Soil Uptake Research Articles

OsPHR2-mediated recruitment of Pseudomonadaceae enhances rice phosphorus uptake

Plants can shape their root microbiome to promote growth and nutrient uptake. PHOSPHATE STARVATION RESPONSE 2 (OsPHR2) is a central regulator of phosphate signaling in rice, but whether OsPHR2 can shape the root microbiome to promote phosphorus uptake is unclear. Here, we investigate the role of OsPHR2 in recruiting microbiota for phosphorus uptake using high-throughput sequencing and metabolite analysis. OsPHR2-overexpressing (OsPHR2 OE) rice showed 69.8% greater shoot P uptake in natural soil compared with sterilized soil under high-phosphorus (HP) conditions, but there was only a 54.8% increase in the wild-type (WT). The abundance of the family Pseudomonadaceae was significantly enriched in OsPHR2 OE roots relative to those of WT rice. Compared with the WT, OsPHR2 OE rice had a relatively higher abundance of succinic acid and methylmalonic acid, which could stimulate the growth of Pseudomonas sp. (P6). After inoculation with P6, phosphorus uptake in WT and OsPHR2 OE rice was higher than that in uninoculated rice under low-phosphorus (LP) conditions. Taken together, our results suggest that OsPHR2 can increase phosphorus use in rice through root exudate-mediated recruitment of Pseudomonas. This finding reveals a cooperative contribution of the OsPHR2-modulated root microbiome, which is important for improving phosphorus use in agriculture.

OsCIPK2 mediated rice root microorganisms and metabolites to improve plant nitrogen uptake

Crop roots are colonized by large numbers of microorganisms, collectively known as the root-microbiome, which modulate plant growth, development and contribute to elemental nutrient uptake. In conditions of nitrogen limitation, the over-expressed Calcineurin B-like interacting protein kinase 2 (OsCIPK2) gene with root-specific promoter (RC) has been shown to enhance growth and nitrogen uptake in rice. Analysis of root-associated bacteria through high-throughput sequencing revealed that OsCIPK2 has a significant impact on the diversity of the root microbial community under low nitrogen stress. The quantification of nifH gene expression demonstrated a significant enhancement in nitrogen-fixing capabilities in the roots of RC transgenetic rice. Synthetic microbial communities (SynCom) consisting of six nitrogen-fixing bacterial strains were observed to be enriched in the roots of RC, leading to a substantial improvement in rice growth and nitrogen uptake in nitrogen-deficient soils. Forty and twenty-three metabolites exhibiting differential abundance were identified in the roots and rhizosphere soils of RC transgenic rice compared to wild-type (WT) rice. These findings suggest that OSCIPK2 plays a role in restructuring the microbial community in the roots through the regulation of metabolite synthesis and secretion. Further experiments involving the exogenous addition of citric acid revealed that an optimal concentration of this compound facilitated the growth of nitrogen-fixing bacteria and substantially augmented their population in the soil, highlighting the importance of citric acid in promoting nitrogen fixation under conditions of low nitrogen availability. These findings suggest that OsCIPK2 plays a role in enhancing nitrogen uptake by rice plants from the soil by influencing the assembly of root microbial communities, thereby offering valuable insights for enhancing nitrogen utilization in rice cultivation.

Reanalysis of NOAA H2 observations: implications for the H2 budget

Abstract. Hydrogen (H2) is a promising low-carbon alternative to fossil fuels for many applications. However, significant gaps in our understanding of the atmospheric H2 budget limit our ability to predict the impacts of greater H2 usage. Here we use NOAA H2 dry air mole fraction observations from air samples collected from ground-based and ship platforms during 2010–2019 to evaluate the representation of H2 in the NOAA GFDL-AM4.1 atmospheric chemistry-climate model. We find that the base model configuration captures the observed interhemispheric gradient well but underestimates the surface concentration of H2 by about 10 ppb. Additionally, the model fails to reproduce the 1–2 ppb yr−1 mean increase in surface H2 observed at background stations. We show that the cause is most likely an underestimation of current anthropogenic emissions, including potential leakages from H2-producing facilities. We also show that changes in soil moisture, soil temperature, and snow cover have most likely caused an increase in the magnitude of the soil sink, the most important removal mechanism for atmospheric H2, especially in the Northern Hemisphere. However, there remains uncertainty due to fundamental gaps in our understanding of H2 soil removal, such as the minimum moisture required for H2 soil uptake, for which we performed extensive sensitivity analyses. Finally, we show that the observed meridional gradient of the H2 mixing ratio and its seasonality can provide important constraints to test and refine parameterizations of the H2 soil sink.

