Availability Of Zn In Soil Research Articles

Rice Husk as a Sustainable Amendment for Heavy Metal Immobilization in Contaminated Soils: A Pathway to Environmental Remediation.

Rice husk is a waste byproduct of rice production. This material has a moderate cost and is readily available, representing 20-22% of the biomass produced by rice cultivation. This study focused on the properties of rice husk in the remediation of soils contaminated by heavy metals. The effect of particle size, pH, and the presence of organic ligands on sorption efficiency was evaluated for Cd, Cu, and Mn. The continuous flow method was used to select suitable operative conditions and maximize the retention of heavy metals. Subsequently, pot experiments were carried out by growing two broadleaf plants, Lactuca sativa and Spinacia oleracea, in aliquots of soil collected in a Piedmont (Northwest Italy) site heavily contaminated by Cu, Cr, and Ni. Rice husk was added to the contaminated soil to evaluate its effectiveness in immobilizing heavy metals. The availability of Cr, Mn, Ni, Cu, Zn, Cd, and Pb in soil was studied using Tessier's sequential extraction protocol. The content of the elements was also analyzed in plants and the uptake of heavy metals was evaluated in relation to the addition of rice husk. The growth of both plants was more efficient in the presence of rice husk due to its ability to reduce the mobility of heavy metals in the soil. The simplicity, cost-effectiveness, and scalability of its employment make the use of rice husk suitable for practical applications in soil remediation.

Effect of Potassium and Zinc on Soil Properties and Fraction of Potassium and Zinc in Soil

A field experiment was carried out on Agronomy Farm, B. A. College of Agriculture, Anand Agricultural University, Anand during rabi season of the year 2020-21. The experiment comprising nine treatment combinations consisted of three levels of potassium (0, 20 and 40 kg/ha) and three levels of zinc (0, 2.5 and 5.0 kg/ha). These treatments were evaluated in Randomized Block Design (factorial) with four replications. The soil of the experimental plot was loamy sand in texture, alkaline in reaction, low in organic carbon and available nitrogen, medium in available phosphorus, potassium and zinc. Results of the experiment revealed that the available K2O in soil was significantly increased due to application of 40 kg K2O/ha (K2) and was found to be at par with application of 20 kg K2O/ha (K1). All other chemical properties of soil (pH, EC, organic carbon, available N, P2O5, S, Fe, Mn, Zn and Cu) were not differ significantly due to application of different levels of potassium. Levels of zinc also failed to produce its significant effect on chemical properties of soil except available Zn in soil as it was significantly increased with the treatment of Z2 (5.0 kg Zn/ha) than control but was found to be at par with treatment Z1 (2.5 kg Zn/ha). Moreover, no any chemical property of soil differ due to the interaction of different levels of potassium and zinc. The water soluble K and exchangeable K fractions in soil significantly increased with the treatment of K2 (40 kg K2O/ha) otherwise non-exchangeable K, total K and different zinc fractions in soil did not differ significantly by the different levels of potassium. Different potassium fractions and total Zn fraction in soil were found to be non-significant under the different zinc levels but all the zinc fractions in soil (water soluble plus exchangeable Zn, carbonate bound Zn, Fe/Mn oxide bound Zn, organically bound Zn and residual Zn) significantly increased with the treatment of Z2 (5.0 kg Zn/ha) and was remained at par with treatment Z1 (2.5 kg Zn/ha). The interaction between potassium and zinc failed to influence significantly on potassium and zinc factions in soil.

Enhancing the growth and zinc efficiency of cherry tomatoes by inoculating endophytic bacteria from zinc hyperaccumulator, Sedum alfredi Hance

Microbial biofertilizers, an innovative and eco-friendly strategy for nutritional improvement, could be utilized for zinc (Zn) efficiency and biofortification. Endophytic bacteria with Zn solubilizing and plant growth-promoting capacities were isolated from hyperaccumulator S. alfredi, and their impacts on the growth and Zn efficiency of cherry tomatoes under Zn-deficiency conditions were investigated. The results showed that most endophytic bacteria promoted the growth of tomato seedlings, while only specific endophytic bacteria played a role in Zn accumulation. Among them, inoculation with SaBA1, SaPS2, SaEN1, and SaPA1 not only significantly increased the fresh weight (FW) of tomato's young leaves by 3.1 to 3.6 times, but also raised the soil available Zn concentration by 0.58–0.92 mg/kg and improved the Zn accumulation in young leaves by 18 % to 30 %. The results indicated that these four bacteria could activate the availability of soil Zn, regulate the distribution of Zn in plants, and enable tomatoes to maintain healthy growth and development under Zn-deficiency conditions. This revealed their immense potential in enhancing crop yield, improving crop Zn nutrition, and boosting crop Zn efficiency.

