pH CaCl2 Research Articles

Predictive Mapping of Soil Properties for Precision Agriculture Using Geographic Information System (GIS) Based Geostatistics Models

In precision Agriculture, geostatistical methods as a predictive tool have been extensively utilized. The approach estimates soil properties spatial variability and dependency. This study was carried out in Ovia north east Local Government Area of Edo State of Nigeria in order to map soil properties (Sand, Clay, pH, OC, P, N and CEC) and redict their spatial variability. Twenty-nine (29) soil samples were collected randomly from Typic Kandiudults soil type under three different land use, teak forest plantation, shrub, and arable farm. The soil samples were air-dried and passed through a 2 mm sieve before being analyzed for pH(CaCl2), SOC, Sand, Clay, Phosphorus, Nitrogen, and CEC. Generated data were statistically and geostatistically computed to explain the spatial variability of soil properties. The traditional method of soil analysis and interpretation are tedious, time-consuming with escalating budgets thus geostatical approach. Available phosphorus yielded large variability with CV=57.08% followed by clay content with CV=49.03%. Spherical, Gaussian, Hole Effect model, Stable, Exponential and Circular models were fitted for all the soil parameters. The result revealed that soil pH, Sand content, TN and CEC were moderate spatially autocorrelated with nugget/sill value of 0.32, 0.21, 0.49 and 0.30 respectively.  SOC also gave a moderate spatially autocorrelated with nugget/sill value of 0.44. And Clay and Available phosphorus were strong spatially autocorrelated with nugget/sill value of 0.15 and 0.13 respectively. Cross-validation of the output maps using the semivariogram showed that the interpolation models are superior to assuming mean for any unsampled area. The output maps will help soil users within the area to proffer best management technology to improve crop, fiber and water production. 
  

Reforested soil under drip irrigation with treated wastewater from poultry slaughterhouse

ABSTRACT The disposal of treated effluents on soil is the main final use of wastewater in Brazil. Although this practice can promote improvements of some soil attributes, there is a need for monitoring in order to ensure that potential environmental impacts are not harmful. Thus, the purpose of this study was to evaluate the effects of treated effluent from a poultry slaughterhouse on the chemical attributes of an Oxisols, in Matelândia-PR, Brazil under drip irrigation. The soil attributes P, K, Fe, Cu, Zn, Mn, pH in CaCl2, H + Al, Al, Ca, Mg, cation exchange capacity (CEC), and percent base saturation (V) were evaluated under four effluent application rates, 0, 100, 200 and 300 m³ ha-1 d-1 with treated effluents on three successive sampling dates. As main results it was observed that high irrigation rates increased soil phosphorus and potassium concentrations. In addition, an association between the increase of soil potential acidity and exchangeable acidity was detected, although pH did not vary significantly either between treatments or between sampling dates.

Application of the Oily-Bubble flotation of Shengli lignite and its optimization

ABSTRACT The upgrading of low-rank coal is important for its utilization. The lignite used in this study had extremely low surface hydrophobicity and responded poorly to the conventional flotation process. Therefore, to enhance its flotation, a laboratory device known as oily-bubble flotation was used. With this device, the combustible matter recovery at a collector dosage of 6.4 kg/t reached 32.94% which was comparable to that of the conventional flotation at the collector dosage of 50 kg/t. For improving recovery, utilization of electrochemical conditions for pulp, i.e., pH, and NaCl and CaCl2 solutions, was used to further enhance the oily-bubble flotation performance. Based on the response-surface methodology, a functional model for combustible matter recovery was established, and the regulator scheme in oily-bubble flotation was optimized to achieve a combustible recovery of 59.19% with pH and NaCl and CaCl2 concentrations of 6.03, 61.26 mmol/L, and 80 mmol/L, respectively. Results showed that an increased combustible matter recovery of 78.69% could be obtained using this optimization scheme.

