Microbiological assessment of lime application to agricultural soils

Wien

2014

Artikel aus einer ZeitschriftUnselbständiges Werk

17215

200190220

Lime is commonly applied on agricultural lands for ameliorating soil acidity. Furthermore the high input of mechanical energy in common agricultural practice can negatively affect soil structure. A promising approach to stabilize the structure and improve the water- and air permeability, is the addition of polyvalent ions like Ca2+ which can be added for example in the form of quicklime (CaO) and limestone (CaCO3). The soil pore system serves as a habitat for soil biota. Microorganisms are essential for the integrity of terrestrial ecosystems as they are key players of many soil functions such as biogeochemical cycling, plant productivity or climate regulation. In this study, we conducted a greenhouse pot experiment using two different sources of calcium ions in order to examine the effect of these amendments on microbial parameters over time. Silty and clayey soils from three different locations in Austria were sampled and incubated with and without the liming materials (application rate 1000 kg ha-1) for 3 months in four replicates. Soil samples were taken with a plastic probe 2, 30 and 86 days after the application of quicklime and limestone to assess short-term and medium-term microbial effects. By adding water in regular intervals the moisture content was kept at ~ 50 % water holding capacity throughout the duration of the experiment. To evaluate the effect of lime on changes in soil microbiology, we determined parameters like pH, extracellular hydrolytic (cellulase, phosphatase, chitinase and protease) and oxidative (phenoloxidase and peroxidase activity) enzyme activities, PLFAs, microbial biomass carbon and nitrogen, dissolved organic carbon and nitrogen, nitrate nitrogen and ammonium nitrogen. Initially, soil pH and DOC were strongly increased by quicklime; however, after the second sampling (30 days) the pH values of all tested soils returned to levels comparable to the soils treated with limestone but the DOC values declined continuously during incubation time. Most microbial results show an immediate inhibition effect of quicklime on potential hydrolytic enzyme activities and an increase in oxidative enzyme activities. These effects seem to be less pronounced in the medium term. In summary our results indicate that the application of quicklime is a feasible measure for immediate stabilization of the structure of compaction-prone soils, showing only short-term impact on most microbial parameters.