The effect of chelating agents on the Zn-phytoextraction potential of hemp and soil microbial activity

BackgroundHemp (Cannabis sativa) is a crop with a wide range of uses, from the production of fiber and seeds to the secondary metabolites for medicinal purposes. In addition, it is characterized by high biomass yield and the ability to accumulate heavy metals, which makes this plant convenient for phytoremediation purposes. In this study, the effect of applying exogenous biodegradable chelating agents, citric acid (CA) and nitrilotriacetic acid (NTA), to zinc-contaminated soil on zinc (Zn) uptake by two industrial hemp varieties ‘Felina 32’ and ‘Monoica’ was studied. The effect of CA and NTA on available Zn in soils was investigated using an ‘in pot’ experiment under controlled conditions. The effect of both tested compounds on soil microbial activity was simultaneously evaluated.ResultsAfter the application of NTA at a concentration of 5 mmol L−1, a > threefold increased accumulation of Zn in the above-ground parts was recorded in the ‘Felina 32’ variety. In the ‘Monoica’ variety, the levels of Zn in the above-ground parts were increased > twofold. NTA affected the soil microbiome negatively, causing decreased enzyme activity (in ‘Monoica’ planted soil) and induced respiration (in ‘Monoica’ and especially in ‘Felina 32’ planted soil). On the other hand, CA application did not lead to significantly increased Zn levels in any of the studied hemp varieties. Together with CA’s negative effects on some soil enzymes, CA enhanced urease activity, dehydrogenase and several respiration types for the ‘Felina 32’ variety and exerted less detrimental effect on the soil microbiome. No toxic effects from increased Zn uptake and accumulation in experimental plants were detected, accounting for the unchanged physiological stress markers (levels of photosynthetic pigments and proline in leaves, chlorophyll fluorescence parameters) and selected growth traits of the above-ground organs and root system.ConclusionsFrom the studied varieties, ‘Felina 32’ seems to be more suitable for Zn-phytoextraction because of its higher tolerance to increased Zn levels, higher biomass production and Zn accumulation capacity. Our results indicate the potential of using the ‘Felina 32’ variety in NTA-assisted Zn phytoextraction from contaminated soils.Graphical

Impact of a phosphate compound on plant metal uptake when low molecular weight organic acids are present in artificially contaminated soils

A phosphate compound can stabilize cadmium (Cd), lead (Pb), and zinc (Zn)-contaminated soils, although its effectiveness in reducing metal availability and plant uptake when low molecular weight organic acids (LMWOAs) are present is uncertain but nonetheless worth evaluating. Here, 3 % NaH2PO4 (a P compound), tartaric acid (TA), oxalic acid (OA), and mixtures of P and TA/OA are used to evaluate Indian spinach (Basella Alba L.) for soil Cd, Pb, and Zn availability and absorption. Additionally, soil metal immobilization options were examined. Of these treatments, P plus low TA (P-TA2), followed by P, decreased shoot Cd, Pb, and Zn the most, with values of 1.03, 2.52, and 104.50 mg kg−1, respectively, somewhat greater than threshold values of WHO, particularly for Pb and Zn. After harvest, P-TA2 contained >2.44, >321.70, and >290.22 mg kg−1 of total oxidizable and residual Cd, Pb, and Zn, showing that 48 %, 80 %, and 58 % of soil metals were immobilized and not taken up by the plant. P-TA2′s zeta potential, followed by P, became steadily more negative as pH increased, confirming that electrostatic adsorption was the main metal immobilization process, notably in P-TA2. However, in XRD studies, P alone generated Cd phosphate, pyromorphite, and hopeite, showing that sorption and precipitation were the predominant metal immobilization mechanisms. Finally, P-TA2 is the best in immobilizing and inhibiting metals in contaminated soils for plant absorption. Since rhizotropic LMWOAs may impact Cd, Pb, and Zn mineral stability, they should be addressed when treating Cd, Pb, and Zn-contaminated soils with P for plant growth studies.

