Aluminum status of synthetic Al–humic substance complexes and their influence on plant root growth

Abstract

Aluminum (Al)–humus complexes are abundant in the A horizons of non-allophanic Andosols and contribute to the unique properties of volcanic ash soils, such as high reactivity with phosphate ions and a low bulk density. Natural non-allophanic Andosols commonly show Al toxicity to plant roots. There have been very few studies examining the contribution of Al–humus complexes to the Al toxicity of plant roots, although the complexes are the probable source of the toxic Al. We extracted humic substances from the A horizon of a non-allophanic Andosol using NaOH solution and reacted the humic substances and partially neutralized the AlCl₃ solution at three pH conditions (pH 4.0, 4.5 and 5.5) to prepare pure Al–humic substance complexes. The Al solubility study (equilibrium study in 10^?2 mol L^?1 CaCl₂) and the Al release study (a stirred-flow method using 10^?3 mol L^?1 acetate buffer solution adjusted to pH 3.5) indicated that all the synthetic complexes easily and rapidly release monomeric Al into the liquid phase with slight changes in pH and ion strength, although the Al contents and their extent of polymerization are considerably different among the complexes. A plant growth test was conducted using a medium containing the Al–humic substance complexes and perlite mixture. Root growth in burdock (Arctium lappa) and barley (Hordeum vulgare L.) was reduced equally by all three complex media, and the roots showed the typical injury symptoms of Al toxicity. These results indicate that in soils dominated by Al–humus complexes the Al released from the Al–humus complexes, as well as the exchangeable Al adsorbed by soil minerals, is definitely toxic to plant roots.     

Biodegradation and insecticidal activity of the toxin from Bacillus thuringiensis subsp. kurstaki bound on complexes of montmorillonite–humic acids–Al hydroxypolymers

The equilibrium adsorption and binding of the active toxin from Bacillus thuringiensis subsp. kurstaki on complexes of montmorillonite–humic acids–Al hydroxypolymers, as well as the biodegradation and the insecticidal activity of the bound toxin, were studied. Seventy percent of the total adsorption occurred within the first hour, and maximal adsorption occurred in <8 h. Adsorption of the toxin on a constant amount of the complexes increased as the amount of the toxin added increased, and equilibrium adsorption isotherms of the L-type were obtained. There was essentially no desorption of the toxin after extensive washing of the toxin–organomineral complexes with double distilled H₂O and 1 M NaCl. The bound toxin was resistant to utilization by mixed microbial cultures from soil and to enzymatic degradation by Pronase E. Free and bound toxin were active against the larvae of Manduca sexta; the bound toxin retained the same activity after exposure to microbes or Pronase, whereas the toxicity of the free toxin decreased significantly. The results of these studies indicate that the release of transgenic plants and microorganisms expressing truncated genes that encode active insecticidal toxins from B. thuringiensis could result in the accumulation of these toxins in soil as a consequence of binding on surface-active soil particles. This persistence could pose a hazard to nontarget organisms, enhance the selection of toxin-resistant target species, and increase the control of target insect pests.     

A Comparison of Super-Valid Restricted and Row–Column Randomization

In complete block experiments, treatments are often randomized within blocks without any other restrictions. When the blocks are rows of plots and the blocks are laid out in parallel so that also columns of plots are formed, there might be random effects of both rows and columns. In this situation, a row–column design is a natural choice. Super-valid restricted randomization is another option. This article compares these randomization procedures for small complete block experiments (5–10 treatments in 3–6 blocks). Validity of a randomization procedure is defined for mixed-effects models. The two randomization procedures are compared with regard to average variance in pairwise comparisons. Row–column randomization is recommended when either there are at least four replicates, or the number of replicates is three and intercolumn variance is not known to be small. These conclusions assume a model with fixed effects of treatments and random effects of rows and columns, and estimation using the REML method and the Kenward and Roger approximation.     

