Soil Productivity Research Articles

Preparation and characterization of green silicon nanoparticles and their effects on growth and lead (Pb) accumulation in maize (Zea mays L.)

The excessive accumulation of heavy metals, particularly lead (Pb) in agricultural soils, is a growing problem worldwide and needs urgent attention. This study aimed to prepare green silicon (Si) NPs using extract of Chenopodium quinoa leaves and evaluated their effects on Pb uptake and growth of maize (Zea mays L.). The results indicated that Pb exposure negatively affected the growth and chlorophyll contents of maize varieties, while SiNPs positively affected these attributes. Pb alone increased the electrolyte-leakage (EL), hydrogen-peroxide (H2O2) and selected antioxidant enzyme activities in leaves, whereas SiNPs decreased EL and H2O2 concentrations and further enhanced the enzyme activities as compared to their respective treatments without SiNPs. Pb-only treatments led to an increase in Pb concentrations and total Pb uptake in both shoots and roots. In contrast, SiNPs resulted in reduced Pb concentrations, with a concurrent decrease in total Pb uptake in shoots compared to the control treatment. The findings demonstrated that foliar application of SiNPs can mitigate the toxic effects of Pb in maize plants by triggering the antioxidant enzyme system and reducing the oxidative stress. Taken together, SiNPs have the potential to enhance maize production in Pb-contaminated soils. However, future research and application efforts should prioritize key aspects such as optimizing NPs synthesis, understanding positive mechanisms of green-synthesized NPs, and conducting multiple crop tests and real-world field trials.

Conjoint Application of Lime, Organics, Inorganic Fertilizers, and Bio-fertilizers Increases Groundnut Productivity, Available Phosphorus and Microbial Biomass Phosphorus in Acidic Soil of Tripura, India

In Tripura, India the soil productivity is less due to its light texture, acidic in nature, low fertility status, low microbial activity. Thus, a field experiment on groundnut (Arachis hypogaea L.) was carried out on acidic soil of Khowai district of Tripura during 2017 and 2018 to evaluate the impact of the application of various combinations of lime, farm yard manure (FYM), poultry manure (PM), and rhizobium with the recommended doses of NPK on groundnut productivity, available phosphorus (P) and microbial biomass phosphorus (MBP) content of acidic experimental soil. The experiment was conducted using a randomized block design (RBD) with 13 treatments with various combinations of application of lime, farm yard manure (FYM), poultry manure (PM), and rhizobium with the recommended doses (RD) of NPK, each having 3 replications. Both initial and post-harvest soil samples were collected and analyzed to estimate the available P and MBP content. Results indicated that the use of the different combinations of the RD of NPK accompanied by the application of lime, organic manure (FYM or PM) and seed treatment with Rhizobium significantly increased available P and MBP content in the post-harvest soil which has resulted in increased seed yield of groundnut compared to the RD of NPK alone. Again, the use of RD of NPK @ 20:60:40 kg ha-1 conjointly with lime (@ 1/5th LR), PM (@ 5 t ha-1), and treating the seeds with Rhizobium @ 20 g kg-1 of seed might be recommended to the growers in achieving higher groundnut productivity with better return in acid soil of Tripura, India, as it showed maximum enhancement in groundnut productivity as well as available P2O5 content in post-harvest soil.

Silicon attenuates aluminum toxicity in sugarcane plants by modifying growth, roots morphoanatomy, photosynthetic pigments, and gas exchange parameters.