Prevalence of antibiotic and metal resistance genes in phytoremediated cadmium and zinc contaminated soil assisted by chitosan and Trichoderma harzianum

Heavy metal in soil have been shown to be toxic with high concentrations and acts as selective pressure on both bacterial metal and antibiotic resistance determinants, posing a serious risk to public health. In cadmium (Cd) and zinc (Zn) contaminated soil, chitosan (Chi) and Trichoderma harzianum (Tri) were applied alone and in combination to assist phytoremediation by Amaranthus hypochondriacus L. Prevalence of antibiotic and metal resistance genes (ARGs and MRGs) in the soil was also evaluated using metagenomic approach. Results indicated that the phytoremediation of Cd and Zn contaminated soil was promoted by Chi, and Tri further reinforced this effect, along with the increased availability of Cd and Zn in soil. Meanwhile, combination of Chi and Tri enhanced the prevalence of ARGs (e.g., multidrug and β-lactam resistance genes) and maintained a high level of MRGs (e.g., chromium, copper) in soil. Soil available Zn and Cd fractions were the main factors contributing to ARGs profile by co-selection, while boosted bacterial hosts (e.g., Mitsuaria, Solirubrobacter, Ramlibacter) contributed to prevalence of most MRGs (e.g., Cd). These findings indicate the potential risk of ARGs and MRGs propagation in phytoremediation of metal contaminated soils assisted by organic and biological agents.

Disturbed electron transport beyond PSI changes metabolome and transcriptome in Zn-deficient soybean

Low Zn availability in soils is a problem in many parts of the world, with tremendous consequences for food and feed production because Zn deficiency affects the yield and quality of plants. In this study we investigated the consequences of Zn-limitation in hydroponically cultivated soybean (Glycine max L.) plants. Parameters of photosynthesis biophysics were determined by spatially and spectrally resolved Kautsky and OJIP fluorescence kinetics and oxygen production at two time points (V4 stage, after five weeks, and pod development stage, R5–R6, after 8–10 weeks). Lower NPQ at 730 nm and lower quantum yield of electron transport flux until PSI acceptors were observed, indicating an inhibition of the PSI acceptor side. Metalloproteomics showed that down-regulation of Cu/Zn-superoxide dismutase (CuZnSOD) and Zn‑carbonic anhydrase (CA) were primary consequences of Zn-limitation. This explained the effects on photosynthesis in terms of decreased use of excitons, which consequently led to oxidative stress. Indeed, untargeted metabolomics revealed an accumulation of lipid oxidation products in the Zn-deficient leaves. Further response to Zn deficiency included up-regulation of gene expression of cell wall metabolism, response to (a)biotic stressors and antioxidant activity, which correlated with accumulation of antioxidants, Vit B6, (iso)flavonoids and phytoalexins.

Does a decade of soil organic fertilization promote copper and zinc phytoavailability? Evidence from a laboratory biotest with field-collected soil samples

Despite chronic contamination, long-term organic fertilization tends to decrease copper (Cu) and zinc (Zn) availability in agricultural soils. Root activities of crop plants can also induce substantial changes in rhizosphere chemistry and consequently in the Cu and Zn availability in the rhizosphere. The balance between these two drivers and the overall effect of organic fertilization on Cu and Zn bioavailability to plants (i.e., phytoavailability) remains a matter of debate. We assessed the effect of a decade of agronomically realistic organic fertilization on Cu and Zn availability in the rhizosphere and their phytoavailability. Using a laboratory biotest, Festuca arundinacea was exposed to 34 soil samples collected from three agricultural field trials that had received no, mineral, or organic fertilization for a decade. Dissolved organic matter (DOM) properties (i.e., concentration, aromaticity, and binding properties toward Cu), pH, and Cu and Zn availability (i.e., total dissolved concentration and free ionic activity) were determined in the rhizosphere solutions. Cu and Zn phytoavailability was measured as the plant uptake flux. Contrary to bulk soils, organic fertilization induced very few changes in the chemistry and Cu and Zn availability in the rhizosphere solutions compared to no and mineral fertilization. Consistently, Cu and Zn phytoavailability did not increase with organic fertilization, but it was mostly driven by soil properties rather than by fertilization. Despite increasing soil Cu and Zn contamination, a decade of soil organic fertilization did not increase Cu and Zn phytoavailability, presumably due to the root-mediated levelling of Cu and Zn availability in the rhizosphere.

