Phosphorus forms leached in a sandy Typic Hapludalf soil under no-tillage with successive pig slurry applications

Abstract

Successive pig slurry (PS) applications can substantially increase phosphorus (P) movement due to leaching, mainly in sandy soils found in areas presenting high rainfall rates. The aim of the current study was to assess the transference of different P forms through leachate in a soil managed under no-tillage system, in a crop rotation system subjected to successive PS applications. The study was carried out from 2005 to 2007; the studied site presents Typic Hapludalf soil and its mean annual rainfall reaches 1,769 mm. The study adopted PS doses 0, 20, 40 and 80 m3 ha-1, which were applied to soil surface before each crop-sowing process. Leachate samples were collected 0.60 m down in the ground at each rainfall event (n = 24) that resulted in solution leaching during the experimental period. Available-P, soluble-P, particulate-P and total-P concentration in the leachate were determined. Successive PS applications increased leachate and P transfers in the leached solution. Phosphorus was transferred via leaching mainly in the particulate form, but soluble-P concentration increase was also observed. The highest P concentrations were observed in the treatment with the highest PS dose, whereas the highest P amounts were transferred in the treatment 40 m3 ha-1 of PS. The total amount of transferred P was very small – 0.2 kg ha-1 year-1 –, but it evidenced the likelihood of groundwater contamination, mainly due to increase in the available-P proportion. In addition, P concentrations in the leachate indicate that high and frequent PS doses should be avoided in sandy soils.