Temporal changes in chemical properties of air‐dried stored soils and their interpretation for long‐term experiments

Abstract

Summary The usefulness of stored soils from long‐term experiments is often questioned because of changes that might occur during storage. We examined changes during long‐term storage (8–69 years) in the chemical properties of soils with a range of pH values (3.4–8.1 in water) from woodland and grassland experiments at Rothamsted Experimental Station in the UK. No significant changes during storage were measured for total C and N. Large but erratic changes in exchangeable Na+ content between 1959 and 1991 were probably caused by contamination of the 1959 samples by perspiration and from sodium‐based glassware. Exchangeable K+ increased during storage but only by a small amount. Small changes in exchangeable Ca2+ and Mg2+ were measured in some samples but not in others. Generally the amount of exchangeable cations increased slightly during storage. This is probably linked to the decreases of 0.4 units in the pH of acid soils, which we attribute to the hydrolysis of approximately 0.25% of the exchangeable Al3+. A doubling of the amount of exchangeable Mn2+ during storage for 32 years was probably caused by re‐equilibration of Mn species. The most practicable way to prepare soil samples for long‐term storage is to dry them in air. However, those who study changes in soil by re‐analysing samples of the soil stored for a long time must (i) use the same methods of analysis, or (ii) demonstrate that different methods lead to the same results, and (iii) know what changes can arise during storage.

Effets de la coupe à blanc d’un peuplement de Douglas (Pseudotsuga menziesii (Mirb.) Franco) sur la fertilité chimique du sol

“…Significant differences only occurred for Al measured by ICP, H, Mn exch and Na exch . If measurement alone cannot explain the changes because of the presence of internal calibration, storage could be at the origin of changes, as previously demonstrated by Blake et al [10]. No specific changes were detected for the organic or mineral layers.…”

“…The increase in manganese (by less than 0.05 cmol c .kg −1 ) was generally attributed to the re-equilibration of Mn species during the first weeks of natural air-drying [8]. Sodium changes were generally attributed to 'contamination' during laboratory treatments [10]. Two possibilities arose: (i) first, the case of elements usually classified as sensitive to changes during storage (Mn, H, Al?…”

Impacts of Carbon Dioxide Gas Leaks from Geological Storage Sites on Soil Ecology and Above-Ground Vegetation

“…Changes in cation exchange capacity (CEC), and the presence of oxides like CaO, MgO, Fe 2 O 3 , and Mn 3 O 4 have also been reported elsewhere (Blake et al, 2000;Billett et al, 1987;Goulding et al, 1998). Leakage of CO 2 may also reduce groundwater pH besides affecting taste, color or smell and cause significant deterioration in the quality of potable groundwater by altering groundwater chemistry (Stenhouse et al, 2009).…”

Indicators of agricultural soil genesis under varying conditions of land use, Steppe Crimea

“…In order to develop resource-saving technologies of land use, which could prevent soil degradation, it is important to understand trends in the long-term changes observed for the material and energetic organization of soils under different practices of land use. Along with the experimentally worked fields where functional transformations in the system "agrotechnologies-soils" are observed over many decades (Blake et al, 2000), soils in regions with a long agrarian history, which have experienced continuous, or with restorative periods, anthropogenic impacts, can be very informative. Soil agrogenic features that result from pedogenesis on an evolutionary scale only become apparent after a considerable period of agrogenesis.…”