Contaminant Mobility in Soils Amended with Fly Ash and Flue-Gas Gypsum: Intact Soil Cores and Repacked Columns

The impact of the land application of coal combustion by-products, fly ash (FA) and flue-gas desulfurization gypsum(FDG), to coarse-textured soils of the southeastern U.S.A. wasinvestigated using batch and dynamic column techniques. Two FAsamples, one an alkaline FA (Alk-FA) and the other an acidic FA(Acid-FA), were evaluated alone and in combination with FDG assoil amendments to an Appling loamy sand (Typic Hapludults). Theeffects of these waste products on clay dispersion, soilhydraulic conductivity (K_sat) and the migration ofcontaminants such as Arsenic (As) and Boron (B) were studiedusing intact soil cores and repacked soil columns. FA or combinationsof FA + FDG were applied to the surface of intact soil cores (10 Mg ha^-1) and repacked soil columns or incorporated withinrepacked soil columns. The columns were saturated and thenleached for a prescribed number of pore volumes to simulateleaching conditions in the field. Effluent pH, electricalconductivity (EC), and turbidity were monitored and leachatefractions were collected for B, As, Ca, Mg, K and Na analysis.Both FA materials were ineffective at decreasing the inherentdispersibility of clay from the A_p horizon in batch tests.In fact, high application rates of the Alk-FA induced some claydispersion in the well-flocculated B_t soil materials, andcolumn results suggest that incorporating the Alk-FA within thesurface soil may actually reduce K_sat. In contrast,treatments with FDG were highly effective at inducing rapid clayflocculation in batch tests and eliminating effluent turbidityfor intact and repacked soil columns. Boron was readily mobilefrom both intact and repacked soil columns, a majority of whichleached from the columns within the first three pore volumes.Boron leaching was greater for combined treatments (FA + FDG),possibly indicative of enhanced solubilization in the presenceof FDG or sulfate (SO₄ ^2-) competition for sorptionsites. Arsenic levels present in the leachates from FA and FDGcolumns were generally lower than control columns and roughlycorrelated with effluent turbidity. Combined treatments (FA +FDG) enhanced Mg and K leaching due to the added competition ofCa for cation exchange sites. Following leaching, the intactsoil cores were sectioned at 5 cm intervals and the pH and EC ofthe soil, as well as the vertical distribution of As and B, weredetermined. Levels of residual As were only slightly higher in the upper section of the FA-amended columns, showing little downward movement, but no clear trend in residual B was observed due to its greater mobility.     

Risks of Boron Toxicity in Canola and Lupin by Forms of Boron Application in Acid Sands of South-Western Australia

Boron (B) deficiency frequently occurs on soils that are low in organic carbon (C) (<1.0% organic C), pH (soil pH_Ca <5.0), and clay content (<5% clay). Acid sands with these soil properties are common in south-western Australia (SWA). Moreover, hot calcium chloride (CaCl₂) extractable B levels are commonly marginal in the acid sands of SWA. This study examined the effects of soluble and slow release soil-applied B fertilizer and foliar B sprays on crops most likely to respond to B fertilizer on these soils, canola (oil-seed rape, Brassica napus L.) and lupin (Lupinus angustifolius L.).

At 25 sites over three years, canola was grown with (0.34 kg ha-¹) or without B applied as borax [sodium tetraborate decahydrate (Na₂B₄O₇·10H₂O) 11% B], and this was followed by nine experiments with B rates [0, 0.55, 1.1 kg ha^?1, applied as borax or calcium borate (ulexite, NaCaB₅O₆(OH)₆·5(H₂O), 13% B] and foliar sprays (0.1% solution of solubor, 23% B) in 2000–2001. A further five sites of B rates and sources experiments were carried out with lupin in 2000–2001. Finally, foliar B sprays (5% B w/v as a phenolic complex) at flowering were tested on seven sites in farmers’ canola crops for seed yield increases. No seed yield increases to soil-applied B were found while foliar B application at flowering increased canola seed yield in only one season across seven locations. By contrast, borax fertilizer drilled with the seed at sowing decreased canola seed yield in nine of 34-farm sites, and decreased lupin yield in two of five trials. Toxicity from drilled boron fertilizer decreased yield could be explained by decreases in plant density (by 22–40%) to values lower than required for optimum seed yield. Seedling emergence was decreased by borax applied at sowing but less so by calcium borate. Foliar B spray application never reduced seed yield due to toxicity effects.