A preliminary study to explain how Streptomyces pactum (Act12) works on phytoextraction: soil heavy metal extraction, seed germination, and plant growth.

Streptomyces pactum (Act12) can both promote plant growth and strengthen heavy metal mobilization. Nevertheless, the mechanisms of how Act12 works during the phytoextraction process are still unknown. The present work investigated whether the metabolites produced by Act12 could influence the seed germination and the growth of potherb mustard and explored its mobilizing effect on soil cadmium (Cd) and zinc (Zn). The results showed that the germination potential and rate of potherb mustard seed treated with Act12 fermentation broth were 1.0- and 0.32-folds higher than those of control, probably due to the interruption of seed dormant stage. We also found that Act12 inoculation not only promoted the dry biomass (6.82%) of potherb mustard, but also increased the leaf chlorophyll (11.8%) and soluble protein (0.35%) production. The boosted seed germination rate under Act12 treatment (up to 63.3%) indicated that Act12 enhanced the resistance of potherb mustard seeds to Cd and Zn and alleviated their physiological toxicity. The generated metabolites during the Act12 fermentation posed positive impact on the availability of soil Cd and Zn. These findings bring new insight into the Act12-assisted phytoextraction of Cd and Zn from contaminated soils.

Influence of nano-zinc oxide and fortified rice residue compost on rice productivity, zinc biofortification, zinc use efficiency, soil quality, zinc fractions and profitability in different rice production systems

Transplanted rice (TPR) faces several limitations, including deteriorating soil quality, zinc (Zn) deficiency, low use efficiency of zinc sulfate (ZnSO4), water scarcity and escalating labor costs, which are dictating the shift toward alternate production systems like direct-sown rice (DSR) and aerobic rice (AR). However, this shift affects soil Zn dynamics and Zn availability to crops. This study was conducted to compare the effectiveness of Zn nutrition (ZnSO4 as soil application and zinc oxide nanoparticles (ZnO NPs) as seed priming alone or with foliar spray) and fortified organic manures (farm yard manure and rice residue) on the rice productivity, Zn use efficiency, grain biofortification, soil quality, Zn fractions and profitability under TPR, DSR and AR. The application of ZnO NPs and fortified rice residue compost significantly improved the yield traits (437 productive tillers m−2 and 186 filled grains panicle−1), grain weight (6.27 Mg ha−1), grain Zn fortification (33.41 mg kg−1) and Zn fractions in all rice production systems. The AR was found to be more encouraging in improving soil organic carbon (11.3%), dehydrogenase activity (21.96%), microbial biomass carbon (17.31%) and DTPA-Zn (10.57%) than TPR and DSR. ZnO NPs seed priming and fortified rice residue resulted in superior zinc use efficiency in both TPR and DSR. The maximum benefit-cost ratio was obtained in DSR with ZnO NPs and fortified rice residue compost. Altogether, DSR with seed priming and foliar spraying of ZnO NPs and fortified rice residue can be a more efficient way to enhance rice productivity, grain Zn fortification and profitability.

Seed-Primed and Foliar Oxozinc Nanofiber Application Increased Wheat Production and Zn Biofortification in Calcareous-Alkaline Soil

