Predicting soil test phosphorus decrease in non-P-fertilized conditions

APPELHANS, STEFANIA C.; CARCIOCHI, WALTER D.; CORRENDO, ADRIAN; GUTIERREZ BOEM, FLAVIO H.; SALVAGIOTTI, FERNANDO; GARCIA, FERNANDO O.; MELCHIORI, RICARDO J.M.; BARBAGELATA, PEDRO A.; VENTIMIGLIA, LUIS A.; FERRARIS, GUSTAVO N.; VIVAS, HUGO S.; CAVIGLIA, OCTAVIO P.; CIAMPITTI, IGNACIO A.

EUROPEAN JOURNAL OF SOIL SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020

1351-0754

Monitoring the availability of phosphorus (P) in soil under continuous cropping facilitates finding deficiency in crops and contributes to improving crop growth and nutrient management models. Soil P availability for crops is usually estimated by soil test P (STP), such as Bray-1. This is widely used in the Americas. The relationship between the decrease of STP Bray-1 and cumulative removal of P was evaluated in non-P-fertilized areas in long-term studies. This removal was the sum of annual P removal over the study period as P exported in grains/crop outside the soil. The objectives were to: (a) quantify changes in STP as a function of cumulative P removal, (b) assess the relationship between relative decrease rate of STP and soil variables as well as annual removal of P by crops, and (c) develop a model to predict decrease of STP Bray-1. Exponential decay functions were used to describe annual cumulative removal of P and STP from soil over time for 12 long-term studies where no addition of P fertilizer was carried out. Changes in the relative rate of decrease of STP, relative to the initial STP Bray-1 value at the onset of the experiment, were predicted by the ratio of soil organic matter to clay and silt and the average annual P removal by exponential decay (R2adj = 0.64; RMSE = 3.2 mg kg −1). We propose this predictive model as suitable to provide estimates of the relative decrease rate of STP by Bray-1 and thereby improve management of P for optimizing crop yield.