Exchangeable Ca Content Research Articles

Soil Quality Assessment Based on Different Properties of Remediated Soil Affected by Various Organic Amendments

Remediated soil can be one of valuable resources for sustainable agriculture after improving its quality and properties with proper treatments. Therefore, this study was conducted to estimate changes in soil properties and soil quality for improving remediated soil contaminated with petroleum as affected by the applications of various organic amendments as soil conditioners including biochar (BC), charcoal (CC), and livestock manure compost (LC). Two remediated soils, remediated soil A and B (RSA and RSB) that previously contaminated with different concentrations of total petroleum hydrocarbons, were alkaline soils with up to 8.5 of soil pH, very low soil organic matter (SOM) contents and available phosphate (available P2O5) concentrations, and very high exchangeable Ca concentrations. Thus, these soils had very unfavorable conditions for crop growth. RSA and RSB were treated with BC, CC, and LC in levels of 0.0%, 1.0%, and 5.0% on dry weight bases. The remediated soils treated with organic soil conditioners were incubated for 2, 4, 8 and 16 weeks at room temperature (24 ± 2°C). SOM contents increased with all the treatments. In particular, SOM in RSB increased up to 19.5 g kg-1 with BC 5.0% treatment (BC5, 16-week), which was 2 times higher than that in both RSA and RSB soils without BC applications (Control soils). Also, available P2O5 concentrations increased to 24.9 mg kg-1 (RSA, 16-week), and 17.0 mg kg-1 (RSB, 8-week) with BC5. However, available P2O5 concentration in the remediated soils was very lower than that of the optimal value for cultivating crops suggested by National Institute of Agricultural Sciences in the Republic of Korea. Available P2O5 was negatively correlated with soil pH (p < 0.01) and exchangeable Ca (p < 0.01). Soil quality index (SQI) and weight additive soil quality index (SQIW) were positively correlated with SOM (p < 0.01). The mean value of soil quality indices were 39.3, 56.0, 40.0, and 54.5 for RSA Control, RSA BC5, RSB Control, and RSB BC5, respectively. The highest soil quality index was found in the remediated soil with BC treatment. The remediated soils require the immediate solution for the poor soil quality, and thus should need methodical and continuous management. Soil quality index (SQI) and weight additive soil quality index (SQIW) of the two remediated soils (RSA and RSB) as influenced by the applications of various organic amendments. Treatment† RSA RSB SQI SQIW SQI SQIW Control 39.3 d‡ 32.6 d 40.0 d 32.4 c BC1 45.5 bc 39.5 bc 45.0 bc 37.2 bc BC5 56.0 a 51.0 a 54.5 a 47.6 a CC1 43.0 cd 36.6 cd 42.5 cd 35.6 bc CC5 48.0 b 42.7 b 47.5 b 40.9 b LC1 39.3 d 32.6 d 41.3 cd 34.0 c LC5 48.0 b 42.7 b 47.5 b 40.5 b †Control, no treated; BC1, 1% of biochar treated; BC5, 5% of biochar treated; CC1, 1% of charcoal treated; CC5, 5% of charcoal treated; LC1, 1% of livestock manure compost treated; LC5, 5% of livestock manure compost treated. ‡Numbers followed by the different letter within a column are significantly different at p <0.05 by Duncan's multiple range test.

Physical and chemical properties of bentonite and its influence on acid and alkaline indicators and fertility of sod-podsolic sandy loamy soil (Retisols)

The article presents data on how bentonite clay (applied at reclamation rates) affects acid-alkaline characteristics and fertility indicators of soil (sod-podsolic sandy loamy soil - retisols). The experiment was conducted in the Nizhny Novgorod region. Physical and chemical properties of the used bentonite clay were preliminary studied. It is characterized by alkaline reaction of aqueous solution (pH 10.9) and of salt extract as well (pH 9.8) and undergoes electrolytic dissociation. The micro-plot field experiment which lasted over 3 years revealed some positive effect of bentonite application. As a result, the lowering of exchangeable soil acidity (by 0.31. pHKci units) and hydrolytic soil acidity (by 0.20 mg-eqv./100 g) was recorded, substantial reduction of aluminium soluble forms content (up to 48 %) was noticed as well, meanwhile the content of exchangeable Ca 2+ and Mg 2+ increased by 0.70 and 0.24 mg-eqv./100 g correspondingly. Bentonite application contributed to humus preservation in the soil and humus content was maintained at 1.221.28 % level. Moreover, this practice helped to increase the content of soluble (available) phosphorus and potassium compounds (on average by 27-30 % depending on experiment trial). The studied bentonite clay was proved to have stabilizing effect on acid-alkaline and nutrition balances in the soil. Some interaction between mineral soil part and bentonite clay is supposed to take place which results in the reconstruction of chemically-active fine particles (so-called active mineral centers) in soil adsorption complex.