Ridge-furrow planting patterns with film mulching improve water use efficiency by enhancing arbuscular mycorrhizal fungi in the rhizosphere and endophyte of summer maize

In a rainfed agroecosystem with limited water resources, the symbiotic interactions between crop-arbuscular mycorrhizal fungi may have a significant impact on field productivity and water absorption and utilization. However, the interaction between AMF characteristics of root endophyte and rhizosphere soil and water use patterns of summer maize has not been studied under ridge-furrow with film mulching planting patterns (RFPM) in dry farmland. Based on a field experiment, we aimed to reveal the effects of different RFPM planting patterns (i.e., ridge/furrow ratio of 40:70 cm (RF40:70), ridge/furrow ratio of 55:55 cm (RF55:55), and ridge/furrow ratio of 70:40 cm (RF70:40)) on the root water use patterns of summer maize, the distribution characteristics of AMF in root endophyte and rhizosphere soil, and their interaction relationship by using the water isotope (δD and δ18O) tracer technique, the high-throughput sequencing technology, MixSIAR model, and the structural equation models. As a result, compared to flat planting without mulching (FP), RF40:70, RF55:55, and RF70:40 significantly increased grain yield by 29.74%, 35.24%, and 45.53%, and water use efficiency by 23.13%, 35.99%, and 50.25%, across the two growing seasons, respectively (P < 0.05). The root characteristic parameters of summer maize decreased with the increase in soil depth, and were mainly distributed in the shallow layer (0–20 cm) and middle layer (20–60 cm). Compared with FP, the distribution ratio of root surface area density, root length density, and root dry weight density in shallow soil layer was significantly increased by 5.03%, 7.46%, and 9.70% averaging the different RFPM treatments, respectively (P<0.05). Besides, compared to FP, the AMF abundance and diversity in rhizosphere soil and root endogenous averaged RFPM treatments increased by 32.32% and 29.66% and 5.88% and 28.43% respectively, in which the abundance and diversity gradually increased with the increase of the ratio of ridge-furrow. The PLS-PM results found that the larger ridge-furrow ratio could significantly increase the yield and WUE of summer maize mainly by increasing the root surface area density, root length density, and the abundance and diversity of AMF in the root endophyte and rhizosphere soil, which increased the water use of the middle and deep layer soils. In summary, the large ridge-furrow ratio can significantly increase the yield and WUE of summer maize by extending the hyphal network of maize root symbiotic AMF, which increases the water uptake of middle and deep layer soil.

Soil phosphorus transformation and plant uptake driven by phosphate-solubilizing microorganisms.

Phosphorus (P) is an important nutrient for plants, and a lack of available P greatly limits plant growth and development. Phosphate-solubilizing microorganisms (PSMs) significantly enhance the ability of plants to absorb and utilize P, which is important for improving plant nutrient turnover and yield. This article summarizes and analyzes how PSMs promote the absorption and utilization of P nutrients by plants from four perspectives: the types and functions of PSMs, phosphate-solubilizing mechanisms, main functional genes, and the impact of complex inoculation of PSMs on plant P acquisition. This article reviews the physiological and molecular mechanisms of phosphorus solubilization and growth promotion by PSMs, with a focus on analyzing the impact of PSMs on soil microbial communities and its interaction with root exudates. In order to better understand the ability of PSMs and their role in soil P transformation and to provide prospects for research on PSMs promoting plant P absorption. PSMs mainly activate insoluble P through the secretion of organic acids, phosphatase production, and mycorrhizal symbiosis, mycorrhizal symbiosis indirectly activates P via carbon exchange. PSMs can secrete organic acids and produce phosphatase, which plays a crucial role in soil P cycling, and related genes are involved in regulating the P-solubilization ability. This article reviews the mechanisms by which microorganisms promote plant uptake of soil P, which is of great significance for a deeper understanding of PSM-mediated soil P cycling, plant P uptake and utilization, and for improving the efficiency of P utilization in agriculture.