Retention and release isotherm of arsenic in arsenic–humic/fulvic equilibrium study

Organic fractions from farm yard manure (FYM), vermicompost, municipal sludge, mustard cake, and surface soil of West Bengal, which was arsenic (As)-contaminated, were extracted and fractionated into fulvic and humic acid (FA and HA, respectively) fractions following standard procedures. These HA and FA samples were characterized by pH-potentiometric titrations, viscometric measurements and visible spectrophotometry. The stability constant (logK) of the complexes formed by these natural with As in aqueous phase was evaluated by the ion-exchange method. The logK values suggest that the organo-As complexes were quite stable. The release isotherm of As from the HA/FA complexes extracted from vermicompost and FYM was assayed in the presence of molybdate, nitrate, phosphate, sulfate and borate. The greatest tendency to displace As from the complexes was shown by sulfate, molybdite, and nitrate.     

Effect of cultivated plants on physico‐chemical characteristics of humic substances of soils amended by sewage sludge

Abstract

Humic substances were extracted from raw sewage sludge samples as well as an alluvial slightly alkaline soil [Typic Xerofluvent (So)], a clay loam soil [Calcixerollic Xerochrept (M)] and the corresponding field plots amended with different rates of sewage sludge and cultivated with corn and cotton respectively, in a two‐year field experiment. These substances have been characterized by chemical and spectroscopic methods. The chemical analyses showed that humic acids (HAs) and fulvic acids (FAs), were effected by the cultivated plant. Humic substances extracted from field plots with cotton showed higher carbon, but less nitrogen (N), total acidity and carboxylic groups content, as compared with those under corn. Generally HAs and FAs extracted from the fields plots amended with sewage sludge had higher N content, lower values of total acidity, carboxylic groups and carbon contents than those from the unamended soils. The FT‐IR spectra of humic (HAs) and fulvic (FAs) acids extracted from sewage sludge indicated the presence of high percentage of aliphatic carbon, polysaccharides and proteinaceous materials. The spectra of the humic matter in the field plots showed less aliphatic but increased amide stretch in comparison with the sludge. The absorption due to C=O in carboxylic groups of the FAs was not pronounced, though the presence of polysaccharides and protein decomposition products was clearly indicated.     

The chemistry of humic and fulvic acids extracted from argentine soils—II. Permanganate oxidation of methylated humic and fulvic acids

Five humic and three fulvic acids, extracted from Argentine soils, were methylated and oxidized with KMnO* solution. The oxidation products were extracted into ethyl acetate, remethylated, separated by preparative gas chromatography and identified by comparing their mass and micro-IR spectra with those of authentic specimens.The major oxidation products from the humic acids were benzenetetra, -penta-, and -tricarboxylic and hydroxybenepentacarboxylic acid. The major compounds isolated from the fulvic acid oxidation products were aside from benzenecarboxylic and phenolic acids, substantial amounts of ethyl-benzylsulfonate and N-methyl-benzylsulfonamide, one complex aromatic ester and two anhydrides. The origin of the S-containing compounds is uncertain; they could be impurities. Weight ratios of benzenecarboxylic to phenolic acids averaged 5·8 for humic acids but only 0·9 for fulvic acids, suggesting an enrichment in phenolic structures in the fulvic acids. Possible structural arrangements for humic and fulvic acids are discussed.     

Humus composition and humification degree of humic acids of alpine meadow soils in the northeastern part of the Qinghai–Tibet Plateau