Phosphorus sorption characteristics and related properties in urban soils in southeast China

Phosphorus (P) is usually enriched in urban soils but the environmental consequences of this P enrichment are not well understood. The objective of this study was to investigate P sorption characteristics as a measure of potential P loss from urban soils due to P enrichment via runoff and leaching. We collected soil samples at 0–5 and 5–15 cm soil depths from urban park areas in Nanchang, China, a rapidly expanding city with low P contents in its natural soils. Soil P sorption indices were characterized by a multiple-point isotherm batch experiment. The 0–5 cm layer had lower Langmuir P sorption maximum (Smax) than the 5–15 cm layer, probably because of its lower amorphous Al oxide (Alox) content and higher soil organic carbon (SOC) content. Stepwise multiple regression showed that the combination of Alox and SOC were the two most important soil properties related to Smax of the studied soils. A two-piece segmented linear regression was fitted to the relationships between labile P fractions (i.e., water extractable-P and anion exchange resin-extractable P) and binding energies (k) and the change point values were identified for k below which labile P decreased linearly. Soils below the change point had greater contents of SOC and exchangeable Ca and Mg and higher pH than those above the change point. These results suggest that parent materials played a major role in regulating P sorption capacities of the urban soils, particularly for the soils in urban green spaces. However, the enrichment of Ca and Mg derived from dissolution of calcareous materials in urban areas could significantly influence P bonding strength and saturation ratio of urban soils.

Soil aggregation may be a relevant indicator of nutrient cation availability

Aggregation was studied in two acidic forest soils (NE France) to investigate the potential link between available Ca and Mg content and soil aggregate size distribution and properties. Clay content influenced the aggregation status while clay mineralogy influenced aggregate stability and dynamics. Aggregation status and reactivity of soil components contributed to the difference of exchangeable Ca and Mg content in topsoil between the two sites. Though nutrient fluxes are important to define forest soil chemical fertility, the quantification of nutrient reservoirs in the soils and their availability to tree uptake is essential. A thorough understanding of nutrient availability requires an investigation of nutrient location and distribution in the soil solid phase. The general aim was to investigate the potential link between available Ca and Mg content and soil aggregate size distribution and their properties (chemical, physical, mineralogical). Soil aggregates were separated according to three size classes (200–2000 μm; 50–200 μm; < 50 μm) in two forest soils of the Lorraine plateau (France), both classified as Luvisols ruptic. The physical, chemical, and mineralogical properties were measured for each aggregate class. We showed that the relative abundance of an intermediate aggregate class [200–50 μm] was relevant to explain the difference of exchangeable Ca and Mg between sites. These aggregates were the poorest in organic and reactive mineral components and were unstable, which may mitigate the retention of Ca and Mg by ion-exchange. This study highlights the role of aggregation and reactivity of soil components as relevant determinants of cation availability to tree uptake in soils.

Effect of pre-treatment of bentonite with sodium and calcium ions on phosphate adsorption onto zirconium-modified bentonite

To understand the influence of the pre-treatment of bentonite with Na+ and Ca2+ on the adsorption of phosphate on zirconium-modified bentonite, three kinds of adsorbent materials including zirconium-modified raw, Na+-pretreated and Ca2+-pretreated bentonites were synthesized and characterized firstly, and afterward their adsorption performance and mechanism for phosphate were studied comparatively. The phosphate adsorption ability for zirconium-modified bentonite decreased after the pre-treatment of bentonite with Na+, but it increased after the pre-treatment of bentonite with Ca2+. The maximum phosphate adsorption capacity calculated from the Langmuir isotherm model for zirconium-modified Ca2+-pretreated bentonites (13.4 mg P/g) was much higher than that for the zirconium-modified raw bentonite (9.06 mg P/g). The pre-treatment of bentonite with Na+ and Ca2+ did not change the interaction type between zirconium-modified bentonite and phosphate, i.e., the coordination of phosphate to zirconium. The decreased phosphate adsorption capacity for zirconium-modified bentonite induced by the Na+ pre-treatment could be mainly attributed to the decrease of the specific surface area and the content of exchangeable Ca. The increased phosphate adsorption capacity for zirconium-modified bentonite induced by the Ca2+ pre-treatment could be mainly due to the increase in the amount of exchangeable Ca. Results of this work suggest that the zirconium-modified Ca2+-pretreated bentonite is more suitably used as an adsorbent for the removal of phosphate from wastewater than the zirconium-modified raw and Na+-pretreated bentonites.