Effect of pH CaCl2 solution on graphene oxide encapsulated alginate (GO-AL) for removing methylene blue dyes

The industry waste pollution is unseparated issue in era of globalization. It’s caused in industry didn’t apply Green Chemistry principle in their production process, so that they still use hazardous chemicals that can pollute the environment, one of them is a methylene blue dye (MB) waste. The remove dyes by the combination technique of electrochemistry and adsorption appeared to be an efficient and simple. This study aims to determine the pH optimum characterization of graphene oxide-alginate composite to degradation of methylene blue in liquid waste. Graphene oxide-alginate was prepared by encapsulation method at 2% CaCl2 (b/v) solution. The material was characterized by X-Ray Diffraction (XRD) and Fourier Transform Infra-Red (FTIR). The XRD characterization results indicated a high 2θ peak at 10.7703 and increased d-spacing of graphite to graphene oxide. The FTIR spectra of graphene oxide-alginate shows the presence of combined adsorption of graphene oxide and alginate. This indicates that the composite GO-AL was successful synthesized. Calcium chloride solubility varies with the changes in the pH of the solution and so will be the cross-linking ability of alginate with calcium ions. The optimum value of GO-AL composite with Eco-Bio method on MB degradation was obtained in CaCl2 solution pH 3 and gave MB degradation of 93.78%.

Soil quality indicator of oxisols grown with sugarcane and native forest in northeastern São Paulo state, Brazil

The evaluation of soil quality is an important tool for degradation monitoring and sustainable management implementation. The objective of this study was to measure physical and chemical soil properties to set soil quality and validate a model of soil quality indicator in latosols (oxisols) under sugarcane cropping and native forest. The study was carried out in the cities of Araras, Santa Ernestina, and Guariba in Sao Paulo State, Brazil. We collected 24 samples of disturbed and undisturbed soil at 0.0–0.10 m layer from three areas grown with sugarcane and neighboring locations under native woodland. We assessed the following soil properties: (a) chemical—pH in CaCl2, organic matter (OM), phosphorus (P), potassium (K+), calcium (Ca2+), magnesium (Mg2+), potential acidity (H + Al), aluminum (Al3+), and sulfur (S); (b) physical—macro- and microporosity, soil bulk density (Ds), aggregate stability, mean weight diameter (MWD), rill (Kr) and interrill (Ki) global erodibility, shear stress (τc), and magnetic susceptibility (MS). Data underwent multivariate statistics to identify the properties that denote soil quality and to set their weights within the functions of soil quality indicator (SQI). This study showed that the multivariate analysis was efficient in determining which physical and chemical properties were most sensitive, of which we can mention total sand, MS, clay, microporosity, Mg, Ca, pH, and OM. We can therefore conclude that the quality indicators of soils grown with sugarcane were lower than those under forest were, showing the need for adoption of conservation management practices.

Models relating soil pH measurements in H2O, KCl and CaCl2 for volcanic ash soils of Cameroon

Soil pH, apparently the most routinely measured soil property is an important indicator of soil quality, serves as a guide for fertilizer recommendations and liming requirements, and is an index of biogeochemical processes in terrestrial ecosystems. This study was conducted to establish relationships among different pH measurements of surface soils (0–20 cm) derived from volcanic ash parent materials in different electrolytes and soil-to-solution ratios following standard methods. Soil pH increased with increase in solution volume and for a particular soil-to-solution ratio; the trend in pH values was pH H2O > pH 0.01 M CaCl2 > pH 1 M KCl. Electrical conductivity values were very low (mean = 0.04 ± 0.01 dSm−1) and were highly and negatively correlated with pH H2O and pH CaCl2. pH CaCl2 values were on average 0.43 units lower than those measured in water, while those measured in KCl were on average 0.73 units lower than those measured in water. Models relating different pH and EC measurements (n = 38) yielded R2 values ranging from 0.774–0.978. Model validation using a dataset of 59 points gave R2 values ranging from 0.843 to 0.958; RMSE from 0.06–0.09; MAE from 0.05–0.09 and index of agreement from 0.75–0.78. The models developed in this study are useful in quality control of pH measurements, for converting pH values of volcanic ash – derived soils in different electrolytes and soil-to-solution ratios and contribute to information necessary for the development of soil data bases at local and regional levels.