Low Zinc (Zn) availability in alkaline calcareous soil is one of the major causes of low cereal yield and quality. Conventional application of Zn sulfate (ZnSO4) fertilizer through soil application attains minimal Zn efficiency as it is readily fixed in such soils. Oxozinc nanofiber (ZnONF) was evaluated for wheat Zn biofortification using different application methods to tackle this issue. Pots in triplicate (each with 7 kg soil) were arranged in a completely randomized design with a control treatment without Zn application. The conventional ZnSO4 fertilizer recommended dose (5.5 µg Zn kg−1 of soil) was used for comparison and applied through soil addition, foliar spray, and seed priming, while the ZnONF was applied through foliar spray, seed coating, and seed priming (@ 0.5 kg ha−1) either alone or in combination with ½ZnSO4 applied to the soil. The application of ZnONF significantly improved wheat plant growth as evidenced by increased plant height (14.5%), spikelets per spike (13.7%), and Zn use efficacy (611%) regardless of application methods as compared to control. The highest Zn uptake efficiency (34%) for nanofibers was obtained for theseed primed, followed by seed coating (23%) and foiar application (7%), respectively. Moreover, at the combined ZnONF and ½ZnSO4 application, further improvements for spike length, number of spikelets spike−1, grain, leaf, root, and stem Zn concentrations, as well as their respective Zn contents, were noted. These results elucidated that Zn nutrition with ZnONF was either at par with or higher than the conventional ZnSO4 fertilizer application despite significantly reduced ZnONF quantity, irrespective of the application method used. Additionally, the combined ZnONF and ½ZnSO4 (foliar spray, seed coating, or seed priming) maximized the crop Zn accumulation, wherein the ½ZnSO4 + ZnONF through foliar application exceeded grain Zn biofortification. Thus, various Oxozinc nanofibers application modes may be recommended for wheat biofortification either separately or in combination with ZnSO4 in Zn deficient calcareous soils for improved Zn nourishment.

Impacts of P inputs on availability of Fe, Mn, Zn and Se in soils

Impacts of P inputs on availability of Fe, Mn, Zn and Se in soils

Impact of plastic sheet mulching on grain Zn concentration, P/Zn ratio and Zn uptake in dryland grown winter wheat

High yield and grain quality are the targets in wheat production. Plastic sheet mulching has improved wheat grain yield in under dryland agriculture, but its impact on grain quality, particularly grain zinc (Zn) concentration is not well known. Seven-site field experiments were conducted during 2014–2016 on drylands of three provinces in the Loess Plateau of China to examine the effect of plastic sheet mulching on wheat grain Zn concentration under different N applications. A split-plot design was adopted with the two main plots (no mulching and plastic sheet mulching) and the subplots with different N application rate. Measurements of Zn uptake, Zn remobilization, Zn distribution to the grain and bioavailability were made, together with biomass, yield and yield components. Study found plastic sheet mulching reduced the grain Zn concentration, and increased the molar ratio of P/Zn, decreasing the Zn bioavailability. Plastic sheet mulching also increased the aboveground Zn accumulation at anthesis by 14.4 %, the straw Zn accumulation at maturity by 14.8 % and the Zn remobilization to the grain by14.2 % but did not affect the availability of soil Zn. For each 100 kg N ha −1 applied under plastic sheet mulching, the grain Zn concentration, the Zn requirement, the aboveground Zn accumulation and remobilization to the grain increased by 3.6 mg kg −1 , 2.8 g Mg −1 , 6.6 g ha −1 and 3.8 g ha −1 , respectively. Aboveground Zn accumulation at maturity and post-anthesis Zn uptake varied with N rates in a linear-plus-plateau model. The reduction in post-anthesis Zn uptake and Zn harvest index were the factors leading to the decrease in grain Zn concentration under plastic sheet mulching. Consequently, under plastic sheet mulching, a rational N fertilizer strategy should be considered to improve the grain Zn concentration in wheat grown in dryland. • Plastic sheet mulching reduces wheat grain Zn bioavailability. • Post-anthesis Zn uptake and Zn harvest index influence wheat grain Zn content. • Rational N fertilization can improve grain Zn content and bioavailability in wheat. • Grain Zn content increased linearly with glutenin content in wheat grain.

Does a decade of soil organic fertilization promote copper and zinc bioavailability to an epi-endogeic earthworm?

