Journal of Soil Science and Plant Nutrition最新文献

The allocation of soil organic carbon (SOC) to its component fractions can indicate the vulnerability of organic carbon stocks to change. The impact of vetiver on the composition and distribution of SOC can provide a complete assessment of its potential to sequester carbon in soil.

Purpose: This study quantified the distribution and impact of SOC under vetiver and the allocation of SOC to particulate (POC), humus (HOC) and resistant (ROC) fractions differentiated based on particle size and chemical composition under vetiver grass compared with other plant types.

Methods: Carbon fractions were measured on soil samples collected from Australia and Ethiopia to a depth of 1.0 m under three plant communities (vetiver, coffee, and Australian native pastures). We used the MIR/PLSR spectra to estimate SOC fractions based on fractionated, and NMR measured values.

Results: The stocks of SOC fractions indicated significant differences in the proportion of labile POC to HOC across sites and vegetation types. The dominant carbon fraction was HOC (71%) for all vegetation types. The average carbon sequestration rate under vetiver for OC was − 2.64 to + 7.69 Mg C ha^− 1 yr^− 1, while for the POC, HOC and ROC was 0.04 to + 1.17, -3.36 to + 4.64 and − 0.35 to + 1.51 Mg C ha^− 1 yr^− 1, respectively.

Conclusion: Growing vetiver and undisturbed native pastures has on average a high accumulation rate of a more stable carbon (HOC) which is less vulnerable to change, and change was largely driven by the HOC fraction. We, therefore, recommend the use and promotion of perennial tropical grasses like vetiver and similar grasses and undisturbed native pastures as potential options to facilitate soil carbon sequestration.

Soil zinc (Zn) deficiency is a major cause of Zn-malnutrition, low yields, and low nitrogen use efficiency (NUE) in wheat. Improving grain Zn concentration and NUE in wheat without compromising yield has become a global concern. A study was therefore conducted to explore the potential of Zn-solubilizing bacteria (ZnSB) and Zn oxide nanoparticles (ZnONPs) for improving Zn biofortification and nitrogen use efficiency (NUE) in wheat. Two strains of ZnSB (Pseudomonas aeruginosa (YZn1) and Stenotrophomonas maltophilia (WZn1)) were isolated from field soil and selected for study based on Zn solubilization efficiency, IAA production, and Zn release efficiency. The potential of soil and foliar applications of ZnONPs separately, or in combination with consortia of ZnSB, to enhance wheat Zn concentrations, productivity and NUE was evaluated. The treatments tested were: Control (T₁), ZnSB (T₂), ZnSO₄ (soil application; T₃), ZnONPs (foliar application; T₄), ZnSB + ZnONPs (soil and foliar applications respectively; T₅), and ZnONPs + ZnSB (soil applications of both) + ZnONPs (foliar application) (T₆). Soil application of ZnONPs when combined with ZnSB and a foliar application of ZnONPs (T₆) significantly (P ≤ 0.05) improved yield and yield traits compared to the control (T₁) and ZnSO₄ (T₃) treatments. Notably, T₆ increased chlorophyll SPAD value, 1000-grain weight, grain yield, harvest index (HI), and grain Zn concentration by 27.61%, 29.63%, 53.54%, 23.07%, and 89.06% respectively, over control (T₁). The T₆ treatment also increased grain zinc concentration and yield relative to T₃ by 20.95% and 6.12% respectively. The NUE was also increased in response to T₆, with significantly higher nitrogen physiological efficiency (48.79 g g^− 1), agronomic use efficiency (27.08 g g^− 1), nitrogen harvest index (80.84%), and partial factor productivity (61.34 g g^− 1). However, the maximum Zn apparent recovery (71.02%) was observed in plants subjected to T₅. Combined application of ZnSB and ZnONPs in the soil along with foliar application of ZnONPs can replace conventional application of ZnSO₄ for maximum yield, Zn-enriched grain, and improved NUE in wheat when grown in Zn-deficient soils.

