Soil Plant Nutrient Research Articles

Effect of organic and green manuring on soil quality and plant nutrient uptake in organically grown strawberry

Effect of organic and green manuring on soil quality and plant nutrient uptake in organically grown strawberry

Precipitation drives the biogeographic distribution of soil fungal community in Inner Mongolian temperate grasslands

Understanding the biogeographic distribution of soil fungal communities is crucial for assessing the impacts of environmental factors on terrestrial biodiversity and ecosystem functioning. Here, we investigated spatial variations of fungal communities across three different types of temperate grasslands along a transect in the Inner Mongolia, China. The aims were to understand the biogeographic patterns of fungi and key drivers shaping soil fungal communities in temperate grasslands. The composition and diversity of soil fungal community across 30 sites of the meadow steppe, typical steppe, and desert steppe along a 1200-km transect were studied through pyrosequencing. The relationships between fungal communities and environmental and biotic factors were assessed. The results showed that the fungal community along this transect exhibited strong dependence on soil moisture content and nitrate concentration, while the fungal alpha diversity was positively correlated with precipitation and below-ground biomass. Drier environment has resulted in a shift towards an Ascomycota-dominating fungal community. Our findings suggest that the distribution and community structure of soil fungal communities are primarily driven by precipitation. Plant biomass and soil nutrient status which are also influenced by precipitation are also predictors of fungal community. Our results provide important implications for understanding the linkages among environmental factors and soil fungal communities in Eurasian steppe ecosystems.

Long–term effect of crop rotation and nutrient management on soil–plant nutrient cycling and nutrient budgeting in Indo–Gangetic plains of India

ABSTRACTIn the present investigation, the long-term effect of pulse crop inclusion in the maize-wheat rotation was assessed for the nutrient availability and soil-plant nutrient cycling under different nutrient management practices. Including pulses in the maize-wheat rotation improved soil organic carbon (SOC) and plant available macronutrients being higher in maize-wheat-mungbean rotation. Inclusion of mungbean to maize-wheat rotation enhanced the nitrogen (33.9%), phosphorus (46.4%), potassium (36.3%), and sulphur (55.5%) uptake in maize crop; likewise, alternate-year chickpea inclusion increased the uptake of these nutrients by 18.2, 19.1, 21.7, 32.1%, respectively. Inorganic fertilization maintained the positive annual balance of nitrogen, phosphorus, and zinc. By contrast, the nutrient balance under organic nutrient management was mostly negative. The magnitude of negative balance of potassium and sulphur was higher in inorganic than that of organic nutrient management. The low nutrient supply (particularly nitrogen) in organic fertilization largely inhibited the yield of cereal crops but not that of pulses. In view of this, the inclusion of pulses in the cereal-cereal systems could cause substantial improvement in soil fertility and sustainability in Indo-Gangetic plains. We infer that supply of nutrients like nitrogen and phosphorus in organic, and potassium and sulphur in recommended inorganic fertilization merit special attention.

Abiotic processes are insufficient for fertile island development: A 10‐year artificial shrub experiment in a desert grassland

AbstractThe relative importance of biotic and abiotic processes in the development of “fertile islands” in dryland systems has rarely been investigated. Here we approached this question by using artificial shrubs, which exclude plant litter production and soil nutrient uptake, but retain the functions of trapping windblown material, funneling of stemflow, and differential rain splash. We conducted a vegetation manipulation study more than a decade ago in the desert grassland of southern New Mexico and subsequently revisited the site in 2012 and 2015. The results show that no notable soil mounds were observed under the artificial shrubs; however, soil texture under the artificial shrubs has gradually changed to resemble the patterns of soil particle‐size distribution under natural shrubs. Our results highlight that with the exclusion of direct biotic additions, soils captured by shrub canopies are not necessarily fertile and thus do not themselves contribute to the development of fertile islands.