Long term impact of Acacia auriculiformis woodlots growing in rotation with cassava and maize on the carbon and nutrient contents of savannah sandy soils in the humid tropics (Democratic Republic of Congo)

Rotational woodlots with N2-fixing trees may be efficient agroforestry systems, allowing farmers to alternate agricultural and wood-energy production on the same area. However, their long-term effect on soil fertility is poorly understood. The aim of this study was to investigate the influence of successive phases of Acacia auriculiformis stands growing in rotation with crops on the chemical properties of sandy and very poor tropical soils. The study was conducted 22 years after the afforestation of humid herbaceous savannah in Mampu, Democratic Republic of Congo. The chemical properties of top soil (0–20 cm) from control savannah plots were compared with those from acacia plots that had undergone one, two or three rotations of acacia during the 22 year period. We found that the soil properties under non-harvested acacia stands in a 1st rotation and under acacia stands in a 2nd or 3rd rotation following charcoal production and maize and cassava cultivation were similar. Soils under all acacia stands had higher C, N and $${\text{NO}}_{3}^{ - }$$ –N contents, but were more acidic, and had lower contents of exchangeable Ca, Mg, K and Na than the control savannah soils. Despite the increase in soil C and N, the sustainability of the acacia rotational agroforestry system after 22 years of practice is in question due to the steady decrease of soil cations, soil acidification and the risk of a decline in tree and crop productivity. To improve the nutrient balance and the sustainability of this system, different practices are recommended such as the debarking of tree stems before carbonization, the restitution of small branches and charcoal residues to the soil, and the supply of natural rock phosphate.

Effects of cover crops on soil quality: Part II. Soil exchangeable bases (potassium, magnesium, sodium, and calcium), cation exchange capacity, and soil micronutrients (zinc, manganese, iron, copper, and boron)

Maintaining and conserving essential soil nutrients using soil management practices, such as incorporating cover crops and no-tillage into crop rotation, has the potential to improve soil quality and fertility as well soil productivity. The effects of cover crops in a no-tillage seed maize (Zea mays L.) production system on soil exchangeable bases and soil micronutrients were investigated in Beaver Crossing (Seward County), Nebraska. The main objective of the research was to investigate the effects of growing cover crops under conservation tillage on soil exchangeable bases (potassium [K], magnesium [Mg], calcium [Ca], and sodium [Na]), cation exchange capacity (CEC), and soil micronutrients (zinc [Zn], copper [Cu], boron [B], iron [Fe], and manganese [Mn]). Extensive field research was conducted in four cover crop growing seasons (2012 to 2013, 2013 to 2014, 2014 to 2015, and 2015 to 2016) on three center pivot-irrigated seed maize or soybean (Glycine max L.) and cover crop rotation large-scale production fields. While extensive soil samples were taken to quantify and analyze the changes in soil exchangeable bases and soil micronutrients from the beginning of 2012 to the end of 2015, all large-scale production fields had cover crops in either seed maize or soybean rotation since 2002. Thus, it is anticipated that the changes in soil exchangeable bases, CEC, and micronutrients are a result of long-term (from early 2002 to late 2015) cover crop impacts on soil in all three research fields. The treatment effects exhibited variation not only between the treatments, but also between the soil layers for the same treatment. Cover crops in seed maize or soybean treatment (SCCC) had a significant effect on soil exchangeable K in the topsoil (0 to 5 cm soil layer). Cover crops did not affect exchangeable K concentration below the 5 cm soil layer. Exchangeable Ca concentrations were unaffected by any land cover treatment imposed in this research. Incorporating cover crops into a no-tillage seed maize or soybean cropping system (SCCC) might help in maintaining the exchangeable Mg concentration more effectively than no cover crop treatment (SC), especially in the 20 to 40 cm soil layer. Cover cropping has significant effects on CEC in the 5 to 40 cm soil depth. At the 5 to 20 cm soil depth, the SCCC treatment resulted in increased CEC by 8.4%, whereas bare soil, cover crop only without seed maize or soybean residue (CC), and SC treatments resulted in 10%, 4.1%, and 21% reduction in CEC, respectively. The SCCC treatment reduced the concentration of micronutrients in the topsoil (0 to 5 cm soil layer). Overall, cover crops (SCCC) have the potential in maintaining the optimum levels of Zn, B, Fe, and Mn in the topsoil (0 to 5 cm soil layer) as compared to the SC treatment. The results of this research suggest that cover cropping has the potential to alter several very important soil chemical properties (and significantly in some cases); however, the impacts primarily occur in the topsoil.

