Free CaCO3 Research Articles

Smart Implantable Hydrogel for Large Segmental Bone Regeneration.

Large segmental bone defects often lead to nonunion and dysfunction, posing a significant challenge for clinicians. Inspired by the intrinsic bone defect repair logic of "vascularization and then osteogenesis", this study originally reports a smart implantable hydrogel (PDS-DC) with high mechanical properties, controllable scaffold degradation, and timing drug release that can proactively match different bone healing cycles to efficiently promote bone regeneration. The main scaffold of PDS-DC consists of polyacrylamide, polydopamine, and silk fibroin, which endows it with superior interfacial adhesion, structural toughness, and mechanical stiffness. In particular, the adjustment of scaffold cross-linking agent mixing ratio can effectively regulate the in vivo degradation rate of PDS-DC and intelligently satisfy the requirements of different bone defect healing cycles. Ultimately, PDS hydrogel loaded with free desferrioxamine (DFO) and CaCO3 mineralized ZIF-90 loaded bone morphogenetic protein-2 (BMP-2) to stimulate efficient angiogenesis and osteogenesis. Notably, DFO is released rapidly by free diffusion, whereas BMP-2 is released slowly by pH-dependent layer-by-layer disintegration, resulting in a significant difference in release time, thus matching the intrinsic logic of bone defect repair. In vivo and in vitro results confirm that PDS-DC can effectively realize high-quality bone generation and intelligently regulate to adapt to different demands of bone defects.

Soil carbon-nutrient cycling, energetics, and carbon footprint in calcareous soils with adoption of long-term conservation tillage practices and cropping systems diversification

Calcareous soils, comprising vast areas in northern and eastern parts of India, are characterized by low soil organic carbon (SOC) with high free CaCO3 that results in low nutrient bioavailability with poor soil structure. Improvement of this soil can be achieved with conservation tillage with residue retention coupled with diversification of cropping system including legumes, and oilseeds in the system. Concerning all these, a long-term experiment was carried out in the calcareous soils having low organic carbon and high free CaCO3 (∼33 %) with varied tillage practices, viz. permanent bed with residue (PB), zero tillage with residue (ZT), and conventional tillage without residue (CT); and cropping systems viz. maize-wheat-greengram (MWGg), rice-maize (RM), and maize-mustard-greengram (MMuGg) during 2015–2021. From this study, it was observed that PB and ZT resulted in ∼25–30 % increment in SOC compared to the initial SOC, while CT showed a 4 % decrease in the SOC. Conservation tillage practices also resulted in better soil aggregation and favourable bulk density of the soil. Furthermore, PB and ZT practice exhibited 10–13 %; 15–18 %; 11–15 %; 40–60 %, 20–36 %, and 23–45 % increments in the soil available N, P, K, soil microbial biomass carbon, dehydrogenase activity, and urease activity, respectively over those under CT. Crop diversification with the inclusion of legume and oilseed crops (MMuGg, and MWGg) over cereal-dominated RM systems resulted in better soil health. Maize equivalent yield and energy use efficiency (%) were also found to be the maximum under PB, and ZT, in combination with the MMuGg system. ZT and PB also reduced the carbon footprint by 465 and 822 %, respectively over CT by elevating SOC sequestration. Hence, conservation tillage practices with residue retention coupled with diversification in maize-based cropping systems with mustard and greengram can improve soil health, system productivity, and energetics, and reduce the carbon footprint in calcareous soils.

Soil physico-chemical propertes of continous sugarcane growing areas of Gangapur tahsil of Aurangabad district

