Phosphorus Availability Research Articles

Afforestation Enhances Potential Bacterial Metabolic Function without Concurrent Soil Carbon: A Case Study of Mu Us Sandy Land

Elucidating the impact of afforestation on soil bacterial community composition and its potential function in afforestation is imperative for comprehending the biochemical processes of land use change. This study employed high-throughput genomic sequencing to determine the bacterial phylogenetic assembly and assess functional groups following afforestation encompassing shrubland and woodland. Compared with non-afforested cropland, the soil organic carbon (SOC) remained unchanged, but significant alterations were observed in the bacterial composition and potential functions under afforestation. Afforestation enhanced bacterial diversity and even shifted the bacteria from the r- to K-strategy, as indicated by higher oligotroph/copiotroph ratios. Soil properties explained 66.45% and 68.9% of the total variation in bacterial community composition at the phylum level and the functional group. A 60.44% decrease in soil water content, a 3.82% increase in pH, a 7.5% increase in bulk density, and a 66.8% decrease in available phosphorus (AP) were the main soil factors affecting both bacterial community composition and functional traits in afforestation. In particular, lower available nutrients, AP, and nitrate nitrogen in afforestation drive the bacterial life history strategies. We conclude that changes in bacterial metabolic functions due to reduced soil available nutrients from dryland afforestation might be the main driver for microbial-inhibited SOC accumulation. These results could provide strong microbiological evidence to help further evaluate the importance of dryland afforestation.

Response of tropical forest productivity to seasonal drought mediated by potassium and phosphorus availability

Tropical forest productivity is increasingly reported to be nutrient limited, which may affect its response to seasonal droughts. Yet experimental evidence on nutrient limitation from Afrotropical forests remains rare. We conducted an ecosystem-scale, full factorial nitrogen (N)–phosphorus (P)–potassium (K) addition experiment in a moist forest in Uganda to investigate nutrient controls on fine litter production and foliar chemistry. The eight factorial treatments were replicated four times in 32 plots of 40 × 40 m each. During the three-year nutrient additions, we found K and P limitations on leaf litter production, exhibiting strong links to ecosystem responses to seasonal drought. Specifically, leaf litterfall consistently decreased in dry seasons with K additions, whereas P additions caused a reduction only during prolonged drought in the first year. Leaf litterfall was not significantly affected by N additions. Furthermore, K additions delayed the timing of leaf litterfall peak, underscoring the crucial role of K in regulating stomatal aperture and signalling during water-stress conditions and suggesting a prolonged leaf lifespan. Foliar N increased with N and P additions whereas K was the most resorbed nutrient. We conclude that the productivity and resilience of tropical forests, particularly under drier conditions, may depend on terrestrial K and P availability.

Increase in potato yield by the combined application of biochar and organic fertilizer: key role of rhizosphere microbial diversity.

The large-scale planting of potatoes leads to soil degradation, thus limiting the potato yield. An effective method of improving soil quality involves the combined application of biochar and organic fertilizer. However, the proportion of biochar and organic fertilizer at which potato yield can be improved, as well as the improvement mechanism, remain unclear. A combined application experiment involving biochar (B) and organic fertilizer (O) with four concentration gradients was conducted using the equal carbon ratio method. On this basis, rhizosphere soil fertility, bacterial community composition, and bacterial diversity in potato crops, as well as the potato yield difference under different combined application ratios, were investigated. Then, the direct and indirect effects of these factors on potato yield were analyzed. The results suggest that soil fertility was improved by the combined application of biochar and organic fertilizer, with the best effect being achieved at a ratio of B:O=1:2. The dominant bacterial communities in the potato rhizosphere included Proteobacteria, Actinobacteria, Gemmatimonadetes, Chloroflexi, and Bacteroidetes. When compared to the control, the relative abundance and diversity index of soil bacteria were significantly improved by the treatment at B:O=1:2, which exerted a stronger effect on improving the relative abundance of beneficial bacteria. Soil available phosphorus (AP), soil pH (SpH), and soil organic carbon (SOC) explained 47.52% of the variation in bacterial composition. Among them, the main factor was the content of soil available nutrients, while SpH generated the weakest effect. The bacterial diversity index showed a significant positive correlation with soil AP, SOC, available potassium (AK), total nitrogen (TN), and C/N ratio, and a significant negative correlation with SpH. Bacterial diversity directly affected the potato yield, while soil fertility indirectly affected potato yield by influencing the soil bacterial diversity. The combined application of biochar and organic fertilizer elevates potato yield mainly by improving the diversity of bacterial communities in potato rhizosphere soil, especially the combined application of biochar and organic fertilizer at a 1:2 ratio (biochar 0.66 t ha-1+organic fertilizer 4.46 t ha-1), which made the largest contribution to increasing potato yield.