Aluminum (Al) inhibits growth and limits plant productivity in acidic soils. An important strategy to increase Al tolerance is the use of silicon (Si) nutrition. Thus, the aim of this study was to evaluate the interactive role of Si in increasing the growth, physiological and morphoanatomy responses of sugarcane plants under Al toxicity. A 4 × 2 factorial scheme in a completely randomized design was used to study the impact of Si (2mM) on attenuating Al toxicity (0, 10, 15 and 20mgL-1, as Al2(SO4)3·18H2O) in sugarcane seedlings. After 45days, Al toxicity affected sugarcane growth by increasing Al uptake and accumulation, modifying root growth, thickness, and morphoanatomy, and decreasing pigment content, gas exchange parameters, and the number of adaxial and abaxial stomata. However, Si attenuated Al toxicity in the sugarcane seedlings by limiting Al uptake and transport to the shoots, causing positive changes in root morphoanatomy, higher pigment content, improving gas exchange parameters, thereby increased growth. Furthermore, cultivar 'CTC9003' showed beneficial impacts from Si supplementation than 'CTC9002', especially under Al toxicity. The findings of this study suggest that Si plays a notable role in improving anatomical and physiological aspects, particularly the growth of sugarcane seedlings under Al toxicity.

Nitrogen management in common bean cultivars in soil infected by Meloidogyne incognita

The selection of an appropriate nitrogen (N) source can mitigate the negative effect of root-knot nematodes on the yield of common beans. A greenhouse experiment was conducted to assess the application efficiency of four N sources (urea, ammonium sulfate, ammonium nitrate, and sodium nitrate) and inoculation with Rhizobium tropici on the yield components, chlorophyll, and total nitrogen (N) leaf contents of four common bean cultivars (IDR Curió, IDR Sabiá, IDR Tuiuiú, and IDR Bem-te-vi). These beans were cultivated in substrates both infected and uninfected with Meloidogyne incognita. In the soil containing phytonematodes, the IDR Curió cultivar exhibited the highest shoot and root dry weight yield, resulting in the greatest root volume, total N content, and grain yield. Among the N sources, the application of either urea or ammonium sulfate proved the most effective in enhancing common bean productivity in soil, irrespective of the cultivar or whether the soil was infected with Meloidogyne incognita.

Effect of doses fertilizer and harvest interval on the intensity of leaf spot diseases, production and quality of citronella grass (Cymbopogon nardus L.) essential oils in ultisols soil

Until now, Indonesia is still a world exporter of essential oils, including citronella oil. So that the role of farming communities in the development of Indonesia's essential oil industry is very helpful. For this reason, a study was carried out on response of fertilization and harvest interval on the intensity of leaf spot diseases of citronella grass, and productivity in ultisols soil which was carried out from October 2020 to September 2022. The experiment was arranged in a randomized block design in factorial with 9 treatments, as the first factor is 3 levels of an organic fertilizer (NPK); P1 = 25 g clumps −1, P2 = 37.5 g clumps −1 and P3 = 50 g clumps −1. The second factor is the harvest interval with three levels which is 4 = harvest interval once every 4 months, 3 = harvest interval every 3 months and 2 = harvest interval once every 2 months, repeated three times. Each treatment plot consisted of 24 clumps with a plant spacing of 1 × 1 × 1 m. Varieties used is Serai wangi 1. Parameters observed were intensity of leaf spot diseases, vegetative growth, livestock production, oil production, quality analysis and R/C ratio. The results showed that there was an effect of fertilizer doses and harvest intervals on the development of leaf spot disease. It was seen that at the application of fertilizer doses of 37.5 g clumps −1 with harvest intervals once every three months showed the lowest disease attacks, namely on Cuvularia sp and Pestalotia sp (5.98%, 5.42% and 7.98 %, 7.44 %). In addition, the development of vegetative growth is also influenced by the application of fertilizer doses and harvest intervals on the parameters of canopy width, plant height, leaf length, leaf width and number of tillers. The best fertilizer dose is 37.50 g clump −1 successively (175.40 cm, 172.29 cm, 113.62 cm, 2.36 cm and 119.59 stems), with harvest intervals every 3 months (179.40 cm, 187.29 cm, 119.44 cm, 2.45 cm and 120.00 stems), as well as fresh leaves production tons/ha/year and oil production kg/ha/year the best is the application of fertilizer doses of 37.50 g clumps−1 with harvest intervals once every 3 months (67.81 tons−ha-year and 578.61 kg−ha- year,with, 67.40 tons–ha-th and 517.60 kg–ha-th). For oil quality, numerically, the application of fertilizer at a dose of 37.50 g of clump −1 with harvest intervals every 3 months is still high. The proper R/C ratio for farming occurs in the 2 nd year by administering a fertilizer dose of 37.50 g clump−1 and harvesting intervals once every 3 months with an increase of 116.67%. So, the citronella grass variety Serai wangi 1 can be developed on ultisol soil types by applying an organic fertilizer (NPK).

