Temporal trends in chemical parameters of upland forest soils in southern Finland

Abstract

Microbial communities in Cerrado soils under native vegetation subjected to prescribed fire and under pasture

The objective of this work was to evaluate the effects of fire regimes and vegetation cover on the structure and dynamics of soil microbial communities, through phospholipid fatty acid (PLFA) analysis. Comparisons were made between native areas with different woody covers ("cerrado stricto sensu" and "campo sujo"), under different fire regimes, and a 20-year-old active palisadegrass pasture in the Central Plateau of Brazil. Microbial biomass was higher in the native plots than in the pasture, and the highest monthly values were observed during the rainy season in the native plots. No significant differences were observed between fire regimes or between communities from the two native vegetation types. However, the principal component (PC) analysis separated the microbial communities by vegetation cover (native x pasture) and season (wet x dry), accounting for 45.8% (PC1 and PC3) and 25.6% (PC2 and PC3), respectively, of the total PLFA variability. Changes in land cover and seasonal rainfall in Cerrado ecosystems have significant effects on the total density of soil microorganisms and on the abundance of microbial groups, especially Gram-negative and Gram-positive bacteria.

Response of wheat to additional nitrogen fertilizer application after pig slurry on over-fertilized soils

Pig slurry is a valuable nutrient resource but constitutes a waste disposal problem in areas of high animal density. In the semiarid area of Pla d’Urgell, in the Ebro Valley, North-East Spain, irrigated crops receive large amounts of nutrients in the form of manure and mineral fertilizers. We studied the effect of pig slurry and additional side-dress mineral fertilizers on irrigated wheat, Triticum aestivum L., on a coarse loam soil, with high soil P and K levels. Yields increased by 62.3% when using pig slurry. The application of ammonium sulfate nitrate sidedress did not significantly increase wheat production. The average apparent recoveries were higher for potassium (88.7%) than for nitrogen (51.3%) and phosphorus (36.3%). Greater amounts of soil NO3-N were measured over the four growing seasons, which was consistent with the amount of N applied. Macronutrient and micronutrient uptake was significant higher for pig slurry treatments, but only small differences were found between the pig slurry and pig slurry plus ammonium sulfate nitrate treatments. The unfertilized treatment showed significantly lower soil P, K, Cu and Zn content than pig slurry treatments; 34%, 21%, 34%, and 26% respectively. These findings could be used to develop a nutrient management plan based on knowledge of soil test results and crop nutrient removal. This could help to improve the use of pig slurry and mineral fertilizers on limited available land areas and prevent the accumulation of potentially toxic elements in soils and the export of nutrients through agricultural drainage.

Phosphorous and nitrogen changes in compost-amended schist soils in vineyards in the D.O. Priorat wine-producing area (NE Spain)

The impact, on nitrogen and phosphorous dynamics, of applying compost at different rates was investigated in soils developed on schist in new terraced vineyards (NTV) and in undisturbed areas (NC). Repacked soil columns amended with 0 (control), 50 t ha –1 (T1) and 100 t ha–1 (T2) of compost were studied under laboratory conditions simulating both situations. The columns were maintained for 1 year, during which time a total of 300 mm of simulated rainfall was applied in ten 30 mm applications. Soil organic matter (OM), nitrogen and phosphorous contents were analysed at the end of the study period and leachates were analysed after each simulated rainfall event. Significant differences in nitrate leaching were observed between the control and the treated soils and these differences were greater in the NC (control = 1.368 g, T1 = 1.526 g and T2 = 1.686 g) than in the NTV soils (control = 0.61 g, T1 = = 1.068 g and T2 = 1.283 g). The relative effect was greater in the NTV soils (T1/control = 1.11 vs. 1.75 and T2/control = 1.23 vs. 2.1 for NC and NTV, respectively). The nitrate concentration in the leached water reached up to 400 mg L–1, which implied a risk of groundwater pollution. Phosphorous losses through leaching were very low with concentrations of < 0.15 mg L–1, without any significant differences between treatments. The phosphorous concentrations in the surface horizon increased by 50.8% in T1 and by 66.8% in T2 in the NC soils, compared with increases of 20.3% and 38%, respectively, in the NTV soils. Due to the high infiltration capacity of the study soils, leaching effects must be considered in order to prevent groundwater pollution.