Dryland forest management alters fungal community composition and decouples assembly of root- and soil-associated fungal communities

Land management practices considerably influence ecosystem processes and functioning, particularly in dryland ecosystems where nutrient and water limitations have direct (via effects on productivity) and indirect (via effects on soil biota) effects on ecosystem properties. Fungi in soils and associated with roots play critical roles in soil nutrient cycling and plant nutrient acquisition, but their responses to land management practices in dryland ecosystems remain equivocal. Here we evaluate the responses of fungal communities in roots and soils associated with a Eucalyptus saligna plantation after six years of forest management practices (irrigation and fertilisation) and in two different microenvironments within treated plots, in the presence and absence of understorey grasses. We observed that the richness and evenness of fungal communities were higher in soil than in root samples, but these two parameters did not vary among any of the management treatments. Effects of fertilisation and irrigation on fungal community composition were observed and appeared to be related to variation in soil pH, moisture, and nitrogen availability. Both fertilisation and irrigation decreased the ratios of ectomycorrhizal fungi to total fungi and increased the frequencies of saprotrophic and/or plant pathogenic fungi. We observed that some OTUs were shared between soil and root-associated fungal communities but that fertilisation was associated with lower frequencies of shared OTUs, suggesting a decoupling of these communities. In the absence of grasses, where only tree roots were present, we observed fewer tight relationships between fungal occurrence in root and soil samples. Our findings highlight the importance of forest management practices for fungal community assembly processes in dryland ecosystems, which may have consequences for the predictability of fungal community dynamics and nutrient cycling.

English

Extension service of the land grant university system is often the first source of public information for emerging soil amendments such as biochar. Biochar is a charcoal product made by heating plant biomass via pyrolysis and is increasingly marketed as an organic soil amendment. As energy-producing pyrolysis industries expand, there is increasing opportunity to utilize locally produced biochar for its potential value in sustainable agriculture. However, the highly variable properties of biochar materials and their effects on plant growth and soil nutrient supply make it difficult to objectively study the effect of this soil amendment and provide guidance to users of locally sourced biochar materials. Therefore, preliminary screening studies are needed to identify potentially beneficial ranges of biochar properties and their effects on soils and plants that can then be rigorously tested in field research. The role of extension in conducting such screening studies is invaluable to providing both guidance to researchers in developing sound study methods, and in educating the public on biochar and the myriad of uncertainties surrounding its use; thereby establishing the need for rigorous research on its properties. In 2014, a simple, yet informative screening trial was performed to identify optimal biochar pyrolysis production temperature, conditioning (that is, degree of crushing) and soil application rate for future field experiments. Lettuce (Lactuca sativa, var. Parris Island Cos) chosen for its short growth period and rapid biomass development, was grown in 9-L pots filled with silt loam field soil amended with biochar and/or fertilizer (or none) made from Utah-sourced cherry wood. The pots were uniformly drip irrigated once daily to keep them near field capacity throughout the study period, thereby eliminating any influence of differential soil-plant-water relations. Three biochar products created from the same cherry wood source, but resulting from three different pyrolysis temperatures (375, 475 and 575°C) and either powder ground (P) or masticated (M) texture were applied to soil at three application rates (1, 2 and 3% by weight). Variation in plant dry weight at harvest within and among treatments was high. Lettuce growth with the addition of biochar was decreased as compared to control treatments in all cases, except for biochar produced at the lowest temperature, 375°C. Results indicate that masticated biochar produced at 375°C and applied to soil at the rate of 2% by mass offers the best combination of beneficial response and ease of handling for future field evaluations. This case study’s benefit for demonstrating the value of preliminary screening trials to inform both future research and public outreach education is discussed.   Key words: Biochar, soil amendments, pyrolysis, plant growth, high temperatures.

