Impact of organic and mineral fertilising on aluminium mobility and extractability in two temperate Cambisols

Abstract

Different fertilisation systems cause changes in the content of mobile aluminium (Al) forms in the soil as a result of soil pH changes. Long-term stationary fertilisation experiments established in 1996 at 2 sites were evaluated. Experiments consisted of unfertilised control treatment and 6 other treatments, combining mineral fertilisation with the application of farmyard manure, sewage sludge and straw. To record the changes in mobile Al forms, we used 5 extraction procedures with agents: water, CaCl<sub>2</sub>, KCl, CaCl<sub>2</sub>/DTPA (CAT) and Mehlich 3 solutions. At treatment nitrogen (N) + straw, topsoil acidification was observed, resulting in the increased content of mobile Al. At treatments with mineral fertilisation (N, NPK), increased content of mobile forms of Al was recorded. Application of cattle manure and sewage sludge helped to stabilise the soil pH and reduce mobile Al forms. The close correlation between the methods determining the exchangeable Al (CaCl<sub>2</sub> and KCl solutions) was observed; however, KCl extraction was more favourable in soils of low Al extractability, as the amount of extracted Al was 3–4 times higher. Positive correlations were determined between Al extracted by Mehlich 3 solution and the content of exchangeable Al. The less frequently used CAT method also turned out to be perspective for mobile Al determination. Furthermore, aluminium content determined in Mehlich 3 extract was compared with mobile phosphorus amounts in H<sub>2</sub>O, CAT and Mehlich 3, respectively. All three investigated phosphorus forms showed significantly negative correlations with Al.

Consecutive soybean (Glycine max) planting and covering improve acidified tea garden soil

“…The exchangeable base, exchangeable Mg 2+ and K + , and organic matter are significantly and positively correlated to the soil pH. This agrees with previous reports that the main buffering substances for acidity in the soil between pH 4.2 and 5.0 included exchangeable base cations [39] and were affected by organic matters [40]. The dramatic increase in exchangeable K + and Mg 2+ could be attributed to soybean planting and covering.…”

“…The exchangeable Al 3+ accounted for >82% in the exchangeable acidity in all treatments and its changes was positively correlated with those of the exchangeable acidity. Changes in exchangeable H + were unstable, but the differences in 40.82% and 90.00%, respectively. The trend of these changes was consistent with those of the exchangeable bases, indicating that K + and Mg 2+ played dominant roles in the increase of the exchangeable bases.…”