Stoichiometry of cationic nutrients in Phaeozems derived from skarn and Acrisols from other parent materials in lowland forests of Thailand

Some soils under tropical forests in western Thailand are derived from skarn complexes of hydrothermally metamorphosed granitic, calcareous and ultramafic rocks. We used data from six large, long-term forest ecological research plots to compare the soils derived from skarn with forest soils derived from granites and sedimentary parent materials elsewhere Thailand. The soils derived from skarn are Vermic Phaeozems and have deep, dark, worm-worked topsoils and bimodal particle size distributions of coarse sand and grit in clay or fine loam matrices. They are eutrophic with respect to both labile and non-labile forms of the mineral nutrients. The soils derived from other parent materials are mostly Acrisols. Analyses of variance for the cationic nutrients taken independently clearly distinguished the Phaeozems from the Acrisols. The two groups are also stoichiometrically distinct with respect to the main cationic nutrients, as depicted graphically by nutrient roses and as quantified as M+:TEB ratios. The cationic stoichiometric proportions also differentiated between the Acrisols on different plots and parent materials; and between the Phaeozems in our study and eutrophic soils in lowland forests elsewhere in the lowland tropics, with the Phaeozems having lower exchangeable Ca and Mg contents but higher exchangeable K. Subsoil cationic stoichiometric profiles appear to derive from parent materials, but those of the topsoil may be modified by selective biotic recycling. Nonetheless, inherited lithogenic stoichiometric ratios are still apparent in our topsoils. The forests on skarn in West Thailand are varied and overlap with those on Acrisols and other soils. This confirms earlier findings that climate and disturbance history have more influence than soils on the regional distribution of forest types in Thailand, although soils can be important at more local scales.

Calcium is cycled tightly in Cryptomeria japonica stands on soils with low acid buffering capacity

Calcium (Ca) is a key cation in the soil acidification process and in the fertility of forest soils. We investigated total concentrations of Ca, magnesium (Mg), and potassium (K) in both soil and fresh leaf litter in eight plantation stands of Cryptomeria japonica divided into two groups of highly contrasting soil acid buffering capacity (ABC). In addition to conventional methods, we used a double-crystal high resolution X-ray fluorescence (HRXRF) spectrometer to determine Ca fractions in soils with low and high ABC. Total Ca had accumulated in the 0–10cm depth horizons of the high-ABC soils, but not in the low-ABC soils. The exchangeable Ca concentration was correlated with total Ca concentration in the 0–10cm depth of the low-ABC soils. Calcium-Kα1,2 emission spectra of the 0–10cm soils obtained by HRXRF spectrometry separated the total Ca into two fractions, suggesting that the predominant Ca constituents had either passed through biological processes or were derived from weathering hydration in both the high- and low-ABC soils. Calcium concentration in the fresh leaf litter was significantly lower in the stands with low-ABC soil than in those with high-ABC soil and was positively correlated with soil exchangeable Ca concentration in the low-ABC stands; no such correlation was observed in the high-ABC stands. Exchangeable Ca pools in the 0–10cm depth range were equal to or less than the annual input of Ca via leaf litterfall in the low-ABC stands, but were seven times the annual input in the high-ABC soils. These results suggested that the accumulation of Ca in the upper soil occurs via the process of Ca circulation within C. japonica ecosystems, and that sufficient supply of Ca for tree needs was accompanied by the large accumulation of available Ca by C. japonica in the high-ABC soils. Nevertheless, it is likely that only small amounts of Ca were circulated in the stands on low-ABC soil. The lack of Ca accumulation in the surface soil and the accompanying tight circulation of Ca in the plant–soil system may explain the observed positive feedback in which ABC is gradually reduced in low-ABC soils.

