Bioactive Nutrient Fortified Fertilizer: A Novel Hybrid Approach for the Enrichment of Wheat Grains With Zinc

Zinc (Zn) is a critical micronutrient that synergizes nutrient use efficiency, and improves plant growth and human health. Low Zn bioavailability in soils affects produce quality and agricultural productivity worldwide ultimately inducing deficiency in humans and animals. Zn deficiency is a leading cause of malnutrition in underdeveloped countries where a widespread population depends upon staple cereals for daily intake of calories. Modern cereal cultivars are inherently low in Zn, eventually, plants need to be enriched with soil application of ZnSO4, but due to higher fixation losses, it becomes an inefficient source. Rhizosphere microbiome contains Zn-solubilizing bacteria (ZSB) that improve Zn bioavailability, thus increase the root function, Zn uptake, and plant growth. Niha Corp developed a hybrid process of bioactive nutrient fortified fertilizer (BNFF), which has been used to formulate Zabardast Urea (ZU) by coating bioactive Zn (BAZ) and ZSB on urea. Data obtained for 15 wheat varieties from 119 farmer field demonstration plots and eight replicated trials on 42 locations across multi-environment conditions conclude that ZU significantly improved the plant biomass and yield by 12% over non-Zn control and produced grains with 57 μg/g Zn contents, which can meet a major part of the recommended dietary allowance (RDA) of humans. The study recommends that this microbe-mediated hybrid invention (ZU) is a feasible approach to boost Zn bioavailability and Zn use efficiency, with enhanced yield and quality that may contribute to improve human health. To the best of our knowledge, this is the first wide-scale field testing of Zn enrichment in the grains of bread wheat using an innovative BNFF Urea Z technology.

Effect of Chelant-Based Soil Washing and Post-Treatment on Pb, Cd, and Zn Bioavailability and Plant Uptake

The remediation of Pb, Cd, and Zn contaminated soil by ex situ EDTA washing was investigated in two pot experiments. We tested the influence of (i) 0, 0.5, 1.0, and 1.5%wt zero-valent iron (ZVI) and (ii) a combination of 5%wt vermicompost, 2%wt biochar, and 1%wt ZVI on the metal availability in EDTA-washed soil using different soil extracts (Aqua regia, NH4NO3) and plant concentrations. We found that EDTA soil washing significantly reduced the total concentration of Pb, Cd, and Zn and significantly reduced the Cd and Zn plant uptake. Residual EDTA was detected in water extracts causing the formation of highly available Pb-EDTA complexes. While organic amendments had no significant effect on Pb behavior in washed soils, an amendment of ≥ 1%wt ZVI successfully reduced EDTA concentrations, Pb bioavailability, and plant uptake. Our results suggest that Pb-EDTA complexes adsorb to a Fe oxyhydroxide layer, quickly developing on the ZVI surface. The increase in ZVI application strongly decreases Zn concentrations in plant tissue, whereas the uptake of Cd was not reduced, but even slightly increased. Soil washing did not affect plant productivity and organic amendments improved biomass production.

Humic acid characterization and heavy metal behaviour during vermicomposting of pig manure amended with 13C-labelled rice straw

Aiming to reveal the humification process of organic waste and its contribution to the heavy metal behaviour affected by earthworm activity, it was studied about the variation of humic acid (HA) and heavy metal behaviour during vermicomposting of the mixed pig manure and 13C-labelled rice straw. The results showed that earthworms could well adapt to the culturing environment and feed organic matter for its growth and reproduction, the vermicomposting process increased the content of humic substances (HS), HA, and fulvic acid (FA) in substrate residues, but led to less transformation of HA into FA. The elemental, ultraviolet absorption spectroscopy, Fourier transform infrared (FTIR) and fluorescence excitation–emission matrix (EEM) analysis indicated that vermicomposting led to more aromatic structures and much higher humification degree in HA, whereas less protein, FA-like substances and plastein in HA. Vermicomposting could enhance the total Cu content and decrease Cu/Zn bioavailability in the substrate residues, and vermicomposting especially can help stabilize Cu in the substrate residues by forming more complexed HA–Cu.