Preliminary screening of the effect of biochar properties and soil incorporation rate on lettuce growth to guide research and educate the public through extension

Extension service of the land grant university system is often the first source of public information for emerging soil amendments such as biochar. Biochar is a charcoal product made by heating plant biomass via pyrolysis and is increasingly marketed as an organic soil amendment. As energy-producing pyrolysis industries expand, there is increasing opportunity to utilize locally produced biochar for its potential value in sustainable agriculture. However, the highly variable properties of biochar materials and their effects on plant growth and soil nutrient supply make it difficult to objectively study the effect of this soil amendment and provide guidance to users of locally sourced biochar materials. Therefore, preliminary screening studies are needed to identify potentially beneficial ranges of biochar properties and their effects on soils and plants that can then be rigorously tested in field research. The role of extension in conducting such screening studies is invaluable to providing both guidance to researchers in developing sound study methods, and in educating the public on biochar and the myriad of uncertainties surrounding its use; thereby establishing the need for rigorous research on its properties. In 2014, a simple, yet informative screening trial was performed to identify optimal biochar pyrolysis production temperature, conditioning (that is, degree of crushing) and soil application rate for future field experiments. Lettuce (Lactuca sativa, var. Parris Island Cos) chosen for its short growth period and rapid biomass development, was grown in 9-L pots filled with silt loam field soil amended with biochar and/or fertilizer (or none) made from Utah-sourced cherry wood. The pots were uniformly drip irrigated once daily to keep them near field capacity throughout the study period, thereby eliminating any influence of differential soil-plant-water relations. Three biochar products created from the same cherry wood source, but resulting from three different pyrolysis temperatures (375, 475 and 575°C) and either powder ground (P) or masticated (M) texture were applied to soil at three application rates (1, 2 and 3% by weight). Variation in plant dry weight at harvest within and among treatments was high. Lettuce growth with the addition of biochar was decreased as compared to control treatments in all cases, except for biochar produced at the lowest temperature, 375°C. Results indicate that masticated biochar produced at 375°C and applied to soil at the rate of 2% by mass offers the best combination of beneficial response and ease of handling for future field evaluations. This case study’s benefit for demonstrating the value of preliminary screening trials to inform both future research and public outreach education is discussed. Key words: Biochar, soil amendments, pyrolysis, plant growth, high temperatures.

Soil Chemical Properties and Plant Nutrient Status as Influenced by Application of Lime, Phosphorus and Compost

Soil Chemical Properties and Plant Nutrient Status as Influenced by Application of Lime, Phosphorus and Compost

Economics of garlic cultivation in Kullu valley as affected by substitution of traditional fertilizers with bio-fertilizers

An investigation was conducted at Krishi Vigyan Kendra, Kullu, Himachal Pradesh to assess the effect of substitution of traditional fertilizers with biofertilizers on economics of garlic cultivation. Experiment consisted of use of various combinations of Azotobacter, phosphorus solubilising bacteria (PSB) and 50–100% dose of traditional NPK fertilizers. From the study it was found that total yield of garlic was significantly influenced by the application of biofertilizers and NPK levels. Highest total yield (20.89 tonnes/ha), net returns (Rs 3,38,442/ha), gross returns (Rs 4,17,800/ha), cost of cultivation (Rs 75,432.5/ha) and benefit cost ratio (4.26) was obtained by using Azotobacter + PSB + 100% NPK. Integration of inorganic fertilizers with biofertilizers and organic manures may reduce the use of synthetic fertilizers and improve the soil health and plant nutrient availability resulting in higher crop yields, besides being environmentally safe, resulting in higher savings and benefit cost ratio.

Plant genotypic variation and intraspecific diversity trump soil nutrient availability to shape old‐field structure and function