Green Manure for Sustainable Crop Production: A Review

Green manuring is an economical and eco-friendly scientific approach to achieve more resilient and sustainable food production for agricultural systems. Incorporation of green manure improves soil condition by increasing soil physical, chemical and biological properties such as organic matter, availability of nitrogen, phosphorus and potassium and also improves soil structure by preventing soil erosion, increasing water holding capacity etc. Green manure acts as a natural fertilizer, releasing nutrients into the soil as it decomposes and increases the nutrient content in the soil and shows positive effect on plant growth and development. Addition of green manure crops contribute to greater fixation of atmospheric nitrogen, and when decomposed, makes the nitrogen availability in the soil, reducing the need for synthetic nitrogen fertilizers in crops. Furthermore, it has a significant impact on several plant growth and yield parameters, resulting in increased agricultural productivity and ecosystem health.

Effect of Phosphate-Deficiency Stress on the Biological Characteristics and Transcriptomics of Panax ginseng

The low availability of phosphorus has become a common problem worldwide. Phosphorus is essential for phenotypic morphology and ginsenoside synthesis. However, the effects of Pi stress on ginseng phenotype and ginsenoside synthesis remain unclear. Phenotypic analyses and transcriptomics revealed the phenotypic construction and regulation of differential genes involved in the physiological metabolism of ginseng under low-Pi stress. Root length and stem length were found to be significantly inhibited by phosphate-deficiency stress in the half-phosphate (HP) and no-phosphate (NP) treatment groups; however, the number of fibrous roots, which are regulated by phytohormones, was found to increase. In ginseng leaves, the indexes of physiological stress, superoxide anion (221.19 nmol/g) and malonaldehyde (MDA) (0.05 μmol/min/g), reached the maximum level. Moreover, chlorophyll fluorescence images and chlorophyll content further confirmed the inhibition of ginseng photosynthesis under low-Pi stress. A total of 579 and 210 differentially expressed genes (DEGs) were shared between NP and total phosphate (TP) and HP and TP, respectively, and only 64 common DEGs were found based on the two comparisons. These DEGs were mainly related to the synthesis of phosphate transporters (PHTs), phytohormones, and ginsenosides. According to KEGG analyses, four DEGs (Pg_s 0368.2, Pg_s3418.1, Pg_s5392.5 and Pg_s3342.1) affected acetyl-CoA production by regulating glycometabolism and tricarboxylic acid cycle (TCA). In addition, related genes, including those encoding 13 PHTs, 15 phytohormones, and 20 ginsenoside synthetases, were screened in ginseng roots under Pi-deficiency stress. These results indicate that changes in the ginseng phenotype and transcriptional regulation of DEGs are involved in the Pi-deficiency stress environment of ginseng, thereby providing new information regarding the development of ginseng for low-Pi tolerance.

Anurans and their contribution to agriculture: a review

Anurans and their contribution to agriculture: a review

Ca(H2PO4)2 and MgSO4 activated nitrogen-related bacteria and genes in thermophilic stage of compost