The characteristics of humus composition are important for understanding the mechanism of carbon storage in the Qinghai–Tibet Plateau. The aim of this study was to characterize the quality of soil organic matter (SOM) in this region. Soil samples from four soil profiles in fenced study sites in the alpine grassland were collected at altitudes of 4200, 4000, 3800, and 3400 m, along the southwest facing slope in the Qilian Mountains. The humus composition and humification degree of the humic acid (HA) were determined by two methods: (1) extraction with 0.5% sodium hydroxide (NaOH) followed by 0.1 M sodium pyrophosphate (Na₄P₂O₇) (OH-PP method); and (2) treating once with 0.1 M hydrochloric acid (HCl) followed by extracting with 0.5% NaOH (Cl-OH method). Physico-chemical analysis revealed higher exchangeable cation content and higher base saturation ratios could be related to slightly acidic to neutral soils, which could be regarded as calcium (Ca)-rich soils. The amounts of combined-form HAs obtained by HCl pretreatment (HA_Cl – HA_OH; ?HA_Cl) were remarkably higher than those extracted with Na₄P₂O₇ (HA_PP), indicating that the combined form of HAs is mainly Ca. In addition, the proportion of HA_PP in the total HAs extracted with both NaOH and Na₄P₂O₇ (HA_OH + HA_PP) obtained in the OH-PP method increased with soil depth and decreasing elevation, indicating that HAs associated with aluminum (Al) and iron (Fe) were distinguished in the subsoils of lower elevation. Therefore, the formation of the organo-mineral complex may contribute to stabilizing SOM in the Qinghai–Tibet Plateau. Moreover, Type A-HA with the highest degree of humification was obtained from the deeper horizons with the Cl-OH method and almost all horizons by extraction with Na₄P₂O₇ in the OH-PP method. Further studies using various spectroscopic analyses are necessary to elucidate the chemical properties of SOM in this region.     

Influence of poultry manure–derived biochars on nutrients bioavailability and chemical properties of a calcareous soil

This study was conducted to investigate the effects of poultry manure (PM) and its derived biochars on chemical properties of a calcareous soil. PM and biochars prepared at 200°C (B200), 300°C (B300) and 400°C (B400) were applied to a calcareous soil at 2% level (w/w) and incubated for 150 days. Selected soil chemical properties and phosphorous, potassium, iron, manganese, zinc and copper availability and recovery were determined at 1, 15, 45 and 150 days of incubation. Soil nutrients availability, organic carbon (OC), electrical conductivity (EC) and cation exchange capacity (CEC) increased by addition of all organic substances. Biochars prepared at higher temperatures were more effective in increasing soil OC with higher durability compared to other treatments. The addition of PM and B200 decreased soil pH, whereas B400 increased it. Although the highest soil EC was observed in B300- and B400-treated samples in the early stages of incubation, the rate of increase in soil EC was higher for PM- and B200-treated soils compared to other treatments. It was concluded that biochar prepared at 300°C had the highest positive effect on nutrients availability and lasts longer in calcareous soil compared to the other produced biochars and PM.     

Comparison of Shoemaker–McLean–Pratt and Modified Mehlich Buffer Tests for Lime Requirement on Pennsylvania Soils

Abstract

The Shoemaker–McLean–Pratt (SMP) buffer test is commonly used in Pennsylvania and throughout the United States to determine the lime requirement (LR) of acid soils. The buffer contains potassium chromate, a carcinogen, and all waste must be collected for disposal in a hazardous waste facility. An alternative to the SMP buffer is the Mehlich buffer. Although the Mehlich buffer contains barium chloride (BaCl₂), also a hazardous and regulated compound, calcium chloride (CaCl₂) has been shown to be an effective substitute. The goal of this study was to compare the SMP buffer and the modified Mehlich buffer (CaCl₂ substituted for BaCl₂) for estimating LR on PA soils and to determine if the modified Mehlich buffer could provide an effective alternative to the SMP test. Twenty‐two agriculturally important Pennsylvania soils with pH values ranging from 4.5 to 6.4 were collected, and the actual LR of each soil was determined by incubating soils for 3 months with calcium carbonate. The modified Mehlich buffer was a more accurate predictor of the lime required to raise soils to either pH 6.5 (r²=0.92) or 7.0 (r²=0.87) in comparison to the SMP buffer (r²=0.87 and 0.82, respectively). Comparison of calibration equations for Mehlich buffer versus lime requirement derived in this study were similar to those developed on soils from other states and geographic regions.     