Summary Individual plant genotypes as well as genotypic diversity can shape the structure and function of ecosystems; however, the abiotic environment may modify these genotypic influences on ecosystem‐level responses. To explore how the interactions between plant genotype, genotypic diversity and soil nutrient availability affect the structure and function of a temperate grassland ecosystem, we manipulated the genotypic diversity of a common perennial herbaceous plant, Solidago altissima (single genotype monoculture and diversity plots) and soil nutrient availability (+nitrogen, +phosphorus, +nitrogen and +phosphorus, unmanipulated control) in a common garden setting. We tracked temporal changes in ecosystem structure (e.g. leaf area index and net primary productivity) as well as a variety of ecosystem functions (e.g. net ecosystem carbon and water exchange and soil carbon efflux) over a growing season. We found that variation in plant genotype identity consistently shaped ecosystem structure (above‐ground net primary productivity) while it inconsistently altered several ecosystem functions across time. For instance, variation in plant genotype identity influenced net ecosystem carbon dynamics early in the growing season while it influenced water dynamics later in the growing season. The strength of the relationship between genotypic diversity and ecosystem function declined over the season and the relationship between ecosystem structure (above‐ground net primary productivity) and function (net ecosystem carbon and water exchange) varied across treatments. Overall, there was a strong correlation between ecosystem structure and function across monoculture genotype plots but a weak relationship between ecosystem structure and function across mixed genotype plots. Surprisingly, soil nutrients did not influence ecosystem structure and had minimal impacts on carbon and water flux. Our data suggest that plant genetic variation, and to some extent plant genotypic diversity, strongly influence ecosystem structure and function in an old‐field ecosystem, but nutrient availability did not directly or interactively influence ecosystem structure or function. A lay summary is available for this article.

Effects of sulfur application and Thiobacillus inoculation on soil nutrient availability, wheat yield and plant nutrient concentration in calcareous soils with different calcium carbonate content

ABSTRACTIn this research, elemental sulfur was applied at eight rates with and without Thiobacillus inoculation in calcareous soils which had 23%, 17% and 8.5% Total Neutralizing Value(TNV). The highest grain yield, biological yield, plant height, and concentrations of iron (Fe) and zinc (Zn) in shoot were obtained with application of S0 at rates which neutralized 2% and 4% of soil TNV, while highest available nutrients and plant-phosphorus (P) were recorded with application of S0 at rates which neutralized 16% and 20% of soil TNV. Maximum indices were recorded in soil which had 17% TNV, so that available P, Fe and zinc (Zn) increased by 167.33%, 35.67% and 81.70% compared with control respectively with application of 9.14 g S° g−1soil. Thiobacillus inoculation increased all of indices (except Fe concentration) compared with non-inoculated control. The results reveal that sulfur application along with Thiobacillus can increase nutrients availability, nutrients uptake and yield of wheat grown in calcareous soils.

Potential mineralizable N and P mineralization of local organic materials in tantalite mine soils

Nitrogen (N) and phosphorus (P) remain the most limiting plant nutrients in most mine soils, particularly in the tropics. We estimated the potential mineralizable N of the biomass of Canavalia brasiliensis and goat manure and P mineralization of Tithonia diversifolia biomass and goat manure in tantalite mine soils of western Rwanda. The mineralizable N was estimated through a four-week incubation of amended soil-sand mixtures followed by fortnightly leaching with 200ml of 0.01M CaCl2. Conversely, Phosphorus mineralization was estimated from four-week incubation of amended soil-resin mixtures. The resins were separated from the soils and eluted with 0.5M HCl to estimate phosphate content. Among the treatments, Canavalia had the highest mineralizable N (130μgg−1 soil, P<0.01) in the Kavumu Technosol while the native forest soil had the lowest (–20μgg−1 soil). Goat manure had negative mineralizable N in all soils but was 30–70% less severe in the “cultivated soils”. P mineralization in goat manure was triple that of Tithonia, constituting 61–71% of total P applied. Each amendment uniquely contributed to N and P supply, suggesting optimum benefits of N and nutrient release as well as soil organic matter accrual through combined application in specific ratios or co-composting.

Plant invasion is associated with higher plant-soil nutrient concentrations in nutrient-poor environments.

Plant invasion is an emerging driver of global change worldwide. We aimed to disentangle its impacts on plant-soil nutrient concentrations. We conducted a meta-analysis of 215 peer-reviewed articles and 1233 observations. Invasive plant species had globally higher N and P concentrations in photosynthetic tissues but not in foliar litter, in comparison with their native competitors. Invasive plants were also associated with higher soil C and N stocks and N, P, and K availabilities. The differences in N and P concentrations in photosynthetic tissues and in soil total C and N, soil N, P, and K availabilities between invasive and native species decreased when the environment was richer in nutrient resources. The results thus suggested higher nutrient resorption efficiencies in invasive than in native species in nutrient-poor environments. There were differences in soil total N concentrations but not in total P concentrations, indicating that the differences associated to invasive plants were related with biological processes, not with geochemical processes. The results suggest that invasiveness is not only a driver of changes in ecosystem species composition but that it is also associated with significant changes in plant-soil elemental composition and stoichiometry.