Effects of pyroligneous acid on acute, chronic, and cyto-genotoxicity to earthworms (Eisenia fetida)

The pyroligneous acid (PA), or wood vinegar, is a byproduct of wood carbonization during the slow pyrolysis process. PA is recognized globally as a safe compound for agriculture due to its various beneficial properties, such as antioxidant, antibacterial, antifungal, and termiticidal properties. However, the impact of different PA concentrations on beneficial soil organisms, such as earthworms has not been investigated. The present study aims to understand the effects of different PA concentrations on earthworm Eisenia fetida. The earthworms were exposed to nine different concentrations of PA in soils, including their control. The acute toxicity assay was performed after 14 days of exposure, and the chronic toxicity assay was performed up to 8 weeks after exposure. The results from the acute toxicity assay demonstrated no significant effect on earthworm mortality. The chronic toxicity assay showed that lower PA concentrations (0.01–0.2% of weight/weight PA in soil) promoted cocoon and juvenile production in soils, whereas higher PA concentrations (0.5 and 1%) had a negative effect. These findings highlight the potential of PA to enhance soil fertility at lower concentrations, up to 0.2%, by stimulating worm activity and subsequent manure production. The outcomes of this study have significant implications for the careful management of PA concentrations within agricultural operations.

Effects and regulation Mechanisms of Phosphorus Fertilizer on Soil Carbon Cycle

This paper reviews the effects and regulation mechanisms of phosphorus fertilizer on soil carbon cycle, which is an important process for soil fertility, productivity, and climate change and introduces the background, significance, main pathways, mechanisms, influencing factors, research progress and challenges. The paper shows that phosphorus fertilizer can affect soil carbon cycle through various pathways, such as affecting plant productivity and carbon allocation, soil organic matter decomposition and mineralization, soil microbial community and function, and soil aggregate formation and stability. The paper also shows that the effects of phosphorus fertilizer on soil carbon cycle are influenced by many factors, such as the type, amount, application method and time of phosphorus fertilizer, and the soil type, climate condition, vegetation type and management measures. The paper concludes that the effects of phosphorus fertilizer on soil carbon cycle are both positive and negative, direct and indirect, short-term and long-term, local and global, forming a complex impact network. The paper suggests that more research is needed to clarify the mechanisms, interactions and feedbacks of the effects of phosphorus fertilizer on soil carbon cycle, and to develop effective models and indicators to evaluate and predict the effects of phosphorus fertilizer on soil carbon cycle. The paper also suggests that rational application of phosphorus fertilizer and scientific management of soil carbon cycle are important for improving crop phosphorus use efficiency, reducing excessive application of phosphorus fertilizer, protecting water resources and soil quality, and mitigating climate change.

Human-powered hydroponic systems: An environmental and economic assessment

Hydroponic systems like vertical farming have been proposed as an alternative and potentially more sustainable option for growing vegetables than conventional soil-based production methods. However, the energy required for the functioning of hydroponic systems is a key contributor to the total environmental impact and economic cost. Human-powered hydroponic systems, which utilise human muscular exertion to power the system, have not been thoroughly investigated, despite their potential as a cost-efficient alternative and less harmful to the environment. This paper presents a prototype of a novel human-powered hydroponic system and assesses its environmental impact and economic costs using life cycle assessment (LCA) and life cycle costing (LCC), considering the cultivation of lettuce as a case study. A scenario analysis was performed to assess the environmental impact of lettuce production using a human-powered hydroponic system compared to conventional soil or greenhouse-based production methods. Using SimaPro LCA software, 18 impact categories included in the ReciPe Midpoint (H) method were evaluated. The results indicated that the battery, followed by the power system, represented the primary environmental hotspots of the human-powered hydroponic system. Improving the yield (production of 6 lettuces of 500 g vs 200 g per 40-day growing cycle) of the human-powered hydroponic system can reduce the environmental impact of lettuce production compared to conventionally soil-based produced lettuce in 11 out of the 18 evaluated impact categories, and when compared to greenhouse-produced lettuce, it generates lower impacts in 14 out of 18 categories. Regarding economic cost, considering a yield of 1.2 kg (6 lettuces of 200 g) per 40-day growing cycle with the human-powered hydroponic system, it is more expensive for the consumer than buying lettuce produced with conventional soil-based open-field agriculture and greenhouses, and break-even points are not achievable within 15 years (the lifespan of the system). However, when considering a yield of 3 kg (6 lettuces of 500 g), the break-even point with greenhouse-produced lettuce was achieved between 10 and 11 years. Therefore, although a break-even point is not achievable within the considered lifespan of the developed system, it could be reached if the yield of the system increased and/or if the system had a longer lifespan, which is mainly determined by the lifespan of the battery.