[Purpose] Soil aggregate indices, crucial indicators of soil structure quality, exhibit spatial and temporal variations influenced by soil conditions. Traditional methods for determining these indices, such as dry-sieving or wet-sieving, are resource-intensive. Previous research has proposed the use of hyperspectral visible near-infrared (Vis-NIR) data for topsoil aggregate index (TAI) estimation in croplands. However, subsoil aggregate index (SAI) spectra are challenging to obtain directly. Regions with severe erosion typically comprise grassland or forestland with steeper slopes rather than cropland. The study analyzes the variation of soil aggregate indices under different land use types of cropland, grassland, and forestland. The potential for indirectly predicting SAI from hyperspectral Vis-NIR is explored. Topsoil and subsoil macro-aggregate values and aggregate stability metrics are observed to be the highest in forestland with a greater slope, gradually increasing with prolonged forest duration. [Methods] A binary particle swarm optimization combined with an artificial neural network proves effective for TAI prediction under diverse land use types. [Results] Secondary soil properties (mean weight diameter, geometric mean diameter, percentage of aggregates destruction, and fractal dimension) outperform direct soil aggregate fractions (macro-aggregate, micro-aggregate, and organo-mineral aggregate) in predicting accuracy. Significant correlations are noted among TAI, among SAI, and between TAI and SAI. Leveraging the strong correlation between TAI and SAI, SAI can be directly predicted from measured TAI or indirectly from predicted TAI based on hyperspectral Vis-NIR. [Conclusions] The study underscores the critical role of spectra in TAI and SAI prediction, particularly in soils prone to erosion under different land use types.

Biofertilizers are microbial cultures that colonize the rhizosphere and help in nutrient uptake by plants. However, despite significant progress in the research and development of various biofertilizer formulations, the practical usage of these falls well short of their capability. Production and optimization of biofertilizer formulations require aseptic conditions and close monitoring throughout the manufacturing process. In this regard, scaling up its production process requires an in-depth understanding of fermentation techniques along with process control parameters. The current study explores various mass production techniques using fermentation technology for upscaling biofertilizer production. Exploration of the potential utilization of nutrients found in domestic and industrial wastewater has been undertaken to cultivate biofertilizer strains through both solid and liquid fermentation. These approaches represent two pathways that could effectively contribute to resource recovery, aligning with the principles of a circular economy. The sustainable large-scale production of biofertilizers also hinges on the optimization of processes and formulations, coupled with the development of suitable carriers.

Graphical Abstract

Zinc (Zn) possesses nutritional importance for humans, animals, and plants, making it a crucial element in their dietary requirements. In the current study, the effect of zinc oxide nanoparticles (ZnONPs) solution at four different concentrations (0, 0.5, 1.0 and 5.0 g/L) at 20-day interval on pea plants grown in Zn-deficient soil was assessed for remediation of Zn deficiency and enhanced Zn fortification. Zinc oxide nanoparticles were synthesized by using sol-gel method and characterized by UV-Vis spectroscopy, Fourier transform infrared (FTIR), Scanning Electron Microscopy (SEM), and X-Ray diffraction (XRD) and EDX pattern. The soil samples were analysed for microbial counts, chemical properties, dehydrogenase activity and vegetative characteristics, nutrient profile, and yield parameters according to their respective methods. The change of solution colour to off-white confirmed the synthesis of ZnONPs. ZnONPs were characterized by UV-Vis spectroscopy with a broad peak at 380 nm. The presence of NH/OH, C-H, C-C, C-O, C-N, Cl-C-O functional groups were confirmed by FTIR spectrum. The crystalline structure with hexagonal arrangements was described by the XRD pattern. The EDX pattern of ZnONPs showed the zinc composition as 45.9% and oxygen was 54.05%. The SEM images showed that the size of ZnONPs was of 37 nm. The application of ZnONPs at a concentration of 5.0 g/L significantly improved the growth and yield parameters. However, the highest value for root characteristics was attained with the application of ZnONPs at a concentration of 1.0 g/L. The microbial soil counts and enzyme activities such as viable cell counts, and dehydrogenase activity was highest at 5.0 g/L ZnONPs treatment. The treatment of ZnONPs successfully reverted the symptoms of Zn-deficiency besides the improvement of the Zn content of plant, although the response was concentration dependent. These findings indicate that ZnONPs can be effectively used for remediation and Zn fortification in pea plants cultivated under low soil Zn concentrations. The present study emphasizes the potential of ZnONPs to address micronutrient deficiencies, promote crop growth, and enhance soil health, offering a sustainable and controlled approach to zinc applications in agriculture.