Comparison of the Effects of Salt Stress and Salt–Alkaline Mixed Stress on the Mineral Nutrition of Sunflower

Sunflowers (Helianthus annuus L.) were treated with salt stress and salt–alkaline mixed stress, which were established by mixing proportions of sodium chloride (NaCl), sodium sulfate (Na₂SO₄), sodium bicarbonate (NaHCO₃), and sodium carbonate (Na₂CO₃). The physiological indices of seedlings, including photosynthesis, growth, and mineral element contents, were determined to compare differences in the physiological responses of sunflower to salt stress and salt–alkaline mixed stress. The results showed that the destructive effects of salt–alkaline mixed stress on growth and photosynthesis were more severe than those of salt stress. The contents of mineral elements in the plants stressed were significantly less under salt–alkaline mixed stress than under salt stress. Data analysis indicated that both stresses caused ionic activity and free concentrations of some mineral elements to decline and even caused precipitation. This was coupled with a reduction of absorption capacity of roots. In conclusion, the mineral nutrition in sunflowers was affected under both salt and salt–alkaline mixed stresses, but the effects were more severe under salt–alkaline mixed stress than salt stress.     

Effect of microwave–chemical pre-treatment on compression characteristics of biomass grinds

The effect of microwave and microwave–chemical pre-treatments on densification characteristics and physical quality of pellets made from wheat and barley straw grinds were investigated. The ground wheat and barley straw samples were immersed in water, sodium hydroxide or calcium hydroxide solution at different concentrations (1 and 2% w/v) and then exposed to microwave radiation at three power levels (295, 603 and 713 W). Chemical composition and bulk and particle densities of samples were determined after pre-treatments. Pre-treated grinds were compressed in a plunger–die assembly with a force of 4000 N and compression and relaxation test data were recorded. The specific energy required for compression and ejection of pellets produced from untreated and pre-treated wheat and barley straw grinds was calculated. The tensile strength of the pellets was also evaluated to investigate the hardness of the pellets. Chemical composition analysis showed that microwave and chemical pre-treatment was significantly able to disintegrate the lignocellulosic structure of wheat and barley straw grinds. Data analysis also indicated that the pellets made from microwave–chemical pre-treated biomass grinds had a significantly higher density and tensile strength than the untreated or samples pre-treated by microwave and distilled water.     

Effect of a decade-long chemical fertilizers and amendments application on potassium fractions and yield of maize​–wheat in an acid Alfisol

Effect of long-term addition of chemical fertilizers with or without amendments was studied on different forms of potassium and the yield of maize and wheat. Continuous application of chemical fertilizers and amendments for 40 years influenced different fractions of potassium significantly. Integrated use of a balanced dose of chemical fertilizer, with farmyard manure (FYM) or lime, sustained higher yields of maize and wheat in comparison to inorganic fertilizers alone. Application of urea (100%) N alone for 40 years resulted in zero yield level. Continuous application of chemical fertilizers either alone or in combination with FYM or lime influenced different fractions of potassium significantly. Continuous cropping without fertilization resulted in depletion to the order of 21.5%, 16.6%, 11.7%, and 5.5% in water-soluble, exchangeable, 0.5 N HCl extractable, and non-exchangeable K, respectively. Different fractions of potassium were found to be positively and significantly correlated with grain and stover/straw yield of maize and wheat.     

