Levels Of Available Phosphorus Research Articles

Precision nitrogen management strategies and high yielding genotypes for enhanced growth, yield, economics, and nitrogen use efficiency in wheat

Current agricultural production systems face challenges of poor economic returns, soil fatigue and negative environmental outcomes from excess use of nitrogenous fertilizers, especially in wheat production under middle gangetic plains. To overcome these challenges, the current study was conducted to optimize nitrogen management in different wheat genotypes with precision nitrogen management tools and approaches. The field experiment was laid out in split-plot design, with three genotypes assigned to the main plot and six nitrogen management practices to the sub-plot. The soil of the experimental field was sandy loam in texture, with low levels of organic carbon and available nitrogen, and medium levels of available phosphorus and potassium. Results revealed that the HD-2967 genotype outperformed others in terms of growth, grain yield (4.7 and 4.81 t ha−1), gross return (1417.41 and 1505.48 US$ ha−1), net return (953.43 and 1019.76 US$ ha−1), and B-C ratio (2.04 and 2.08) in 2015-16 and 2016-17, respectively. Among the nitrogen management practices, application of 150 kg N ha−1 in three equal splits demonstrated improved crop growth, grain yield (4.7 and 4.81 t ha−1), and economic returns (gross return, 1500.40 and 1607.65 US$ ha−1, net return, 1025.40 and 1110.38 US$ ha−1 and B: C ratio, 2.17 and 2.23) in 2015-16 and 2016-17, respectively. However, it resulted in higher nitrogen losses. Green seeker guided N application significantly reduced apparent nitrogen losses compared to all other nitrogen applied treatments. These findings provide valuable insights for optimizing wheat production by selecting appropriate genotypes and implementing precision nitrogen management techniques to enhance yield, profitability, and environmental sustainability.

Exploring the Organic Acid Secretion Pathway and Potassium Solubilization Ability of Pantoea vagans ZHS-1 for Enhanced Rice Growth

Soil potassium deficiency is a common issue limiting agricultural productivity. Potassium-solubilizing bacteria (KSB) show significant potential in mitigating soil potassium deficiency, improving soil quality, and enhancing plant growth. However, different KSB strains exhibit diverse solubilization mechanisms, environmental adaptability, and growth-promoting abilities. In this study, we isolated a multifunctional KSB strain ZHS-1, which also has phosphate-solubilizing and IAA-producing capabilities. 16S rDNA sequencing identified it as Pantoea vagans. Scanning electron microscopy (SEM) showed that strain ZHS-1 severely corroded the smooth, compact surface of potassium feldspar into a rough and loose state. The potassium solubilization reached 20.3 mg/L under conditions where maltose was the carbon source, sodium nitrate was the nitrogen source, and the pH was 7. Organic acid metabolism profiling revealed that strain ZHS-1 primarily utilized the EMP-TCA cycle, supplemented by pathways involving pantothenic acid, glyoxylic acid, and dicarboxylic acids, to produce large amounts of organic acids and energy. This solubilization was achieved through direct solubilization mechanisms. The strain also secreted IAA through a tryptophan-dependent metabolic pathway. When strain ZHS-1 was inoculated into the rhizosphere of rice, it demonstrated significant growth-promoting effects. The rice plants exhibited improved growth and root development, with increased accumulation of potassium and phosphorus. The levels of available phosphorus and potassium in the rhizosphere soil also increased significantly. Additionally, we observed a decrease in the relative abundance of Actinobacteria and Proteobacteria in the rice rhizosphere soil, while the relative abundance of genera associated with acid production and potassium solubilization, such as Gemmatimonadota, Acidobacteria, and Chloroflexi, as well as Cyanobacteria, which are beneficial to plant growth, increased. These findings contribute to a deeper understanding of the potassium solubilization mechanisms of strain ZHS-1 and highlight its potential as a plant growth-promoting rhizobacteria.