Above- and belowground plant mercury dynamics in a salt marsh estuary in Massachusetts, USA

Abstract. Estuaries are a conduit of mercury (Hg) from watersheds to the coastal ocean, and salt marshes play an important role in coastal Hg cycling. Hg cycling in upland terrestrial ecosystems has been well studied, but processes in densely vegetated salt marsh ecosystems are poorly characterized. We investigated Hg dynamics in vegetation and soils in the Plum Island Sound estuary in Massachusetts, USA, and specifically assessed the role of marsh vegetation for Hg deposition and turnover. Monthly quantitative harvesting of aboveground biomass showed strong linear seasonal increases in Hg associated with plants, with a 4-fold increase in Hg concentration and an 8-fold increase in standing Hg mass from June (3.9 ± 0.2 µg kg−1 and 0.7 ± 0.4 µg m−2, respectively) to November (16.2 ± 2.0 µg kg−1 and 5.7 ± 2.1 µg m−2, respectively). Hg did not increase further in aboveground biomass after plant senescence, indicating physiological controls of vegetation Hg uptake in salt marsh plants. Hg concentrations in live roots and live rhizomes were 11 and 2 times higher than concentrations in live aboveground biomass, respectively. Furthermore, live belowground biomass Hg pools (Hg in roots and rhizomes, 108.1 ± 83.4 µg m−2) were more than 10 times larger than peak standing aboveground Hg pools (9.0 ± 3.3 µg m−2). A ternary mixing model of measured stable Hg isotopes suggests that Hg sources in marsh aboveground tissues originate from about equal contributions of root uptake (∼ 35 %), precipitation uptake (∼ 33 %), and atmospheric gaseous elemental mercury (GEM) uptake (∼ 32 %). These results suggest a more important role of Hg transport from belowground (i.e., roots) to aboveground tissues in salt marsh vegetation than upland vegetation, where GEM uptake is generally the dominant Hg source. Roots and soils showed similar isotopic signatures, suggesting that belowground tissue Hg mostly derived from soil uptake. Annual root turnover results in large internal Hg recycling between soils and plants, estimated at 58.6 µg m−2 yr−1. An initial mass balance of Hg indicates that the salt marsh presently serves as a small net Hg sink for environmental Hg of 5.2 µg m−2 yr−1.

Uptake and translocation of brominated flame retardants in tomato plants (Solanum lycopersicum L.): Results from a standard soil-based biotest

The uptake and translocation of four polybrominated diphenyl ethers (PBDEs) and four novel brominated flame retardants (NBFRs) in tomato plants (Solanum lycopersicum L.) were investigated via the RHIZOtest, a standard soil-based biotest, optimized for organic compounds. Tomato plants were exposed to soil samples spiked with 0 (i.e. control), 5.00 or 50.00 ng g−1dw of each compound. Compared of those of the control, exposure to increasing spiking concentrations resulted in average reductions of 13% and 26% (w/w) in tomato plant biomass. Higher concentrations of NBFRs were analyzed both in roots, ranging from 0.23 to 8.01 ng g−1dw for PBDEs and from 1.25 to 18.51 ng g−1dw for NBFRs, and in shoots, ranging from 0.09 to 5.58 ng g−1dw and from 0.47 to 7.78 ng g−1dw for PBDEs and NBFRs, respectively. This corresponded to an average soil uptake of 5% for PBDEs and 9% for NBFRs at the lower soil-spiking level, and 3% for PBDEs and 6% for NBFRs at the higher soil spiking level. Consequently, among both initial spiking levels, the soil-root concentration factor (RCF) values were lower on average for PBDEs (0.13 ± 0.05 g dw soil g−1dw roots) than for NBFRs (0.33 ± 0.16 g dw soil g−1dw roots). Conversely, nondifferent values of the root-shoot transfer factor (TF) were calculated for both PBDEs (0.54 ± 0.13 g dw roots g−1dw shoots) and NBFRs (0.49 ± 0.24 g dw roots g−1dw shoots). The differences and similarities reported in the RCF and TF between and within the two groups of compounds can be explained by their properties. The calculated RCF and TF values of the PBDEs exhibited a decreasing trend as the number of bromine atoms increased. Additionally, a robust negative linear correlation was observed between RCF values and the respective logKow values for the PBDEs, at both soil-spiking levels. The root uptake of NBFRs exhibited a negative correlation with their hydrophobicity; however, this was not observed in the context of root-to-shoot transfer. The presence of a second aromatic ring appears to be the key factor influencing the observed variations in NBFRs, with biphenyl NBFRs (BTBPE and DBDPE) characterized by lower uptake and reduced translocation potential than monophenyl PBEB and HBB. Understanding the transfer of these compounds to crops, especially near plastic recycling waste sites, is crucial for understanding the risks of their potential inclusion in the human food chain.