The present investigation was undertaken with an object to know the soil fertility status of continuous sugarcane grown area of Gangapur taluka of Aurangabad district. For this purpose, the soil samples were collected (0-15 cm) from 35 villages of Gangapur taluka. From each village 3 samples were collected. Total 105 samples were analyzed in this study. The collected soil samples were analyzed for chemical properties such as soil pH, electrical conductivity, organic carbon and calcium carbonate. Soil pH in sugarcane growing area was ranged from 7.3 to 8.1. Out of 105 soil samples 66 soil samples were mildly alkaline (7.4-7.8) in reaction whereas 36 soil samples were found moderately alkaline in reaction. Only 3 soil samples were found neutral (6.6-7.3) in reaction. Present study indicates that the soils of Gangapur tehsil are neutral to alkaline in reaction. Soil EC of sugarcane growing soils ranged from 0.20 to 0.55 dSm-1. Electrical conductivity of total sugarcane grown area was normal (< 1.0 dSm-1). These soils were categorized as normal in respect of electrical conductivity. Soil organic carbon content in sugarcane grown area was ranged from 0.36 gkg-1 to 0.89 gkg-1 with 57% soil samples have high organic carbon, 38% soil samples have medium organic carbon and only 5% soil samples have low organic carbon. Majority of these soils were high in organic carbon content. The free CaCO3 content in sugarcane growing soils was ranged from 5.9% to 8.5%. Generally, all soil samples exhibit medium status of calcium carbonate, these samples were categorized as calcareous.

PHOSPHATE SORPTION CHARACTERISTICS OF GANGES MEANDER FLOODPLAIN SOILS OF BANGLADESH

Three representative soils belonging to Amjhupi, Ishurdi and Sara series from the Ganges meander floodplain soils in Jessore district were collected to observe phosphate sorption characteristics and to evaluate the best fitted adsorption equation for the soils. The highest phosphate sorption was observed in Amjhupi series and the lowest was in Sara soil series. Differences in P sorption were significantly (p<0.05) influenced by clay content, CEC and pH of the soils. Free CaCO3, EC, OM and available P were found insignificant in affecting P adsorption. The Langmuir equation was best fitted to the equilibrium P sorption data and maximum R-square. Amjhupi soil series would require more P to be supplied to maintain a desired P level in soil solution than others.

Solubilization of phosphorus by low molecular weight organic acids and amino acids in calcareous soils

In order for plants to perform well in nutrient-deficient calcareous soils, they have an efficient adaptive technique of root exudate secretion, which contains low molecular weight organic acids. They enhance nutrient release and thereby increase the nutrient availability in calcareous soils. The present study aimed to investigate the effect of concentration and time of incubation of low molecular weight organic acids on P solubilization from calcareous soils collected from various locations of Coimbatore district with varying levels of calcareousness. An incubation experiment was conducted with five calcareous soils with varying levels of free CaCO3 viz., (1, 7.5, 12.5, 17.5 & 21.5%) by incubating with seven different concentrations (0, 20, 40, 60, 80 & 100 mM) of four organic (citric, malic, oxalic and acetic acid) and two amino acids (glycine and lysine) for nine incubation time intervals (5, 10, 20, 30, 60, 120, 240, 960 & 1440 mins) on a factorial experiment based on completely randomized design (CRD). Available P was analyzed to find the solubilization efficiency of various organic and amino acids. The organic acids were more efficient when compared to amino acids in P solubilization, especially citric acid followed by oxalic and malic acids, at 100 mM concentration incubated for 1440 mins. Also, the solubilization increased with increasing concentration and incubation time, irrespective of the soil calcareousness, but the magnitude of phosphorus extraction decreased with increasing soil calcareousness. Incubating the calcareous soils with 100 mM of citric acid for 1440 min solubilized more amount of phosphorus. Hence it can be concluded that addition of 100 mM citric acid will influence the phosphorus release even from highly calcareous soils.

Phosphorus Releasing Potentials of Amino Acids and Low Molecular Weight Organic Acids from Highly Calcareous Soils

