Journal of Soil Science and Plant Nutrition最新文献

One of the primary factors contributing to the low productivity of the rice-based cropping systems in Eastern India is the imbalanced use of fertilizers and the improper timing of post-rice crops within the cropping window. Smart practices that boost system productivity and profitability and reduce energy-carbon-water footprints are crucial in changing climate. Therefore, the present study was carried out to identify the most energy-carbon-water efficient production practices having higher productivity and profitability for a rice-based cropping system in Eastern India. The experiment was laid out in a split-plot design with four replications. In the main plots, six treatments comprising different nitrogen (N) management options (100% soil test-based N, 75% soil test-based N + green manuring and 50% soil test-based N + green manuring) and two rice cultivars (manaswini and hasanta) were allocated. The sub-plots consisted of three different crop establishment strategies (zero tillage, conventional tillage and furrow-irrigated raised bed) for the post-rice crops. The 75% soil test-based N with green manuring, among the N management options, provided the highest system yield and profitability, registering 12.9 and 24.1% increases over 100% soil test-based N, respectively. Among crop establishment methods, zero tillage (ZT) and furrow-irrigated raised bed (FIRB) gave similar system yields and net returns. In comparison to conventional tillage (CT), ZT produced 10.7 and 24.9% greater system productivity and profitability, respectively, while FIRB produced 13.2 and 24.8% higher yields and net returns. Both ZT and FIRB had higher energy use efficiency (18.1 and 19.5%, respectively) and carbon efficiency (9.7 and 9.1%, respectively) than the CT. The FIRB led to a 5.7% saving in system water requirements and 20.2% higher system water productivity as compared to the CT. The study concluded that 75% soil test-based N with green manuring and ZT or FIRB in post-rice crops could be the best suitable practices for the rice-toria-sweet corn system for higher system yield and net returns with low energy-carbon-water footprints under changing climate in the long run.

Graphical Abstract

In recent decades, the overuse of chemical fertilizers has posed significant environmental challenges worldwide, prompting a shift towards sustainable agricultural systems that emphasize bio-organic fertilizers to enhance soil and plant health. The split-plot experiment examined the effects of different fertilizer types (vermicompost (VC), livestock manure (LM), and Azotobacter chroococcum), cultivation times (June 19 and June 30, 2021; June 19 and June 30, 2022), and genetic cultivars (Single Cross 704 and Masil 703). The results showed a significant increase in Chl a, with an average increase of 1.44 mg g^-1 FW in 2021 and 1.42 mg g^-1 FW in 2022, Chl b, with an increase to 0.86 mg g^-1 FW in 2021 and constant levels in 2022, and total Chl, which increased to 2.3 mg g^-1 FW in 2021 after the application of VC and A. chroococcum. Similarly, carotenoid content increased significantly with VC application compared to the control group, with increases of 0.062 and 0.066 mg g^-1 FW in the two crop years, respectively. In addition, the first cultivation time showed higher levels of Chl a, Chl b, total Chl, carotenoids and nutrient uptake compared to the second cultivation time. In addition, the application of bio-organic fertiliser resulted in increased seed protein content, with the highest levels observed being 8.42% in 2021 and 8.69% in 2022. Seed nutrient uptake, particularly calcium (Ca) (21.96 mg kg^-1 DW), potassium (K) (270.7 mg kg^-1 DW), phosphorus (P) (19.94 mg kg^-1 DW) and iron (Fe) (1.76 mg kg^-1 DW), was significantly increased by VC and A. chroococcum, with further increases observed with VC application. Forage yield was significantly influenced by the experimental treatments, with VC and A. chroococcum showing the highest yields, reaching 80.94 t h^-1 and 79.75 t h^-1 respectively in 2021. Overall, the study highlights the potential benefits of VC and A. chroococcum in improving the nutritional content and yield of maize crops.