Characterization of an oxalate-phosphate-amine metal–organic framework (OPA-MOF) exhibiting properties suited for innovative applications in agriculture

Targeting an innovative application for metal–organic frameworks (MOFs) in agriculture, a hydrothermal method is employed to synthesize two compounds of urea-templated iron-based oxalate-phosphate-amine MOFs, OPA-MOF (I) and (II). The compounds, forming powders of highly crystalline masses of platy morphology, crystallize in the orthorhombic system with space group Pccm and subtly different unit cells: a = 10.150(2), b = 11.770(2) and c = 12.510(3) A for compound (I) and a = 10.170(2), b = 11.886(2) and c = 12.533(3) A for compound (II). Both compounds are of elemental composition C8Fe8N16O52P8 and consist entirely of the plant nutrient elements P, N and Fe, organized by corner-shared FeO6 and PO4 units, which connect to oxalate units in a and c directions to form the framework. The N-containing guest species from the decomposed urea template were found to prefer sites close to the edges of the large (~10 × 8.6 A) framework pores along the c axis, leaving central pore areas empty. Identification of the guest was challenging due to potential H2O/NH4 mixing from the hydrothermal conditions, in addition to rotational and occupational disorder. While both compounds have suitable N and P contents for their application as fertilizers, compound (I) displays the better oxalate solubility required to initiate bacterial mineralization of the structural oxalate, resulting in structural collapse. This is the proposed release mechanism for the plant nutrients in soil. Compound (II) has unsuitably high oxalate solubility, potentially caused by a higher connectivity of larger macroscopic pores to the surface, which was visible in SEM, i.e., a macroscopic effect rather than a crystallographic effect. The utilization of such MOFs in agriculture might help to address reduced soil fertility from acidification, and provide a pathway for more efficient control of nutrient supply than conventional fertilizers.

Impact of drip fertigation on leaf nutrient status and yield attributes in chilli (Capsicum annuum L.) Hybrid CCH1

A field experiment to study the soil, plant nutrient status and yield of hybrid chilli ( Capsicum annuum L.) CCH1 as influenced by fertigation of N and K fertilizers was carried out during 2010-12. The experiment was laid out in Randomized Block Design with three replications and the treatments included were three levels (125, 100 and 75 % recommended dose) each of water soluble and straight fertilizers. The soil nutrient parameters viz ., available soil nitrogen, phosphorus, potassium content and plant nutrient parameters viz ., leaf nitrogen, phosphorus and potassium were recorded. The yield parameters like number of fruits per plant, fruit girth, and fruit weight, green fruit yield per plant and per plot were also recorded. The study revealed that the soil and plant nutrient contents in general increased up to 120 days and then declined. Among the several treatments, NPK @ 100 per cent recommended dose of water soluble fertilizers along with liquid biofertilizers registered the highest value for the soil, plant nutrient content and yield parameters.

Effect of sulphur and iron fertilization on performance and production potential of urdbean [Vigna Mungo (L.) Hepper] and nutrients removal under inceptisols