Aims: The present study was conducted to investigate the potentials of amino acids and low molecular weight organic acids, two major components of plant root exudates on phosphorus release from highly calcareous soils.
 Study Design: Factorial experiment based on completely randomized design was used.
 Place and Duration of Study: Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India between 21st and 22nd of December 2020.
 Methodology: An incubation experiment was conducted with two amino acids (glycine and lysine) and four low molecular weight organic acids (citric acid, malic acid, oxalic acid and acetic acid) at seven different concentrations (0, 20, 40, 60, 80 & 100 mM) for assessing their potentials of phosphorus release from highly calcareous soils (>15% free CaCO3). The soils were incubated for a time interval of 5, 10, 20, 30, 60, 120, 240, 960 & 1440 minutes. Available Phosphorus status in the soils treated with both acids were analyzed after the expiry of each incubation time.
 Results: Organic acids had higher impact on phosphorus release than amino acids. Kinetic data obtained from the experiment were adequately described by Simple elovich (r2 ≥ 0.90, P < .001) and Power function (r2 ≥ 0.80, P < .001) models for both acids. Glycine among amino acids and citric acid among low molecular weight organic acids were highly effective in releasing phosphorus from highly calcareous soils.
 Conclusion: The experiment concludes that, incubating the highly calcareous soils with 100 mM citric acid for 1440 minutes increased the kinetics of phosphorus release. The Simple elovich model was the best fitted model to explain the phosphorus release from calcareous soils as influenced by amino acids and low molecular weight organic acids.

Effect of long-term fertilization on phosphorus fractions in different soil layers and their quantitative relationships with soil properties

Investigating the dynamics and distribution of soil phosphorus (P) fractions can provide a basis for enhancing P utilization by crops. Four treatments from a 29-year long-term experiment in black soil with maize cropping were involved in this study: no fertilizer (CK), inorganic nitrogen and potassium (NK), inorganic nitrogen, phosphorus, and potassium (NPK), and NPK plus manure (NPKM). We analyzed soil P fractions in different soil layers using a modified Hedley sequential method. The long-term NPKM treatment significantly increased total P by 0.6–1.6 times in the different soil layers. The Olsen-P concentration far exceeded the environmental threshold for soil Olsen-P (50.6 mg kg−1) in the NPKM treatment in the 0–60 cm soil profile. Moreover, the concentrations and proportion of labile and partially labile inorganic P (Pi) fractions (i.e., NaHCO3-extracted Pi, NaOH-extracted Pi, and dilute HCl-extracted Pi) to the sum of all P fractions (Pt) in the 0–60 cm soil profile were higher in the NPKM treatment than in the NPK treatment, indicating that manure could promote the transformation of non-labile into more labile forms of P in soil, possibly by manure reducing P fixation by soil particles. Soil organic matter, Mehlich-3 extractable iron (Fe), and organic-bound aluminum were increased by fertilization, and were the main factors influencing the differences in the P fractions in the 0–20 cm soil layer. Soil mineral components, i.e., free Fe oxide and CaCO3, were the main factors influencing the P fractions in the subsoil. The soil P transformation process varied with soil layer and fertilization. Application of manure fertilizer can increase the labile (Olsen) P concentrations of the various soil layers, and thus should reduce the mineral P fertilizer requirement for crop growth and reduce potential environmental damage.

Metal Nutrient Distribution and Availability in Vegetable Growing Soils of Coimbatore District, Tamil Nadu

Knowledge about distribution and bio availability of micronutrients is critically needed for better production of agricultural products both quantitatively and qualitatively. The study intended to evaluate the micronutrient status, availability and its interaction with soil properties in the vegetable ecosystem. This study looks at the availability of micronutrient metal cation with their diversified soil properties. A total number of 25 surface soil samples were collected from major vegetable growing areas and basic soil parameters such as pH, electrical conductivity, organic carbon, clay, cation exchange capacity, and free CaCO3 were examined. Micronutrients, both total and accessible, were also determined in soil. Zn and Fe deficiencies were found to a tune of 36 and 24 percent respectively in the overall soil samples, respectively. Deficiencies in Mn and Cu were found in extremely small quantities. Calcareous soils contribute to 40% of the soils analysed. Among the different soil properties, pH and CaCO3 showed a significant negative impact on micronutrient bioavailability whereas organic carbon and clay enhances the availability of micronutrients. The total micronutrient was not significantly correlated with the bioavailability of their respective nutrients.