Green manure incorporation enhanced soil labile phosphorus and fruit tree growth.

The incorporation of green manures substantially enhances the conversion of external phosphorus (P) fertilizers and soil-reserved P into forms readily available to plants. The study aims to evaluate the influence of green manure additions on soil phosphorus dynamics and citrus growth, considering different green manure species and initial soil phosphorus levels. Additionally, the research seeks to elucidate the microbiological mechanisms underlying the observed effects. A citrus pot experiment was conducted under both P-surplus (1.50 g·P·kg-1) and P-deficient (0.17 g·P·kg-1) soils with incorporating legume (Leg), non-legume (Non-Leg) or no green manure residues (CK), and 18O-P labeled KH2PO4 (0.5 g, containing 80‰ δ18Op) was additionally introduced to trace the turnover characteristics of chemical P fertilizer mediated by soil microorganisms. In P-surplus soil, compared with the CK treatment, the Leg treatment significantly increased soil H2O-Pi (13.6%), NaHCO3-Po (8.9%), NaOH-Pi (9.5%) and NaOH-Po (30.0%) content. It also promoted rapid turnover of P sources into H2O-Pi and NaHCO3-Pi pools by enhancing the phoC (576.6%) gene abundance. In contrast, the Non-Leg treatment significantly augmented soil H2O-Pi (9.2%) and NaHCO3-Po (8.5%) content, facilitating the turnover of P sources into NaHCO3-Pi pools. Under P-deficient soil conditions, compared with the CK treatment, the Leg treatment notably raised soil H2O-Pi (150.0%), NaHCO3-Pi (66.3%), NaHCO3-Po (34.8%) and NaOH-Pi (59.0%) content, contributing to the transfer of P sources into NaHCO3-Pi and NaOH-Pi pools. This effect was achieved through elevated ALP (33.8%) and ACP (12.9%) activities and increased pqqC (48.1%), phoC (42.9%), phoD (21.7%), and bpp (27.4%) gene abundances. The Non-Leg treatment, on the other hand, led to significant increases in soil NaHCO3-Pi (299.0%) and NaHCO3-Po (132.6%) content, thereby facilitating the turnover of P sources into NaHCO3-Pi and NaOH-Pi pools, except for the phoC gene abundance. Both Leg and Non-Leg treatments significantly improved citrus growth (7.3-20.0%) and P uptake (15.4-42.1%) in P-deficient soil but yielded no substantial effects in P-surplus soil. In summary, introducing green manure crops, particularly legume green manure, emerges as a valuable approach to enhance soil P availability and foster fruit tree growth in orchard production.

Nitric oxide synthase expression in Pseudomonas koreensis MME3 improves plant growth promotion traits

The development of novel biotechnologies that promote a better use of N to optimize crop yield is a central goal for sustainable agriculture. Phytostimulation, biofertilization, and bioprotection through the use of bio-inputs are promising technologies for this purpose. In this study, the plant growth–promoting rhizobacteria Pseudomonas koreensis MME3 was genetically modified to express a nitric oxide synthase of Synechococcus SyNOS, an atypical enzyme with a globin domain that converts nitric oxide to nitrate. A cassette for constitutive expression of synos was introduced as a single insertion into the genome of P. koreensis MME3 using a miniTn7 system. The resulting recombinant strain MME3:SyNOS showed improved growth, motility, and biofilm formation. The impact of MME3:SyNOS inoculation on Brachypodium distachyon growth and N uptake and use efficiencies under different N availability situations was analyzed, in comparison to the control strain MME3:c. After 35 days of inoculation, plants treated with MME3:SyNOS had a higher root dry weight, both under semi-hydroponic and greenhouse conditions. At harvest, both MME3:SyNOS and MME3:c increased N uptake and use efficiency of plants grown under low N soil. Our results indicate that synos expression is a valid strategy to boost the phytostimulatory capacity of plant-associated bacteria and improve the adaptability of plants to N deficiency.Key points• synos expression improves P. koreensis MME3 traits important for rhizospheric colonization• B. distachyon inoculated with MME3:SyNOS shows improved root growth• MME3 inoculation improves plant N uptake and use efficiencies in N-deficient soil