Soil Quality after Six Years of Paper Mill Industrial Wastewater Application

The application of wastewater to irrigate soils may be an attractive option for paper mills, especially when the effluents can also provide nutrients to plants. Since there could be negative environmental effects, such activity must be preceded by a thorough evaluation of the consequences. The changes in soil quality of a Neossolo Fluvico Distrofico (Typic Udifluvent) were evaluated over a period of six years of irrigation with treated effluent from a wood pulp company. Although effluent application for six years did not affect soil resistance to penetration and soil hydraulic conductivity, it promoted a decrease in the mean size of aggregates and an increase in clay dispersion. Effluent application increased soil pH but did not change exchangeable Ca and Mg contents and organic carbon. After a full rotation of eucalyptus cultivation common in Brazil (six years), no negative effects in tree growth were found due to effluent irrigation. However, effluent addition caused higher values of Na adsorption ratio and intermediate electrical conductivity in the soil, which indicates a possible negative effect on soil quality if the application continues over a longer period. Therefore, a monitoring program should be carried out during subsequent crop rotations, and alternatives must be studied to obtain better effluent quality, such as adding Ca and Mg to the wastewater and using gypsum in the soil.

Silicon Release from Local Materials in Indonesia under Submerged Condition

Five inorganic materials (steel slag, silica gel, electric furnace slag, fly ash and Japanese silica fertilizer) and six organic materials (rice husk-biochar, rice straw compost, media of mushroom, cacao shell-biochar, rice husk-ash and elephant grass), were evaluated as Si fertilizer sources for rice plants (Oryza sativa L.) in two soil types (red clayey and sandy soil). Evaluation was carried out by incubating them at 30oC under submerged condition for 70 days. The soil solution was replaced at day 7, 14, 21, 42, 49, 56, 63 and 70 and the amount of silicon (Si) release, pH, Eh, calcium (Ca), magnesium (Mg), iron (Fe) and manganese (Mn) concentrations in soil solutions were determined. The amount of Si release ranged from n.d. (not detected)-32444.7 mg Si kg-1 and 105.84-48524.0 mg Si kg-1 in red clayey and sandy soil solutions, respectively during 70 days of incubation. Reduction in soil Eh was accompanied with an increase in the solubility of the soil Si especially for silica gel, electric furnace slag, elephant grass and media of mushroom. Higher exchangeable Ca content in soil tended to suppress Si release from rice straw compost, rice husk-ash and cacao shell-biochar. Considering the results of present study and availability of the materials, we concluded that steel slag of the inorganic materials and rice straw/husk and cacao shell-biochar of organic materials had the highest potential as Si fertilizer source in Indonesia.

Soil Management in the Breede River Valley Wine Grape Region, South Africa. 4. Organic Matter and Macro-nutrient Content of a Medium-textured Soil

Eight cover crop treatments were applied for 12 consecutive years on a medium-textured soil (18% clay) in a vineyard near Robertson (33 0501 S, 19054'E). Full surface mulching combined with full surface chemical control from bud break to harvest (BB), i.e. T3, and no cover crop combined with BB (T2) were also applied. The control (Ti) consisted of mechanical control in the work row and chemical control in the vine row from bud break to harvest. After 10 years, the %C in the 0 to 600 mm soil layer of the minimum cultivated treatments increased, except in the 0 to 300 mm soil layer, in which Festuca arundinacae was established (Tii), and the 150 to 300 mm soil layer, in which Vicia dasycarpa (grazing vetch) was controlled in the vine row from bud break and in the work row from berry set (end of November) (T7). The %C in the 0 to 150 mm soil layer of the cover crop treatments also exceeded the 0.9% level above which the application of N is deemed unnecessary on these soils. During the first three years the total inorganic N in the 0 to 600 mm soil layer of the treatments in which an N-fixing cover crop was sown was higher (mostly significant) than that of Ti, T2, T3 and Til during full bloom, veraison and post-harvest. Over the medium term, grazing vetch controlled chemically on the full surface from bud break (T6) caused the total inorganic N in the 0 to 600 mm soil layer during full bloom to exceed the level at which the grapevines need additional N. During veraison, this was achieved with T7. Over the long term this was achieved during full bloom with T6 and T7. During veraison, T7 gave a similar result. T3 or the use of annuals as winter-growing cover crops may supply the fertifiser needs of the grapevines post-harvest. Although differences in the P concentration and exchangeable Ca and Mg concentrations occurred between some treatments, no significant trends were observed. The level of K in all the treatments was between two and six times higher than the optimal level for the clay loam soils in the Breede River Valley.