Soil Physico-chemical Properties as affected by Long-term Application of Organics and Inorganic NPK Fertilisers under Rice-wheat Cropping System in Calcareous Soil of Bihar

A balanced application of organics and inorganic fertilisers could be beneficial to both soil nutrient availability, soil health and crop growth. The experiment was conducted on light textured highly calcareous soil at Research Farm of Dr. Rajendra Prasad Central Agricultural University, Pusa. Four levels of inorganic fertiliser treatments were applied i.e. 50, 100 and 150% of NPK along with no NPK as control as main plot treatments while four levels of organic treatment (i.e. no organics, compost, crop residue and compost+ crop residue) were applied as sub plot treatments in a split plot design with a total sixteen (16) treatments with three replications to investigate the long term effect of application of various doses of recommended fertiliser along with organic amendments on various physico-chemical properties of calcareous soils after 32nd crop cycle . Data was collected on various physico-chemical properties i.e. Soil pH, electrical conductivity (dSm-1), soil organic carbon (g kg-1), free CaCO3 (%), cation exchange capacity [cmol (p+) kg -1], bulk Density (Mg m-3) and water holding capacity (w/w %). The result revealed that soil pH was reduced by 3.9% while electrical conductivity (EC) was reduced by 45% over initial (1988). Both soil pH and EC were reduced by 1.7% and 15.4% respectively in plots receiving combined application of compost and crop residue along with 150% NPK over control. Organic carbon was improves by 33% over initial (1988) which had direct effect on reduction in soil bulk density (32%) and improved water holding capacity (29%) over the control in plots receiving 150% NPK along with combined application of compost and crop residue. Soil cation exchange capacity and free CaCO3 also showed an alternate trend former being enhanced and later being reduced after 32nd crop cycle in rice-wheat cropping system. Application of different levels of NPK along with different organics improved the overall soil physico-chemical properties which further have direct relation with enhanced crop growth and productivity.

Improved Method of Boron Fertilization in Rice (Oryza sativa L.)–Mustard (Brassica juncea L.) Cropping System in Upland Calcareous Soils

Calcareous soils are highly deficient in boron (B) due to having high levels of free CaCO3 and low organic matter. This has become one of the most important deficient micronutrients in Indian soil after zinc (Zn). For various rice (Oryza sativa L.)-based cropping systems, B fertilization is essential for increasing crop productivity and the biofortification of the crop, thus a suitable soil application protocol for B fertilization is required for B-deficient soils. In a six-year experiment, different rates of B application, namely, 0.5, 1.0, 1.5, and 2.0 kg ha−1 y−1, were evaluated to determine the effects of three different modes of B fertilization, i.e., applied only in the first year, applied in alternating years, and applied every year, in a rice (Oryza sativa L.)–Indian mustard (Brassica juncea L.) cropping system. It was observed that the application of B at 1.5 kg ha−1 every year or 2 kg ha−1 in alternate years resulted in the highest yield of rice and mustard, as well as the maximum system productivity of the rice–mustard cropping system. Application of 2 kg ha−1 of B in the initial year showed the maximum B uptake by rice, while application of 1.5–2.0 kg ha−1 of B every year resulted in the maximum B uptake by the mustard crop. Application of B at 2 kg ha−1 in alternate years or 1.5 kg ha−1 every year was the best B-application protocol in B-deficient calcareous soils for ensuring the highest productivity of the rice–mustard cropping system and B availability in the soil.

Status of available phosphorus, forms and distribution of phosphorus in soil under major cropping systems of Nellore district, A.P

An investigation was undertaken during 2018-19 in Southern zone of A.P. to study the Status of available phosphorus and forms of Phosphorus in soil under major cropping systems of Nellore district. The Ca-P was observed to be the predominant P fraction under all major cropping systems could be attributed to high CaCO3 content. The highest mean values for saloid-P (16.67 mg kg-1), total-P (538.21 mg kg-1) and other forms of P (342.07 mg kg-1) were recorded in groundnut-paddy cropping system and Fe- P (68.77 mg kg-1) and Al-P (61.85 mg kg-1) were highest in paddy-paddy cropping system, whereas available P2O5 (166.82 kg ha-1) and Ca-P (173.15 mg kg-1) were highest in groundnut-paddy and fallow-bengalgram systems, respectively. pH showed positive and significant relation with total-P (r= 0.507**) and other forms of P (r= 0.573**) where as free CaCO3 showed positive and significant correlation with Ca-P (r= 0.432*) in calcareous soils of S.P.S.R. Nellore district. Available P2O5 showed positive and significant correlation with saloid-P (r= 0.456*), Al-P (r= 0.765**) and Fe-P (r= 0.559**), saloid-P showed significant and positive correlation with total-P (r= 0.477*) and other forms of P (r= 0.510**). Al-P showed positive and significant correlation with Fe-P (r= 0.885**). Similarly, Ca-P showed positive and significant relation with total-P (r= 0.418*).