Synergistic enhancement of regeneration capacity and ecological functions of Robinia pseudoacacia L. plantations in the Loess Plateau

Contemporary forestry research prioritizes the advancement of high-quality forestry, especially in ecologically vulnerable areas. To this end, enhancing the ecological function and natural regeneration capacity of planted forest stands is crucial. This study investigated synergistic or trade-off relationships between stand regeneration capacity and the ecological functions (including water conservation, soil conservation, carbon sequestration, and understory plant diversity) of Robinia pseudoacacia L. (RP) plantations in the Caijiachuan watershed of the Loess Plateau using Root Mean Square Deviation. The results indicated that stand regeneration capacity exhibited synergistic, moderate trade-off, and high trade-off relationships with soil and water conservation, stand carbon sequestration, and understory plant diversity, respectively. Notably, stand regeneration capacity had a synergistic relationship with the overall forest ecological function (sum of the above functions), suggesting that the overall forest ecological function can be simultaneously improved by enhancing stand regeneration capacity. Redundancy analyses revealed that the regeneration capacity was primarily influenced by soil moisture content (SMC), stand density (SD), total transmitted light, herbaceous species richness, litter accumulation, and soil available phosphorus (AP). According to the stand optimization model, the highest regeneration capacity of RP was observed under the following conditions: 1742 trees·hm−2 for SD, 15.29 % for SMC (higher than the mean value of 33.53 % for the existing RP), 41.69 mg·kg−1 for AP (higher than the mean value of 15.84 %), and 1.84 for LAI (lower than the mean value of 20.0 %). Therefore, to achieve the simultaneous enhancement of the regeneration capacity and overall ecological function of RP stands, foresters should prioritize adjusting SD to an appropriate range through thinning or replanting. Additionally, regular pruning of specific branches of individual trees is essential to mitigate the adverse effects of high LAI on stand regeneration. Where feasible, soil moisture and nutrients can also be increased, but excessive levels of AP should be avoided.

Can the use of phytase in feed improve the performance and health of broiler chickens?

This study aimed to evaluate the effect of phytase supplementation on feeds with reduced nutritional calcium and phosphorus on broiler chickens from 1 to 49 days of age. Chickens fed five experimental diets distributed in a completely randomized design, with eleven replicates of 20 chickens each, were used for evaluating performance, bone quality, and serum mineral levels. The diets consisted of one positive control (PC); one negative control (NC), with reduced levels of available phosphorus and calcium; and four diets consisting of NC feed supplemented with phytase at levels 0, 500, 1000, or 1500 U/kg. Supplementation with 1000 FU/kg of phytase in diets based on corn, and soybean meal is ideal for obtaining excellent performance and bird welfare results reducing nutrient excretion and improving digestion and absorption of nutrients by the animal.

Assessment of salt-affected soil in selected rice irrigation schemes in Tanzania: understanding salt types for optimizing management approaches

Salt-affected soils have serious implications for agricultural land quality and productivity, leading to a reduction in the net cultivable area available for food production. This issue has emerged as one of the foremost global challenges in recent years, impacting both food security and environmental sustainability. This research focuses on soil characterizations conducted in three irrigation schemes to understand the types, distribution, and nature of salt-affected soils. Auger observations served as the basic methodology for soil unit delineation in this study. Twelve representative soil pits with a depth of more than 160 cm were described, and undisturbed and disturbed samples were collected and analyzed for physical and chemical properties. The schemes were characterized by low levels of available phosphorus, organic carbon, and total nitrogen, as well as variations in exchangeable bases. Furthermore, 37.5% of the analyzed horizons highlighted the presence of salt-affected soils. Sodium was the predominant cation, followed by magnesium, potassium, and calcium. Likewise, HCO3− was the dominant anion, followed by Cl− and SO42−. The results of this study reveal the existence of two types of salt-affected soil. Uturo irrigation scheme had sodic soils, while the Ndungu irrigation scheme had saline-sodic soils. Additionally, both sodic and saline-sodic soils have been discovered in the Mawala irrigation scheme. The root cause of this challenge is inherent soil conditions, exacerbated by inadequate drainage infrastructure. Therefore, measures such as the application of gypsum followed by salt leaching, improving soil drainage by incorporating organic matter, improving drainage infrastructure, and using rice-tolerant varieties are recommended to mitigate salt stress and improve soil fertility. It is imperative to establish a robust framework for continuous monitoring and regular assessment of soil health to enable timely interventions and informed decisions for sustainable agricultural management.