At the present time, incessant cereal-cereal cropping along with haphazard use of nutrients including micronutrients is posing menace to agricultural sustainability and environmental safety. Thus, the present investigation was conducted during kharif season 2013 on sandy loam soil of S.V.P.U.A &amp; T Meerut (Uttar Pradesh) to evaluate sulphur and iron fertilization on performance and production potential vis-à-vis nutrient removal by using F test. The data on active growth and yield with their contributing trait were calculated on net plot area basis (18 m&lt;sup&gt;2&lt;/sup&gt;). Moreover nutrient content in plant, qualities and available soil nutrient status were recorded as per the standard procedure. The experimental results revealed that plant height, number of branch per plant and dry weight at 30 and 60 DAS, number of nodules per plant, number of pods per plant, qualities and nutrient contents were affected significantly by different sulphur and Iron levels. Application of RDF along with sulphur 40 kg ha&lt;sup&gt;-1&lt;/sup&gt; and Fe 2.5 kg ha&lt;sup&gt;-1&lt;/sup&gt; gave the maximum grain yield (10.83 q ha&lt;sup&gt;-1&lt;/sup&gt;) which increased by 83.56% over control, besides it also improved all growth attributes at 30 and 60 DAS and number of pods per plant. Furthermore, grain yield was positively related with number of branches, number of nodules at 60 DAS (42.46) and number of pods (45.90). The maximum total uptake of P, K, S and Fe by urdbean was recorded as 5.34 kg ha&lt;sup&gt;-1&lt;/sup&gt;, 30.21 kg ha&lt;sup&gt;-1&lt;/sup&gt;, 5.22 kg ha&lt;sup&gt;-1&lt;/sup&gt;, 871.57 g ha&lt;sup&gt;-1&lt;/sup&gt; respectively by using RDF + Sulphur 40 + Fe 5.0 kg ha&lt;sup&gt;-1&lt;/sup&gt;, whereas maximum total N uptake (60.03 kg ha&lt;sup&gt;-1&lt;/sup&gt;) was noticed under RDF + Sulphur 40 + Fe 2.5 kg ha&lt;sup&gt;-1&lt;/sup&gt;. It is a legume crop so it is tremendously eco-friendly and useful for sustainable agriculture and soil health.

Element concentration in leaves and nutrient resorption efficiency on dry-red soil and vertisols in dry and hot valley in Yuanmou, China.

By performing a pot experiment, the study compared leaf and litter element concentration between the dry-red soil and vertisols, and analyzed the interactive effects of soil types and species on leaf nutrient concentration and nutrient resorption efficiency. The results showed that the soil type significantly affected the concentrations of N, P, Ca, Mg, Cu, Zn, Fe and N:P in leaves as well as the concentrations of N, P, Mn and N:P in leaf litters. Concentrations of N, Mn and N:P in leaves and litters derived from the dry-red soil were significantly higher than those from the vertisols. In contrast, concentrations of P, Ca, Mg, Fe, Cu and Zn in leaves and concentration of P in litters derived from the dry-red soil were significantly lower than those from the vertisols. Leaf N concentration was 34.8% higher, and leaf P concentration was 40.0% lower from the dry-red soil compared with those from the vertisols. N, P and K showed net resorption while the other elements showed accumulating patterns when leaf was senesced. Accumulation of Ca, Mg and Mn of senesced leaves was significantly higher on the dry-red soil than on the vertisols. Species identities only significantly affected leaf N concentration. Interactions of species and soil taxonomy significantly affected nutrient concentration neither in leaves nor in leaf litters, indicating that soil taxonomy influenced plant nutrient concentration in a similar way across multiple species. The influences of soil types on plant element concentration could have further effects on litter decomposition, plant-soil nutrient feedback and biogeochemical cycle in this dry and hot valley.

Soil–Plant Nutrient Status and their Relations in Maize-Growing Fields of Wolaita Zone, Southern Ethiopia

ABSTRACTThis study investigates the soil–plant nutrient status and relationship in Wolaita, Southern Ethiopia. Maize leaves, soil samples and field history were collected. The result indicated that continuous cultivation without fallowing, complete crop residue removal and inadequate fertilization were common practices. The soil was low in organic carbon, total nitrogen, available phosphorus, potassium, sulfur, boron and copper. Tissue analysis indicated 100, 84, 54 and 28% deficiency of nitrogen, phosphorus, potassium and copper, respectively. Significant and positive correlations (r = 0.70, 0.40 and 0.50) of soil phosphorus, calcium and copper with tissue content were observed. Soil pH was correlated with tissue phosphorus (r = 0.4), iron (r =—0.3) and manganese (r = −0.7). Overall, the levels of calcium, magnesium, iron, manganese and zinc were adequate for maize. Therefore, fertilizer application addressing nitrogen, phosphorus, potassium and copper deficiencies is recommended for the study area.