Fertility Status of Groundnut Growing Calcareous Vertisols of Dharwad District, Karnataka

A soil survey was carried out in different groundnut growing calcareous Vertisols of Dharwad district, Karnataka, India. One hundred surface composite soil samples were collected from five talukas (mandal) of Dharwad district and analyzed for soil chemical properties and nutrient status. The results showed that soil pH, electrical conductivity, organic carbon, free CaCO3 content ranged from 6.9-8.9, 0.15-1.79 dS m-1, 2.40-9.10 g kg-1, 5.8 -22.2 respectively across the regions. Available nitrogen, phosphorus (P2O5), potassium (K2O) and sulphur contents widely varied from 107-268, 18.5 - 56.0 and 386- 876, 14.8- 41.0 kg ha-1, respectively. On the basis of nutrient index values, groundnut growing calcareous soils of Dharwad were categorized as deficient in available nitrogen, medium in available phosphorus and high in available potassium. Most of the samples were deficient in available Fe and Zn whereas DTPA-extractable Cu and Mn were above the critical limits. A significant and positive correlation was found between organic carbon and available nitrogen (r=0.730**). However, a negative correlation was observed between Soil pH and micro nutrients while CaCO3 was negatively correlated with available iron (r=-0.31**).

Studies on forms and distribution of phosphorus in the different soil series of a sub-watershed in northern dry zone of Karnataka

A study was undertaken during 2018-19 in the soils of Babaleshwar East sub-watershed of Vijayapura district which belongs to Northern dry zone of Karnataka to study the forms of phosphorus and their relationship with soil properties. Thirteen soil series were identified in the study area, one representative soil profile was selected from each soil series and horizon-wise soil samples were analyzed for different fractions of phosphorus. Saloid-P, Fe-P, Al-P, Org-P and available-P decreased with profile depth in all the soil series and were positively and significantly correlated with organic carbon. Reductant soluble-P, occluded -P and Ca-P and total-P did not follow definite trend in most of the soil series. Occluded-P was negatively correlated with free CaCO3, whereas Ca-P and total-P were significantly and positively correlated with free CaCO3. Fe-P, Al-P and reductant soluble -P significantly and negatively correlated with pH and free CaCO3. Among the inorganic phosphorus fraction Ca-P was dominant as the soils are under semi-arid region.

Effect of soil physicochemical properties on yield and quality of sweet orange (Citrus sinensis (L.) osbeck)

A large number of biotic and abiotic factors are responsible for decline and low fruit yield both in quantity and quality observed in the citrus across the YSR district, hence the present study was conducted to determine the effect of soil physicochemical properties on fruit yield and quality of sweet orange (Citrus sinensis (L.) Osbeck) in YSR district of Andhra Pradesh, India. To carry out this investigation 50 sweet orange orchards aged between 12 to 13 years were selected. Soil samples were collected from 0–30 and 3060 cm depth of the orchards, and analyzed for physicochemical properties. Determined soil parameters like pH, free CaCO3, sodium adsorption ratio (SAR), exchangeable sodium percentage (ESP), organic C, and assessed the impact of these properties on fruit yield and quality of sweet orange. Results indicated that soil pH (r = -0.512**), free CaCO3 (r = -0.329*), SAR (r = -0.424**) and ESP (r = -0.522**) were influenced the fruit yield negatively significantly. Fruit yield (r = 0.360*) and fruit weight (r = 0.330*) was positively and significantly influenced by soil organic C content. Soil pH, SAR and ESP showed a significant negative relation with per cent fruit juice and vitamin C, whereas soil CEC had significant positive correlation with total soluble solids (r = 0.366**) and vitamin C (r = 0.364**) content of the fruit juice.