Utilizing the Fusion Characteristics of Multispectral and Electronic Noses to Detect Soil Main Nutrient Content

Soil nutrients are essential for plant growth, and it is crucial to accurately detect their levels. However, current methods for detecting soil nutrients still have low accuracy and high costs. In this study, we propose a multi-source fusion feature approach that combines multispectral image technology with electronic nose gas response technology to achieve rapid, high-precision, and cost-effective detection of soil nutrients, including soil organic matter (SOM), total nitrogen (TN), available potassium (AK), and available phosphorus (AP). To begin, a multispectral camera was used to collect spectral images and extract seven index features. Additionally, an electronic nose was used to collect soil pyrolysis gases to obtain the response curve and extract seven response features. These two sets of features were effectively fused to form a 106 × 98 fusion feature space. Secondly, principal component analysis (PCA) and Pearson correlation coefficient (PCC) algorithms were used to optimize and reduce the dimensionality of the fused feature space. Finally, a predictive model of the relationship between the feature space and the nutrient content of the soil samples was established using the random forest (RF) and partial least squares regression (PLSR) algorithms. The predictive performance of the model was used to evaluate the accuracy of soil nutrient detection. The results showed that the PLSR modeling of the optimized feature space of PCA achieved high accuracy in predicting the levels of main soil nutrients, with R2 values for SOM, TN, AK, and AP of 0.96, 0.95, 0.84, and 0.73, and the RMSE values of 0.56, 0.07, 3.21, and 3.70, respectively. Compared to using only electronic nose gas response technology, the soil nutrient detection with multi-source data features method in this study not only improved the accuracy for SOM and TN but also for metal elements AK and AP in soil. The spectral index features proposed in this study were able to compensate for the limitations of the electronic nose response features, and modeling with the fusion feature space resulted in an accurate prediction of SOM, TN, AK, and AP levels.

Effects of Conventional Non-Biodegradable Film-Derived Microplastics and New Biodegradable Film-Derived Microplastics on Soil Properties and Microorganisms after Entering Sub-Surface Soil

Plastic film mulching, widely used in agriculture, leads to microplastic (MP) pollution in soils. While biodegradable polybutylene adipate terephthalate (PBAT) films may offer a solution, their impacts on subsurface soils and microorganisms remain unclear. To investigate the effects of conventional non-biodegradable polyethylene (PE) and biodegradable PBAT MPs on the properties of sub-surface soils and microbial communities, MPs were added at varying doses in a field experiment and incubated for 160 days. Physicochemical characteristics, nutrient dynamics, and microbial composition, diversity, and networks of soils were analyzed using standard techniques and 16S rRNA/ITS gene sequencing. Correlations between soil properties and microbes were assessed. Both MP types significantly altered soil characteristics, with PBAT-MP elevating pH and the levels of available phosphorus and potassium more than PE-MP. Microbial composition shifts occurred, with low-addition PBAT-MP promoting plastic-degrading genera. The assessment of α/β-diversity indicated that PBAT-MP predominantly influenced fungi while PE-MP impacted bacteria. An examination of microbial co-occurrence networks highlighted that PE-MP primarily disrupted fungal interactions, whereas PBAT-MP streamlined network complexity. Correlation analyses revealed that PBAT-MP promoted fungal diversity/network resilience correlating to nutrients. PE-MP and PBAT-MP significantly altered native soil/microbe relationships. PBAT-MP may exert greater, yet unknown, impacts over time through its biodegradation into newer and smaller fragments. Future research needs to integrate multi-omics and stable isotope science to elucidate the deep mechanistic impacts of degraded film-derived MPs on microbial ecological functions and biogeochemical cycles. Attention should also be paid to the long-term accumulation/transport of MPs in agricultural soils. Overall, this work deepens the impact and understanding of MPs from plastic film on sub-surface soil ecology. Furthermore, it provides a theoretical foundation for managing ‘white pollution’ in the film-covered farmlands of arid and semi-arid regions in China.

The influence of biochar from animal and plant on the transformation of phosphorus during paper mill sludge composting.