Eleven-Year Canopy Nitrogen Addition Enhances the Uptake of Phosphorus by Plants and Accelerates Its Depletion in Soil

Soil phosphorus (P) is a critical factor that limits plant productivity. Enhanced nitrogen (N) deposition has the potential to modify P transformation and availability, thereby potentially affecting the long-term productivity of forests. Here, we conducted an 11-year-long field experiment to simulate N deposition by adding N to the forest canopy in a N-limited northern subtropical forest in central China and assessed the changes in soil organic P mineralization, P fractions, microbial biomass P content, phosphatase activity, and plant P content under N deposition. Our objective was to establish a theoretical framework for addressing the P supply and sustaining plant productivity in soils with low P availability, particularly in a changing global setting. The results demonstrated a substantial reduction in the levels of total, organic, and available P owing to the canopy addition of N. Furthermore, there was a marked decrease in the proportion of organic P in the total P pool. However, no substantial changes were observed in the soil inorganic P content or the proportion of inorganic P within the total P across different treatments. Canopy N addition significantly enhanced the microbial biomass P content, phosphatase activity, and organic P mineralization rate, suggesting that in soils with limited P availability, the primary source of P was derived from the mineralization of organic P. Canopy N addition substantially increased the P content in leaves and fine roots while concurrently causing a considerable decrease in the N:P ratio. This indicates that N deposition increases P demand in plants. Correlation analysis revealed a significant negative association among the total, organic, and available P levels in the soil and plant P concentrations (p < 0.05). This suggests that the primary cause of the reduced fractions of P was plant uptake following canopy N addition. Various studies have demonstrated that N deposition induces an augmented P demand in plants and expedites the utilization of available P. A substantial reduction in potentially accessible soil P caused by N deposition is likely to exacerbate regional P depletion, thereby exerting adverse impacts on forest ecosystem productivity.

NH3 and greenhouse gas emissions during co-composting of lignite and poultry wastes and the following amendment of co-composted products in soil

ABSTRACT Ammonia (NH3) and greenhouse gas (GHG) emissions are substantial contributors to C and N loss in composting. Lignite can increase N retention by absorbing N H 4 + and NH3. However, the effects of co-composting on NH3 and GHG emissions in view of closing nutrient cycle are still poorly investigated. In the study, poultry litter was composted without (CK) or with lignite (T1) or dewatered lignite (T2), and their respective composts N H 4 + Com_CK, Com_T1, and Com_T2) were tested in a soil incubation to assess NH3 and GHG emission during composting and following soil utilization. The cumulative NH3 flux in T1 and T2 were reduced by 39.3% and 50.2%, while N2O emissions were increased by 7.5 and 15.6 times, relative to CK. The total GHG emission in T2 was reduced by 16.8% compared to CK. Lignite addition significantly increased nitrification and denitrification as evidenced by the increased abundances of amoA, amoB, nirK, and nirS. The increased reduction on NH3 emission by dewatered lignite could be attributed to reduced pH and enhanced cation exchangeable capacity than lignite. The increased N2O was related to enhanced nitrification and denitrification. In the soil incubation experiment, compost addition reduced NH3 emission by 72%∼83% while increased emissions of CO2 and N2O by 306%∼740% and 208%∼454%, compared with urea. Com_T2 strongly reduced NH3 and GHG emissions after soil amendment compared to Com_CK. Overall, dewatered lignite, as an effective additive, exhibits great potential to simultaneously mitigate NH3 and GHG secondary pollution during composting and subsequent utilization of manure composts.