Long-term Investigation of Soil Chemical Properties in Paddy Fields Located in Different Topographic Areas of Jeonbuk Province

The aim of this study was to examine the selected soil chemical properties of paddy fields in different topographic areas to efficiently manage nutrient valances of the paddy fields in Jeonbuk Province. Three-hundred soil sampling sites in paddy fields were selected from the different topographic areas in Jeonbuk Province. The soil samples were collected every four years from 1999 to 2015. Soil pH and exchangeable K and Mg concentrations declined during the experimental periods. However, almost all the chemical properties were within the proper levels for paddy soil, except exchangeable Mg concentration. Distributed areas of the paddy fields with soil pH below 5.5 continuously increased, but the paddy fields with lower concentrations of soil organic matter and available P₂O 5 than the proper levels declined after 2007. In addition, the paddy fields with available SiO₂ below the proper concentration decreased from 83.3% of the total paddy fields studied in 1999 to 61.0% of the total fields investigated in 2015. The paddy fields with lower exchangeable K and Mg than the proper levels increased after 2003 whereas the fields with lower exchangeable Ca concentration decreased. Dominant landform of coastal and plain areas was fluvio-marine plains that was distributed in 53.7% and 40.9%, respectively. Local valley and fans was a dominant landform of mountainous and middle-mountainous areas, which was 51.8% and 67.6%, respectively. Dominant soil textures distributed in coastal and plain areas were silty loam and loam. Those in mountainous and middle-mountainous areas were sandy loam and loam, respectively. Soil pH was relatively higher in coastal area and the comparatively higher content of soil organic matter was found in costal area than other areas. The concentrations of available P₂O 5 , exchangeable Ca, and exchangeable Mg were generally higher in mountainous, coastal, plain areas, respectively, but available SiO₂ and exchangeable K concentrations were not significantly different among the different topographic areas.

Can sustainable management models for olive groves adequately satisfy their nutritional needs?

Two sustainable management models were studied, in order to investigate if they were successful in satisfying the nutritional needs of mature olive groves (20 year-old olive trees- Olea europaea, cv. ‘Koroneiki’), situated in two geographical regions of Greece (Thessaloniki, Central Macedonia, Northern Greece, and Corfu, Ionian Islands, Western Greece). Nutrient supply in both olive orchards was based, during the last 20 years, on pruning material recycling, as well as on cow manure (8t/ha/year, in the grove of Corfu) and patent kali (5kg/tree/year, in the grove of Thessaloniki) application. Soil analysis revealed that pH was slightly alkaline in the olive grove of Thessaloniki and acidic (6.00–6.34) in the olive orchard of Corfu; organic matter content was approximately two times greater in the grove of Corfu. Exchangeable Ca concentrations in deeper soil layers (20–40 and 40–60cm) of the olive orchard of Thessaloniki were approximately two times greater, compared to those found in the grove of Corfu. In contrast, 2–14.5 times greater K exchangeable concentrations, but only in deeper layers (20–40 and 40–60cm), were found in the grove of Corfu. DTPA extractable Fe, Mn and Zn concentrations were 9–14, 3–5, and 3–5.5 times greater (depending on soil layer) in the olive orchard of Corfu, compared to those found in Thessaloniki. Leaf K concentrations were significantly greater in the grove of Corfu (1.2–1.4%d.w.), while Fe concentrations in the same olive orchard exceeded 120ppm. Generally, most of the leaf nutrient concentrations for both groves were within the normal levels of sufficiency, or within the over-sufficiency range (e.g. those of N and K in the grove of Corfu, and P in both olive orchards). Only leaf B concentrations in January (17–19p.p.m.), in both orchards, and leaf Mn levels in the grove of Corfu were slightly (but not seriously) deficient to marginal. Consequently, it can be concluded that both studied sustainable management models for mature olive groves (no soil tillage, pruning material and weed cuts recycling, in addition to: (i) patent kali, or (ii) manure supply) were successful. Thus, the two models are commercially and environmentally sustainable for olive cultivation, especially in marginal, degraded, and/or hilly Mediterranean areas. Finally, they are of great socioeconomic importance in specific rural areas (where olive-growers combine olive oil production with domestic animal breeding).