Biochar has effect on phosphorus adsorption, release, and transformation. This study compared the influence of biochar derived from animal (AB) and plant (PB) during paper mill sludge composting. Results indicated AB not only accelerated sludge decomposition but also had significantly higher levels of available phosphorus (AP) than PB and CK (no biochar), with AP contents in the order of AB > PB > CK. Compared to CK, AB was found to increase the relative abundance of thermophilic bacteria, and PB diversified the microbial community. Based on Pearson and RDA results, TOC/TN ratio (C/N) and organic matter (OM) explained above 50% of the variance in microbial community and phosphorus fractions. Thermophilic bacteria with high levels of OM and C/N promoted the conversion among labile and moderately labile organic phosphorus, moderately labile inorganic phosphorus, and AP. Biochar could enhance the AP conversion pathway, leading to increased levels of AP.

Soil Physicochemical Properties Variation under Annual Crop and Coffee Landuse in the Chentale Watershed, Upper Blue Nile Basin, Ethiopia

A detrimental decline in soil fertility has been attributed to losses in arable land productivity in Ethiopia. In this line, several studies were conducted to enable informed decisions; however, monitoring soil property dynamics in different biophysical, climatic, and cropping systems is yet to be adequate to support and influence decision and policymakers. To this end, this study evaluated soil physicochemical properties on land managed for annual crops and coffee land use in the Chentale watershed, the upper Blue Nile basin, Ethiopia. About 24 soil samples were collected from the two land uses and soil depths (topsoil: 0–15 cm and subsoil: 15–30 cm) with 6 replications for soil properties analysis. The result showed that most of the soil parameters varied significantly with land uses and were higher with coffee landuse (p<0.01) than with cropland. Furthermore, a neutral pH range, clay loam texture, medium level of organic matter (3.93%) and nitrogen (0.18%), high level of available phosphorus (23.35 PPM), and high to very high level of exchangeable base were recorded from coffee landuse than from cropland. Whereas the mean values of organic matter (OM) and total nitrogen (TN) decreased significantly (p<0.05) decreased in the subsoil. However, most of the physical and chemical properties of the soil did not vary significantly with depth. Moreover, low pH, low OM content, and low TN are the main properties of soil considered constraints of soil fertility in cropland at both depths. Therefore, it is recommended to maintain agroforestry practices, reduce the intensity of tilling, and supply organic materials to sustain the productivity of cropland.

Root response and phosphorus acquisition under partial distribution of phosphorus and water‐soluble organic matter

AbstractUnderstanding how phosphorus and water‐soluble organic matter (WSOM) from animal manure compost contribute to root development is essential for enhancing phosphorus utilization efficiency under their combined application. This study aims to determine mechanisms underlying root responses and phosphorus acquisition based on the partially varying available phosphorus levels in root zone soil following WSOM. The plant growth test was performed using a specifically designed pot where the root elongation was guided into the soil of different root compartments with either phosphorus combined with WSOM or single phosphorus or WSOM. The results revealed high levels of available phosphorus in the root zone soil of individual plants in the presence of WSOM induced small root weight. Phosphorus concentrations in the root exhibited a negative correlation with root weight. Improved root structure development even in the presence of WSOM induced to increase uptake of phosphorus and other nutrients in the plant. Furthermore, a positive linear relationship was observed between nutrient uptake and aboveground dry weight. These findings provide pioneering experimental evidence demonstrating that root development varies to some extent depending on the level of available phosphorus induced by the combined application of phosphorus and WSOM, even within the root zone soil of individual plants. Given that plant growth varied based on partial root development even when phosphorus and WSOM were combined, this study suggests that implementing appropriate phosphorus fertilizer application while considering the augmented availability of phosphorus via the combined application of animal manure compost can promote root development and nutrient uptake, resulting in improved plant growth.