High-resolution spatial patterns and drivers of terrestrial ecosystem carbon dioxide, methane, and nitrous oxide fluxes in the tundra

Abstract. Arctic terrestrial greenhouse gas (GHG) fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) play an important role in the global GHG budget. However, these GHG fluxes are rarely studied simultaneously, and our understanding of the conditions controlling them across spatial gradients is limited. Here, we explore the magnitudes and drivers of GHG fluxes across fine-scale terrestrial gradients during the peak growing season (July) in sub-Arctic Finland. We measured chamber-derived GHG fluxes and soil temperature, soil moisture, soil organic carbon and nitrogen stocks, soil pH, soil carbon-to-nitrogen (C/N) ratio, soil dissolved organic carbon content, vascular plant biomass, and vegetation type from 101 plots scattered across a heterogeneous tundra landscape (5 km2). We used these field data together with high-resolution remote sensing data to develop machine learning models for predicting (i.e., upscaling) daytime GHG fluxes across the landscape at 2 m resolution. Our results show that this region was on average a daytime net GHG sink during the growing season. Although our results suggest that this sink was driven by CO2 uptake, it also revealed small but widespread CH4 uptake in upland vegetation types, almost surpassing the high wetland CH4 emissions at the landscape scale. Average N2O fluxes were negligible. CO2 fluxes were controlled primarily by annual average soil temperature and biomass (both increase net sink) and vegetation type, CH4 fluxes by soil moisture (increases net emissions) and vegetation type, and N2O fluxes by soil C/N (lower C/N increases net source). These results demonstrate the potential of high spatial resolution modeling of GHG fluxes in the Arctic. They also reveal the dominant role of CO2 fluxes across the tundra landscape but suggest that CH4 uptake in dry upland soils might play a significant role in the regional GHG budget.

Enhancing maize yield and zinc uptake through foliar application of zinc sulfate in calcareous soil of Peshawar, Pakistan

Zinc deficiency in maize plants is a common problem, particularly in calcareous soils with pH above 7. This study aimed to investigate the impact of zinc sulfate (ZnSO4) applied in different forms (foliar and soil application) and concentrations on maize yield, zinc uptake, and nutrient use efficiency (NUE) in calcareous soil. The results demonstrated that zinc application significantly increased maize yield, zinc uptake, NUE, and the uptake of Nitrogen, Phosphorus, and Potassium. Foliar application of ZnSO4 was more effective than soil application in enhancing zinc uptake, with the highest uptake observed in plants treated with 1.5% ZnSO4 foliar spray. Additionally, zinc application increased zinc content in grains and surface soil, with the highest zinc content in grains found in plants treated with 1.5% ZnSO4 foliar spray and the highest zinc content in surface soil observed in plants treated with 10 kg ha-1 ZnSO4 soil application. These findings suggested that foliar application of ZnSO4 is an effective strategy for improving zinc uptake and grain zinc content in maize plants grown in calcareous soils.

Can knowledge transfer speed up climate change mitigation in agriculture? A randomized experimental evaluation of participatory workshops

Livestock management is recognized as the largest source of greenhouse gas (GHG) and ammonia emissions in agriculture. Despite the many available mitigation options, they are often not taken up by farmers even when they are economically beneficial for farms. Effective knowledge transfer is among the critical policy instruments to increase the adoption of new mitigating measures. Recently, there has been a shift in agricultural knowledge transfer from a linear, top-down learning model towards more participatory approaches that emphasise peer-to-peer learning. However, effectiveness of the new model has rarely been evaluated. Our study assessed the impact of participatory workshops on farmers’ uptake of climate-friendly soil and manure management practices that can help reduce GHG and ammonia emissions. A group of 438 cattle-rearing farmers from two Slovenian regions participated in a randomised experimental evaluation, of which 225 received training and 213 participated in a control group. After attending the participatory workshops, farmers had statistically significant and on average 25% higher knowledge levels of climate change and mitigation measures. Furthermore, the intention to perform mitigation measures was significantly higher, on average by 19%, compared to the control group. The workshops also had a significant positive effect on attitudes towards mitigation measures, climate change beliefs, social norms, psychological distance and perceived behavioural control. However, previous personal experience (habits) had a stronger effect on intentions than participation in workshops. Based on the results we provide recommendations on how to best use various policy tools to increase the adoption of mitigation measures.