While long-term organic fertilizer (OF) applications tend to decrease copper (Cu) and zinc (Zn) availability in agricultural soils, earthworm bioturbation has been reported to have the opposite effect. Thus, the consequences of OF amendments in earthworm-inhabited soils on Cu and Zn bioavailability to earthworms are still under debate. Here, we assessed the effect of a decade of agronomically realistic OF applications on Cu and Zn availability in earthworm-inhabited soils and the consequences on Cu and Zn bioavailability to earthworms. An epi-endogeic species (Dichogaster saliens) was exposed in microcosms to three field-collected soils that had received either no, mineral, or organic fertilization for a decade. Dissolved organic matter (DOM) properties (i.e., concentration, aromaticity, and binding properties toward Cu), pH, and Cu and Zn availability (i.e., total concentration and free ionic activity) were determined in the solution of the soil containing earthworms. Cu and Zn bioavailability was assessed by measuring the net accumulation (ng) and concentration of Cu and Zn in earthworms (mgkg-1). Despite soil Cu and Zn contamination induced by a decade of OF applications, organic fertilization induced an increase in soil pH and DOM properties that drove the reduction of Cu and Zn availability in earthworm-inhabited soils, while bioturbation had little effect on soil pH, DOM properties, and Cu and Zn availability. Consistently, Cu and Zn bioavailability to earthworms did not increase with OF applications. From an ecotoxicological perspective, our results suggest that agronomically realistic applications of OF for a decade should not pose a risk to earthworms in terms of Cu and Zn net accumulation, but further studies have to be undertaken to understand consequent long-term toxicity after exposure.

INTERACTIVE EFFECT OF ZINC AND IRON ON PHYSICO-CHEMICAL PROPERTIES OF SOIL OF FIELD PEA

A field experiment was conducted during Rabi season (November 2021-February 2022) at Central Research Farm NAI. SHUATS, analysed under RBD having nine treatments and three replications having three level of Zinc 0%, 50%, 100% and three level of Iron 0%, 50%, 100%. The results reported the significant improvement in soil chemical properties (EC (dS m-1) Organic Carbon (%), Available Nitrogen (Kg ha-1). Available Phosphorus (kg ha-1), Available Potassium (Kg ha-1), Available Zinc (mg Kg-1), Available Iron (mg Kg-1). However, Bulk density (Mg m³), Particle density (Mg m³), pH showed Non-significant improvement. Chemical properties of the soil increased with application of levels of Zn and Fe, Available NPK, Zn and Fe where found in moderate range. The application of Zn and Fe significantly improved the soil Physico-chemical properties. Increase in level of Zn application decreased in available Fe and P in the soil and increase in level of Fe application increased in available P and decreased in available Zn in soil.

Goethite-based carbon foam nanocomposites for concurrently immobilizing arsenic and metals in polluted soils

Although different amendments have been used for the immobilization of metals and metalloids in contaminated soils, in most of them there are still important challenges that need to be faced in order to achieve an optimal result. In this work, a new material based on a carbon foam impregnated with goethite nanoneedles has been developed with the aim of evaluating its effect on the mobility and availability of As, Cd, Cu, Pb and Zn in an industrial soil. For this purpose, leaching, sequential extraction and phytotoxicity studies have been carried out. The results were compared with the same carbon foam without goethite impregnation. When the soil was treated with goethite-based carbon foam nanocomposite, the mobility of metal(loid)s was markedly reduced, with the exception of Zn, which showed moderate immobilization. The presence of acid groups on the surface of the carbon foam, together with a high surface area, led to a strong immobilization of pollutants. Moreover, the modification of the foams using goethite nanoneedles, imply that the novel nanocomposite obtained is effective to remediate simultaneously metal and metalloid-polluted soils, without any relevant effect on soil toxicity.

Antagonistic effect of copper and zinc in fertilization of spring wheat under low soil phosphorus conditions

Sound micronutrient management requires an understanding of nutrient interactions and transformation processes in soil–plant systems which can regulate bioavailability and plant uptake. A series of studies were conducted under controlled environment and field conditions to evaluate wheat response to Cu and Zn fertilization on P-deficient soils from western Canada. The grain and straw yields of wheat were reduced in two (Waskada and Tisdale) of three soils used in the controlled environment study, while yield was not affected at the Echo field site in 2016 when both Cu and Zn sulfate fertilizer were applied at 5 kg·ha–1 rates. Zinc concentration in soil and plant tissues was increased to apparent toxic levels with fertilizer addition in Waskada soils. An imbalance in tissue P:Zn concentration related to micronutrient fertilization was observed in Waskada and Tisdale soils. The availability of Cu and Zn in post-harvest soils was increased with increasing rate of these fertilizers' addition. Chemical and spectroscopic speciation using sequential extraction and X-ray absorption near edge structure, respectively, revealed that Cu and Zn were mostly speciated as carbonate phases, and complexation of these elements with carbonate and phyllosilicate minerals is likely the process controlling bioavailability in the soils.