Estudio metodológico sobre la medición de pH y conductividad eléctrica en muestras de compost

En el presente trabajo se estudió la influencia de la relación compost/extractante sobre las mediciones de pH y conductividad eléctrica (CE) utilizando agua y una solución de CaCl2 0,01 M como extractantes, tanto en la suspensión como en el sobrenadante del extracto centrifugado. Los resultados muestran que la medición de pHCaCl2 es independiente de la cantidad de extractante a diferencia de la medición en extracto acuoso, que incrementa con la dilución y se ajusta más a una función polinómica. En consecuencia, la medición debe realizarse donde la pendiente curva sea mínima o nula y la medición sea más independiente de la cantidad de extractante. Esto ocurre en relaciones compost/extractante superior a 1:8 para el extracto acuoso y superior a 1:5 para el extracto de CaCl2. Igualmente, el pHH2O es menor que el pHCaCl2, por lo que este último es un mejor extractante de acidez y, por ende, más cercano a la realidad de la muestra. Las mediciones de CE también presentan un comportamiento polinómico, por lo que deben ser realizadas a relaciones compost/extractante mayores de 1:6, donde los valores de CE son más independientes de la cantidad de extractante, realizando la corrección del blanco respectivo.

P-271 - Nitration alters laminin polymerization

Reactive nitrogen species (RNS) are produced by cells at sites of inflammation and can modify proteins. Nitration is used as a biomarker of damage and may contribute to multiple pathologies. We have shown that the extracellular matrix protein laminin (LN) co-localizes with nitrative damage in human atherosclerotic lesions, and that nitration decreases cell binding to LN in vitro. Study aim: To investigate how nitration affects laminin self-assembly and polymerization. Methods: Sites of nitration were determined by LC-MS. Polymerization was induced by pH changes and CaCl2. Dynamic light scattering was used to examine the extent of polymerization. Structure of LN polymers was investigated with scanning electron microscopy (SEM). Results: Extensive nitration was observed on the protein at specific sites. Nitrated LN underwent polymerization, but displayed increased light scattering, indicating altered particle size. SEM showed that untreated LN formed a homogenous ordered structure, whereas nitrated LN displayed a segmented, patchy and disordered pattern. Conclusions: While the extent of LN polymerization is not affected by nitration, the structure of LN polymers is altered. Such alterations in polymer structure could lead to decreased cell adhesion and altered ECM integrity.

Replacement of liming and NPK fertilization with turkey litter in degraded areas grown with Urochloa decumbens

Soil fertility and acidity correction in recovering areas require high doses of correctives and fertilizers. Therefore, the use of low-cost products may be an alternative in infertile areas. The objective of this study was to evaluate the effect of soil fertilization and correction methods on the yield of degraded areas cultivated with Urochloa decumbens and soil chemical attributes. The study was conducted in Orthic Quartzarenic Neosol in Mineiros, Goiás, Brazil, from October 2011 to September 2013. The experiment included soil samples treated with 2 Mg ha-1 of dolomitic limestone, a standard fertilizer (45, 54, and 75 kg ha-1 of N, P, and K, respectively), or 3 Mg ha-1 of turkey litter, and a control sample without correction/fertilization. Each treatment included four replicates in a completely randomized block design. The experimental plots consisted of areas of 4.0 m2 (2.0 ?? 2.0 m). The dry matter yield of forage grass and the following soil chemical attributes were evaluated: organic matter, hydrogen potential (pH in CaCl2), phosphorus (resin), potassium, calcium, magnesium, cation exchange capacity (CEC), and base saturation. The data were subjected to analysis of variance, and the means were compared using Tukey’s test at a level of significance of 0.05. Fertilization did not affect the pH, potassium, and CEC of the soil. Fertilization with turkey litter increased the levels of organic matter, phosphorus, calcium, magnesium, and base saturation compared with soils subjected to standard fertilization or liming. Furthermore, soils fertilized with turkey litter presented higher dry matter yield of Urochloa decumbens compared with unfertilized soils or soils subjected to acidity correction by liming but were not significantly different from soils treated with standard fertilizers. Therefore, fertilization with 3 Mg ha-1 of turkey litter is recommended for improving degraded pastures.