Applications of Biofertilizers and Phosphorus Influence Nutrient Uptake and Nutrient Use Efficiency in Chickpea (Cicer Arietinum L.)

ABSTRACT The objective of the study was to investigate the effects of sole applications of biofertilizers and phosphorus as well as their integrated use in lentil. The field experiment was conducted to study the effect of phosphorus (0, 15, 20 and 25 kg P2O5 ha−1) and biofertilizer inoculation treatments [uninoculated control, Mesorhizobium, Mesorhizobium + RB-1 (Pseudomonas argentinensis) and Mesorhizobium + RB-2 (Bacillus aryabhattai)] on nutrient uptake, nutrient use efficiency and residual nutrient status of soil after the harvest of chickpea. Mesorhizobium + RB-1 recorded the highest uptake of nitrogen (73.7, 59.0 and 132.7 kg ha−1 in grain, straw and total, respectively), phosphorus (8.29, 11.34 and 19.63 kg ha−1 in grain, straw and total) and potassium (23.48, 43.36 and 66.84 kg ha−1 in grain, straw and total) as well as partial factor productivity (113.1 kg grain kg−1 P2O5). Application of 25 kg P2O5 ha−1 recorded the highest phosphorus concentration (0.39% in grain and 0.26% in straw), phosphorus uptake (8.35, 12.32 and 20.67 kg ha−1 in grain, straw and total, respectively) and phosphorus status in soil after crop harvest (18.7 and 16.7 kg P ha−1 in 0–15 and 15–30 cm soil layers, respectively). Partial factor productivity was recorded the highest with the application of 15 kg P2O5 ha−1 (132.2 kg grain kg−1 P2O5). It can be concluded that dual applications of biofertilizers [Mesorhizobium + RB-1 (Pseudomonas argentinensis)] and 25 kg P2O5 ha−1 improve nutrient uptake by the crop and build up of nutrients in the soil after the harvest of the crop.

Effect of phosphorus and sulphur levels on soil nutreint status in sunflower(Helianthus annuus L.)

A field experiment was conducted to study the response of Sunflower to Phosphorus and Sulphur levels at Agricultural College Farm, Bapatla, during rabi, 2018. The experiment was laid out in randomized block design with factorial concept replicated thrice with ten treatments. The Phosphorus and Sulphur status in soil increased with increasing levels of phosphorus from 0 to 135 kg P2O5 ha-1 but significant upto 90 kg P2O5 ha-1 whereas, the highest level of sulphur i.e., 30 kg S ha-1 recorded significantly higher uptake of Phosphorus and Sulphur soil at all growth stages of Sunflower.

Spatial controls of methane uptake in upland soils across climatic and geological regions in Greenland

In the Arctic, the spatiotemporal variation of net methane uptake in upland soils depends on unresolved interactive controls between edaphic and microbial factors not yet included in current models, underpinning the uncertainty of upscaling the Arctic methane budget. Here we show that upland soils in Greenland are consistent methane sinks (−1.83 ± 0.19 nmol methane g−1 dw d−1) across a N-S (64–83 °N) pedoclimatic transect. We demonstrate that methane oxidizers abundance, soil pH, and available soil copper are important controls on the spatial variation in methane oxidation. We revised a soil biogeochemical model with a high-resolution land classification and meteorological data for Greenland and tested it against our methane uptake measurements. The model simulated well the magnitudes of observed methane uptake but not the spatial variation across all sites. This work provides novel insights into the controls of methane uptake, which are critical for the accuracy of methane budgets.