Growing pigs’ diets with increased phytase activity and reduced available phosphorus resulted in similar performance and environmental impacts

The objective of this study was to evaluate, through a life cycle assessment, the environmental impacts of the postweaning growth of pigs fed with diets with reduced levels of available phosphorus and increased phytases. In Trial I (nitrogen and phosphorus balance), 25 crossbreed barrow pigs (BP 400 × BM 500 Biriba’s®), with an average weight of 23.05 ± 3.24 kg and average starting age of 60.75 ± 4.73 days, were assigned to five dietary treatments using a randomized block design, with five replications and each animal as an experimental unit. Five experimental diets were evaluated: each increasing phytase activity units (FTU) (control [0], 250, 500, 750 and 1 000 FTU) and decreasing levels of available phosphorus (0.435, 0.375, 0.315, 0.255 and 0.195%), respectively. Due to phytase supplementation, all diets meet the requirements for available phosphorus. The pigs received two daily meals. Total collection of feces was performed, adding 2 g of ferric oxide as a fecal marker. Feces were collected daily, stored in plastic bags and frozen. All excreted urine was collected in plastic buckets containing 20 mL of HCl (1:1), and a 20% aliquot was frozen for further analysis. In Trial II (performance), 40 crossbreed barrow pigs (BP 400 × BM 500 Biriba’s®) with an initial average weight of 15.11 ± 0.67 kg, average starting age of 50.63 ± 0.81 and finishing age of 72.43 ± 2.07 days were assigned using a randomized block design to five dietary treatments, with eight replications and each animal as an experimental unit. The pigs were weighed at the beginning and at the end of the trial, as were the feed supplies and refusals. These data were used to calculate the feed conversion ratio, average daily gain and average daily feed intake. The life cycle analysis was based on the CML 2001 (baseline) method V3.02, as implemented in the Simapro software, version 8.05 (PRé Consultant, 2014). These data may further serve as a reference for the study of the impact of phytase supplementation during other breeding phases, or even in other animals whose environmental impacts are being studied.

Effect of 25-hydroxycholecalciferol supplementation with different dietary available phosphorus levels for broilers

ABSTRACT 1. Based on the hypothesis that 25-hydroxycholecalciferol (25-OH-D3) inclusion would optimise dietary mineral digestibility and ameliorate growth performance and bone mineralisation in available phosphorus (AvP) deficient-fed broilers, a trial was conducted to evaluate its effect on diets with different levels of AvP. 2. Broilers aged 1–21 d were randomly assigned one of the eight treatments, consisting of four dietary levels of AvP (0.45%, 0.42%, 0.39%, and 0.36%) and with or without supplementation with 25-OH-D3 at 69 μg/kg of feed. All diets contained 100 µg/kg of vitamin D3 (cholecalciferol). 3. The addition of 25-OH-D3 resulted in higher feed intake and body weight gain, and lower FCR (P < 0.05) compared to non-supplemented diets, whereas AvP levels had a quadratic effect only on feed intake. There were no interactions between treatment factors. 4. Increasing AvP levels linearly reduced the ileal digestibility of Ca and P (P < 0.01) and supplementing 25-OH-D3 increased both Ca and P ileal digestibility (P < 0.05), without any interactions observed for ileal digestibility. 5. There was an interaction, whereby 25-OH-D3 inclusion increased serum metabolites in broilers fed 0.36% to 0.42% AvP compared to the non-supplemented diets (P < 0.001), whereas, at 0.45% AvP, diets with or without 25-OH-D3 had similar results. 6. The P content in bone linearly increased in line with AvP levels (P < 0.05) and supplementation of 25-OH-D3 increased ash bone content (P < 0.001). 7. Broilers can benefit from 25-OH-D3 supplementation combined with cholecalciferol with regard to Ca and P utilisation and vitamin D status, allowing for a reduction of dietary AvP levels down to 0.36% without impairing growth performance or bone status.

Halotolerant Phosphate Solubilizing Bacteria as Growth Promoter for Mung Bean, Pea and Wheat Crops

Sustainable agriculture necessitates innovative solutions that enhance crop yield while minimizing environmental impact. This study evaluates the efficacy of three halotolerant phosphate solubilizing bacterial (PSB) strains viz., Enterobacter bugandensis PH27, Psychrobacter faecalis PH28, and Bacillus amyloliquefaciens PH30 treatment across growth stages of pea GDF-1, wheat GW-451, and mung bean GM-4 varieties. Our analysis reveals that B. amyloliquefaciens PH30 threatment consistently outperformed other isolates, significantly enhancing seed germination rates and key growth metrics such as plant height, dry weight, and leaf area. Additionally, PH30 improved soil fertility by elevating levels of available phosphorus. The data suggest a multi-pronged mechanism of action for PH30 involving phytohormone production, nutrient chelation, and phosphate solubilization.