This study was conducted to investigate the effects of Ca(H2PO4)2 and MgSO4 on the bacterial community and nitrogen metabolism genes in the aerobic composting of pig manure. The experimental treatments were set up as control (C), 1% Ca(H2PO4)2 + 2% MgSO4 (CaPM1), and 1.5% Ca(H2PO4)2 + 3% MgSO4 (CaPM2), which were used at the end of composting for potting trials. The results showed that Ca(H2PO4)2 and MgSO4 played an excellent role in retaining nitrogen and increasing the alkali-hydrolyzed nitrogen (AN), available phosphorus (AP), and available potassium (AK) contents of the composts. Adding Ca(H2PO4)2 and MgSO4 changed the microbial community structure of the compost. The microorganisms associated with nitrogen retention were activated. The complexity of the microbial network was enhanced. Genetic prediction analysis showed that the addition of Ca(H2PO4)2 and MgSO4 reduced the accumulation of nitroso-nitrogen and the process of denitrification. At the same time, despite the reduction of genes related to nitrogen fixation, the conversion of ammonia to nitrogenous organic compounds was promoted and the stability of nitrogen was increased. Mantel test analysis showed that Ca(H2PO4)2 and MgSO4 can affect nitrogen transformation-related bacteria and thus indirectly affect nitrogen metabolism genes by influencing the temperature, pH, and organic matter (OM) of the compost and also directly affected nitrogen metabolism genes through PO43− and Mg2+. The pot experiment showed that composting with 1.5% Ca(H2PO4)2 + 3% MgSO4 produced the compost product that improved the growth yield and nutrient content of cilantro and increased the fertility of the soil. In conclusion, Ca(H2PO4)2 and MgSO4 reduces the loss of nitrogen from compost, activates nitrogen-related bacteria and genes in the thermophilic phase of composting, and improves the fertilizer efficiency of compost products.Key points• Ca(H2PO4)2 and MgSO4 reduced the nitrogen loss and improved the compost effect• Activated nitrogen-related bacteria and altered nitrogen metabolism genes• Improved the yield and quality of cilantro and fertility of soil

Diversity and Composition of Soil Acidobacterial Communities in Different Temperate Forest Types of Northeast China.

To gain an in-depth understanding of the diversity and composition of soil Acidobacteria in five different forest types in typical temperate forest ecosystems and to explore their relationship with soil nutrients. The diversity of soil Acidobacteria was determined by high-throughput sequencing technology. Soil Acidobacteria's alpha-diversity index and soil nutrient content differed significantly among different forest types. β-diversity and the composition of soil Acidobacteria also varied across forest types. Acidobacterial genera, such as Acidobacteria_Gp1, Acidobacteria_Gp4, and Acidobacteria_Gp17, play key roles in different forests. The RDA analyses pointed out that the soil pH, available nitrogen (AN), carbon to nitrogen (C/N) ratio, available phosphorus (AP), total carbon (TC), and total phosphorus (TP) were significant factors affecting soil Acidobacteria in different forest types. In this study, the diversity and composition of soil Acidobacteria under different forest types in a temperate forest ecosystem were analyzed, revealing the complex relationship between them and soil physicochemical properties. These findings not only enhance our understanding of soil microbial ecology but also provide important guidance for ecological conservation and restoration strategies for temperate forest ecosystems.

Effect of Exogenous Organic Matter on Phosphorus Forms in Middle-High Fertility Cinnamon Soil.

To slow down the chemical fixation of phosphate fertilizer, reduce the risk of active phosphorus leaching, stimulate the inherent phosphorus resource activity of soil, and improve phosphorus supply capacity. This study utilized a combination of field experiments and indoor chemical analysis. Six types of exogenous organic matter (fulvic acid, biochar, compound microbial fertilizer, high-energy microbial inoculum, pig manure-vermicompost, cow manure-vermicompost) were added based on conventional fertilization. The experiment was conducted under the wheat-maize rotation system in the Huang-Huai-Hai region. Compared with control (CK) without exogenous organic matter (EOM), all the other treatments with EOM had an enhancing effect on the available phosphorus of the cultivated soil. During the maize harvest, the combined application of biochar, pig manure-vermicompost and cow manure-vermicompost treatment significantly increased the content of available phosphorus in 0-20 cm soil by 45.87-56.59% compared with CK. The combined application of fulvic acid, biochar, pig manure-vermicompost and cow manure-vermicompost treatment significantly increased the content of Ca2-P in 0-20 cm soil by 34.04-65.14%. The content of Ca10-P in each treatment with EOM exhibited a lower level compared to CK. EOM could slow down the fixation of phosphorus to some degree. Correlation analysis revealed significant associations between Ca2-P, Ca8-P, Al-P, Fe-P, neutral phosphatase activity, acid phosphatase activity, and the available phosphorus content in the soil. The combined application of fulvic acid, biochar, and cow manure-vermicompost could enhance the activity of neutral and acid phosphatase in topsoil to a certain extent, thereby facilitating the conversion of phosphorus into highly available Ca2-P. EOM could enhance the soil phosphorus availability and decelerate the conversion of soil phosphorus into O-P and Ca10-P forms with low availability. Among all treatments, biochar exhibited the most pronounced efficiency in mitigating phosphorus leaching downward. All the EOMs had the potential to enhance the conversion of phosphorus into soluble phosphorus (Ca2-P), thereby mitigating the chemical fixation of soil phosphorus and ameliorating non-point source pollution caused by phosphorus. EOM enhanced the activity of neutral and acid phosphatase, which was beneficial to the conversion of organic phosphorus to inorganic phosphorus and increasing the content of available phosphorus. All EOMs had good effects on the retention of soil effective phosphorus, among which biochar had the best effect on retaining effective phosphorus in the tillage layer and blocking phosphorus leaching downward.