Hyperaccumulator Solanum nigrum L. Intercropping Reduced Rice Cadmium Uptake under a High-Bed and Low-Ditch Planting System

Anthropogenic activities have raised cadmium (Cd) concentrations in agricultural soil, emerging as a primary catalyst for the decline in crop yield. Intercropping of two or several plants is one technique among many Cd phytoremediation techniques that has gained enormous attention recently. However, the impact of cultivation modes on Cd movement in rice plants when intercropped with heavy metal (HM) hyperaccumulator plants remains unclear. Thus, this study was designed to explore the effects of cultivation modes and the intercropping of rice with Solanum nigrum L. on rice growth and Cd uptake in Cd-contaminated soil. The experimental design encompassed five treatments: dry cultivation of monocultured rice, monocultured Solanum nigrum L., and intercropped rice–Solanum nigrum L.; flood cultivation of monocultured rice; and intercropped rice–Solanum nigrum L. in a high-bed and low-ditch planting system. The results revealed a significant increase in rice growth when intercropped with Solanum nigrum L., with a notable increase of 18.32 g∙plant−1 observed in rice biomass in dry cultivation under the intercropping system. In contrast, a more modest increase of 3.67 g∙plant−1 was observed in the high-bed and low-ditch intercropped rice–Solanum nigrum L. mode. The soil total Cd was higher in dry cultivation of monocultured rice and Solanum nigrum L. compared to intercropped rice/Solanum nigrum L.-cultivated soil, with lower values recorded for intercropped rice/Solanum nigrum L. under the high-bed and low-ditch planting system. In contrast, no significant effect was noted on soil exchangeable Cd content based on the planting pattern and cultivation mode. Intercropping with Solanum nigrum L. demonstrated a significant reduction of Cd content in various rice tissues, particularly in roots at the maturity stage, while Cd content was reduced across all rice tissues under the high-bed and low-ditch planting system. The Cd content in the stem, leaves, and bran of monocropped rice was higher compared to intercropped rice. This study suggests that the rice–Solanum nigrum L. intercropping system effectively reduces rice Cd uptake, particularly under the high-bed and low-ditch planting system.

Evaluating the Effects of Controlled Drainage on Nitrogen Uptake, Utilization, Leaching, and Loss in Farmland Soil

Controlling drainage during the growth stage is one of the means to provide suitable water and fertilizer conditions for crops, alleviate environmental pollution, and increase crop yield. Therefore, in this study, we studied three drainage treatments: free drainage (FD) and growth-stage subsurface controlled drainage (CD) at depths of 40 cm (CWT1) and 70 cm (CWT2). We used the HYDRUS-2D model to simulate the dynamic changes of NO3-N in the 0–100 cm soil layer as well as NO3-N uptake by crops, leaching after irrigation and fertilization, and loss through subsurface pipes in 2020 (model calibration period) and 2021 (model validation period). The degree of agreement between the simulated and measured values was high, indicating a high simulation accuracy. CD increased the soil NO3-N content and crop NO3-N uptake, and decreased NO3-N leaching and loss. We observed significant differences in the soil NO3-N content after irrigation at the budding stage of oilseed sunflower between CD and FD, with the largest difference seen for the 0–40 cm soil layer. CD increased crop yield, and the average oilseed sunflower yield of the CWT1 and CWT2 treatments increased by 4.52% and 3.04% relative to the FD treatment (p &lt; 0.05). CD also enhanced nitrogen use efficiency. In moderately salinized soil, CD at 40 cm (CWT1) reduced the nutrient difference in vertical and horizontal directions while retaining water and fertilizer. CWT1 stabilized the groundwater depth, reduced the hydraulic gradient of groundwater runoff, and decreased the drainage flow rate. The NO3-N leaching and loss dropped, which promoted crop nitrogen uptake and utilization, improved nitrogen use efficiency, reduced nitrogen loss, and had a positive effect on protecting the soil and water environment. The results demonstrate that CD is a suitable drainage method for the experimental area.

Dosing of leonardite/struvite compounds as phosphorus fertilizers increased biomass and nutrient uptake in a calcareous soil