Soil Property and Fertilizer Additive Effects on Ammonia Volatilization from Urea

Core Ideas Total exchange capacity was the best soil predictor of volatilization from urea. Urease activity and pH were not effective predictors of volatilization from urea. NBPT effectively reduces ammonia volatilization compared with nonamended urea. NBPT efficacy was reduced in more acidic soils. Calcium salt of maleic‐itaconic copolymer did not reduce ammonia volatilization. Urea efficiency can be substantially reduced through nitrogen loss as ammonia (NH3–N), which is controlled by soil properties and environmental conditions. A laboratory incubation measured the effects of a range of soil properties on ammonia volatilization over 7 d from 168 kg N ha–1 as surface‐applied urea and the efficacy of two fertilizer additives: urea plus a commercial formulation of N‐(n‐butyl) thiophosphoric triamide (NBPT) + N‐(n‐propyl) thiophosphoric triamide (NPPT) (urea + NBPT/NPPT) and urea plus a commercial formulation of calcium salt of maleic‐itaconic copolymer (MIP) from 79 soils across the United States. Total exchange capacity (TEC), 0.01 mol L–1 CaCl2 pH (pH), soil organic matter (SOM), hydroxide buffering capacity (OHBC), clay content, and urease activity were measured as predictors. Generalized regression models identified that TEC, clay content, OHBC, and SOM accounted for most variation in NH3–N losses in urea (R2 = 0.69) and urea + MIP (R2 = 0.67). Total exchange capacity was the strongest predictor of volatilization; greater TEC resulted in lower NH3–N losses. pH and TEC accounted for the most variation in NH3–N loss among soils fertilized with urea + NBPT/NPPT (R2 = 0.58). Volatilization increased with lower pH in urea + NBPT/NPPT, indicating that NBPT efficacy decreases in acidic soils, potentially due to faster chemical degradation. The addition of NBPT/NPPT to urea significantly reduced volatilization from 24.5 to 6.3% of applied N (P < 0.0001), whereas urea + MIP did not reduce volatilization (P = 0.9707).

High soil acidity under native shrub encroachment in the Cobar Pediplain, south-eastern Australia

This study investigated the chemical characteristics of shallow (0–30 cm) soil profiles under shrubs in areas of dense encroachment and compared them with shallow soil profiles under nearby large trees. Consistent patterns of high soil acidity were found under shrubs, as well as lower litter alkalinity, lower relative concentrations of calcium (Ca2+), lower effective cation exchange capacity, and higher aluminium (Al3+) and sodium (Na+) in the soil profile compared with under trees. Soil pH (CaCl2) was strongly correlated with the Ca content of surface litter. These findings suggest that shrubs (which at most sites included the shrub form of tree species) cycle alkalinity differently from large and mature trees, resulting in high acidity in the shallow soil profile acidity, and possible loss of alkalinity via surface movement of material from areas of dense encroachment.

Bequest of the Norseman—The Potential for Agricultural Intensification and Expansion in Southern Greenland under Climate Change

The increase of summer temperatures and a prolonged growing season increase the potential for agricultural land use for subarctic agriculture. Nevertheless, land use at borderline ecotones is influenced by more factors than temperature and the length of the growing season, for example soil quality, as the increasing lengths of dry periods during vegetation season can diminish land use potential. Hence, this study focuses on the quality of the soil resource as possible limiting factor for land use intensification in southern Greenland. Physical and chemical soil properties of cultivated grasslands, reference sites and semi-natural birch and grassland sites were examined to develop a soil quality index and to identify the suitability of soils for a sustainable intensification and expansion of the agriculture. The study revealed that soils in the study area are generally characterized by a low effective cation exchange capacity (CECeff) (3.7 ± 5.0 meq 100 g−1), low pH CaCl2 (4.6 ± 0.4) and low clay and silt content (3.0 ± 1.0% and 38.2 ± 4.7%, respectively). Due to the high amount of coarse fraction (59.1 ± 5.8%) and the low amount of soil nutrients, an increasing threat of dry spells for soils and yield could be identified. Further, future land use intensification and expansion bears a high risk for concomitant effects, namely further soil acidification, nutrient leaching and soil degradation processes. However, results of the soil quality index also indicate that sites which were already used by the Norseman (980s–1450) show the best suitability for agricultural use. Thus, these areas offer a possibility to expand agricultural land use in southern Greenland.

Probing the Surface Charge on the Basal Planes of Kaolinite Particles with High-Resolution Atomic Force Microscopy.