Impact of poultry manure on fruit quality attributes and nutrient status of guava (Psidium guajava.) cv. L 49 plant

Management of nutrients in guava refers (Psisdium guajava L.) to maintenance of the soil fertility and plant nutrient supply to an optimum level for sustaining the desired crop productivity and fruit quality through optimization of benefits from all the possible sources in an integrated manner. Qualitative and quantitative attributes of guava fruit cv. Lucknow 49 were analyzed with the aim of corresponding the nutrients to the quality of the fruit where fertilizer dose of N were manipulated in different treatments. Soil and leaf study were conducted to analyze the status of nutrients in guava. The pooled analysis of two year data indicated that after fruit harvest the highest soil organic carbon (0.72%) was obtained with the treatment comprising (Azotobacter + 100% N poultry manure. Soil N and P (271.36 and 19.86 kg/ha), Ca and Mg (7.12 and 2.82 meq 100/g soil), respectively, were recorded maximum with the treatment comprising Azotobacter + 50% N poultry manure + 50% N urea. The same treatment also showed highest leaf N and P (1.78 and 0.16%), Ca and Mg (2.09 and 0.91%) contents, respectively, on dry weight basis. The highest soil K (148.53 kg/ha) and leaf K (1.27% on dry weight basis) contents were obtained with the application of Azotobacter + 75% N poultry manure + 25% N urea. The pooled analysis of two year data also indicated that 50% N poultry manure + 50% N urea showed highest fruit yield (42.89 kg/plant), maximum fruit length (8.47 cm), breadth (8.02 cm), weight (248.80 g) and pulp weight (218.68 g) while, Azotobacter + 50% N/tree through FYM + 50% N/tree through inorganic fertilizer showed highest TSS (13.01°B), total sugars (8.68%) and minimum physiological loss in weight (13.20%) after 10 days during storage under ambient conditions. The results suggested that fertilization of guava with chemical fertilizers can be minimized when nitrogen is applied half with poultry manure and half with urea augmented with Azotobacter.

Structural and functional differentiation of the root-associated bacterial microbiomes of perennial ryegrass

The microbiomes inhabiting plant roots and their adjacent soil environment play significant roles in plant growth, health, and ecological services. Recent studies have provided detailed insights into many phytomicrobiomes, but our understanding of the root-associated microbiomes of perennial ryegrass is still very limited. Here we carried out a stratified rhizobox experiment involving a fluvo-aquic soil and red soil under elevated (750 ppm) and ambient (350–400 ppm) CO2, and used deep amplicon sequencing to investigate the ryegrass root-associated bacterial microbiomes across compartments (the bulk soil, 2-mm outer rhizosphere, rhizosphere, rhizoplane, and endosphere). We observed increased relative abundances of Proteobacteria (mainly Rhizobiaceae and Enterobacteriaceae) in the rhizosphere, rhizoplane, and endosphere compared with the bulk soil and outer rhizosphere. The dominant bacterial genera (mainly Methylobacterium, Rhizobium, Pseudomonas, Stenotrophomonas, and Enterobacter) which facilitate plant growth and soil nutrient cycling were enriched in the rhizosphere, rhizoplane, and endosphere compared with outer rhizosphere. PICRUSt predicted moderate functional differentiation of bacterial microbiomes across compartments. The bacterial α-diversity showed a decreased trend along a spatial gradient from the bulk soil to the endosphere. The β-diversity and network analyses indicated significant differences in the root-associated bacterial microbiomes between the fluvo-aquic soil and red soil. In conclusion, our study suggests that the filtration and acquisition of the ryegrass root-associated bacterial microbiomes are largely controlled by indigenous soil microbial communities, rather than the changes in root rhizodeposition caused by elevated CO2.