Effects of Selenium–Zinc Interactions on the Bioavailability of Selenium/Zinc in Soil and Its Mechanism

Purpose Biofortification is a core strategy in solving the malnutrition of selenium (Se) and zinc (Zn) for global human being. However, whether Se and Zn co-biofortification can manipulate soil Se/Zn bioavailability and its mechanism still remains unclear. Methods The pot experiment was conducted to investigate the co-amendment of selenate and Zn sulfate on the growth of pak choi, especially on the uptake of Se and Zn, and to elucidate the effect of soil pH and soil enzyme activity on the bioavailability of Se/Zn in soil and its mechanism. Results Results showed that plant growth inhibition caused by the application of high Se rate was significantly alleviated with Zn supplements, and the biomass in the shoots and roots of pak choi in Se2.5Zn20 and Se2.5Zn50 treatments significantly increased (67.0%–112.8%) compared with the Se2.5Zn0 treatment. Additionally, Se and Zn co-amended application significantly enhanced soil available Se/Zn content compared with correspond single Se/Zn treatments. The increase of soil available Zn content could be attributed to the significant decrease in the soil pH, while the increase of soil available Se was from the biochemical conversion caused by the activity of catalase, urease, and alkaline phosphatase. Conclusion Se–Zn co-amendment can ameliorate bioavailability of Se/Zn in soil by regulate the pH and enzyme activity of soil.

Bioavailability of Zinc in Bread Wheat Grown in the Calcareous Soils of the Kurdistan Region of IRAQ

A survey of wheat grain from 120 fields in Sulaimanyah province, Kurdistan region, Iraq was undertaken in 2017. We evaluated the concentrations of phosphorus (P), Zn and phytic acid (PA) and the estimated Zn bioavailability in wheat grain grown in the calcareous soils of the region. Concentrations of P in wheat grain were higher than the recommended value of 3570 mg kg− 1; PA was within the range of other countries but Zn concentration in 88% of wheat grain samples fell below the value recommended for human nutrition of 41.6 mg kg− 1. Bioavailable Zn intake (mg d− 1) was estimated assuming bread consumption of 300 g day− 1 in the region. Considering PA and Zn intake suggested only 21.5 ± 2.9% of whole grain flour Zn was bioavailable. Thus the effective Zn intakes from whole wheat was only 1.25–2.05 mg d− 1 for the local population. Typical dietary Zn was below recommended levels (11 mg d− 1), due to low soil Zn uptake by wheat and the large concentrations of PA in wheat grains, probably from over-use of phosphate fertilizer.

Determination of poultry manure and plant residues effects on Zn bioavailable fraction in contaminated soil via DGT technique

A greenhouse experiment was aimed at assessing the effects of poultry manure, sorghum, and clover residues (0 and 15 g kg− 1) on the zinc (Zn) bioavailable fraction in contaminated calcareous soil using two chemical assay, including diffusion gradient in thin films (DGT) and diethylene triamine pentaacetic acid-triethanolamine (DTPA-TEA), and a bioassay with corn (Zea mase L.). The results showed that poultry manure, clover, and sorghum residues application increased dissolved organic carbon (DOC) by 53.6 and 36.1, and 9.2%, respectively, with respect to unamended soils, as well as decreasing soil pH by 0.42, 0.26, and 0.06 units, respectively. These changes did result in increases of Zn effective concentration (CE) and DTPA-Zn, and plant Zn concentration as a result of the increased exchangeable form of Zn. In the sorghum residues-amended soils, a reverse trend was observed for CE-Zn compared to the DTPA method. Correlation analyses revealed that unlike CE-Zn, DTPA-Zn had a significant positive correlation with organic fractions that can be considered as an equivalent to the fact that the DTPA method had been overestimated Zn available to the plant. The best correlations between corn metal concentrations and soil metal bioavailability were obtained for CE-Zn using DGT technique, which also provided the best Zn bioavailability estimate. It is concluded that sorghum residues could be used to reduce the phytotoxicity risk of Zn in calcareous contaminated soil, and DTPA method is the less robust indicator of Zn bioavailability than DGT technique.