In the short term, biochar effectively retains water and nutrients, thereby enhancing water productivity and nitrogen (N) use efficiency, consequently increasing crop yield. Over time, however, the ability of biochar to regulate water and N may diminish, leading to changes in its mechanisms for enhancing yield. Therefore, the time-dependent effects of aged biochar on yield enhancements need to be assessed. We conducted a two-year field experiment using a split-plot design with varying periods of biochar addition as the main plots, denoted as one year (Y₁), two years (Y₂), five years (Y₅), and six years (Y₆), and three addition rates as the subplots, denoted as no biochar addition (C₀), 6 t·hm⁻² biochar (C₆), and 12 hm⁻² biochar (C₁₂). The results showed that under identical conditions, short-term biochar addition significantly outperformed medium- to long-term addition in enhancing maize yield, water productivity, N-use efficiency, and soil fertility index (SFI). There was no significant difference between the Y₆C₆ treatment and the control with no biochar addition, however high biochar addition may help mitigate this decline. Structural Equation Model (SEM) analysis demonstrated a positive correlation between increases in soil NH₄⁺-N and NO₃⁻-N content and SFI. Additionally, nitrate nitrogen (NO₃⁻-N) content positively affected water productivity. However, with extended periods of biochar addition, the effect of NO₃⁻-N on both SFI and water productivity weakens, whereas that of ammonium nitrogen (NH₄⁺- N) on SFI intensifies, influencing yield. Therefore, C₁₂ treatment not only improves yield, water productivity, and N-use efficiency but also mitigates the reduction of positive effects on crops and soil after medium- and long-term addition of biochar.

The root-knot nematode, Meloidogyne incognita, poses a significant economic threat as an endoparasite for various vegetables, including cabbage. Utilizing botanicals is an essential aspect of green technology to combat root-knot nematode infection. This study investigates the efficacy of four botanicals (Oxalis corniculata, Ricinus communis, Lantana camara, and Pluchea lanceolata) as emerging phyto-nematicides against M. incognita using both in vitro experiments (J2 mortality after 24, 36 and 48 hours exposure to 3000, 2000, 1000, 500, and 0 mg/L of the four botanicals and then determination egg hatching of M. incognita after 3 and 5 days incubation with various concentrations of the selected botanicals) and pot experiments. In the in vitro study, different extracts from the leaves of botanicals were applied to the second juvenile stage (J2) of M. incognita. The highest mortality of J2 and reduction in egg hatching for O. corniculata extract (89.96 and 86.79%), while the lowest effects (9.01 and 11.50 %) were observed for P. lanceolata extract. The extract of O. corniculata caused complete damage to the morphology of J2 via rupturing the cuticle of posterior, middle, and interior portion. In the pot experiment, M. incognita adversely affected growth shoot length (51.37%), root length (55.10%), fresh head weight (63.14%), and dry head weight (61.79%) by down-regulation of biochemical and epidermal traits compared to un-inoculated plants. However, the soils amended with botanicals especially O. corniculata recorded highest retardation of M. incognita infestation in cabbage roots, hence improved the growth and yield compared to the infected plants. The most beneficial effect denoted by O. corniculata at 100 g/pot on the infected cabbage plants associated with improving carotenoids (83%), chorophyll (117%), and nitrate reductase activity (79%) compared to stressed plants only. Also, O. corniculata at 100 g/pot maximally increased the number of stomata (130%), lengths (87%), and width (141%) of stomatal pore infected cabbage plants compared to the infected plants. These findings recommended the importance of O. corniculata as an eco-friendly organic phyto-nematicide that effectively restrict the damaging impacts of M. incognita on cabbage and may be other crops.

Purpose

The use of urease inhibitors (UIs) has been proposed to reduce nitrogen (N) losses, including ammonia (NH₃) volatilization from N fertilizers applied soils. However, the effects of soil properties on UIs efficiency for mitigating NH₃ emissions remains less clear.