Influence of Integrated Application of Nano-Chelated Trace Elements and Sulfur on Desi Chickpea in the Short-Season Mediterranean-Type Environment

AbstractChickpea is one of the most important legume crops in the Mediterranean semiarid regions. Soils of these regions generally have free CaCO3, high pH and low organic matter, which reduce the availability of micronutrients and cause their deficiencies. In order to study the effects of integrated application of different level of elemental sulfur (0, 15, 30 kg·ha−1) and nano-chelated micronutrients (Zn, Fe, Mn) on growth and agro-morphological traits of chickpea (Cicer arietinum L.), a field experiment was conducted in the semiarid regions of the northwestern part of Iran. Evaluation of morphological traits showed that application of high level of sulfur significantly improved plant height, the number of primary branches and canopy width compared to the control. The longest growth period was recorded for plants grown by application of high level of sulfur and nano-chelated Zn fertilizer. The obtained data revealed that application of nano-chelated Zn fertilizer resulted in a significant increase in seed number per plant and seed weight compared to other nano-micronutrient fertilizers. Overall, the best growth performance and the highest seed yield were obtained from the integrated application of Zn and high level of sulfur. The findings showed that soil micronutrient deficiencies are partly due to high alkalinity of the soil, and application of sulfur beyond 15 kg·ha−1 can be an effective method to increase the efficacy of nanofertilizers. Integrated application of micronutrient and sulfur should be considered as an efficient agronomic management option for chickpea production systems in semiarid region.

Assessment of available macro and micronutrient status of coastal Jamnagar District in Saurashtra region of Gujarat

Two hundred surface (0–20 cm) soil samples from the ten talukas of coastal Jamnagar district viz., Jamjodhpur, Bhanvad, Kalyanpur, Dwarka, Kalavad, Jamnagar, Lalpur, Jamkhambhalia, Jodiya and Dhrol were collected from the cultivated soils, and were analyzed for different chemical properties. Soils were deficient with respect to available N and S, whereas medium in available P and high in available K status. The soils are alkaline in reaction with overall pH2.5 8.18. Soils of entire district were calcareous (free CaCO3 54.9%) in nature with low to medium in organic carbon. Among the DTPA extractable micronutrients, Mn and Cu found sufficient, whereas the soils are medium in Fe and Zn. The nutrient index found for available N (1.59) and S (1.62), medium for available P (1.68) and high for K (2.67), DTPA extractable Zn (1.59) low, and high for Fe (2.35), Mn (2.36) and Cu (2.48) in the soils of Jamnagar district. Significant and positive correlation was found between soil organic carbon content and pH, available N, Mn and Zn. The soil pH was found to negatively correlated with available N, P, K and S.

Characteristics of the soils of Ladakh region of Jammu and Kashmir

The cold arid region of Ladakh has high variability in soil characteristics. Soils of the region are quite distinct from those of other zones due to differences in climate, topography, vegetation and rocks. The paper details soil characteristics along with physiography, geology and climate of the region. Soils not only vary in physico-chemical properties but also in genesis and classification as well as microbiological properties. Such properties have been studied in typical soil profiles. By and large, the soils are shallow to very shallow in depth. They vary widely in colour, texture, structure and permeability depending upon topography and vegetation. Under the predominant influence of physical weathering, these soils usually consist of coarse materials and are often called Skeletal soils with admixtures of distinguished rock fragments, colluvial materials and screes. Most of the morphological characteristics like colour, texture and permeability seem to be inherited from the so formed regolith due to very slow rate of soil forming process. Calcareous nature of parental rocks in the form of limestone, dolomitic limestone and shale, is responsible for the genesis of soils having free CaCO3. Based on the surface and subsurface diagnostic horizons, morphological, physico-chemical and chemical characteristics of the soils, they have been classified into three main orders viz. Entisols, Inceptisols, Mollisols with occasional presence of Alfisols.