Short communication. Potential to mitigate anthropogenic CO2 emissions by tillage reduction in dryland soils of Spain

Spain is one of the countries with the highest greenhouse gas (GHG) emissions within the EU-27. Consequently, mitigation strategies need to be reported and quantified to accomplish the goals and requirements of the Kyoto Protocol. In this study, a first estimation of the carbon (C) mitigation potential of tillage reduction in Mediterranean rainfed Spain is presented. Results from eight studies carried out in Spain under rainfed agriculture to investigate the effects of no-tillage (NT) and reduced tillage (RT) compared with conventional tillage (CT) on soil organic carbon (SOC) were used. For current land surface under conservation tillage, NT and RT are sequestering 0.14 and 0.08 Tg C yr-1, respectively. Those rates represent 1.1% and 0.6% of the total CO2 emissions generated from agricultural activities in Spain during 2006. Alternatively, in a hypothetical scenario where all the arable dryland was under either NT or RT management, SOC sequestration would be 2.18 and 0.72 Tg C yr-1 representing 17.4% and 5.8% of the total 2006 CO2 equivalent emissions generated from the agricultural sector in Spain. This is a significant estimate that would help to achieve GHG emissions targets for the current commitment period of the Kyoto Protocol.

Phosphorus status of diverse soils in Finland as influenced by long-term P fertilisation 2

Selostus: Pitkäaikaisen fosforilannoituksen vaikutus Suomen peltojen fosforitilaan. 2. Kemiallisten testien muutokset suhteessa fosforitaseeseen sekä aikaisemmin ja koevuosina lisätyn fosforin multaussyvyyteen

Assessing changes in Cd phytoavailability to tomato in amended calcareous soils.

A plot study was conducted to assess changes in Cd phytoavailability to a tomato cultivar in an agricultural soil in Southeastern Spain amended in two different ways (A and B), under controlled conditions. The experimental soil corresponded to a fine-loamy carbonatic thermic Calcidic Haploxeroll (Soil Survey Staff, 1998). A) Soil was amended with a single application of sewage sludge from a municipal source that had a total Cd concentration of 0.5 mg kg-1 at a rate that represented a final average concentration in the mixture of soil and sludge of less than 50 µg Cd kg-1. B) The amendment consisted of the addition of a mineral fertiliser with the same amount of NPK as in the sewage sludge application. The final levels of Cd were supposed to be negligible. A plot series without amendments was also performed (C). DTPA plus triethanolamine, and ammonium acetate extractable fractions in soils were analysed for all the plots. The time-dependent Cd accumulation in different parts of the tomato plants was studied by means of a Cd salt treatment. For each block (A, B, and C) four levels of Cd (0, 3, 30, 100 mg kg-1) were added as CdCl2. There was a significant increase in plant Cd after the initial cropping. Tomato stems, leaves and fruits were analysed separately for Cd determination. Differential Cd distribution and accumulation in tomato parts was detected.

Soil quality assessment through a multi-approach analysis in soils of abandoned terraced land in NE Spain