Effects of Biochar on Soil Inorganic Phosphorus Components, Available Phosphorus, Enzyme Activities Related to Phosphorus Cycle, Microbial Functional Genes, and Seedling Growth of Populus euphratica under Different Water Conditions

Cow dung is a kind of high quality and renewable biological resource. Biochar made from cow dung can be used as a soil amendment to improve soil nutrient status. The relationship between soil water and phosphorus is very close, and the water status determines the form, content, and availability of phosphorus. In order to investigate the effects of biochar on soil inorganic phosphorus components, available phosphorus, enzyme activities related to the phosphorus cycle, microbial functional genes, and seedling growth under different soil water conditions were investigated. Field experiments were carried out by setting different water conditions (30%, 60%, and 100%) and biochar addition (0 t hm−2, 2.63 t hm−2, 5.26 t hm−2, and 7.89 t hm−2). The results showed that applying biochar significantly increased the soil’s accessible phosphorus content and the phosphorus content in both the aboveground and subsurface parts of P. euphratica seedlings. This is mainly attributable to biochar’s direct and indirect effects on soil properties. Because biochar is naturally alkaline, it raises soil pH and reduces acid phosphatase activity in the soil around P. euphratica seedlings in the rhizosphere. Perhaps the alkaline phosphatase level first showed an upward trend due to the combined impacts of water and biochar, and then it started to decline when the biochar addition was increased. Soil phosphorus functional genes phoC, phoD, gcd, and pqqc had an increase in copy number with biochar addition but not without treatment. Indirectly, the biochar treatment increased the soil’s phosphorus availability by increasing the population of the phosphate-solubilizing bacteria Fusarium and Sphingomonas. Soil phosphorus availability is positively affected by biochar under various water conditions. This impact is due to chemical and microbiological mechanisms.

Advancements in Biochar Modification for Enhanced Phosphorus Utilization in Agriculture

The role of modified biochar in enhancing phosphorus (P) availability is gaining attention as an environmentally friendly approach to address soil P deficiency, a global agricultural challenge. Traditional phosphatic fertilizers, while essential for crop yield, are costly and environmentally detrimental owing to P fixation and leaching. Modified biochar presents a promising alternative with improved properties such as increased porosity, surface area, and cation exchange capacity. This review delves into the variability of biochar properties based on source and production methods and how these can be optimized for effective P adsorption. By adjusting properties such as pH levels and functional groups to align with the phosphate’s zero point of charge, we enhance biochar’s ability to adsorb and retain P, thereby increasing its bioavailability to plants. The integration of nanotechnology and advanced characterization techniques aids in understanding the structural nuances of biochar and its interactions with phosphorus. This approach offers multiple benefits: it enables farmers to use phosphorus more efficiently, reducing the need for traditional fertilizers and thereby minimizing environmental impacts, such as greenhouse gas emissions and P leaching. This review also identifies existing research gaps and future opportunities for further biochar modifications. These findings emphasize the significant potential of modified biochar in sustainable agriculture.

Soil Phosphorus Distribution across Diverse Land Use Systems: A Comprehensive Review

Phosphorus (P) is a crucial nutrient necessary for healthy plant growth. While soils typically contain a sufficient total amount of P (200-300 mg P kg–1), less than 1% of it is readily available to plants. In India, despite an adequate total P content, approximately 42% of soils are deficient in plant-available P2O5 and 38% have medium availability. The dynamics of phosphorus in soil are influenced by various processes, including dissolution-precipitation, sorption-desorption, and mineralization-immobilization reactions. These dynamics are highly responsive to agricultural practices and land-use patterns, which play a significant role in shaping the P distribution of P in the soil. One major factor that affects the distribution and availability of phosphorus in the soil is a change in land use. When natural ecosystems are transformed into plantations or croplands, it substantially alters the physical, chemical and biological properties of the soil. This transformation impacts soil fertility and can lead to significant changes in the distribution of P within different chemically defined pools. Consequently, this affects the availability and stability of P in the soil. Soil P fractionation, a method used to assess P availability, solubility and dynamics, is a suitable tool to understand how P behaves under different land-use systems. However, the specific effects of land-use changes on P fractions are not well-documented. To gain a better understanding of how land-use changes impact the distribution and availability of different P fractions in the soil, research studies have been conducted.