Phosphorus (P) is one of the essential macronutrients for plant metabolism. Regardless of its great quantity in inorganic and organic forms, it is generally inaccessible for plant utility due to bond formation with other ions present in soil. Due to the excessive use of agrochemicals, environmental issues have reached their peak. This has increased the interest of the scientific community in finding a sustainable alternative to chemical fertilisers. Diverse microbes like Rhizobium spp., Serratia spp., Pseudomonas spp., Bacillus spp., Azotobacter spp., Penicillium spp., Rhizopus spp., Fusarium spp., and various actinomycetes have been isolated and screened as phosphorus solubilizing microorganisms (PSMs). The PSMs also act as biological control agents (bioagents) and help to withstand extreme stress circumstances (like heavy metal toxicity) by producing ACC deaminase. With the advent of time, organic farming is gaining attention as this technology is highly eco-friendly, so utilisation of potential microorganisms for solubilisation of phosphorus will improve soil health and crop productivity. PSMs possess significant heavy metal remediation potential; therefore, they can be used in restoration of contaminated soil as well as in enhancing plant health. This review will provide in-depth knowledge about PSMs and their role in sustainable agriculture and bioremediation of toxicants.

Salt stress has detrimental effects on crops. Chitosan (CTS), a biocompatible, nontoxic, and biodegradable copolymer, plays a multifaceted role in regulating plant stress adaptation. The root application of CTS demonstrates more efficient activation of antioxidant activity, thereby enhancing stress tolerance in plants compared to other methods. This study aimed to evaluate the role of root-applied CTS on the photosynthetic system and antioxidant defense mechanisms of maize seedlings under salt stress. A hydroponic experiment was conducted with the root application of six concentrations (0, 25, 50, 100, 200, 400 mg·L^− 1) of CTS under salt stress conditions (150 mM). The results revealed that CTS significantly improved biomass accumulation, tolerance index, root development, photosynthetic parameters, pigment contents, ascorbate (AsA) and glutathione (GSH) contents, antioxidant enzyme activities, and soluble protein content, while decreasing sodium (Na) absorption and malondialdehyde (MDA) levels in maize seedlings under salt stress. Partial least squares (PLS) analysis highlighted the pivotal roles of photosynthetic parameters and pigment contents in maize tolerance to salt stress. Furthermore, 100 mg·L^− 1 CTS demonstrated the most effective reduction in salt-induced oxidative damage, with a reduction of 39.48% in the leaf and 40.22% in the root, leading to significant increases in biomass accumulation (61.59% in the shoot and 39.61% in the root) and tolerance indexes (61.57% in the shoot and 39.59% in the root). Based on these results, it can be concluded that root application of CTS, particularly at 100 mg·L^− 1, can effectively alleviate the negative effects of salt stress on maize seedlings. This suggests that CTS can be an effective tool for enhancing stress tolerance in maize seedlings, potentially improving crop resilience in saline environments. Future research should focus on the long-term effects of CTS application in field conditions to determine the sustainability and practical applicability of CTS in various agricultural settings.

Purpose

Auxins, especially indole-3-acetic acid (IAA), influences microbial physiology, but their effects on the plant microbiome are underreported. This study aimed to understand the impact of exogenously supplemented IAA or IAA produced by Azospirillum on maize rhizosphere microbiome.

Methods

One-week-old maize seedlings were inoculated with Az39 (A. argentinense’s strain), Az39 + L-Trp (Azospirillum-produced IAA), L-Trp (rhizosphere-produced IAA), and exogenous IAA to study their effects on the maize microbiome. Rhizosphere samples were collected after 14 days for DNA extraction, sequencing via Illumina MiSeq, and bioinformatic analysis were made to explore prokaryotic community composition and predict metabolic functions.

Results

Differences in the Shannon index were observed between Az39 inoculation and exogenous L-Trp application, and between Az39 inoculation and Az39 + L-Trp for phylogeny and observed features. Azospirillum inoculation influences on bacterial structure bacterial structure. Genus Actinospica and Bradyrhizobium were associated with IAA treatment, Rokubacteriales and Puia with L-Trp, and Cupriavidus and Pseudomonas with Az39 + L-Trp. Azospirillum and Sphingobium were linked to Az39 inoculation. We identified fifty microbial taxa following the exogenous application of IAA application and twenty-two with potential rhizosphere IAA production. Nitrogen fixation was the most abundant metabolic function in the prokaryotic rhizosphere.

Conclusion

Our results show prokaryotic groups specifically increase in the maize rhizosphere following application of Azospirillum, the IAA produced by Azospirillum, or the rhizosphere community and the exogenous IAA. These groups could be considered specific markers of the IAA activity in the rhizosphere.