Effects of depth of straw returning on maize yield potential and greenhouse gas emissions.

Appropriate straw incorporation has ample agronomic and environmental benefits, but most studies are limited to straw mulching or application on the soil surface. To determine the effect of depth of straw incorporation on the crop yield, soil organic carbon (SOC), total nitrogen (TN) and greenhouse gas emission, a total of 4 treatments were set up in this study, which comprised no straw returning (CK), straw returning at 15cm (S15), straw returning at 25cm (S25) and straw returning at 40cm (S40). The results showed that straw incorporation significantly increased SOC, TN and C:N ratio. Compared with CK treatments, substantial increases in the grain yield (by 4.17~5.49% for S15 and 6.64~10.06% for S25) were observed under S15 and S25 treatments. S15 and S25 could significantly improve the carbon and nitrogen status of the 0-40cm soil layer, thereby increased maize yield. The results showed that the maize yield was closely related to the soil carbon and nitrogen index of the 0-40cm soil layer. In order to further evaluate the environmental benefits of straw returning, this study measured the global warming potential (GWP) and greenhouse gas emission intensity (GHGI). Compared with CK treatments, the GWP of S15, S25 and S40 treatments was increased by 9.35~20.37%, 4.27~7.67% and 0.72~6.14%, respectively, among which the S15 treatment contributed the most to the GWP of farmland. GHGI is an evaluation index of low-carbon agriculture at this stage, which takes into account both crop yield and global warming potential. In this study, GHGI showed a different trend from GWP. Compared with CK treatments, the S25 treatments had no significant difference in 2020, and decreased significantly in 2021 and 2022. This is due to the combined effect of maize yield and cumulative greenhouse gas emissions, indicating that the appropriate straw returning method can not only reduce the intensity of greenhouse gas emissions but also improve soil productivity and enhance the carbon sequestration effect of farmland soil, which is an ideal soil improvement and fertilization measure.

Effects of cadmium exposure on gut microbiota and antibiotic resistance genes in Haliotis diversicolor abalone

Heavy metals in soil, water, and industrial production can affect the antibiotic resistance of bacteria. Antibiotic resistance in gut microbiota has been extensively researched. The effects of cadmium (Cd) was investigated on the gut microbiota and antibiotic resistance genes (ARGs) of Haliotis diversicolor, a commercially important abalone species. By exposing H. diversicolor to four concentrations of Cd (0 μg L−1 (control), 6.5 μg L−1 (low), 42.25 μg L−1 (medium), and 274.63 μg L−1 (high)) for 30 and 60 days, 16 types of ARG (aadA-01, aadA-02, cfr, dfrA1, ermB, floR, folA, mecA, sul2, tetB-01, tetC-01, tetD-01, tetG-01, tetM-02, tetQ, vanC-01), and 1213 genus and 27 phylum microbiomes were detected. ARGs can be resistant to aminoglycoside, beta-lactamase, macrolide-lincosamide-streptogramin B, multidrug, florfenicol, macrolide, sulfonamides, tetracyclines, and vancomycin. Cadmium exposure significantly alters the abundance of tetC-01, tetB-01, tetQ, sul2, and aadA-01. About 5% (61) of genus-level microorganisms were significantly affected by Cd exposure. Microbiota alpha and beta diversities in the 60-day 42.25 μg L−1 Cd treatment differed significantly from those in other treatments. In addition, 26 pathogens were detected, and two pathogens (Vibrio and Legionella) were significantly affected by Cd exposure. Significant correlations between pathogens and ARGs increased with increased Cd concentration after 60 days of Cd exposure. Cadmium exposure may cause gut microbiota disturbance in H. diversicolor and increase the likelihood of ARG transfer to pathogens, increasing potential ecological and economic risks.