Biochar boosted high oleic peanut production with enhanced root development and biological N fixation by diazotrophs in a sand-loamy Primisol

Peanut yield and quality face significant threats due to climate change and soil degradation. The potential of biochar technology to address this challenge remains unanswered, though biochar is acknowledged for its capacity to enhance the soil microbial community and plant nitrogen (N) supply. A field study was conducted in 2021 on oil peanuts grown in a sand-loamy Primisol that received organic amendments at 20 Mg ha−1. The treatments consisted of biochar amendments derived from poultry manure (PB), rice husk (RB), and maize residue (MB), as well as manure compost (OM) amendment, compared to no organic amendment (CK). In 2022, during the second year after amendment, samples of bulk topsoil, rooted soil, and plants were collected at the peanut harvest. The analysis included the assessment of soil quality, peanut growth traits, microbial community, nifH gene abundance, and biological N fixation (BNF) rate. Compared to the CK, the OM treatment led to an 8 % increase in peanut kernel yield, but had no effect on kernel quality in terms of oil production. Conversely, both PB and MB treatments increased kernel yield by 10 %, whereas RB treatment showed no change in yield. Moreover, all biochar amendments significantly improved oilseed quality by 10–25 %, notably increasing the proportion of oleic acid by up to 70 %. Similarly, while OM amendment slightly decreased root development, all biochar treatments significantly enhanced root development by over 80 %. Furthermore, nodule number, fresh weight per plant, and the nifH gene abundance in rooted soil remained unchanged under OM and PB treatments but was significantly enhanced under RB and MB treatments compared to CK. Notably, all biochar amendments, excluding OM, increased the BNF rate and N-acetyl-glucosaminidase activity. These changes were attributed to alterations in soil aggregation, moisture retention, and phosphorus availability, which were influenced by the diverse physical and chemical properties of biochars. Overall, maize residue biochar contributed synergistically to enhancing soil fertility, peanut yield, and quality while also promoting increased root development, a shift in the diazotrophic community and BNF.

Exploring phosphorus starvation tolerance in aus (Oryza sativa L.) rice: An analysis of stress tolerance attributes and understanding the effect of PSTOL1 gene

AbstractThe limited availability of Phosphorus (P) in the soil poses a significant challenge to of rice productivity in rainfed tropical regions. There has been a constant demand of diverse donors for enhancing tolerance to P‐deficient soils. In this study, we evaluated 181 aus rice accessions of the 3000 Rice Genome Project (3 K‐RGP) for grain yield and six other agronomical traits under control (~20 mg kg−1 available P) and low‐P (8–10 mg kg−1 available P) field trials. The objectives were to assess the level of low‐P tolerance in the aus germplasm and select stable high‐yielding accessions using stress tolerance attributes. We also surveyed the presence of PSTOL1 gene and Pup1 polymorphisms to find the effect of PSTOL1 as well as t Pup1 haplotypes on low‐P tolerance. Principal component analysis (PCA) using five stress tolerance attributes revealed that attributes like mean productivity (MP) and stress tolerance index (STI) are useful for selecting high‐yielding accessions with stable yield under stress and control conditions. Notably, accessions like Kalabokari, Devarasi, ARC 12021, Jasure Aus, ARC 7336 and ARC 12101 had higher level of tolerance than the check varieties Vandana and Sahbhagi Dhan. Majority of aus accessions carried the PSTOL1 gene (73%) and had the tolerant haplotype of Pup1 (65%) like the tolerant checks. Although, at large, the PSTOL1‐positive accessions were more vigorous, and high yielding under low‐P, there were a few PSTOL1‐negative aus accessions showing higher level of tolerance. The findings suggest that non‐PSTOL1 type tolerance exists in aus rice which needs to be substantiated through further studies.