Organic management for yams (Dioscorea spp.) intercropped in coconut (Cocos nucifera) plantation: Evidences from a validation trial in the coastal humid tropics of Kerala, India

A field experiment was conducted under Network Project on Organic Horticulture during 2015–17 (April-January) at ICAR-Central Plantation Crops Research Institute (ICAR-CPCRI), Kasaragod, to validate the ICAR-CTCRI developed organic farming technologies in yams under intercropping in an organically raised mature coconut garden (>48 years). Three species of Dioscorea [(greater yam (D. alata), lesser yam (D. esculenta) and white yam (D. rotundata)] were tested under four production systems, viz. traditional, conventional, integrated and organic, and replicated thrice in split plot design in a mature coconut garden. Organic practice was similar to conventional as revealed from the identical impacts on yield, tuber quality and soil chemical properties. Yield under organic management was 98.6% of conventional farming. D. alata and D. esculenta were more responsive (+8 to 10%) to organic management, but organic management lowered yield by 30% in dwarf white yam (D. rotundata). The organic farming package comprising farmyard manure, green manure cowpea, neem cake and ash resulted in higher available N, exchangeable Ca and available Zn in soil and significant improvement in K, higher P and Mg contents in yam tubers. However, the highest profit was realized from coconut + D. alata in integrated system (`1,87,057/ha). Among yams, greater yam (D. alata) was the most productive and profitable under organic management (`1,46,634/ha) in intercropping set up.

Impact of ZnSO4 and ZnEDTA applications on wheat Zn biofortification, soil Zn fractions and bacterial community: Significance for public health and agroecological environment

Application of Zn fertilizer can improve cereal Zn concentration, and affect soil microbial ecology by increasing soil Zn concentration. We investigated the effects of three-year continuous applications of different Zn fertilizers (i.e., ZnSO4 and ZnEDTA) on wheat Zn biofortification, soil Zn fractions and bacterial community on a Zn deficient calcareous soil. The results showed that ZnEDTA application induced a higher grain Zn concentration and bioavailability than those in the case of ZnSO4 application, which met the target of wheat Zn biofortification within three years. Correspondingly, ZnEDTA application resulted in a higher Zn availability in soil than ZnSO4 application by facilitating Zn transformation into exchangeable and organic matter loosely bound fractions. Bacterial diversity and richness were not affected, but the bacterial community was altered after three years Zn applications. ZnEDTA application significantly decreased the relative abundances of Nocardioides, Arthrobacter, Blastococcus, Gemmatimonas, and Streptomyces as compared with ZnSO4 application. Meanwhile, ZnEDTA application lowered α-glucosidase, β-glucosidase, and β-xylosidase activities in soil as compared with ZnSO4 application. These results indicated that ZnEDTA application is an effective practice to achieve wheat Zn biofortification, but attention needs to be paid to the potential environmental risks associated with the decreased activities of microbes and enzymes in soil.

Growth, yield and zinc accumulation in garlic (Allium sativum L.) as affected by zinc supply on zinc deficient soils

Zinc deficiency in soils and plants is the worldwide problem causing considerable yield reduction and indirectly affects human health due to its lesser concentration in the crop produces grown on zinc deficient soils. Hence to know the effect of zinc supply on the growth, clove yield and Zn accumulation, four field experiments were conducted with varied levels of zinc sulphate (0, 5, 10, 25, 37.5 and 50 kg ha-1) using garlic variety Ooty 1 as test crop on zinc deficient sandy loam soils during the Rabi season of 2018-19. Soils with deficient zinc availability showed better response to different levels of zinc sulphate and application of recommended NPK along with 10 kg zinc sulphate ha-1 was found sufficient and economical in increasing the clove yield of garlic by 20.6 per cent. The same treatment resulted in higher farm income with the benefit cost ratio of 3.28. Slight yield reduction (5-7%) at all the four farms was observed for the higher levels of zinc sulphate addition (37.5 and 50 kg ha-1). The highest soil Zn availability, zinc accumulation and uptake by garlic crop were obtained with the addition of 50 kg zinc sulphate ha-1. Although there was a higher variability in the garlic crop response to zinc levels at all the farms, zinc sulphate addition at different levels considerably improved the growth and yield of garlic and also increasing the zinc accumulation in cloves and plants on zinc deficient soils.