Characterization and suitability assessment of the soils of Iwo series for cocoa production in rainforest area Southwestern, Nigeria

Characterization and soil suitability assessment is a vital tool for understanding the nature and status of soils. It is one of the strategies for achieving food security as well as sustainable environment. This study was conducted to assess the suitability of the soils of Iwo series for sustainable production of cocoa. The study was carried out in 2022, in an area located approximately between 7°32' N and 7°33' N and longitudes 4°32' E and 4°40' E within the Teaching and Research Farm (T&amp;R-F) of Obafemi Awolowo University (OAU), Kajola, Ile-Ife, Nigeria. Three profile pits were established, described and sampled with one at different physiographical units following the guideline for soil profile description according to FAO/UNESCO guideline. The soil samples collected were analyzed for particle size distribution, pH, total nitrogen, available phosphorus, exchangeable bases, and organic matter using standard method. Land characteristics obtained were matched with the crop requirements for cocoa to obtain the soils’ suitability classes using parametric method. The results showed that all the soils are well drained and deep. The texture of the soils ranged from sandy loam to sandy clay loam at the surface and sandy clay loam to clay at subsurface. Soil reaction ranged from highly acidic to slightly acidic (4.2-5.8 water and 3.9- 5.7 pHCaCl2) with low to moderate amounts of organic matter (0.4 to 1.74%) and available nitrogen (0.02-0.14%). Available phosphorus varied from 0.52-24.77 mg/kg in all the horizons in the profiles with the highest values at the surface soil horizons, an indication that soil organic matter contributes significantly to the available P in these soils. The exchangeable bases were low and the relative abundance of the exchangeable bases followed the order: Ca&gt; Mg &gt; Na&gt;K at the exchangeable site. Suitability evaluation of the soils was carried out using parametric approach and the result showed that the soils of mapping units A and B are presently not suitable (N1) while mapping unit C is marginally suitable for cocoa production. With the appropriate fertility management, the soils of mapping unit A were classified as marginally suitable (S3) while soils of mapping unit B and C were classified as moderately (S2) for cocoa production. The limiting factors were mainly low soil fertility (low level of available phosphorus, macro-nutrients, nitrogen and organic matter). Therefore, combined application of organic fertilizer with inorganic fertilizers should be encouraged for optimum productivity.

EFFECTS OF POTASH SOURCES ON RABI MAIZE YIELD, QUALITY, AND THEIR LASTING EFFECTS ON SUBSEQUENT SUMMER GROUNDNUT

The effect of potash sources on rabi maize (Zea mays L.) production and quality, as well as their carryover to the subsequent summer groundnut (Arachis hypogaea L.), was studied. The experimental field featured a flat, gently sloping surface that was well-drained and composed of loamy sand. Low levels of organic carbon and accessible nitrogen, medium levels of available phosphorus and potassium, and a slightly alkaline response were found in the top 15 centimetres of the soil in the experimental area. There were 14 distinct potash applications, including a control (no fertilisers) (T1), 30 kilogrammes per hectare (tonnes) of potassium dihydrogen phosphate (MOP), 30 kilogrammes per hectare (tonnes) of sodium dihydrogen phosphate (SOP), 30 kilogrammes per hectare (tonnes) of schoenite (T4), 30 kilogrammes per hectare (tonnes) of potassium monobasic (KMB) at 1 litre.

SWEET transporters of Medicago lupulina in the arbuscular-mycorrhizal system in the presence of medium level of available phosphorus.

