Ingvar Nilsson

Influence of lime on soil respiration, leaching of DOC, and C/S relationships in the mor humus of a haplic podsol

Abstract Mor humus samples from separate plots in a field-liming experiment in southern Sweden were incubated in a leaching experiment. Lime applications of 0.16, 0.35, and 0.88 kg/m 2 dolomite lime were made 7 y before sampling. The leachates from the two highest lime applications had a pH of 7.0 and 5.3, respectively. The control and the lowest lime application had a pH of 3.9. Humus material receiving the largest lime application also showed the highest level of dissolved organic carbon (DOC) leaching (180 mg DOC/L) during the first 100 d of the experiment, probably owing to the increased negative charge caused by the high pH, which increased the solubility. The DOC concentration decreased in all treatments towards the end of the experiment owing to an increase in protonation caused by nitrate formation (nitrification). The C/S ratio in the organic matter of the leachates from the limed humus was lower than that in the control leachates. A positive correlation between DOC leaching and biological activity, measured as soil respiration, was found in humus material that had received the two highest lime applications.

Dynamic transformation of sewage sludge and farmyard manure components. 1. Content of humic substances and mineralisation of organic carbon and nitrogen in incubated soils

Abstract An incubation experiment was conducted with farmyard manure (FYM) and two municipal sewage sludges (SS): one from Russia (SSR) and one from Sweden (SSS) using a sandy loam soil at 25°C for 6 weeks. The objectives were to investigate mineralisation of organic C and N and transformations of humic substances (HS). Cumulative C mineralisation was about 0.8–1% of total C and cumulative N mineralised was about 3–7% of the pre-incubation total N contents in the treatments. The organic materials contained 1.2–1.5% humic acids (HA) and 0.8–1.4% fulvic acids (FA). Incubating the soils with manures did not markedly influence soil humus composition, indicating that SS-borne organic C was not converted into HS during the short-term incubation. SSR was more resistant to decomposition than SSS, although both SS were less susceptible than FYM to changes in all parameters.

Carbendazim sorption-desorption in Vietnamese soils

Four Vietnamese soils (denoted AG, CT, ST and TG) which differed with respect to pH (pH 2.9-5.4), clay (17-50%) and organic matter (0.3-9.8%) content, were selected for sorption and desorption studies of carbendazim using the batch equilibration technique. Sorption increased with increasing organic carbon (OC) and clay content. Kd values for carbendazim sorption on AG, CT, ST, TG soils at initial concentration of 20 microg/g were 12.5, 127, 8.1 and 9.6 ml/g, respectively. The OC partition coefficients (Koc) for AG, CT, ST and TG were 1140, 1300, 2700 and 960 ml/g, respectively. Carbendazim was strongly sorbed and the binding was less reversible in the acid sulfate soil (CT), than in the other soils. The CT soil had both the highest OC content (9.8%) and the highest clay content (49.8%). The influence of pH on carbendazim sorption was studied in the ST and CT soils. Sorption of carbendazim by the sandy ST soil (OC 0.3%; clay content 26.3%) increased as the pH decreased, while sorption of carbendazim by the CT soil decreased as pH decreased.

Influence of dolomitic lime on DOC and DON leaching in a forest soil

The influence of liming on leaching and distribution of dissolved organic carbon (DOC) and nitrogen (DON) in mineral soil was investigated in a leaching experiment with soil columns. Soil samples from separate horizons (O, A and B horizons) were collected from control and limed plots in a field liming experiment in a spruce forest in southern Sweden. The field liming (0.88 kg m−2) had been carried out 8 years before sampling. To minimize the variation among replicates, soil profiles were reconstructed in the laboratory so that the dry weight was the same for each individual soil horizon regardless of treatment. Two soil column types were used with either the O+A horizons or the O+A+B horizons. One Norway spruce seedling (Picea abies (L.) Karst) was planted in each soil column. Average pH in the leachate water was greater in the limed treatment than in the control treatment (5.0 versus 4.0 for O+A columns and 4.3 versus 3.8 for O+A+B columns). After reaching an approximate steady state, the leaching of DOC was 3–4 times greater from the limed O+A and O+A+B columns than from the corresponding control columns but the leaching of DON increased (3.5 times) only in the limed O+A columns. There was a significant correlation between DOC and DON in the leachates from all columns except for the control O+A+B columns, which indicated a decoupling of DOC and DON retention in the B horizon in the control treatment. This might be explained by a selective adsorption of nitrogen poor hydrophobic compounds (C/N ratio: 32–77) while there was a lower retention of nitrogen rich hydrophilic compounds (C/N ratio: 14–20). Proportionally more hydrophobic compounds were leached from the limed soil compared to the unlimed soil. These hydrophobic compounds also became more enriched in nitrogen after liming so in the limed treatment nitrogen might be adsorbed at nearly the same proportion as carbon, which might explain the fact that there was no decoupling of leached DOC and DON from the B horizon after liming.