Boron fertilizer drilled with the seed increased the B concentration in plant dry matter at early to mid-flowering. Boron application decreased the oil concentration of grain of canola at four sites. The oil yield of canola was significantly decreased at seven sites.

Notwithstanding the marginal B levels on acid sands of the SWA region, care needs to be taken on use of borax fertilizer as toxicity was induced in canola and lupin; with 0.34 to 1 kg B ha^?1(3-10 kg borax ha^?1) at sowing depressing seed yield, mostly by decreasing plant density. Rather than making general recommendation for B fertilizer application based on 0.01M CaCl₂ soil extractable B, soil and plant analysis should be used to diagnose B deficiency and B fertilizer use limited to calcium borate or foliar borax rather than soil-applied borax on low B sands.     

Economic viability of Phaseolus vulgaris (BRS Estilo) production in irrigated system in a function of application of leaf boron

Foliar fertilization may be a viable strategy to boron supply in irrigated cropping systems with common beans (Phaseolus vulgaris), since it prevent B leaching. The aim of this work was to evaluate the economic viability and physiological parameters of the common beans production in irrigated cropping systems using sources and increasing foliar boron doses. A field experiment was carried out using an experimental block design in a factorial scheme 2?×?5?×?3, with two sources of B (boric acid and borax) and five doses: 0 (control), 2, 4, 6 e 8?kg?ha^?1, with three repetitions. Foliar B applications were performed at 40 days after seeds germination, in pre-flowering stage. Physiological process (transpiration, stomatal conductance, CO₂ internal concentration, net photosynthesis, and relative chlorophyll index), B level in leaves and grain yield were measured. These data were used to determine the economic viability of B fertilization in common beans. Both boric acid and borax increased B levels in common beans leaves. Borax affected some physiological process reducing stomatal conductance and increasing net photosynthesis. Using borax, the highest net photosynthesis was observed at a rate of 4?kg?ha^?1, while the boric acid increased net photosynthesis linearly after increasing B doses application. An enhance of 311?kg?ha^?1 in the grain yield was observed using borax related to the control (without B application); however, grain yield decreased linearly after application of increasing B doses, as boric acid. Comparing the economic viability of sources and doses of B, the highest profitability is obtained using borax at a rate of 4?kg?ha^?1, which promoting a differential profit of US$534.44 per hectare compared to common beans cropping without B.     

Formulation,synthesis and characterization of boron phosphate (BPO4) compounds as raw materials to develop slow‐release boron fertilizers

We investigated the use of boron phosphate (BPO₄) as a slow‐release boron (B) source. Boron phosphate compounds were synthesized by mixing boric acid (H₃BO₃) and phosphoric acid (H₃PO₄) and heating at temperatures of 25 to 1000°C for 1 or 24 h. X‐ray diffraction (XRD) patterns and chemical analysis confirmed the formation of BPO₄. The crystallinity of these compounds increased with increasing temperature and heating time. The compounds synthesized at 300°C or less were hygroscopic and clumped together, while those synthesized at 500 to 1000°C were non‐hygroscopic and free‐flowing. The solubility of these compounds was assessed at different pH and P concentrations, and compared to the solubility of ulexite and colemanite. The solubility of the BPO₄ compounds decreased with increasing synthesis temperature and with decreasing pH. The solubility and the kinetics of B release from BPO₄ compounds synthesized at 500 and 800°C were slower than for most commonly used B sources. Given their slow dissolution, the BPO₄ compounds may have potential to continuously supply B to crops in environments where B leaching is a problem. The compounds synthesized at 500 and 800°C show potential for co‐granulation with macronutrient fertilizers such as mono‐ammonium phosphate to produce slow‐release B‐enriched granules.     