Non-renewable sources of phosphorus (P) are running out, so it is necessary to recover P from secondary recyclable materials. This study aims to recover P from domestic sewage sludge as Leo/MAP (Leonardite/magnesium ammonium phosphate) composites and use them as phosphorus fertilizer. The characteristics of Leo/MAP composites, solubility, and kinetic of P-release from them were evaluated. The properties of composites were determined by using XRF (X-ray fluorescence) spectroscopy, as well as structural analysis by using SEM.(Scanning electron microscopy) In addition, the effect of Leo/MAP composites was investigated on the responses of the Moldavian Balm (Dracocephalum Moldavica) under greenhouse conditions compared with traditional P-fertilization (TSP (Triple-superphosphates)) – and unfertilized check in terms of morphological characteristics, and concentration of nutrients (P, Mg, and N) in a calcareous soil. Microscopic images of manufactured composites showed they are free of PO (Parasitic ova) and the presence of FC (Fecal coliforms) in the samples was negative. The results showed that PRecovery (%) from domestic sewage sludge increased by application of leonardite, and the solubility and the dissolution rate of P, N, and Mg from composites in HCl (0.5 M) and citric acid (20 g/L) are more than that in water. The kinetic of P release from composites was better fitted the Korsmeyer-peppas equation (R2 = 0.96–0.99) in water, and to the first-order equation (R2 = 0.87–0.98) in citric acid and HCl solutions. The n value of the Korsmeyer-peppas model showed that the mechanism of P release from the composites is based on the Fickian-diffusion (n < 0.45). The highest positive impact of P-fertilization on morphological characteristics, and concentration of nutrients in Moldavian Balm plants were as follows: L75/MAP > L50/MAP > L25/MAP > L0/MAP. Therefore Leo/MAP composites, especially with a high amount of leonardite, are applicable to increase the growth of Moldavian Balm in a calcareous soil that is one of the important medical plants with its unique characteristic for human's health.

Conservation tillage and fertiliser management strategies impact on basmati rice (Oryza sativa L): crop performance, crop water productivity, nutrient uptake and fertility status of the soil under rice-wheat cropping system.

The sustainability of paddy production systems in South Asia has recently been affected by a decline in soil health and excessive water usage. As a response to the global energy crisis, escalating costs of synthetic fertilisers, and growing environmental concerns, the utilization of organic plant-nutrient sources has gained considerable attention. Emerging adaptation technologies, including conservation tillage and innovative approaches to fertilizer management, present practical choices that can significantly contribute to the long-term preservation of soil fertility. The two year-long field experiment was completed in sandy loam soil during rainy (Kharif) seasons in 2019 and 2020 at the crop research centre farm of Sardar Vallabhbhai Patel University of Agricultural & Technology, Meerut, Uttar Pradesh to analyze the impacts of different tillage establishment of the crop and its methodologies as well as integrated nutritional management approaches on rice growth, yield, productivity of water, nutrient uptake, and fertility status of soil under a rice-wheat rotation system. The experiment was set up in a factorial randomized block design and replicated three times in a semi-arid subtropical environment. The conventionally transplanted rice puddled (CT-TPR) grew substantially better taller plants, and higher dry matter buildup leads to increased yields than transplanted rice under raised wide bed (WBed-TPR). WBed-TPR plots had more tillers, LAI, CGR, RGR, and yield characteristics of the rice in two year study. CT-TPR increased grain yield by 4.39 and 4.03% over WBed-TPR in 2019 and 2020, while WBed-TPR produced the highest water productivity (0.44 kg m-3) than CT-TPR, respectively. The 100% RDF+ ZnSO4 25 kg ha-1 + FYM (5 t ha-1) + PSB (5 kg ha-1) + Azotobacter 20 kg ha-1 (N6) treatment outperformed the other fertiliser management practices in terms of crop growth parameters, yields of grain (4,903 and 5,018 kgha-1), nutrient uptake and NPK availability, organic soil carbon. Among the fertilizer management practices, with the direct applications of the recommended dose of fertilizer (RDF), farm yard manure (FYM), phosphate solubilizing bacteria (PSB), Azatobactor and zinc worked synergistically and increased grain yields by 53.4, 51.3, 47.9 and 46.2% over their respective control treatment. To enhance rice productivity and promote soil health, the study suggests that adopting conservation tillage-based establishment practices and implementing effective fertilizer management techniques could serve as practical alternatives. It is concluded that the rice yield was improved by the inclusive use of inorganic fertiliser and organic manure (FYM). Additionally, the study observed that the combination of conventional puddled transplanted rice (CT-TPR) and N6 nitrogen application resulted in enhanced rice crop productivity and improved soil health.

Improving Wheat Growth and Nutrient Uptake in Calcareous Soil: a Novel Approach with Carbon Dots as a Slow-Release Zinc Fertilizer

Improving Wheat Growth and Nutrient Uptake in Calcareous Soil: a Novel Approach with Carbon Dots as a Slow-Release Zinc Fertilizer