The potential role of durum wheat–chickpea intercropping in promoting plant growth and yield in low soil phosphorus availability under field conditions

The potential role of durum wheat–chickpea intercropping in promoting plant growth and yield in low soil phosphorus availability under field conditions

Effect of corn–soybean meal-based diets with low calcium and available phosphorus in male broilers on performance, tibia criteria and jejunum histomorphology

Abstract This study was conducted to determine the effect of reducing calcium (Ca) and available phosphorus (AvP) on performance, carcass yield, tibia traits and jejunum histomorphology in broilers. For this purpose, 480 one-day-old Ross 308 male chicks were distributed into four trial groups with eight subgroups. During the starter period, birds were fed with recommended or reduced Ca and AvP contents of 66.7 and 62.5 g/kg, respectively. Calcium and AvP contents of the groups were as follows: control: 8.70 g/kg Ca, 4.40 g/kg AvP for grower and 7.80 g/kg Ca, 3.90 g/kg AvP for finisher; LCP1: 8.30 g/kg Ca, 4.20 g/kg AvP for grower and 7.10 g/kg Ca, 3.50 g/kg AvP for finisher; LCP2: 7.90 g/kg Ca, 4.00 g/kg AvP for grower and 6.00 g/kg Ca, 3.00 g/kg AvP for finisher; LCP3: 7.00 g/kg Ca, 3.80 g/kg for grower and 5.00 g/kg Ca, 3.00 g/kg AvP for finisher. Performance variables have been calculated from the data of each period, and samples were obtained from the slaughtered birds on the final day of the trial (42nd day) for carcass and tibia traits and jejunum histomorphology. Reducing dietary Ca and AvP did not affect the broiler performance, carcass yield and mortality. Tibia ash decreased in LCP2 and LCP3 groups (P < 0.01). Villus width and villus surface area increased in LCP2 and LCP3. Overall, feeding with a diet 100 g/kg lower than the recommended Ca and AvP did not affect performance in broilers, but improved jejunal development.

Soil Ecological Stoichiometric Characteristics and Influencing Factors of Degraded Alpine Grassland in Northwest Sichuan

Alpine grasslands are important ecosystems providing a variety of ecosystem services. However, alpine grassland degradation poses significant threats impacting soil health, stabilization and soil ecosystem function. This study aims to investigate the soil ecological stoichiometric characteristics and influencing factors in alpine grasslands, to find the primary contributing factors in soil degradation process. Soil samples were collected from alpine grassland areas with varying degrees of degradation, including non-, lightly, moderately and severely degraded (ND, LD, MD, SD). Soil characteristics including soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), available nitrogen (AN), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) were measured. The results revealed that soil TN, N:P ratios and C:P ratios were below the average level of China’s soil, while C:N ratio were above the average. With increasing aggravation of grassland degradation, SOC, TP, AN, MBN and MBC significantly decreased. Correlation were observed between SOC and C:N ratios as well as C:P ratios in alpine grassland with different degradation degrees (P < 0.05). The C:N ratios in degraded grasslands were lower than those in ND grasslands but higher than the average level of China’s soil. Additionally, the N:P and C:P ratios of LD and MD were significantly higher than those of ND, but lower than the China’s soil average level. In conclusion, soil degradation in alpine grasslands is associated with lower TN contents, higher C:N ratios, and lower N:P ratios, which can impact soil organic matter decomposition and act as plant growth restriction factor. This study provides comprehensive insights into the ecological stoichiometry of alpine grasslands, understanding these factors is essential for the sustainable management of alpine grasslands and restoration strategies for the ecosystem services.

Enhanced rock weathering increased soil phosphorus availability and altered root phosphorus-acquisition strategies.