The abandonment of agricultural land in mountainous areas has been an outstanding problem along the last century and has captured the attention of scientists, technicians and administrations, for the dramatic consequences sometimes occurred due to soil instability, steep slopes, rainfall regimes and wildfires. Hidromorfological and pedological alterations causing exceptional floods and accelerated erosion processes has therefore been studied, identifying the cause in the loss of landscape heterogeneity. Through the disappearance of agricultural works and drainage maintenance, slope stability has resulted severely affected. The mechanization of agriculture has caused the displacement of vines, olives and corks trees cultivation in terraced areas along the Mediterranean catchment towards more economically suitable areas. On the one hand, land use and management changes have implicated sociological changes as well, transforming areas inhabited by agricultural communities into deserted areas where the colonization of disorganized spontaneous vegetation has buried a valuable rural patrimony. On the other hand, lacking of planning and management of the abandoned areas has produced badlands and infertile soils due to wildfire and high erosion rates strongly degrading the whole ecosystems. In other cases, after land abandonment a process of soil regeneration has been recorded. Investigations have been conducted in a part of NE Spain where extended areas of terraced soils previously cultivated have been abandoned in the last century. The selected environments were semi-abandoned vineyards, semi-abandoned olive groves, abandoned stands of cork trees, abandoned stands of pine trees, scrubland of Cistaceaea, scrubland of Ericaceaea, and pasture. The research work was focused on the study of most relevant physical, chemical and biological soil properties, as well as runoff and erosion under soils with different plant cover to establish the abandonment effect on soil quality, due to the peculiarity and vulnerability of these soils with a much reduced depth. The period of observation was carried out from autumn 2009 to autumn 2010. The sediment concentration of soil erosion under vines was recorded as 34.52 g/l while under pasture it was 4.66 g/l. In addition, the soil under vines showed the least amount of organic matter, which was 12 times lower than all other soil environments. The carbon dioxide (CO2) and total glomalin (TG) ratio to soil organic carbon (SOC) in this soil was 0.11 and 0.31 respectively. However, the soil under pasture contained a higher amount of organic matter and showed that the CO2 and TG ratio to SOC was 0.02 and 0.11 respectively indicating that the soil under pasture better preserves the soil carbon pool. A similar trend was found in the intermediate soils in the sequence of land use change and abandonment. Soil structural stability increased in the two soil fractions investigated (0.25-2.00 mm, 2.0-5.6 mm) especially in those soils that did not undergo periodical perturbations like wildfires. Soil quality indexes were obtained by using relevant physical and chemical soil parameters. Factor analysis carried out to study the relationship between all soil parameters allowed to related variables and environments and identify those areas that better contribute to soil quality towards others that may need more attention to avoid further degradation processes

Factors affecting Hg (II) adsorption in soils from the Rio Negro basin (Amazon)

Mercury (II) adsorption studies in top soils (top 10 cm) from the Rio Negro basin show this process depends strongly on some selected parameters of the aqueous phase in contact with the soils. Maximum adsorption occurred in the pH range 3.0-5.0 (>90%). Dissolved organic matter shows an inhibitory effect on the availability of Hg (II) to be adsorbed by the soils, whereas a higher chloride content of the solution resulted in a lower adsorption of Hg (II) at pH 5.0. Soils with higher organic matter content were less affected by changes in the salinity. An increase in the initial Hg (II) concentration increased the amount of Hg (II) adsorbed by the soil and decreased the time needed to reach equilibrium. A Freundlich isotherm provided a good model for Hg (II) adsorption in the two types of soil studied. The kinetics of Hg (II) adsorption on Amazonian soils showed to be very fast and followed pseudo-second order kinetics. An environmental implication of these results is discussed under the real scenario present in the Negro River basin, where acidic waters are in contact with a soil naturally rich in mercury.

Mercury in soils and sediments from gold mining liabilities in Southern Amazonia

The 1980-1990 Amazonian gold rush left an enormous liability that increasingly has been substituted by developing fish aquaculture. This work aimed at the identification of the mercury levels in the environment, associated with fish farms located in the North of Mato Grosso State, Southern Amazon. Sediment and soil samples were analyzed for total organic carbon and total mercury. Results indicate that the chemical characteristics of the sediment largely depend on the management procedures of the fish pond (liming, fish food used and fish population). The soils presented relatively low concentrations when compared with other data from the literature.

A screening method for detection of hexavalent chromium levels in soils

A rapid and low cost method to determine Cr(VI) in soils based upon alkaline metal extraction at room temperature is proposed as a semi-quantitative procedure to be performed in the field. A color comparison with standards with contents of Cr(VI) in the range of 10 to 150 mg kg-1 was used throughout. For the different types of soils studied, more than 75% of the fortified soluble Cr(VI) were recovered for all levels of spike tested for both the proposed and standard methods. Recoveries of 83 and 99% were obtained for the proposed and the standard methods, respectively, taking into account the analysis of a heavily contaminated soil sample.

Stratification of regional sampling by model-predicted changes of carbon stocks in Forested mineral soils

Selective papers of the workshop on "Development of models and forest soil surveys for monitoring of soil carbon", Koli, Finland, April 5-9 2006.