Boron Requirement of Irrigated Cotton in a Typic Haplocambid for Optimum Productivity and Seed Composition

Boron (B) deficiency hampers cotton (Gossypium hirsutum L.) growth and productivity globally, especially in calcareous soils. The crop is known as a heavy feeder of B; however, its reported plant analysis diagnostic norms for B-deficiency diagnosis vary drastically. In a 2-year field experiment on a B-deficient [hydrochloric acid (HCl)–extractable 0.47 mg B kg^?1], calcareous, Typic Haplocambid, we studied the impact of soil-applied B on cotton (cv. CIM-473) growth, productivity, plant tissue B concentration, and seed oil composition. Boron was applied at 0.0, 1.0, 1.5, 2.0, 2.5, and 3.0 kg B ha^?1, as borax (Na₂B₄O₇·10H₂O), in a randomized complete block design with four replications, along with recommended rates of nitrogen (N), phosphorus (P), potassium (K), and zinc (Zn). Boron use improved crop growth, decreased fruit shedding, and increased boll weight, leading to seed cotton yield increases up to 14.7% (P < 0.05). Improved B nutrition of plants also enhanced seed oil content (P < 0.05) and increased seed protein content (P < 0.05). Fiber quality was not affected. Fertilizer B use was highly cost-effective, with a value–cost ratio of 12.3:1 at 1 kg B ha^?1. Fertilizer B requirement for near-maximum (95% of maximum) seed cotton yield was 1.1 kg B ha^?1 and HCl-extractable soil B requirement for was 0.52 kg ha^?1. Leaf tissue B requirement varied with leaf age as well as with plant age. In 30-day plants (i.e., at squaring), B-deficiency diagnosis critical level was 45.0 mg kg^?1 in recently matured leaves and 38.0 mg kg^?1 in youngest open leaves; at 60 days old (i.e., at flowering), critical concentration was 55.0 mg kg^?1 in mature leaves and 43.0 mg kg^?1 in youngest leaves. With advancement in plant age critical B concentration decreased in both leaf tissues; that is, in 90-day-old plants (i.e., at boll formation) it was 43.0 mg kg^?1 in mature leaves and 35.0 mg kg^?1 in the youngest leaves. As critical concentration range was narrower in youngest leaves (i.e., 35–43 mg kg^?1) compared with mature leaves (i.e., 43–55 mg kg^?1), B concentration in youngest leaves is considered a better indicator for deficiency diagnosis.     

Assessing suitability of different extractants for determining available boron in soil

In the present study, the extractability of available Boron (B) by different extractants was tested in relation to soil properties. Soil samples from different parts of Indo-Gangetic flood plains of West Bengal were collected and available B extracted with various extractant viz. hot calcium chloride (CaCl₂) (HCC), Potassium di-hydrogen phosphate (PDP), tartaric acid (TA) and MCC. Plant availability of B was assessed by growing wheat (Triticum aestivum L.cv.K-1006) in such soils through pot experiments. HCC showed the highest available B content as well as highest correlation coefficient value with all plant growth parameters and soil properties. The B extracting efficiency of the tested extractants was found in the order of HCC > PDP > TA > MCC. Results showed that dry matter yield, plant B concentration and uptake was increased significantly after application of Borax. Linear Correlations, Multiple regression analysis using Mallow's Cp statistics proved HCC to be the best extractant for estimating available B in experimental soils.     

Borax Production from Borax Slime, an Industrial Waste

Borax slime is formed during the production of borax from tincal, which is an important borate ore. It is a liquid containing the suspanded solid particles at high levels and is formed under the rich-in-borax solution in the reactor. This waste is discharged into the Marmara Sea and so causes environmental problems in Band?rma Golf. In this work, Borax production is aimed from the slime containing B₂O₃ at important levels. As a result it was found that B₂O₃ can be recovered and therefore the B2O3 pollution can be prevented by removing it from the waste.     