Salt stress is identified as a significant abiotic stress that hampers agricultural sustainability globally. The study was carried out to investigate the potential mitigating effects of selenium nanoparticles (Se-NPs) on salt stress in soybean. Two weeks old grown soybean seedlings were subjected to salt stress conditions (4000 mg L^− 1 of sea salts). The plants were foliar sprayed with Se-NPs at concentrations of 0.0, 0.5, 1.0 and 1.5 mg L^− 1 twice. The first application was applied at four weeks from sowing and the second application was added after two weeks from the first application. Compared to control, Se-NPs application mitigates the negative effect of salinity on plant growth to a variable extent. This improvement may be attributed to several factors such as increased the concentrations of photosynthetic pigments, total soluble sugars and total protein. In addition, Se-NPs alleviated the adversely effect of oxidative stress by increasing the antioxidant activities and potassium contents without markedly increase in the sodium content of the soybean leaf tissues. Also, Se-NPs enhanced the biosynthesis of secondary metabolites such as total phenolic content under salinity. Moreover, Se-NPs spray significantly reinforced the development of conducting secondary tissues in the leaves and roots of the treated plants. GmHKT1 gene transcription was markedly up-regulated in salinized soybean and foliar sprayed with Se-NPs as a molecular strategy to cope with the salinity. Based on the obtained results, among the different doses of Se-NPs, soybean plants sprayed with 1.0 mg L^− 1 Se-NPs showed better salt tolerance. The foliar spray of Se-NPs may be considered as a promising approach to enhance salt tolerance in soybean plants, which could have significant implications for improving agricultural sustainability in salt-affected regions.

Plant growth-promoting rhizobacteria (PGPR) increase plant root growth, potentially improving soil nitrogen (N) uptake, and productivity. Legumes, for instance mungbean, could also benefit from a rise in potential infection sites for nodulation, thereby increasing rates of biological N₂ fixation (BNF). Consequently, the objectives of this study were (i) to assess whether PGPR had an effect on mungbean root biomass and if that was linked to N accumulation and productivity; (ii) to identify whether multi-strain inoculation showed greater efficacy in increasing N accumulation and overall productivity than single-strain inoculation; (iii) to test whether N acquisition was based on BNF rather than on soil N uptake. Field trials were conducted in two seasons at the University of Agriculture, Faisalabad with mungbean cultivar NM11 and multi-strain inoculation consisting of Rhizobium phaseoli, Bacillus subtilis, and Pseudomonas fluorescens. The strains were tested additionally in the second season as single-strain inoculation. Multi-strain and inoculation with P. fluorescens alone had no effect on root biomass, total plant-N, BNF or soil N uptake. Inoculation with B. subtilis, however, resulted in significantly increased root dry matter (+ 211 kg ha^− 1), total dry matter (+ 1.7 t ha^− 1), and total plant-N (+ 36 kg ha^− 1). Only inoculation with R. phaseoli enhanced BNF (+ 24%). Yield was not affected by any inoculation. The results suggested that total plant-N was based on soil N uptake rather than on BNF and demonstrated that only single strains affected total N accumulation, pointing to antagonistic mechanisms of the strains in a mixed inoculum.

The crop phosphorus (P) utilization efficiency of commercial fertilizers is only 10–15%, leaving much P fixed in the soil. Coating fertilizer can lessen this problem, but most of the current available options are potentially toxic and expensive. This study-investigated nanobiochar as a coating material for engineering “smart” di-ammonium phosphate (DAP) fertilizer that controls P and nitrogen (N) release in soil, ultimately enhancing nutrient utilization by maize. Biochar was produced from farmyard manure and ball-milled to obtain nanobiochar. Different nanobiochar concentrations (2.5%, 5%, and 10% w/w) were used to coat the DAP granules in a fluidized-bed coater. The release of N and P was studied after immersing both coated and uncoated DAP fertilizers in water. In a pot experiment, five treatments, i.e.i) control (C), ii) uncoated DAP (UF), iii) 2.5% nanobiochar-coated DAP (CUNB1), iv) 5% nanobiochar-coated DAP (CUNB2), and v) 10% nanobiochar-coated DAP (CUNB3) were introduced, after which maize was sown. The presence of a uniform nanobiochar coating on DAP was confirmed by the discrete carbon peaks observed through X-ray diffraction and FTIR spectroscopic analyses. In a laboratory study, the slowest release of N and P was observed for CUNB3. Remarkably, the application of CUNB1 substantially increased the microbial biomass carbon and N by 104% and 147%, respectively, while enhancing the plant-available P, N, and potassium (K) by 40%, 70%, and 46%, respectively, compared with those of C. This treatment increased maize shoot dry matter yield by 88%, accompanied by marked increases of 229%, 205%, and 67% in maize P, N, and K uptakes compared to C, respectively. However, other coating treatments failed to increase these parameters compared with those of UF, confirming that these coatings had the slowest nutrient availability for short-duration crops. The 2.5% nanobiochar concentration can be recommended for coating DAP fertilizer to reduce problems of P fixation and enhance P availability, crop growth and nutrients uptake, hence contributing to sustainable fertilizer management practices in agroecosystem.