Gibberellin-Mediated Sensitivity of Rice Roots to Aluminum Stress.

Aluminum toxicity poses a significant constraint on crop production in acidic soils. While phytohormones are recognized for their pivotal role in mediating plant responses to aluminum stress, the specific involvement of gibberellin (GA) in regulating aluminum tolerance remains unexplored. In this study, we demonstrate that external GA exacerbates the inhibitory impact of aluminum stress on root growth of rice seedlings, concurrently promoting reactive oxygen species (ROS) accumulation. Furthermore, rice plants overexpressing the GA synthesis gene SD1 exhibit enhanced sensitivity to aluminum stress. In contrast, the slr1 gain-of-function mutant, characterized by impeded GA signaling, displays enhanced tolerance to aluminum stress, suggesting the negative regulatory role of GA in rice resistance to aluminum-induced toxicity. We also reveal that GA application suppresses the expression of crucial aluminum tolerance genes in rice, including Al resistance transcription factor 1 (ART1), Nramp aluminum transporter 1 (OsNramp4), and Sensitive to Aluminum 1 (SAL1). Conversely, the slr1 mutant exhibits up-regulated expression of these genes compared to the wild type. In summary, our results shed light on the inhibitory effect of GA in rice resistance to aluminum stress, contributing to a theoretical foundation for unraveling the intricate mechanisms of plant hormones in regulating aluminum tolerance.

Soil fertility impact on recruitment and diversity of the soil microbiome in sub-humid tropical pastures in Northeastern Brazil

Soil fertility is key point to pastures systems and drives the microbial communities and their functionality. Therefore, an understanding of the interaction between soil fertility and microbial communities can increase our ability to manage pasturelands and maintain their soil functioning and productivity. This study probed the influence of soil fertility on microbial communities in tropical pastures in Brazil. Soil samples, gathered from the top 20 cm of twelve distinct areas with diverse fertility levels, were analyzed via 16S rRNA sequencing. The soils were subsequently classified into two categories, namely high fertility (HF) and low fertility (LF), using the K-Means clustering. The random forest analysis revealed that high fertility (HF) soils had more bacterial diversity, predominantly Proteobacteria, Nitrospira, Chloroflexi, and Bacteroidetes, while Acidobacteria increased in low fertility (LF) soils. High fertility (HF) soils exhibited more complex network interactions and an enrichment of nitrogen-cycling bacterial groups. Additionally, functional annotation based on 16S rRNA varied between clusters. Microbial groups in HF soil demonstrated enhanced functions such as nitrate reduction, aerobic ammonia oxidation, and aromatic compound degradation. In contrast, in the LF soil, the predominant processes were ureolysis, cellulolysis, methanol oxidation, and methanotrophy. Our findings expand our knowledge about how soil fertility drives bacterial communities in pastures.

Review of the Responses of Various Soil Amendments in Sandy Soils

The primary constraints with sandy soils are low soil organic matter content, poor nutrient availability, heavy losses of applied nutrients and lower water holding capacity. Improving the productivity of sandy soils, particularly in developing countries, could be a viable solution to food insecurity and poverty. Large extent of sandy soil is one of the major constraints for crop production in the Eastern Province of Sri Lanka. Meanwhile, various soil amendments can be applied to improve the performances of cropping systems in sandy soils. Nevertheless, a comprehensive knowledge on which soil amendment would work better across different scales is not well known. To address this knowledge gap, this review was conducted using published literature. Systematic review approach was adopted, and the data were extracted from 65 highly relevant papers. The data were analyzed to calculate the percentage changes on crop yields, soil organic matter and soil carbon, in response to the applications of different soil amendments. The review highlighted the potential of several soil amendments to improve the crop performances in sandy soils. Interestingly, rice straw biochar and the municipal solid waste compost have greatly increased crop yields especially in rice at the rate of 0.9% w/w and 3% w/w in soil weight basis, respectively. Highest improvement in soil organic matter and soil carbon was observed under the applications of compost and spent grain, respectively. Therefore, rice straw biochar and compost could be evaluated to improve the productivity of sandy soils, especially in the Eastern region of Sri Lanka. Although the spent grain was promising, the availability for large scale applications may be limited in Sri Lanka. Testing of these soil amendments would require long-term experiments incorporating different crops and cropping systems. 
 Keywords: Compost, Biochar, Sandy soil, Soil amendments

