9, and 4.5 mg kg − 1 of these fractions per 100 kg of applied P. Likewise, these fractions were related with P uptake in the maize test crop with 1.6, 1.5, and 1 kg of P uptake ha − 1 in mg kg − 1 increase in each of these fractions, respectively. Then, these fractions may be responsible for the legacy - P after 10 years of continuous fertilization in a Luvic Phaeozem of the Pampas region.
Biassoni, M. M.; Vivas, H. S.; Gutiérrez Boem, F. H. & Salvagiotti, F. (2023).Changes in soil phosphorus (P) fractions and P bioavailability after 10 years of continuous P fertilization.Soil and Tillage Research,232,art.105777
Biassoni, María Micaela, Vivas, Hugo S., Gutiérrez Boem, Flavio Hernán, Salvagiotti, Fernando.2023. "Changes in soil phosphorus (P) fractions and P bioavailability after 10 years of continuous P fertilization".Soil and Tillage Research 232:art.105777.
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