The practice of leaching boron and soluble salts from fly ash-amended soils

The leachability of B and salts from two fly ash-amended soils was conducted in a column leaching experiment. Fly ash was applied to the surface 3 cm of a Baywood (acid) sand and an Arizo (calcareous) sandy, loam at 5% by weight; the columns were continously leached with Colorado River water at two different pH's. Boron from fly ash was solubilized more readily in the Baywood than in the Arizo soil. Addition of fly ash increased B levels in the leachates from 0.25 to 2.35 μg ml^?1 (Baywood) and 0.93 μg ml^?1 (Arizo). Acidified leaching water had no significant effect on B leaching patterns but resulted in leaching higher soluble salts. Approximately 348 and 161 cm of water for the Arizo and the Baywood soils respectively, would be required to reduce the B concentration below a critical limit for B sensitive crops. It is suggested that crops planted when fly ash is applied for disposal/recycling on land should be both salt and B tolerant.     

Mobilization of Cu and Zn in contaminated soil by nitrilotriacetic acid

Batch and upflow column leaching experiments were used to evaluate the nature and extent of Cu and Zn solubilization from contaminated soil by nitrilotriacetic acid (NTA) in 0.025 M NaClO₄. In batch soil suspensions, NTA levels of 10^?5 to 10^?3 M substantially promoted Cu and Zn release from the metal-enriched soil. The ability of NTA to enhance Cu and Zn solubility decreased with increasing solution acidity probably due to competitive binding of NTA by protons and Fe released by hydrous oxide dissolution. However, in the pH range typically encountered in northeastern U.S. soils, soluble metal levels were nearly constant for a given NTA concentration. Leaching soil columns with NTA solutions enhanced Cu release more than Zn, as the enrichment ratio (cumulative metal leached by NTA compared to the 0.025 M NaClO₄ control leachate) after 85 pore volumes displacements was 23.6 and 4.3 for Cu and Zn, respectively. While Cu release by 0.01 M CaCl₂ differed little from the control, 0.01 M CaCl₂ was substantially more effective than 10^?5 M NTA in displacing bound Zn. The data reflect different retention mechanisms for Cu and Zn in this soil.     

Relation between available boron and boron extracted from soils by hot water or phosphoric acid

Abstract

A measure of biologically available B (BAB) was obtained by assaying the amount of B removed from a small volume of soil by sunflowers grown until they displayed B deficiency symptoms. Four different mineral soils and one organic soil which had been treated in the field with variable lime and B applications 2 years prior to sampling were compared. The amount of B extracted with hot water from soils before cropping was well correlated with BAB. The B extracted by the more intensive hot water extraction methods was closely related to the absolute level of BAB. Digestion of soils with concentrated H₃PO₄ resulted in the dissolution of larger amounts of B than that extracted with hot water. The proportion of H₃PO₄ soluble B that was measured as BAB was quite variable. Thus H₃PO₄ was a less suitable extractant than hot water for assaying the amount of soil B available to plants during a short growing period. In no case was the difference between the B extracted from soils before and after cropping as large as the BAB values.     

Effects of Application of Boron on Growth,Yields, and Quality of Red Bayberry

ABSTRACT

Three field experiments at three sites in east Zhejiang Province were conducted to determine the influence of applications of boron (B) on growth, yield, and quality of the red bayberry trees (Myrica rubra Sieb. et Zuca) with a manure species of “Buqizhong” in Linhai city. Ground B application or foliar B spraying significantly improved length and incidence rates of spring and summer shoots and increased fruit set rates, which resulted in the increases in fruit yield (13.7–17.5% for ground B application or 13.2–27.3% for foliar B spraying) and in improvement of fruit quality. The optimum yields were recorded with the treatments of ground B application of 40 g tree^?1 of borax or foliar B spraying of 2.0 g L^?1 of borax. Spring shoot incidents for the treatment of ground application of 50 g borax tree^?1 every year during the experiment (4B₅₀) were significantly higher than that for the treatment of ground application of 50 g borax tree^?1 only in the first year of the experiment (B₅₀), but the yield difference between them was not significant at P = 0.05. The increased yield effect of ground B application could last for 3 years. Boron application of red bayberry trees can be carried out by foliar-spraying 2.0 g borax L^?1 every year or ground application of 50 g borax tree^?1 every 3 years. The results of this study showed that application B could significantly improve the growth and increased fruit yield and quality of the red bayberry trees not exhibiting any vegetative symptoms of B deficiency.     