Assessment of the impact of methods of biologization of the agrocenosis of apple trees (<i>Malus domestica</i> Borkh.) on soil fertility and plant productivity

The influence of methods of biologization of the agrocenosis of the orchard, including soil blackening with cereal-legume mixtures of perennial grasses in combination with the introduction of biofertilizers of various spectrum of action, on soil fertility and productivity of apple trees (Malus domestica Borkh.) has been studied. The study was carried out in a two-factor long-term field experiment on meadow soils of the Salgir River valley (Republic of Crimea). It was revealed that the biologization of the agrocenosis of the apple tree contributed to the enrichment of the soil with organic matter, increased the content of its active components, led to the accumulation of mobile forms of phosphorus and potassium with a slight decrease in the content of nitrate nitrogen in the soil. At the same time, the concentration of nutrients in the leaves of the apple tree, including nitrogen, increased. All this contributed to an increase in the yield of fruits. Quantitative relationships between indicators of soil fertility and productivity of apple trees have been revealed. The obtained dependencies allowed us to build a model of productivity of Golden Delicious apple trees during the biologization of its agrocenosis. The most effective combination of the studied methods of biologization is the use of soil blackening with a cereal-bean mixture 3 (CBM3) with bacterization of the root system of an apple tree with a nitrogen-fixing strain (NFS).

Cationic micronutrient fractions in some tropical Alfisols and Inceptisols as affected by organic amendments and simulated moisture regimes: an incubation study

Cultivation of rice is severely jeopardized by the intangible behavior of micronutrients under variable moisture and organics leading to its inconsistent availability. The present study has been conducted to determine the effect of organic amendments and moisture regimes on cationic micronutrients like zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn). Controlled situation incubation study using thrice replicated factorial randomized design with (3 organic amendments × 2 moisture regimes × 2 incubation periods) levels was conducted. Continuous submergence (CS), 50 g kg−1 rice straw and 150 days of incubation (DOI) restored higher soluble and Exchangeable (SE) manganese and iron; while SE-Cu was facilitated under alternate wetting and drying (AWD) condition. SE-Zn was found higher under AWD, no organic administration and 60 DOI. Again AWD, 50 g kg−1 rice straw and 60 DOI recovered higher Mn, Cu, Fe and Zn in organically bound fractions. The adoption of CS, 50 g kg−1 rice straw and 150 DOI recovered higher Mn, Cu, Fe and Zn in manganese and amorphous iron oxide bound fractions; while AWD, no rice straw administration and 60 DOI recovered higher Mn, Cu, Fe and Zn in crystalline iron oxide bound fractions. Substantial change in all the studies fraction resulted into alteration in plant availability of Mn, Cu, Fe and Zn. Under the scenario of global increasing water demands, AWD apart from saving 30-40% moisture improves availability of Cu and Zn which is further accentuated by organic matter, sustaining soil productivity and ensuring food security.

Single and co-inoculation of biofilm-forming rhizobacteria with macroalgae extract increase barley productivity in organic matter-limited soil