Enhanced rock weathering (ERW) has been proposed as a measure to enhance the carbon (C)-sequestration potential and fertility of soils. The effects of this practice on the soil phosphorus (P) pools and the general mechanisms affecting microbial P cycling, as well as plant P uptake are not well understood. Here, the impact of ERW on soil P availability and microbial P cycling functional groups and root P-acquisition traits were explored through a 2-year wollastonite field addition experiment in a tropical rubber plantation. The results show that ERW significantly increased soil microbial carbon-use efficiency and total P concentrations and indirectly increased soil P availability by enhancing organic P mobilization and mineralization of rhizosheath carboxylates and phosphatase, respectively. Also, ERW stimulated the activities of P-solubilizing (gcd, ppa and ppx) and mineralizing enzymes (phoADN and phnAPHLFXIM), thus contributing to the inorganic P solubilization and organic P mineralization. Accompanying the increase in soil P availability, the P-acquisition strategy of the rubber fine roots changed from do-it-yourself acquisition by roots to dependence on mycorrhizal collaboration and the release of root exudates. In addition, the direct effects of ERW on root P-acquisition traits (such as root diameter, specific root length, and mycorrhizal colonization rate) may also be related to changes in the pattern of belowground carbon investments in plants. Our study provides a new insight that ERW increases carbon-sequestration potential and P availability in tropical forests and profoundly affects belowground plant resource-use strategies.

Predicting Soil Organic Matter, Available Nitrogen, Available Phosphorus and Available Potassium in a Black Soil Using a Nearby Hyperspectral Sensor System.

Black soils, which play an important role in agricultural production and food security, are well known for their relatively high content of soil organic matter (SOM). SOM has a significant impact on the sustainability of farmland and provides nutrients for plants. Hyperspectral imaging (HSI) in the visible and near-infrared region has shown the potential to detect soil nutrient levels in the laboratory. However, using portable spectrometers directly in the field remains challenging due to variations in soil moisture (SM). The current study used spectral data captured by a handheld spectrometer outdoors to predict SOM, available nitrogen (AN), available phosphorus (AP) and available potassium (AK) with different SM levels. Partial least squares regression (PLSR) models were established to compare the predictive performance of air-dried soil samples with SMs around 20%, 30% and 40%. The results showed that the model established using dry sample data had the best performance (RMSE = 4.47 g/kg) for the prediction of SOM, followed by AN (RMSE = 20.92 mg/kg) and AK (RMSE = 22.67 mg/kg). The AP was better predicted by the model based on 30% SM (RMSE = 8.04 mg/kg). In general, model performance deteriorated with an increase in SM, except for the case of AP. Feature wavelengths for predicting four kinds of soil properties were recommended based on variable importance in the projection (VIP), which offered useful guidance for the development of portable hyperspectral sensors based on discrete wavebands to reduce cost and save time for on-site data collection.

The Impact of Artificial Restoration of Alpine Grasslands in the Qilian Mountains on Vegetation, Soil Bacteria, and Soil Fungal Community Diversity.

To understand how the soil microbial community structure responds to vegetation restoration in alpine mining areas, this study specifically examines the grassland ecosystem in the Qianmalong mining area of the Qilian Mountains after five years of artificial restoration. High-throughput sequencing methods were employed to analyze soil bacteria and fungi microbial characteristics in diverse grassland communities. Combined with modifications in vegetation diversity as well as soil physicochemical properties, the impact of vegetation restoration on soil microbiome diversity in this alpine mining area was investigated. The findings indicated that the dominant plants were Cyperus rotundus, Carex spp., and Elymus nutans. As the extent of the grassland's restoration increased, the number of plant species, importance values, and plant community diversity showed an increasing trend. The plant functional groups were mainly dominated by Cyperaceae, followed by Poaceae. Plant height, density, plant cover, frequency, and aboveground biomass showed an increasing trend, and soil water content (SWC) increased. While soil pH and soil electrical conductivity (EC) exhibited a declining trend, available phosphorus (AP), total phosphorus (TP), total nitrogen (TN), nitrate nitrogen (NO3-N), soil organic carbon (SOC), and soil water content (SWC) showed an increasing trend. The dominant bacterial communities were Actinobacteriota, Proteobacteria, Acidobacteriota, Chloroflexi, Firmicutes, and Gemmatimonadota, while the dominant fungal communities were Ascomycota, Mortierellomycota, Basidiomycota, unclassified_k_Fungi, and Glomeromycota. Significant differences were detected within soil microbial community composition among different degrees of restoration grasslands, with bacteria generally dominating over fungi. SWC, TP, and TN were found to be the main soil physicochemical factors affecting the distribution of soil bacterial communities' structure; however, SOC, TN, and NO3-N were the primary factors influencing the soil distribution of fungal communities. The results of this study indicate that different degrees of vegetation restoration in alpine mining areas can significantly affect soil bacterial and fungal communities, and the degree of restoration has varying effects on the soil bacteria and fungi community structure in alpine mining areas.