Effects of lime and two incubation techniques on sulfur mineralization in a forest soil

Abstract Limed and unlimed mor humus was incubated at 15°C in an open system and a closed one to evaluate the sulfur mineralization capacity in a Norway spruce stand in southern Sweden. Samples were collected 6yr after dolomitic lime (8800 kg ha −1 ) had been applied to determine the long-term effect of liming on sulfur mineralization. The open-incubation columns were periodically leached with a simulated throughfall solution, lacking sulfate. Soil in the open and closed incubation vessels was destructively sampled and extracted with distilled water. Extracts and percolates were analyzed for NO 3 −1 , SO 4 2− and total S. Soil microbial activity was monitored as CO 2 evolution. The open incubation resulted in a higher net S mineralization in both the limed and control humus; i.e. 24.47 vs 14.17 and 13.60 vs —0.60μg SO 2− 4 -S g −1 dw 82 days −1 , in the control and limed treatment respectively. Nitrate formation was mainly affected by the liming itself, and differences related to incubation technique were only observed in the control treatment. Limed humus had a lower net S mineralization regardless of the incubation technique used. Organic S leaching from the open incubation columns was higher in the limed treatment than in the control, 17.6 and 6.9μg Sg −1 dw 82 days −1 , respectively. Limed humus had the highest microbial activity irrespective of the incubation technique. Immobilization of sulfate seemed to be greater in the limed incubation than in the control. The fact that the organic C-to-S ratio was lower in the limed percolation water than in the control also indicates that such a difference exists.

Dynamic transformation of sewage sludge and farmyard manure components. 2. Copper, lead and cadmium forms in incubated soils

Abstract An incubation experiment was conducted with farmyard manure (FYM), a Russian and a Swedish municipal sewage sludge (SSR and SSS, respectively) suing a sandy loam soil (pHwater 6.8) at 25°C for 6 weeks to study the Cu, Cd and Pb contents of soils. The metals were sequentially extracted with 1 M NH4NO3 (available forms) and 0.1 M Na4P2O7 (organically bound forms). There was a shift from the pyrophosphate-soluble pool to the NH4NO3-soluble pool, regardless of treatment. Thus, incubating soils increased available metal forms and decreased organically bound forms. SSS and FYM did not cause marked changes in the two metal fractions, whereas SSR application significantly (P = 0.05) affected them. The two pools were positively correlated (r = 0.993, P = 0.001), indicating that the pools did not change at the expense of each other. The increase in metal solubility in the 1 M NH4NO3 solution is important from both plant nutrition and environmental viewpoints.

Sewage sludge: Soil conditioner and nutrient source II. Availability of Cu, Zn, Pb and Cd to barley in a pot experiment

The effects of sewage sludge (SS) application on NH4NO3‐extractable Cu, Zn, Pb and Cd as well as metal uptake by barley (Hordeum vulgare L.) were investigated using a sandy loam soil (pH in water = 6.7). Treatments comprised three replicates each and were as follows: untreated soil (control), two that received a Russian (SSR) and two that received a Swedish SS (SSS). The SS application based on N applied at rates of 100 (SSR1 and SSS1) and 300 (SSR3 and SSS3) mg N kg−1 dry soil, respectively. Soil metal levels determined immediately after mixing the soils with SS were markedly increased. However, cropping the soils strongly decreased their Cu, Zn and Pb levels, while leaving substantial amounts of residual Cd in the soils, regardless of the treatment. Metal uptake in shoots and roots was significantly (P = 0.05) enhanced by SS applications. Rates of metal uptake in roots were significantly (P = 0.05, n = 64) correlated with the pre‐cropping soil metal contents. The bulk of the metals absorbed by the plant...

220Rn and its progeny in buildings in Sweden

Abstract Measurements of 220 Rn have been performed in some 90 buildings during 1992 and 1993, as parts of two different investigations. In the first study, 220 Rn progeny measurements were undertaken in 53 dwellings and 7 workplaces at 13 different locations in south and central Sweden. Most buildings were situated in areas with elevated natural thorium concentrations. The 222 Rn progeny concentration was measured at the same time. The thorium and uranium activity concentrations in the rock and soil surrounding the buildings were also measured. Typical 220 Rn progeny values (equilibrium equivalent concentration of 220 Rn) in the living areas were in the range 0.1 to 1.0 Bq m −3 (8 to 76 nJ m −3 , Potential Alpha Energy Concentration (PAEC)) with a mean of 0.9 Bq m −3 (68 nJ m −3 ). The measurements in the basements had a mean of 1.5 Bq m −3 (114 nJ m −3 ). A few measurements of 220 Rn gas were performed in basements and showed typical values between 10 and 80 Bq m −3 , with a maximum of 430 Bq m −3 . As part of a study of long-term variations of 222 Rn in dwellings located in different parts of Sweden, 24-h continuous measurements of 220 Rn gas were performed in 28 of these dwellings. In this study, the buildings were chosen regardless of natural thorium concentrations. The mean of these measurements was 13 Bq m −3 . One high value of 150 Bq m −3 was found. The estimated number of dwellings with 220 Rn progeny levels exceeding 20 Bq m −3 EET in Sweden is about 200. The estimated population mean for 220 Rn progeny in Swedish homes is 0.5 Bq m −3 (38 nJ m −3 ). This would give an approximate annual effective dose to the average Swede of 0.1 mSv.