Context Limitation in soil organic matter interferes with plant growth and productivity. Chemical fertilisers can provide limiting nutrients to plants, especially in barren soil, but they have detrimental effects on living organisms; therefore, plant growth-promoting (PGP) rhizobacteria may be an alternative to synthetic fertilisers to improve plant tolerance to nutrient stress. Aims This study evaluated the effects of single and co-inoculation of two PGP rhizobacterial strains with macroalgae (Cladophora glomerata) extract on barley growth. We also tested the ability of the respective strains to produce biofilm and exopolysaccharide (EPS) at different pH values under in vitro conditions. Methods Plants were cultivated in an organic matter-limited alkaline soil under field conditions. Key results All treatments increased barley growth parameters to some extent. Growth parameters increased most in Bacillus + macroalgae extract (B + MA) and Bacillus + Azotobacter + macroalgae extract (B + A + MA) treatments. These two treatments significantly enhanced shoot length by 22.9–25.7%, dry weight of shoot + spike by 118.2–154.5%, total weight of grains by 76.5–78.1%, and number of grains per spike by 94.8–112.1% in comparison with the control. The respective two treatments also increased biofilm formation and EPS production in response to alkaline pH. Conclusions Barley productivity may be increased by using PGP strains with greater potential to produce biofilm and EPS, and inoculating them with macroalgae extract. The B + MA treatment could be applied singly or in combination with Azotobacter. Implications Single or co-inoculation of such PGP bacteria with macroalgae extract may be commercialised to enhance barley productivity in organic matter-limited soils.

Effect of soil nutrient management and land configuration on rhizospheric microbial diversity under cotton (Gossypium spp.)-wheat (Triticum aestivum) cropping system in semi-arid region

Microbial diversities in the vicinity of root rhizosphere play a crucial role in promoting plant and soil ecosystem health and productivity. They have great potential as key indicators of soil health in agro-ecosystems enhancing the availability of nutrients. Therefore, a study was carried out during 2019–20 and 2020–21 at research farm of Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana to investigate the rhizospheric microbial diversities under cotton (Gossypium spp.)-wheat (Triticum aestivum L.) cropping system as affected by land configuration and nutrient management. Experiment consisted of 5 nutrient treatments replicated thrice and two land configurations, viz. raised bed (RB) and flatbed (FB) planned in factorial randomized block design (RBD). The results of experiment under RB revealed that farmyard manure (FYM) and FYM with biofertilizer and cow urine formulation (FYM + Org) showed the highest bacterial, fungal, phosphate solubilizing bacteria, azotobacter and actinomycetes population (6.92 to 7.51, 24.63 to 26.80, 7.61 to 7.68, 8.74 to 9.15,7.27 to 7.66 cfu/g soil, respectively). The decrease in microbial diversity was observed under inorganic fertilizer application through soil test crop response approach with targeted yield of 5.5 and 2.8 mg/ha (STCR5.5/2.8) and 6.0 and 3.2 mg/ha (STCR6.0/3.2) and control for cotton and wheat, respectively. Higher microbial population and soil organic carbon was found in RB compared to FB. The STCR5.5/2.8 and STCR6.0/3.2 recorded highest cotton and wheat yield followed by FYM and FYM+Org and least in control under cotton-wheat system. Thus, the study suggests that RB planting with an addition of manures along with biofertilizer and cow urine formulation could be a sustainable and feasible practice through enhanced microbial population raising soil fertility leading to increase the crop yields under semi-arid regions.

Concentrations of Potentially Toxic Elements in Topsoils of Urban Agricultural Areas of Rome

Urban agricultural soils have important social, environmental, and economic roles in big cities, contributing to their sustainability. However, food production in urban soils may be compromised due to soil pollution that resulted from decades of industrial, non-regulated environmental activity and mobile transport. In this study, 12 soils from the urban agricultural area of Rome (Italy) were analyzed for the potentially toxic elements (PTEs) Be, Ba, Pb, Co, Ni, V, Zn, Hg, Cd, As, Cu, and Cr. All but one of the soils under analysis were characterized by at least one PTE concentration above the threshold limit defined by the D.Lgs 152/06 for agricultural soils. Multivariate analysis showed that the soils could be classified into five clusters: clusters I and II had relatively lower mean PTE concentrations; clusters III, IV, and V had relatively higher mean PTE concentrations with several PTE concentrations above the threshold proposed by ILD. Three factors contributing to the variability of the PTE’s concentration in the soils under investigation were identified: a geological factor related to PTE As, Ba, Be, and V; an anthropogenic factor related to Pb and Cu; and a mixed factor related to Co, Cr, Ni, and Zn. High PTE content may limit the utilization of urban soils for food production.