Interaction of contaminated sediment from a salt marsh with estuarine water: evaluation by leaching and ecotoxicity assays and salts from leachate evaporation

Purpose

Wastes from a former Portuguese steel plant were deposited between 1961 and 2001 on the riverbank of a tributary of the Tagus River creating a landfill connected to the river, posing a potential contamination risk to the Tagus estuary ecosystem. This study aims to assess the transfer of chemical elements from contaminated sediments to the estuarine water from cycles of sediment leaching so as to evaluate the ecotoxicity of the leachates, and to analyze the solid phases crystallized from those leachates.

Materials and methods

Landfill sediment and estuarine water samples were collected during low tide. Sediment samples were analyzed for pH, electric conductivity (EC), C_org, NPK, and iron oxides. Leaching assays (four replicates) were done using estuarine water (200 cm³/replicate) and 1.5 kg of sediment per reactor. Each reactor was submitted to four leaching processes (0, 28, 49, and 77 days). The sediment was kept moist between leaching processes. Sediment (total (acid digestion) and available fraction (diluted organic acid extraction-Rhizo)) elemental concentrations were determined by inductively coupled plasma–instrumental neutron activation analysis (ICP/INAA). Leachates, and estuarine and sediment pore waters were analyzed for metals/metalloids by ICP/mass spectrometry (MS) and carbonates/sulfate/chloride by standard methodologies. Ecotoxicity assays were performed in leachates and estuarine and pore waters using Artemia franciscana and Brachionus plicatillis. Aliquots of the leachates were evaporated to complete dryness (23–25 °C) and crystals analyzed by X-ray powder diffraction (XRD).

Results and discussion

Sediment with pH?=?8 and high EC and C_org was contaminated with As, Cd, Cr, Cu, Pb, and Zn. The element concentrations in the available fraction of the sediment were low compared to the sediment total concentrations (<1 % for Rhizo extraction). The concentrations of potentially hazardous elements in the estuarine water were relatively low, except for Cd. Concentrations of hazardous elements in the leachates were very low. Calcium, K, Mg, Na, and chloride concentrations were high but did not vary significantly among the four leaching experiments. Total concentrations of carbonate were much higher in leachates than in estuarine water. Both estuarine water and leachates showed negligible toxicity. Crystals identified in the solids obtained from the leachates by evaporation were halite, anhydrite, epsomite, dolomite, and polyhalite.

Conclusions

The sediment showed the capacity to retain the majority of the potentially hazardous chemical elements. Remobilization of chemical elements from sediment by leaching was essentially negligible. The variation of total concentrations of Ca, carbonate, and sulfate in leachates indicates that the sediment contained reactive sulfides. Due to its composition, the sediment seems to be a dynamic system of pollution control, which should not be disturbed.

     

Boron deficiency and toxicity symptoms for several crops as related to tissue boron levels

Boron deficiency symptoms in snap beans (Phaseolus vulgaris L.) showed as general yellowing of tops with slow flowering and pod formation, while toxicity caused reduced growth and burned dark brown older leaves especially on the edges. In radish (Raphanus sativus L.)_f B deficiency resulted in roots which were brown upon cutting and had thick periderm. Even at 4 ppm applied B, no visible B toxicity was noted in radish. The plant tissue B levels of less than 9 to 12 ppm were associated with B deficiency in radish and beans; and greater than 125 ppm with B toxicity in beans. In tomatoes (Lycopersicon esculentum, Mill) B deficiency resulted in reduced growth while B toxicity at 4 ppm applied B caused poor and slow germination. Boron deficiency and toxlcity in tomatoes were related to < 12 and > 172 ppm B, respectively, in tissue. No B deficiency was noted in corn (Zea mays L.) and timothy (Phleum pratense L.). The B toxicity in these two crops appeared as marginal burning and dark brown tips of older leaves and was related to greater than 98 and 176 ppm tissue B in corn and timothy, respectively.     