Arbuscular mycorrhiza (AM) fungi receive photosynthetic products and sugars from plants in exchange for contributing to the uptake of minerals, especially phosphorus, from the soil. The identification of genes controlling AM symbiotic efficiency may have practical application in the creation of highly productive plant-microbe systems. The aim of our work was to evaluate the expression levels of SWEET sugar transporter genes, the only family in which sugar transporters specific to AM symbiosis can be detected. We have selected a unique "host plant-AM fungus" model system with high response to mycorrhization under medium phosphorus level. This includes a plant line which is highly responsive to inoculation by AM fungi, an ecologically obligate mycotrophic line MlS-1 from black medick (Medicago lupulina) and the AM fungus Rhizophagus irregularis strain RCAM00320, which has a high efficiency in a number of plant species. Using the selected model system, differences in the expression levels of 11 genes encoding SWEET transporters in the roots of the host plant were evaluated during the development of or in the absence of symbiosis of M. lupulina with R. irregularis at various stages of the host plant development in the presence of medium level of phosphorus available for plant nutrition in the substrate. At most stages of host plant development, mycorrhizal plants had higher expression levels of MlSWEET1b, MlSWEET3c, MlSWEET12 and MlSWEET13 compared to AM-less controls. Also, increased expression relative to control during mycorrhization was observed for MlSWEET11 at 2nd and 3rd leaf development stages, for MlSWEET15c at stemming (stooling) stage, for MlSWEET1a at 2nd leaf development, stemming and lateral branching stages. The MlSWEET1b gene can be confidently considered a good marker with specific expression for effective development of AM symbiosis between M. lupulina and R. irregularis in the presence of medium level of phosphorus available to plants in the substrate.

Isolation of Phosphate-Solubilizing Microorganisms and the Formulation of Biofertilizer for Sustainable Processing of Phosphate Rock.

As phosphorus (P) bioavailability is limited in arable lands, chemical fertilizers are being used by farmers to increase crop production. Phosphate-solubilizing microorganisms (PSMs) increase the bioavailability of sparingly soluble inorganic and organic soil phosphorus. Therefore, the current study was an effort to evaluate the phosphate-solubilizing efficiency of PSMs using tricalcium phosphate (TCP) and Eppawala rock phosphate (ERP). The efficiency of phosphate solubilization by a series of identified isolates was compared using TCP (5 g L-1) and ERP (5 g L-1) as a P source in Pikovskava's broth. Twelve microbial isolates that showed a higher efficiency in phosphate solubilization were selected for the production of the biofertilizer. The isolate F10 in ERP broth was characterized by the highest significant level of available phosphorus (896.98 ± 10.41) mg L-1, followed by F5 (Aspergillus sp.) in TCP broth 991.43 ± 1.37 mg L-1. A pot trial was carried out by using Capsicum annuum L. as the test plant in two soil conditions: sterilized soil and non-sterilized soil with six treatments and four replicates. The significantly highest plant height, leaf length, and width were shown by chili plants treated with the formulated biofertilizer. Therefore, the application of native PSMs appeared to be an efficient method of solubilizing sparingly soluble P compounds into plant-available forms.

Effect of Some Soil Mineral Levels on Their Contents in Different Plant Parts and on the Yield of Chickpea-Rhizobium Symbioses

Chickpea is a legume with high nutritional value. It is mainly grown in arid and semi-arid areas soils, which are characterized by a deficiency in mineral elements, a severe water deficit and a poor soil quality. Our work aims to evaluate the effect of different mineral elements in the soil on nodular biomass, growth and yield of chickpea. The physico-chemical analyses of the soil and the agronomical and physiological parameters showed that the level of available phosphorus in the soil positively affected the growth parameters in the chickpea studied plants. Our results also confirmed the positive effect of adequate plant P nutrition on yield. Indeed, among the studied fields, agricultural soil 7 presented the highest potassium content and seeds yield (12.87 mg/g DM and 62 seeds per plant, respectively). In parallel, soil 7 recorded the highest value of available phosphorus 23.52 ppm. On the contrary, soil 5 was the least rich in P content (6.73 ppm). A positive correlation was recorded between the sodium concentration in the soil and in the aerial parts (<i>r </i>=0.73). The results also showed that the aerial part was richer in calcium than the root part and the nodules. Moreover, other positive correlations were recorded between the calcium concentration in the soil and in the aerial part and in the root part (<i>r </i>=0.76 and <i>r </i>=0.54; respectively).