High-resolution atomic force microscopy is used to map the surface charge on the basal planes of kaolinite nanoparticles in an ambient solution of variable pH and NaCl or CaCl2 concentration. Using DLVO theory with charge regulation, we determine from the measured force–distance curves the surface charge distribution on both the silica-like and the gibbsite-like basal plane of the kaolinite particles. We observe that both basal planes do carry charge that varies with pH and salt concentration. The silica facet was found to be negatively charged at pH 4 and above, whereas the gibbsite facet is positively charged at pH below 7 and negatively charged at pH above 7. Investigations in CaCl2 at pH 6 show that the surface charge on the gibbsite facet increases for concentration up to 10 mM CaCl2 and starts to decrease upon further increasing the salt concentration to 50 mM. The increase of surface charge at low concentration is explained by Ca2+ ion adsorption, while Cl– adsorption at higher CaCl2 concentrations partially neutralizes the surface charge. Atomic resolution imaging and density functional theory calculations corroborate these observations. They show that hydrated Ca2+ ions can spontaneously adsorb on the gibbsite facet of the kaolinite particle and form ordered surface structures, while at higher concentrations Cl– ions will co-adsorb, thereby changing the observed ordered surface structure.

Effects of external factors on soil reflectance measured on-the-go and assessment of potential spectral correction through orthogonalisation and standardisation procedures

Reflectance spectroscopy is an alternative to describe soil properties, with potential to reduce costs and environmental impacts of conventional practices related to this activity. Acquisition of soil spectra on-the-go has several advantages over 'in-situ' static approaches, like deriving information with high spatial density. However, issues concerning on-the-go spectral measurements exist, mainly due to sensor movement and heterogeneous soil condition in the field. Procedures to mitigate these drawbacks, like external parameter orthogonalization (EPO) and direct standardization (DS), have mainly been applied so far to static spectral readings. In this study, EPO, DS and orthogonal signal correction (OSC) are tested in the context of on-the-go spectra acquisition for prediction of soil properties related to liming (i.e., pH in CaCl2, pH in SMP buffer, concentration of organic matter, calcium and magnesium, potential acidity, sum of basis, cation exchange capacity and its saturation by basis, lime requirement and moisture content). A detailed dataset (300 soil samples coupled with laboratory and field spectral measurements) was acquired in two sites in Brazil with contrasting soil attributes (site 1 with ‘clayey texture’ – Ferralsol; site 2 with ‘sandy texture’ – Alisol), and variability of soil properties was increased in these sites through application of different limestone rates in experimental plots. Spectral correction procedures slightly improved the accuracy of lime requirement predictions, with reduction of root mean squared error (RMSE) from 1.43 to 1.17tha−1, for study site 1 after applying OSC, and from 0.59 to 0.44tha−1, for study site 2 after DS was implemented. However, models based on laboratory data still performed considerably better with RMSE of 0.99 and 0.43tha−1 for site 1 and 2, respectively. ‘Global’ (i.e., one general correction model for a given field) or ‘specific’ models (i.e., several correction models, derived according to clusters obtained through fuzzy k-means applied to OSC components) performed considerably worse in comparison with other studies. Probably occurrence of external factors affecting the spectral information was not constant in the mapped fields. Also, different external factors may have affected the spectra at the same time and efficiency of the correction procedures decreased. Considering the high sensitivity of predictions based on field data to the approach used to interpolate the spectra and the poor performance of the correction methods applied in this context, more investigation is needed to improve predictions based on spectral data acquired on-the-go. Homogeneous spatial distribution of factors not related to the properties of interest, or at least in a degree allowing correction by the methods tested here, may not happen when current measurement systems are used. Despite that, spatial patterns described by wet-chemical analysis could be represented, at certain extent, through predicted values of lime requirement (LR), derived from field spectra. For instance, predictions after spectral correction resulted in autocorrelation patterns and map of LR comparable with those observed using conventional methods, for the site 1. These results, coupled with a semiquantitative potential of predictions based on field data after spectral correction, indicate that on-the-go measurements have potential for soil properties characterization, although full quantitative potential will require further advances in sensing solutions and chemometric methods applied in this context.