Changes of Chemical and Biological Properties of Distinct Forest Floor Layers after Wood Ash Application in a Norway Spruce Stand

The effect of wood ash (WA) fertilisation on chemical and biological properties of forest floor layers was studied in a Norway spruce (Picea abies (L.) Karst.) stand in the central part of Slovakia at an altitude of 1300 m above sea level. In the forest floor, litter (OL), fragmented (OF), and humic (OH) horizons with average thickness of 1.5, 2, and 4 cm, respectively, could be distinguished. Three replicates of two wood ash treatments (3 and 6 t·ha−1) and a control were established in the autumn of 2012. Soil samples from OL, OF, OH and A-horizon were taken 0.5, 1, 6 and 12 months after the WA application. In soil samples chemical (pH, C and N content, C:N ratio, concentration of exchangeable Ca, Mg and K) and microbial properties (basal respiration, catalase activity, structure of microbial community based on BIOLOG assay) were determined. Our results showed that the changes in microbial and chemical properties do not occur simultaneously in particular horizons. WA application in autumn lead to a significant increase in pH, base cation concentration, and distinct losses in C and N content in the OL layer in the first month; however, at the beginning of the vegetation period, the most pronounced effect of WA was observed in OF and especially OH horizons; no changes were found in the A-horizon. Different properties of particular forest floor horizons led to a vertical stratification of the microbial community. Each forest floor horizon had particular properties, leading to a vertical stratification of the microbial community; deeper horizons had more homogenous functional groups.

Effects of Vermicompost Application on the Growth and Ginsenoside Content of Panax ginseng in a Reclaimed Field

The objective of this study was to evaluate the effects of the application of vermicomposts on the growth parameters and ginsenoside content of ginseng roots. Food waste vermicompost (FW), cow manure vermicompost (CM), and paper sludge vermicompost (PS) were applied at 10 and <TEX>$40t\;ha^{-1}$</TEX>, respectively. One-year-old seedlings were transplanted and 4-year-old roots were harvested. Soil nitrate and phosphate concentrations were increased in the plots applied with FW and CM at <TEX>$40t\;ha^{-1}$</TEX>. Soil pH and exchangeable Ca concentrations were higher at FW <TEX>$40t\;ha^{-1}$</TEX> than at CM <TEX>$40t\;ha^{-1}$</TEX>. Root yield increased when treated with FW <TEX>$40t\;ha^{-1}$</TEX> in comparison to the yield for the control. The incidences of root rot disease and ginsenoside content were not significantly affected by the treatments. The results suggested that application of vermicompost might not show a relationship between root biomass and ginsenoside content. It further showed that proper use of vermicompost can promote root yield without a reduction in root quality or an increase in the incidence of root rot disease in reclaimed fields.

Effect of soil coarseness on soil base cations and available micronutrients in a semi-arid sandy grassland

Abstract. Soil coarseness is the main process decreasing soil organic matter and threatening the productivity of sandy grasslands. Previous studies demonstrated negative effect of soil coarseness on soil carbon storage, but less is known about how soil base cations (exchangeable Ca, Mg, K, and Na) and available micronutrients (available Fe, Mn, Cu, and Zn) response to soil coarseness. In a semi-arid grassland of Northern China, a field experiment was initiated in 2011 to mimic the effect of soil coarseness on soil base cations and available micronutrients by mixing soil with different mass proportions of sand: 0 % coarse elements (C0), 10 % (C10), 30 % (C30), 50 % (C50), and 70 % (C70). Soil coarseness significantly increased soil pH in three soil depths of 0–10, 10–20 and 20–40 cm with the highest pH values detected in C50 and C70 treatments. Soil fine particles (smaller than 0.25 mm) significantly decreased with the degree of soil coarseness. Exchangeable Ca and Mg concentrations significantly decreased with soil coarseness degree by up to 29.8 % (in C70) and 47.5 % (in C70), respectively, across three soil depths. Soil available Fe, Mn, and Cu significantly decreased with soil coarseness degree by 62.5, 45.4, and 44.4 %, respectively. As affected by soil coarseness, the increase of soil pH, decrease of soil fine particles (including clay), and decline in soil organic matter were the main driving factors for the decrease of exchangeable base cations (except K) and available micronutrients (except Zn) through soil profile. Developed under soil coarseness, the loss and redistribution of base cations and available micronutrients along soil depths might pose a threat to ecosystem productivity of this sandy grassland.

Alleviating aluminum toxicity in an acid sulfate soil from Peninsular Malaysia by calcium silicate application