Land use change and intensification though they contributed to increases in food production, have remained one of the main threats to soil biodiversity due to their negative impacts on the health and fertility of the soil. Nematodes have been used as a tool for assessing the structure and functions of soils in agroecosystems because indices of nematode community can reflect current changes and functions over time of the ecological processes in the soil. Although nematodes are largely considered important drivers in the decomposition of organic matter and nutrient cycling, their community structure and functional responses to land use change and intensification, and agricultural practices remain poorly understood. Therefore, this review aims to evaluate the response of soil nematodes to land use change and intensification, as well as the potential influence of management practices on their community structure and population dynamics. Besides, due to the fact that nematodes are soil inhabitants, their activities are largely controlled by the physical and biological conditions of the soil. A variation in the soil micro-ecological environment may affect their community structure and functional responses. Furthermore, we investigate the impact of agricultural intensification, such as monocropping, greater use of chemical fertilizers, and the application of pesticides on nematode populations. We also evaluate how sustainable agricultural techniques like organic farming, crop rotation, and decreased tillage affect the health of nematode populations. This study will give a thorough knowledge of how these factors interact to affect soil health and ecosystem function. Further insights about how root interactions in multi-species systems affect the rhizosphere ecology and influence the nematode community will be discussed.

This research monitored the effect of integrated fruit-based farming system on production and rhizosphere microbiome of apple under dry temperate climate. The study also aims to understand the relationships among soil properties, production parameters and fruit yield of apple trees. Six cropping systems including, apple + pea, apple + kidney beans, apple + barley, apple + maize, apple + buckwheat, apple + garlic and apple monoculture were studied. The cropping systems treatments were cultivated with integrated farming approach, where measurements of the key indicators of productivity and nutrient cycling. Three blocks of district Kinnaur viz., Nichar, Kalpa and Pooh were selected. A representative sample size of five sub-locations with four orchards in each sub-location and six apple-based cropping systems (CS) was collected from each block. The current study also examined the significance of microbial communities on nutrient dynamics and biological cycling on apple in legumes, pulses and millets-based cropping systems. Apple + pea increased plant height, tree girth, canopy diameter, shoot growth, and apple leaf area of trees. Maximum generative traits of trees were recorded for apple + pea and apple + kidney bean cropping systems. Fruit yield in apple + pea was determined higher than apple + buckwheat. Soil pH changed towards neutral. When compared to monoculture, apple + pea cropping system showed an increase in post-harvest soil chemical indicators. Microbial biomass in terms of bacteria, actinobacteria, soil fungi, AM fungi, Azotobacter and phosphorus solubilizing bacteria were also improved. Path analysis revealed a positive direct influence of soil chemical and microbial properties on yield. PCA determined that the first principal component caused maximum cumulative variance of 97.19 per cent. Soil organic carbon, microbial biomass carbon, rhizosphere microbial population and nutrient availability were improved as a consequence of intercropped residues left over after harvest. In this study, apple-based cropping systems significantly improved nutrient dynamics, rhizosphere and microbial biomass due to crop residual management by intercropped companion crops left over in soil. Adoption of apple with pea intercrop has shown significant improvements in yield and soil fertility compared to conventional methods. The study thus concluded that transitioning to cropping systems has positive effects on apple cultivation which can be a viable alternative to conventional farming.