Soil Quality, Carbon Sequestration and Yield of Maize (Zea mays L.) under Maize/Legume Cropping System in Alfisols of a Savanna Zone, Nigeria

The role of maize-legume cropping system on soil quality, carbon sequestration and yield of maize in a Northern Guinea Savanna Alfisol, Nigeria was assessed in 2014 and 2015 rain-fed cropping seasons. The experiment was a Randomized Complete Block Design (RCBD), replicated three times and treatments were Sole (Mono crop) Maize (M), Desmodium (D) and Soybeans (S); Maize/soybeans intercrop (MS), Maize/Desmodium intercrop (MD), Maize Strip cropped with Soybean (MS 2:4) and Maize Strip cropped with Desmodium (M:D 2:4). Data obtained were evaluated for Organic carbon, available phosphorus, total nitrogen, soil pH, and CEC, Bulk density, Soil moisture, mean weight diameter and grain yield of Maize. Results show that mean soil acidity (pH water, 6.37; pH CaCl2, 5.78), mean organic carbon (5.23 to 5.69 g·kg-1) and mean total nitrogen improved (0.66 g·kg-1) in 2015 over values in 2014. Mean weight diameter (MWD) increased from 0.59 in 2014 to 1.05 in 2015; indicating a better aggregation across treatments. Treatment M resulted in significantly higher bulk density (Bd) than other treatments at 8 weeks after planting (WAP) and 16WAP, suggesting that soils under mono-crop maize were impaired for sustainable crop production. Soil organic carbon (SOC) sequestered in macro aggregates under MS (1.38 g·kg-1) was significantly higher than the other treatments. Best maize grain yield (GY) was under sole maize (M) and maize strip cropped with Desmodium (MD2:4) (3.13 t·ha-1 and 2.90 t·ha-1 in 2015, respectively). Maize strip cropped with Desmodium and maize/soybean intercrop enhanced better soil chemical and physical properties than sole maize. Soil quality (SQ) under MD2:4 ranked best (SQ1) for sustainable maize grain production and environmental conservation. Therefore, land use strategies that focus protection of soil organic carbon against further depletion and erosion, contribute nitrogen and/or replenishment of depleted carbon stocks through management techniques that involve legume/cereal cropping systems are advocated for sustainable agricultural production in the Nigerian Savanna zone Alfisols.

Ammonium-based fertilizers enhance Cd accumulation in Carpobrotus rossii grown in two soils differing in pH

Nitrogen fertilization has been shown to improve Cd uptake by plants but there is little information on the effect of N form. This study examined the effects of N form on Cd bioavailability and phytoextraction in two soils differing in pH. Plants of halophytic species Carpobrotus rossii were grown in an acidic Sodosol [pH (CaCl2) 4.9] and a neutral Vertosol (pH 7.2) spiked with 20 mg kg−1 Cd as CdCl2. Three N forms, KNO3, (NH4)2SO4 and (NH2)2CO at a rate of 24 mg N kg−1 were applied at weekly intervals, together with nitrification inhibitor dicyanodiamide. Cadmium availability was measured, and Cd speciation in the rhizosphere analysed using synchrotron-based X-ray absorption spectroscopy. The uptake, translocation and accumulation of Cd in plants were also assessed. The reduced N forms (NH4+ and urea), compared to NO3−-N, decreased rhizosphere pH by 0.25 units in Sodosol and 0.72 units in Vertosol, but decreased Cd-phosphate (by 23%) only in the Vertosol. Moreover, the reduced N forms increased the extractable Cd concentration in the rhizosphere of the Vertosol by 92% and of the Sodosol by 14%. They increased root Cd concentration by 70% and Cd uptake per unit root length by 40% in the Vertosol, and increased the translocation of Cd from the roots to the shoots by 76% in the Sodosol. The results suggest that the supply of NH4+-based N favors Cd phytoextraction in C. rossii.

Variabilidade espacial de atributos químicos do solo cultivado com soja sob plantio direto

During the 2012/2013 agricultural year, in the city of Campo Novo do Parecis, MT, the study aimed to analyze the spatial variability of soybean and of the fertility attributes of Typic Tropudox under no-tillage. The sampling grid for data collect was installed in an area of 5.0 ha. The productivity of soybeans, plant population, organic matter, P, Ca+2, Mg+2, K+, Al+3, H+ + Al+3, pH (CaCl2), sum bases, cation exchange capacity and base saturation were evaluated. A classic descriptive analysis was carried out with the help of the SAS statistical software, correlation and regression analysis with Excel and semivariograms were then modeled for all attributes, giving the respective cross-validations and kriging charts with the GS+ 7.0 software. Most surveyed attributes presented spatial dependence, and modeled their semivariograms by predominantly Gaussian type. The geostatistical ranges used for the attributes analyzed should not be less than 43.8 m, being the distance at which the attribute values are related to each other. The study of the variability of soil attributes and the adoption of techniques that help in the management of soil, such as geostatistics, is essential to proper plant development.