Abstract. In response to human population increase, the utilization of acid sulfate soils for rice cultivation is one option for increasing production. The main problems associated with such soils are their low pH values and their associated high content of exchangeable Al, which could be detrimental to crop growth. The application of soil amendments is one approach for mitigating this problem, and calcium silicate is an alternative soil amendment that could be used. Therefore, the main objective of this study was to ameliorate soil acidity in rice-cropped soil. The secondary objective was to study the effects of calcium silicate amendment on soil acidity, exchangeable Al, exchangeable Ca, and Si content. The soil was treated with 0, 1, 2, and 3 Mg ha−1 of calcium silicate under submerged conditions and the soil treatments were sampled every 30 days throughout an incubation period of 120 days. Application of calcium silicate induced a positive effect on soil pH and exchangeable Al; soil pH increased from 2.9 (initial) to 3.5, while exchangeable Al was reduced from 4.26 (initial) to 0.82 cmolc kg−1. Furthermore, the exchangeable Ca and Si contents increased from 1.68 (initial) to 4.94 cmolc kg−1 and from 21.21 (initial) to 81.71 mg kg−1, respectively. Therefore, it was noted that calcium silicate was effective at alleviating Al toxicity in acid sulfate, rice-cropped soil, yielding values below the critical level of 2 cmolc kg−1. In addition, application of calcium silicate showed an ameliorative effect as it increased soil pH and supplied substantial amounts of Ca and Si.

Impact of Lowland Rainforest Transformation on Diversity and Composition of Soil Prokaryotic Communities in Sumatra (Indonesia).

Prokaryotes are the most abundant and diverse group of microorganisms in soil and mediate virtually all biogeochemical cycles in terrestrial ecosystems. Thereby, they influence aboveground plant productivity and diversity. In this study, the impact of rainforest transformation to intensively managed cash crop systems on soil prokaryotic communities was investigated. The studied managed land use systems comprised rubber agroforests (jungle rubber), rubber plantations and oil palm plantations within two Indonesian landscapes Bukit Duabelas and Harapan. Soil prokaryotic community composition and diversity were assessed by pyrotag sequencing of bacterial and archaeal 16S rRNA genes. The curated dataset contained 16,413 bacterial and 1679 archaeal operational taxonomic units at species level (97% genetic identity). Analysis revealed changes in indigenous taxon-specific patterns of soil prokaryotic communities accompanying lowland rainforest transformation to jungle rubber, and intensively managed rubber and oil palm plantations. Distinct clustering of the rainforest soil communities indicated that these are different from the communities in the studied managed land use systems. The predominant bacterial taxa in all investigated soils were Acidobacteria, Actinobacteria, Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria. Overall, the bacterial community shifted from proteobacterial groups in rainforest soils to Acidobacteria in managed soils. The archaeal soil communities were mainly represented by Thaumarchaeota and Euryarchaeota. Members of the Terrestrial Group and South African Gold Mine Group 1 (Thaumarchaeota) dominated in the rainforest and members of Thermoplasmata in the managed land use systems. The alpha and beta diversity of the soil prokaryotic communities was higher in managed land use systems than in rainforest. In the case of bacteria, this was related to soil characteristics such as pH value, exchangeable Ca and Fe content, C to N ratio, and extractable P content. Archaeal community composition and diversity were correlated to pH value, exchangeable Fe content, water content, and total N. The distribution of bacterial and archaeal taxa involved in biological N cycle indicated functional shifts of the cycle during conversion of rainforest to plantations.

Robinia pseudοacacia as a valuable invasive species for the restoration of degraded croplands

Deforestation was, for many years, a common practice in Greece in order for the old forest sites to be used as croplands. These deforestations had a very negative influence on soil fertility, especially in the cases where soil depth was restricted, and very sharp inclinations occurred. All these cases were followed by increase of soil surface runoff and extended soil erosion. The continuously decreased crop yields led very often to the abandonment of cultivation. In order to restore such areas and to enhance agricultural development, different rules from the European Agricultural Fund for Rural Development (EAFRD), in the frame of axis 4 “Forestation of Agricultural Lands” were applied. For the study of the influence of restoration on soil fertility, a research project was performed in the whole community area of Gomati (Chalkidiki, Macedonia, Northern Greece), and soil chemical properties have been determined in: i) degraded agricultural sites, ii) restored with Robinia pseudoacacia (black locust) lands, as well as: iii) in mixed native forests. The results showed that the restoration of the degraded agricultural lands with R. pseudoacacia, 20years after the establishment of these plantations, led to 1.3–3 times greater (depending on soil layer) organic matter content, 1.2–2.5 times greater N quantity, and in many cases to significantly higher P and K concentrations, compared to the degraded agricultural lands and to the native forest areas, respectively. The highest exchangeable Ca and Na concentrations were recorded in the mixed native forest soils, while the highest DTPA extractable Fe and Mn concentrations were found in the degraded agricultural soils, compared to the other two land use types. Finally, most leaf nutrient concentrations in black locust plantations were adequate to optimum for plant growth and nutrition, with the exceptions of those of K, Cu and Fe, which were deficient, critical and excessive, respectively.