Long-term Tillage Alters Soil Properties and Rhizosphere Bacterial Community in Lime Concretion Black Soil under Winter Wheat–Summer Maize Double-Cropping System

Tillage practices can directly affect soil quality, influencing soil properties, crop growth, and soil microbial community characteristics. However, the influence of long-term tillage practices on the rhizosphere bacterial community in lime concretion black soil remains largely unknown. In this study, the effects of nine-year rotary tillage (RT), no-tillage (NT), subsoiling tillage (ST), and plow tillage (PT) on soil chemical properties, microbial community structure, and correlations between bacterial communities and soil properties in the maize rhizosphere were investigated. The results revealed that the maize yield in ST and PT was higher by 10.61% and 10.26% than that in RT and by 10.25% and 9.90% than that in NT, respectively. The soil organic matter (SOM) and total nitrogen (TN) contents in NT and ST were significantly higher than those in RT and PT, whereas the available phosphorus (AP) content in ST and PT was significantly higher than that in NT and RT. The diversity and richness of the soil bacterial communities exhibited a trend of NT &gt; RT &gt; PT &gt; ST. The principal component analysis revealed that the soil bacterial community differed among treatments. Linear discriminant analysis effect size (LEfSe) analysis demonstrated that Proteobacteria, Armatimonadetes, Verrucomicrobia, and Chloroflexi could serve as crucial biomarkers. Phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) results revealed that genes involved in carbon, lipid, and xenobiotic metabolism were enriched under ST and PT, whereas those involved in nitrogen and carbon fixation were enriched under NT. Besides, Proteobacteria, Verrucomicrobia, and Armatimonadetes were positively associated with AP levels and negatively associated with pH; however, Acidobacteria, Bacteroidetes, and Planctomycetes exhibited an opposite trend. Overall, ST and PT improved the soil properties and environmental suitability by increasing the bacterial keystone taxa; thus, these practices improved crop yield. These findings could enhance our understanding of the rhizosphere functional microbial community in lime concretion black soil for winter wheat–summer maize double-cropping system.

Effects of Sugarcane Leaf Return and Fertilizer Reduction on Maize Growth, Yield and Soil Properties in Red Soil.

In order to make better use of the vast sugarcane leaf straw resources and reduce the overuse of chemical fertilizers in the subtropical red soil region of Guangxi, this study aimed to determine the effects of sugarcane leaf return (SLR) and fertilizer reduction (FR) on maize growth, yield component and yield, and soil properties. A pot experiment with three SLR amounts (full SLR (FS), 120 g/pot; half SLR (HS), 60 g/pot; and no SLR (NS) with three FR levels including full fertilizer (FF), 4.50 g N/pot, 3.00 g P2O5/pot, and 4.50 g K2O/pot; half fertilizer (HF), 2.25 g N/pot, 1.50 g P2O5/pot, and 2.25 g K2O/pot; and no fertilizer (NF)), without nitrogen, phosphorous, and potassium added, was conducted to assess the effects of different SLR amounts and chemical FR levels on maize growth, yield, and soil properties. Compared with no sugarcane leaf return and the no-fertilizer treatment (CK), SLR and FR could increase maize plant height, stalk diameter, number of fully developed maize plant leaves, total leaf area and chlorophyll content, soil alkali-hydrolyzable nitrogen (AN), available phosphorus (AP), available potassium (AK), soil organic matter (SOM), and electrical conductivity (EC). The maize yield component factors of FS and HS were higher in NF treatment than those in NS treatment. The relative increase rate of treatments retained FF/NF and HF/NF under FS or HS condition on 1000 kernel weight, ear diameter, plant air-dried weight, ear height, and yield than that under NS condition. FSHF had not only the largest plant air-dried weight but also the highest maize yield (3225.08 kg/hm2) among nine treatment combinations. The effects of SLR on maize growth and yield and soil properties were lower than those of FR. SLR and FR combined treatment did not affect maize growth but affected maize yield significantly. Soil properties improved more with SLR + FR treatment than with SLR or FR application alone. The plant height, stalk diameter, number of fully developed maize plant leaves, and total leaf area, as well as AN, AP, AK, SOM, and EC levels in soil, were enhanced by SLR and FR incorporation. The experimental results indicated that applying reasonable FR combined with SLR increased AN, AP, AK, SOM, and EC, which improved maize growth and yield and enhanced soil properties in red soil. Hence, FSHF might be a suitable combination of SLR and FR.