Comparison of Conductimetric and Colorimetric Methods with Distillation–Titration Method of Analyzing Ammonium Nitrogen in Total Kjeldahl Digests

The distillation–titration method (DTM) is a standard procedure used by most laboratories to measure ammonium-nitrogen (NH₄-N) in the total Kjeldahl N (TKN) digests of various kinds of agricultural and environmental samples. These samples may have TKN contents ranging from less than 100 ppb to as high as percentage levels. However, the DTM procedure generally leads to a very low throughput because it is labor intensive and time-consuming. At the current practical quantitation limit (PQL) of 300 ppb established at the Feed and Environmental (FEW) Laboratory, University of Georgia, the DTM procedure is less applicable to low TKN surface water samples. In this study, we therefore compared the performance of diffusion conductivity method (DCM) and colorimetric method (CM) with DTM in measuring NH₄-N in the TKN digests of 29 different samples representing surface waters, lagoons, manures, poultry litters, and environmental wastes. Acceptable accuracy and precision were achieved for various QC samples by all three methods. For widely different sample matrices and TKN contents, the NH₄-N in the TKN digests measured by DCM and CM both agreed well with that measured by DTM. However, the linear working range of CM is limited within 0.2 to 5.0 ppm, whereas DCM is linear at a wider range of 0.01 to 2000 ppm. With DCM, the PQL of TKN is at 13 ppb, much less than the 300 ppb in DTM and 520 ppb in CM. Both DCM and CM require increasing the pH of the working TKN digest to a highly alkaline range. To meet such pH requirement, the minimum dilution need for DCM is twofold, where as that CM is fourfold. Because of greater mandatory dilution requirement coupled with a greater PQL, CM may often fail to measure NH₄-N in the working TKN digest of some low TKN surface water samples. On the other hand, with some environmental waste samples containing TKN at percentage level, CM would require multistep dilution of the digests prior to measurement, thus allowing dilution-related error as well as requiring additional labor. In contrast, DCM can measure both low TKN surface waters and high TKN environmental wastes without any major limitations. Moreover, DCM may work well without any adjustment of sample background in the calibration standards. Thus DCM appears to be an attractive alternative to the labor-intensive and time-consuming DTM for measuring NH₄-N in the TKN digests of various kinds of agricultural and environmental samples in the analytical services laboratories.     

Agronomic, chemical and genetic variability of saffron (Crocus sativus L.) of different origin by LC-UV–vis-DAD and AFLP analyses

The identification of a bi-univocal correspondence between geographical origin of saffron (Crocus sativus L.) and the composition of its stigmas has recently been the subject of many research papers, which have focused on the analysis of the differences among the so called “minor components”, such as flavonoids and volatiles, in the secondary metabolic pattern of this spice. Saffron pigments (crocetin esters), on the other hand, constitute the majority of the metabolites found in its stigmas, and their spectrophotometric measurement is still used as an official method to determine the quality of the spice in terms of coloring power. To our knowledge, no attempts have been made to find a correspondence between the geographical origin of different saffron samples and their morphological traits and pigments pattern. In this paper, we have demonstrated that saffron corms of different origins, grown in the same experimental field, produce daughter corms with different dimensions and still produce stigma samples with different pigment profiles. Furthermore, daughter corm dimensions and pigment profile even more so, may be related to the origin of the sample, and therefore pigments can be used as chemotaxonomic markers. Compositional analyses results were corroborated by genetic data obtained using AFLP molecular markers.     

Biomass and Cu and Zn Uptake of Two Turfgrass Species Grown in Sludge Compost–soil Mixtures

Two kinds of common turfgrass, fescue and ryegrass, were grown in soils amended with 20?×?80% sludge compost (SC) in this research. The effects of SC on two kinds of soil and response of fescue and ryegrass to the SC amendment were studied. The results showed that urease activity, extractable content of Cu and Zn and Electrical conductivity of both soils increased while pH decreased with the increase of SC amendment. However, the change of these parameters also depended strongly on soil characteristics. Sludge compost at the ≤40 and ≤60% levels can improve growth of fescue and ryegrass, respectively. The biomass of fescue grown in substrate with 40% SC increased 27% in a red soil and 44% in a yellow loamy soil compared to the control. The biomass of ryegrass grown in substrate with 60% SC increased 120% in the red soil and 86% in the yellow loamy soil. Sludge compost amendment at these levels did not significantly affect soluble salt contents of soil or Cu and Zn in plant tissue. Therefore, rational use of sludge compost can take advantage of its beneficial effect as a nutrient source for plant production while avoiding the potential deleterious effects on soil and plant.     