Methods

An incubation study was conducted, to evaluate the efficiency of urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) on NH₃ volatilization. The soils were used from six different counties (Zhouzhi, Yangling, Changwu, Luochuan, Ansai and Shenmu) of the Loess Plateau, China characterized different soil properties. The treatments were control (no N), urea (0.2 g N kg^− 1 soil) and urea + 0.5% NBPT.

Results

The cumulative NH₃ volatilization loss in urea applied six different soils were 42.8–56.1 mg kg^− 1 (21.4–28.1% of N applied). The NH₃ emission rate rapidly increased in Shenmu, Ansai and Luochuan soils and recorded highest (28.1, 27.1 and 25.8% of N applied), probably due to more sand particles and higher soil pH. In contrast, Zhouzhi, Changwu and Yangling soils showed gradual increase in NH₃ emission rate and recorded lowest (21.4, 21.5 and 23.2% of N applied), might be due to more clay particles and low soil pH. Urea + 0.5% NBPT delayed urea hydrolysis and significantly reduced NH₃-N loss by 47.1–55.5% in different soils. The soil texture, pH, urease activity (UA), calcium carbonate (CaCO₃) and organic matter content were the main soil factors affected the rate of NH₃ volatilization and NBPT effectiveness.

Conclusion

This study validated that NBPT application has immense potential in mitigating NH₃ volatilization from different soils.

Adequate fertilization is the primary pre-requisite for sustainable crop production. Nanofertilizers are considered as new class of fertilizers and development and testing of these fertilizers are been an exciting research areas. Herein, we developed nanobiochar based nitrogen and potassium fertilizers through chemical methods and as prepared fertilizers were tested on groundnut (Arachis hypogaea L.) to evaluate their bio-efficacy. The nanobiochar-based nitrogen (NB-N) and potassium (NB-K) fertilizers were characterized by employing appropriate techniques, including dynamic light scattering for particle size analysis (NB-N (20.3 nm); NB-K (18 nm)) and zeta potential measurements (NB-N (33.2 mV); NB-K (-33.4 mV)), Fourier Transform Infrared (FT-IR) spectroscopy, X-Ray Diffraction (XRD) and Scanning electron microscopy (SEM). Upon soil application in conjunction with the commercial fertilizers, the treatment 50% N + 50% NB-N + 100% P + 100% K recorded significantly higher pod yield (25.38%) and haulm yield (34.42%) compared to recommended dose of fertilizers(23.70 and 27.30 g/plant respectively) in groundnut. Further, NB-N and NB-K fertilizers significantly improved plant height (17%), root nodules (41%), chlorophyll content (19%) and dry matter production (34%) when compared to the recommended dose of fertilizers application. Higher nitrogen, phosphorus and potassium contents (14.39%, 49.21% and 33.33% respectively) were recorded with the same treatment compared to recommended dose of fertilizers (2.20, 0.63 and 1.45% respectively). Overall, the study shows that nanobiochar-based fertilizers have the potential to enhance crop productivity and soil fertility and also demonstrated the soil application of nanobiochar based fertilizers for sustainable agricultural practices.

This study investigated the impact of three avocado cultivars on selected soil physicochemical properties in Central Ethiopia, to enhance the knowledge on the influence of avocado cultivars on soil physicochemical properties, and assist smallholders in cultivar selection in agroforestry. Trees planted in farmers´ fields 8 years earlier were revisited. Soil samples were collected from 0–20 cm and 20–40 cm depth at three radial distances from trees (1 m and 2 m from tree trunk, and at 5 m from the canopy edge as a control). Soil texture, bulk density, moisture content, pH, electrical conductivity, soil organic carbon, total nitrogen and available phosphorus were determined. Soil moisture content and electrical conductivity were overall higher and bulk density was lower (p < 0.05) under the canopies of the avocado trees than in the control and soil organic carbon, total nitrogen and available phosphorus tended to increase in spite of nutrient inputs to the control whilst the trees were unfertilized. Differences between the studied cultivars were small, but Hass tended to have the largest impact on soil nutrient levels, whilst Ettinger and Nabal tended to have a somewhat larger effect on the soil organic carbon concentration. Integrating these avocado cultivars on farms can improve soil fertility in the study area. However, for optimal agricultural soil health and sustainable avocado production, cultivar and site-specific soil management practices must be applied.