Boron toxicity in kiwifruit plants (Actinidia deliciosa), treated with nitrate,ammonium, and a mixture of both

The objective of this research was to study the effects of nitrogen (N) forms (NO₃^–, 2.6 mM; NH₄⁺, 2.6 mM; NO₃^–, 1 mM + NH₄⁺, 1.6 mM) on the growth and mineral composition of kiwifruit plants exposed to three boron (B) levels (0.025, 0.1, 0.3 mM). The kiwifruit plants were grown in a 1:1 sand : perlite mixture and irrigated daily with nutrient solutions. Shoot height, mean shoot dry weight, the number of leaves, mean leaf dry weight, and N concentration of NH₄‐treated plants were significantly higher compared to the NO₃^– treatment at all B levels. The concentration of 0.3 mM B significantly reduced shoot height for all N treatments. Boron toxicity symptoms appeared 14 days after starting the experiment, when plants were treated with 0.1 and/or 0.3 mM B. The nitrate supply reduced the B concentration of roots, but B levels of different leaf parts were hardly affected by the N form. Furthermore, the NH₄‐N form significantly reduced the Mg concentration of the leaves.     

Soil boron and soybean leaf boron in relation to soybean yield

Abstract

Boron applied in 2 soybean field experiments at rates up to 2.12 kg/ha was not detectable in Ap or B₂ horizon soil extracts approximately 6 weeks after B addition, although leaf B contents reflected added B. There was a measurable difference between the 2 fields in extractable B. Where the Ap horizon averaged 0.05 ppm B, soybean leaf content ranged 14 to 40 ppm B and no yield response was obtained with 0.56 to 2.24 kg/ha of added B. Where the Ap horizon averaged 0.11 ppm B, and leaf content reached 63 ppm B, soybean yield was reduced approximately two‐thirds by 2.24 kg/ha of added B.

Data from these 2 field experiments and previous micronutrient field studies, where yield response to B fertilization was obtained when leaf B was 9 to 10 ppm in soybean leaves, suggest that plant tissue analyses for B can be used to evaluate B fertilization needs. Soil tests may not be useful for detecting B deficiency in coarse‐textured soils, but may aid in detection of areas where B levels are high.     

Immobilization of Boron and Arsenic in Alkaline Coal Fly Ash through an Aging Process with Water and Elucidation of the Immobilization Mechanism

We previously reported that a simple treatment—addition of only small amounts of water to coal fly ash (CFA) to form CFA paste followed by aging for 1–4 weeks—is advantageous for the immobilization of highly soluble B, F, Cr, and As. In this study, we investigated the leachability of Ca, SO₄, B, and As over time from non-aged and aged CFA samples to elucidate a possible immobilization mechanism. For this purpose, two types of CFA samples, one showing effective immobilization of B and As by water addition and aging (sample A) and the other showing less or no immobilization (sample B), were examined. Calcium and SO₄, B, and As in non-aged sample A dissolved immediately after the start of the leaching test, indicating that these elements existed in highly soluble particles. After the rapid dissolution, their concentrations in the leachate gradually increased, possibly due to the dissolution of glassy phases. During the 1-week leaching test, the B and As concentrations in the leachate finally decreased. The addition of only small amounts of water to CFA (Sample A) for aging produce both alkaline and supersaturation conditions for the formation of several types of Ca-bearing secondary minerals such as calcite and ettringite, which are formed under alkaline conditions. Boron and As originally existing as highly soluble particles in CFA are expected to be incorporated into and/or sorbed on these secondary minerals as water-insoluble phases. Compared to non-aged CFA, their leachability from the aged sample A remained lower throughout the entire leaching test. Possibly due to these secondary minerals being formed on the CFA surface, B and As dissolutions associated with glassy phases are also prevented. In contrast, the pH of the leachate from CFA (sample B) at the beginning of the leaching test was acidic and then abruptly became alkaline. This means that water-soluble particles that can produce acidic conditions are also contained in these alkaline CFAs. Dissolution of these substances during aging makes it difficult to generate alkaline conditions in the CFA paste. Consequently, the formation of secondary minerals and the concomitant immobilization of toxic elements are prevented.     