Evaluation of rice–legume–rice cropping system on grain yield,nutrient uptake,nitrogen fixation,and chemical,physical, and biological properties of soil

To achieve higher yields and better soil quality under rice–legume–rice (RLR) rotation in a rainfed production system, we formulated integrated nutrient management (INM) comprised of Azospirillum (Azo), Rhizobium (Rh), and phosphate-solubilizing bacteria (PSB) with phosphate rock (PR), compost, and muriate of potash (MOP). Performance of bacterial bioinoculants was evaluated by determining grain yield, nitrogenase activity, uptake and balance of N, P, and Zn, changes in water stability and distribution of soil aggregates, soil organic C and pH, fungal/bacterial biomass C ratio, casting activities of earthworms, and bacterial community composition using denaturing gradient gel electrophoresis (DGGE) fingerprinting. The performance comparison was made against the prevailing farmers’ nutrient management practices [N/P₂O₅/K₂O at 40:20:20 kg ha⁻¹ for rice and 20:30:20 kg ha⁻¹ for legume as urea/single super-phosphate/MOP (urea/SSP/MOP)]. Cumulative grain yields of crops increased by 7–16% per RLR rotation and removal of N and P by six crops of 2 years rotation increased significantly (P < 0.05) in bacterial bioinoculants-based INM plots over that in compost alone or urea/SSP/MOP plots. Apparent loss of soil total N and P at 0–15 cm soil depth was minimum and apparent N gain at 15–30 cm depth was maximum in Azo/Rh plus PSB dual INM plots. Zinc uptake by rice crop and diethylenetriaminepentaacetate-extractable Zn content in soil increased significantly (P < 0.05) in bacterial bioinoculants-based INM plots compared to other nutrient management plots. Total organic C content in soil declined at 0–15 cm depth and increased at 15–30 cm depth in all nutrient management plots after a 2-year crop cycle; however, bacterial bioinoculants-based INM plots showed minimum loss and maximum gain of total organic C content in the corresponding soil depths. Water-stable aggregation and distribution of soil aggregates in 53–250- and 250–2,000 μm classes increased significantly (P < 0.05) in bacterial bioinoculants-based INM plots compared to other nutrient management plots. Fungal/bacterial biomass C ratio seems to be a more reliable indicator of C and N dynamics in acidic soils than total microbial biomass C. Compost alone or Azo/Rh plus PSB dual INM plots showed significantly (P < 0.05) higher numbers of earthworms’ casts compared to urea/SSP/MOP alone and bacterial bioinoculants with urea or SSP-applied plots. Hierarchical cluster analysis based on similarity matrix of DGGE profiles revealed changes in bacterial community composition in soils due to differences in nutrient management, and these changes were seen to occur according to the states of C and N dynamics in acidic soil under RLR rotation.     

Different chemical composition and storage mechanism of soil organic matter between active and permafrost layers on the Qinghai–Tibetan Plateau

Journal of Soils and Sediments - Although many studies have paid attention to the storage and dynamics of organic carbon (OC) in the Arctic permafrost, there are limited reports for low-latitude...     

Removal of Indigo Blue in Aqueous Solution Using Fe/Cu Nanoparticles and C/Fe–Cu Nanoalloy Composites

Actually, there is a growing interest in finding efficient low-cost materials that allow the removal of chemical substances from water in order to decrease the environmental impact. The use of nanoscale systems is a new area of investigation for the elimination of polluting agents from water among other useful applications in science and technology. In this work, removal of indigo blue in water solutions has been evaluated using Fe/Cu nanoparticles and composites of C/Fe–Cu nanoalloy. The first composite was using carbon obtained by pyrolysis of sewage sludge with Fe/Cu nanoparticles (MCL-NP); the second one was made with commercial activated carbon and Fe–Cu nanoparticles (CAC-NP). Synthesis of materials were carried out by the sodium borohydride reduction of FeSO₄?7H₂O and CuSO₄?5H₂O aqueous mixture. Batch adsorption and isotherm experiments were carried out in order to know the behavior of each adsorbent material employed. The experimental data were adjusted to Langmuir, Freundlich, and BET models.     