Potential factors affecting accumulation of unsupported 210Pb in soil

Airborne 210Pb, daughter of 222Rn, is frequently used as a tracer in different studies concerning atmospheric transport, sedimentation, soil erosion, dating, etc. Concentration of 210Pb was measured in 40 soil samples collected in urban and industrial areas in order to get evidence of possible influence of some factors on accumulation of airborne 210Pb in soil. Different soil properties such as the content of organic matter, free CaCO3, and available phosphorus (P2O5) were measured to explore their possible correlation with the amount of 210Pb. Special attention was given to the correlation between 210Pb and stable lead accumulated in the soil. Several samples were taken near a battery manufacturer to check if extremely high concentrations of lead can affect the uptake of the airborne 210Pb in soil. Soil samples were also taken at different depths to investigate the penetration of lead through the soil.

Dynamics of soil chemistry in different serpentine habitats from Serbia

To enhance understanding of edaphic conditions in serpentine habitats, a thorough investigation of chemical and mechanical properties of three soils from disjunct ultramafic outcrops in the central Balkans was undertaken. Soil from a nearby chemically-contrasting limestone habitat was also analyzed. Three plant species differently associated with serpentine (Halacsya sendtneri, Cheilanthes marantae, and Seseli rigidum) were references for site and soil selection. Twenty elements were scanned for, and fourteen were measured in seven sequentially-extracted soil fractions. Quantified soil properties also included: pH, levels of free CaCO3, organic matter, P2O5, K2O, N, C, S, cation exchange capacity, total organic carbon, field capacity and soil mechanical composition. The usual harsh components for plant growth in serpentine soil such as elevated Mg:Ca ratio, high levels of Ni, Cr, or Co, were significantly lower in the available fractions. There was a significant positive correlation of organic matter and field capacity, with most available Ca (70-80%) found in the mobile, rather than the organically-bound fraction. This showed that a more favorable Mg:Ca ratio is highly dependent upon a higher field capacity, which is also in accordance with a more developed vegetation. Increasing the availability of metals (Al, Ba, Ca, Cr, Cu, Mg, Ni, Zn) in a more developed serpentine grassland and forest vegetation, occurred only simultaneously with decrease of the Mg:Ca ratio and rise in other factors of fertility (N, P, K). Progressive development of ecosystem complexity therefore raised the availability of metals, but also reduced harsh Mg:Ca ratio disproportion, boosted levels of nutrients and raised soil field capacity. Principal components analysis confirmed that the main differences among serpentine habitats lay primarily in factors of fertility. The common habitat which hosts all three reference species offers intermediate conditions in a plant habitat selection gradient. Comparing serpentine with limestone showed ample difference in total content and availability of most of the surveyed elements, but very few differences in other chemical properties. The fragility of soil and ecosystem, and biological value of serpentine habitats demand intensive research and protection of these diversity and endemism hotspots of the Balkan Peninsula.

Influence of soil calcium carbonate on yield and quality of Nagpur mandarin

This article examines the macronutrient status and quality of 11-14 years old of five Nagpur mandarin orchards of Saoner tahsils, Nagpur district as influenced by soil calcium carbonate. Calcareous soils (pH 7.41 to 8.38) with high free CaCO3 content (3.13 to 15.48%) indicating that these soils are moderate to high calcareous in nature and it adversely affects the availability of macronutrients and yield of Nagpur mandarin. In context of nutrient status for these mandarin soils contain, available nitrogen is low (38 to 251 kg ha-1), available phosphorus is low to medium (10 to 22 kg ha-1) and available potassium is low to high (48 to 385 kg ha-1). Leaves that are 4 to 6 months old from non-fruiting terminals contain optimum leaf macronutrient concentration (%) as 1.80–2.50 nitrogen (N), 0.11–0.15 phosphorus (P) and 0.62–0.97 potassium (K) in relation to fruit yield of 13.6–19.6 tonnes ha-1. The findings show a low amount of macronutrients in leaves and reduced yield. In addition the poor quality oranges observed was influenced by increased content of CaCO3. Key words: CaCO3, nutrient status, mandarin yield, quality