Combination of High Zn Density and Low Phytic Acid for Improving Zn Bioavailability in Rice (Oryza stavia L.) Grain

Background Zn deficiency is one of the leading public health problems in the world. Staple food crop, such as rice, cannot provide enough Zn to meet the daily dietary requirement because Zn in grain would chelate with phytic acid, which resulted in low Zn bioavailability. Breeding new rice varieties with high Zn bioavailability will be an effective, economic and sustainable strategy to alleviate human Zn deficiency. Results The high Zn density mutant LLZ was crossed with the low phytic acid mutant Os-lpa-XS110–1, and the contents of Zn and phytic acid in the brown rice were determined for the resulting progenies grown at different sites. Among the hybrid progenies, the double mutant always displayed significantly higher Zn content and lower phytic acid content in grain, leading to the lowest molar ratio of phytic acid to Zn under all environments. As assessed by in vitro digestion/Caco-2 cell model, the double mutant contained the relatively high content of bioavailable Zn in brown rice. Conclusions Our findings suggested pyramiding breeding by a combination of high Zn density and low phytic acid is a practical and useful approach to improve Zn bioavailability in rice grain.

Determination of Poultry Manure and Plant Residues Effects on Zn Bioavailable Fraction in Contaminated Soil Via DGT Technique

A greenhouse experiment was aimed at assessing the effects of poultry manure, sorghum, and clover residues (0 and 15 g kg-1) on the zinc (Zn) bioavailable fraction in contaminated calcareous soil using two chemical assay, diffusion gradient in thin films (DGT) and DTPA-TEA, and a bioassay with corn (Zea mase L.). The results showed that poultry manure, clover, and sorghum residues application increased dissolved organic carbon (DOC) by 53.6 and 36.1, and 9.2%, respectively, with respect to unamended soils, as well as decreasing soil pH by 0.42, 0.26, and 0.06 units, respectively. These changes did result in increases of Zn effective concentration (CE) and DTPA-Zn, and plant Zn concentration as a result of the increased exchangeable form of Zn. In the sorghum residues-amended soils, a reverse trend was observed for CE-Zn compared to the DTPA method. Correlation analyses revealed that unlike CE-Zn, DTPA-Zn had a positive correlation significantly with organic fractions that can be considered as an equivalent to the fact that the DTPA method had been overestimated Zn available to plants. The best correlations between corn metal concentrations and soil metal bioavailability were for CE-Zn using DGT technique, which also provided the best Zn bioavailability estimate. It is concluded that sorghum residues could be used to reduce the phytotoxicity risk of Zn in calcareous contaminated soil, and DTPA method is the less robust indicator of Zn bioavailability than DGT technique.

Higher bioavailability of Cu and Zn in the eastern part of Johore Causeway: Will the pattern remain the same beyond 2030?

The purpose of this paper is to discuss Cu and Zn concentrations in Perna viridis soft tissues from the western and eastern parts of Johore Singapore Causeway. The polluted eastern portion of the Causeway had greater levels of Cu and Zn in different areas of the soft tissues of mussels than the western part. This indicated the eastern section of the semi-enclosed Causeway had higher Cu and Zn bioavailability than the western part. With some reports of high metal levels in the eastern part of the Causeway from 2015 to 2018, it is predicted that there will be a plausible constant source of anthropogenic metal contamination in the eastern part of the Causeway beyond 2030 if anthropogenic activities are not effectively controlled.