Occurrence of Cu and Cr in the sedimentary humic substances and pore water from a typical sugar cane cultivation area in São Paulo,Brazil

Purpose

The purpose of this paper is to study the interactions of sedimentary humic substances (SHS) from a sugarcane cultivation area with Cu(II) and Cr(III) and to evaluate the occurrence of these metals in the pore water and SHS.

Materials and methods

For this study, the northwestern region of the State of São Paulo, Brazil, which is considered the region with the highest production of sugar cane in the state, was selected. Samples of sediment were collected from four sampling sites in the Preto, Turvo, and Grande rivers. The SHS and pore water were extracted from the sediment using the method suggested by the International Humic Substances Society and centrifugation, respectively. The complexing capacity (CC) of the SHS for Cu(II) and Cr(III) was determined by individually titrating these metals with an ultrafiltration system using tangential flow. The total concentrations of Cr and Cu were determined for the pore water, sediments, and humic substances with graphite furnace atomic absorption spectrometry and Zeeman background correction after an acid digestion, according to the methods described in US EPA Method 3050B.

Results and discussion

The SHS from a site in the Turvo River, which is typically cultivated with sugarcane, possessed the highest concentration of Cu bound to SHS (25.0%), the largest CC (0.63 mmol Cu g^?1 HS) and the highest concentration of this metal in the pore water (1.38 mg Cu Kg^?1 sed.). For Cr, the SHS collected from a location on the Preto River dam had the largest CC (0.90 mmol Cr g^?1 HS) and the lowest Cr content in the pore water (0.29 mg Cr Kg^?1 sed.), indicating that there was an inverse relationship between the CC and the concentration of metal available in the pore water.

Conclusions

Sedimentary humic substances might be one of the regulatory factors controlling the availability of Cu and Cr in the sediments found in a typical region that has been planted with sugarcane. Distinct behaviors were observed between the two elements investigated; higher CC and a larger fraction of Cu(II) were found in the pore water of samples originating from sugarcane crops. The opposite behavior was observed for the Cr(III) species.     

Effect of conjoint use of bio-organics and chemical fertilizers on yield,soil properties under French bean–cauliflower-based cropping system

This study investigates the effect of conjoint use of bio-organics (biofertilizers + crop residues + FYM) and chemical fertilizers on yield, physical–chemical and microbial properties of soil in a ‘French bean–cauliflower’-based cropping system of mid hills of the north-western Himalayan Region (NWHR) of India. Conjoint bio-organics at varied levels of NPK chemical fertilizers increased yield of ‘cauliflower’ over corresponding single application. Incorporation of crop residues with 75% of the recommended NPK application resulted in the highest yield (19 t ha^?1). Conjoint use of bio-organics produced a yield (15.65 t ha^?1), which was statistically on a par with 75% of the recommended NPK application alone. This indicated a saving of 75% NPK chemical fertilizers. In the case of ‘French bean’, the effect was non-significant. The results also showed significant higher soil available N (351.3 kg ha^?1) under 75% NPK + biofertilizers, whereas the highest soil available K (268.3 kg ha^?1) was recorded under 75% NPK + crop residues. Lowest bulk density (1.03 Mg m^?3), highest water holding capacity (36.5%), soil organic matter (10.6 g kg^?1), bacterial (4.13 × 10⁷ cfu g^?1) and fungal (6.3 × 10⁷ cfu g^?1) counts were recorded under sole application of bio-organics. According to our study, we concluded that the combination of NPK fertilizers and bio-organics increased yield except French bean, soil available N, K and saved chemical fertilizers under ‘French bean–cauliflower’-based cropping system.