Changes in the Activity of Phosphatase and the Content of Phosphorus in Salt-Affected Soils Grassland Habitat Natura 2000

The subject of this study was the humus horizons in the salt-affected soils of Natura 2000 (Ciechocinek, Poland). In the adequately prepared soil, there were determined: pH in CaCl2, total organic carbon (TOC), exchangeable cations (Ca2+, Mg2+, Na+, K+), salinity (EC1:5), the content of total (TP) and available phosphorus (AP), the activity of alkaline (AlP) and acid (AcP) phosphatases. TOC affected the degree of saturation of the sorption complex with basic cations, as confirmed by correlation analysis. In the analysed soil samples a series of quantitative cations of basic character is as follows: Ca2+>Na+>K+>Mg2+. Increased salinity has modified the qualitative and quantitative composition of the soil solution. Correlation analysis confirmed the significant relationship between the conduction of the electrolytic soil and the content of sodium and potassium cations. The highest value of EC1:5 was found in the soil sampled near the ditch (sites 12, 13, 16). According to PN-R-04023 (1996), this soil classifies as class V with a very low content of P available but the availability factor for phosphorus value ranged from 2.773 to 5.252% indicating that soil P was sufficient for plant growth in this habitat. Significant positive correlations were found between salinity, alkaline phosphatase and exchangeable K+, Na+. Significant negative correlations were found between EC1:5 with P available and the availability factor for this nutrient (AF). The positive significant correlations among soil alkaline phosphatase and some physicochemical properties suggested that salinization had effects on these variables. Alkaline phosphatase may be used as indicators of soil quality in salinized grassland habitat Natura 2000.

CHANGES IN CHEMICAL PROPERTIES BY USE AND MANAGEMENT OF AN OXISOL IN THE AMAZON BIOME

ABSTRACT The proper soil use and management are essential for a sustainable production, thus the pursuit for systems that minimize damages to the environment and improve soil fertility is continuous. The objective of this study was to evaluate changes in soil fertility by the use and management of an Oxisol (Latossolo Vermelho-amarelo, SiBCS) in the Amazon biome. The soil uses and management systems evaluated were native forest, native pasture, minimum tillage system and conventional tillage system. The chemical atributes of the soil layers 0.00-0.10, 0.10-0.20, 0.20-0.30 and 0.30-0.40 m were evaluated. The soil pH (CaCl2) and the contents of organic matter, available phosphorus and exchangeable potassium, calcium, magnesium and aluminum were evaluated and the saturation by Al, effective cation exchange capacity and soil potential were determined. The highest pH values were found in the native pasture area, and the highest exchangeable aluminum contents were found in the layers 0.00-0.10 and 0.10-0.20 m of the conventional tillage system. The highest phosphorus availability was found in the layer 0.00-0.10 m of the native forest area. The highest potassium availability was found in the minimum tillage system. The lowest calcium and magnesium values were found in the layers 0.00-0.10 and 0.10-0.20 m of the conventional tillage system. The highest soil organic matter content was found in the layer 0.00-0.10 m of the native forest area. The nutrient availability for plants decreases in soils managed using the conventional tillage system. Soil uses and management systems of little soil disturbance are recommended to minimize environmental degradation in the Amazon biome.

Behaviour of 137Cs in forest humus detected across the territory of the Czech Republic

The activity concentration of 137Cs in samples of coniferous forest humus collected across the territory of the Czech Republic in 1995 and 2005 was analysed, and it was found significantly correlated with the surface deposition caused by the Chernobyl accident. The effective (12.8 y) and environmental (22.3 y) half-lives of radiocaesium in humus were calculated and compared with those in spruce bark. The impact of important forest stand factors, that is, precipitation, content of organic matter, age of trees and pH, on the behaviour of 137Cs in humus was studied. It was observed that humus samples with a higher proportion of organic matter, higher pH(H2O) and pH(CaCl2) contained higher amounts of 137Cs. Conversely, with the age of trees, the activity concentration of 137Cs in humus is decreasing. Higher precipitation and humus acidity decrease the reduction rate of the 137Cs in humus. These stand factors increase bioavailability of 137Cs in humus. The transfer and retention of available 137Cs in biomass of organisms living in humus for a long time can satisfactorily explain the longer residence time of 137Cs in humus affected by the studied factors.