Scaling-up of boron sources for yield and quality of large seeded peanut cultivars under varied agro-ecological conditions in India

Boron (B) deficiency is a common factor in light-textured soils causing poor pod filling and yield in large seeded peanut. Field trials were conducted in soils having 0.20–0.45 mg kg^?1 available B to find out the effectiveness of commercial-grade B sources in large seeded peanuts. B application induced early flowering, increased pods, yield and yield attributes, shelling and 100-seed weight. Soil application of 2.0 kg B ha^?1 as commercial-grade Agricol, Solubor and Borosol increased these parameters to a similar degree as obtained by borax, but were superior over their foliar applications. Similarly, the responses of foliar applications of 1.0 kg B ha^?1 as Chemiebor, Solubor and Borosol were more effective in humid areas. However, foliar applications led to scorching of peanut leaves during dry weather. Thus, soil application of 2.0 kg B ha^?1 is essential to enhance productivity and pod filling in large seeded peanut.     

Impact of Varying Ca/Mg Waters on Ionic Balance,Dispersion, and Clay Flocculation of Salt-Affected Soils

Inceptisols and Vertisols are two dominant soil orders that support major agricultural production in India. These soils often exist in semi-arid and arid regions. Low precipitation and high evaporation demand leads to salt accumulation in these areas. The problem of salt accumulation is further compounded by the presence of saline/alkaline groundwaters. We evaluated the effect of modified Ca/Mg waters on ionic composition, dispersion, and clay flocculation of sodic Inceptisols, saline-sodic Inceptisols, and normal Vertisols from different parts of India. A completely randomized factorial design with three replications of individual soils were sequentially leached with five pore volumes of deionized, saline water of 60 and 120 me L^?1 total electrolyte concentration (TEC) at a fixed SAR of 5.0 mmol^1/2 L^?1/2 and Ca:Mg ratio of 2:1, 1:1 and 1:2. Application of saline waters decreased pH and increased EC of the soil leachates after leaching five pore volumes of three Ca/Mg ratios of 60 and 120 me L^?1 solutions in sodic Inceptisols and normal Vertisols. In saline-sodic Inceptisols, application of saline waters decreased both pH and electrical conductivity (EC) of the soil leachates. Preferential Ca²⁺ holding in soil was only noticed in sodic Inceptisols when leaching process was performed with independent saline waters, but Mg²⁺ has a tendency to hold in soil upon application of independent saline waters for all soils except sodic Inceptisols. Periodic application of deionized water could increase soil dispersion and decreased flocculation of clay particles. Mg²⁺ ion had less flocculating vis-à-vis high-dispersion effect on soil clays than the Ca²⁺ ion.     

COMPARATIVE EFFICIENCY OF BORAX AND GRANUBOR AS BORON FERTILIZERS FOR LENTIL AND SOYBEAN GROWN ON ALLUVIAL ALKALINE SOILS

The two sources of boron (B), i.e., borax and granubor, were evaluated for their efficiency to lentil and soybean grown on alluvium derived soils of Punjab, India. Agronomic efficiency, physiological efficiency, and B recovery were estimated for both the sources and crops. The application of 0.75 kg B ha^-1 through borax and granubor increased lentil seed yield by 21.4 and 23.3%, respectively, over control indicating 2% higher response with granubor application. Boron content in lentil seed increased from 12.2 μg g^-1 in control treatment to the maximum of 24.1 μg g^?1 with the application of 1.25 kg B ha^?1 through granubor. There was 24.6% increase in seed yield of soybean with the application of 1.25 kg B ha^?1 through either of fertilizer source. Total B content increased to maximum of 59.8% over control when B was applied through borax. Apparent B recovery% and recovery efficiency were higher for granubor compared to borax for both the crops.