Plant Nutrient Availability Research Articles

Incorporation of Crop Residues into Soil: A Practice to Improve Soil Chemical Properties

Crop residues have the potential to enhance soil fertility, but this is dependent on their biochemical properties. This study aimed to evaluate the chemical composition, and nutrients release patterns of selected crop residues (corn stalk, rice straw, millet straw and sorghum stalk). Thus, 20 g of each crop residue were put in litter bags and placed in a plastic pot containing 10 kg of soil with a moisture content of 40% - 60%. Five replications were considered per type of residue and some samples were taken every 4 weeks. Results showed that crop residues got a pH varying between 5.09 and 6.5. The lowest C content (33.11%) and nitrogen (0.27%) were measured in sorghum stalk when the highest C content (47.6%) and nitrogen content (0.55%) were registered in corn stalk. The highest phosphorus content (0.58%) was got in corn stalk. Potassium content was higher in millet straw than in others. The highest calcium content (0.37%) and magnesium (0.29%) were found in rice straw. There was an increase of soil chemical composition after crop residues burial. Significant increase in carbon, nitrogen, and phosphorus content was noted in soil at week 4 with the highest at week 16. At the end of the experiment, the highest C content (53.1%) and the highest nitrogen content (0.88%) in the soil were observed after burial of rice straw. The highest phosphorus content (0.82%) registered in the soil was got with millet straw. Nutrient release efficiency of crop residues occurred in the following order: rice straw > millet straw > sorghum stalk > corn stalk. This study has demonstrated that rice straw and millet straw released nutrients faster and this is beneficial for early planted crops, while sorghum stalk and corn stalk released nutrients slowly which is appropriate for long-term availability of plant nutrients.

Processes that influence dissolved organic matter in the soil: a review

ABSTRACT: In tropical regions, climate conditions favor fast decomposition of soil organic matter (SOM), releasing into the soil organic composts in solid, liquid, and gaseous forms with variable compositions. Dissolved organic matter (DOM), a complex mixture of thousands of organic compounds, is only a small fraction of the decomposition products; however, it is highly mobile and reactive to the soil. Therefore, DOM play a key role in soil aggregation (formation of organometallic complexes), energy source for microorganisms, as well as C storage, cycling, and provision of plant-available nutrients. DOM multifunctionality to sustain soil functions and important ecosystem services have raised global scientific interest in studies on DOM fractions. However, previous studies were conducted predominantly under temperate soil conditions in natural ecosystems. Therefore, there is paucity of information on tropical soil conditions under agricultural systems, where DOM turnover is intensified by management practices. This review synthesized information in the literature to identify and discuss the main sources, transformations, and future of DOM in soils. We also discussed the importance of this fraction in C cycling and other soil properties and processes, emphasizing agricultural systems in tropical soils. Gaps and opportunities were identified to guide future studies on DOM in tropical soils.

Plant Nutrient Availability and pH of Biochars and Their Fractions, with the Possible Use as a Component in a Growing Media

Biochar has the potential to be used as a growing media component, and therefore plays a role in reducing peat usage. It has unique properties apart from the ability to sequester carbon. Here we investigated the nutrient contents of four commercial biochars and their fractions. The biochars’ feedstock was wood waste, except for one with paper fibres and husk. The fine or finer fractions in wood waste biochars contained higher levels of nutrients that were available to plants. The coarse fraction of the biochar derived from husk and paper fibre feedstock had a higher level of total N, P and K in contrast to the other three biochars. The pH of the finer fraction (pH of 9.08) was also higher compared with coarse fraction (pH of 8.71). It is important that when biochar a is used as a component of a peat based growing media, particle size information should be provided, as fractions from the same biochar can have different levels of total extractable nutrients and pH levels. If biochar is used to replace or reduce lime application rates of a peat-biochar mixtures, one must take into account the levels of total and extractable Ca and Mg levels, as these can vary. The variation of these elements was not only between biochars’ feedstocks, even at similar pH-values, but within different fractions in the same biochar. We concluded that biochars should be characterized from the feedstock as well as from the particle size aspect, as it could have a profound effect on nutrient availability of Ca and Mg. This could lead to nutrient imbalances in cultivating plants on substrate mixtures. In addition to nutrient ratios, the suitable pH-level for a given grown species should be adjusted.

Agronomic potential of biochar prepared from brewery byproducts

This work investigated the effect of biochar produced from brewery byproducts, spent grain and surplus yeast on the physicochemical characteristics of a calcareous loam soil and plant growth of maize (Zea mays L.). Maize is a plant which needs high nitrogen fertilization, while the effect of acidic or neutral biochars on alkaline calcareous soils has only been assessed in a few studies. The effect of biochars on dry weight, as well as the level of macro- and micronutrients in soil, and above- and belowground plant tissues, were investigated, in a 30 day experiment after seedling emergence of maize (Zea mays L.), in the presence and absence of nitrogen fertilization.The results indicated that biochar from organic brewery by-products significantly increased the dry weight of the aboveground part of the plant by 59–186%, relative to the control, without the addition of inorganic N fertilization, and by 46–157% with the addition of inorganic N fertilization. The dry weight of the belowground plant tissues significantly increased by 83–92% and 46–106%, relative to the control, with or without the addition of inorganic N fertilization, respectively. Biochar addition, especially at 5% application rate individually or in a mixture, significantly increased the phosphorus content of plant tissues. The content of potassium in the plants was affected mainly by the addition of biochar derived from surplus yeast, while the concentration of calcium and magnesium in plant tissues was positively affected by spent grain biochar, in absence of inorganic nitrogen fertilization. Addition of biochars produced from brewery byproducts improved soil fertility parameters, particularly the contents of total organic carbon (by 133% and 118% with or without fertilization, respectively), total nitrogen (by 120% and 81% respectively) and available phosphorus in the studied loam calcareous soil. Overall, biochar from brewery wastes showed the potential to enhance plant growth and nutrient availability, thus it is a promising organic fertilizer for sustainable agriculture.

Most Plant Nutrient Elements Are Retained by Biochar in Soil

Biochar may contain substantial amounts of plant nutrient elements, and at typical rates of application, may supply luxury levels of K, Ca, P, and other plant nutrients. However, little is known of the agronomic effectiveness of these nutrients because they exist in diverse compounds and are located in the microporous matrix of biochar particles. We have identified the compounds and location of nutrient elements in three biochars and observed their release from biochar particles in soil. Much K was quickly released from biochar but little or no Ca, Mg, S, and P were released over eight months, which represents a very different behavior from chemical fertilizers that are mostly water soluble. There is clearly a need to determine the availability to plant nutrients in biochar. Appropriate laboratory methods should be developed for measuring the availability of plant nutrients as standard methods of fertilizer analysis are ineffective.

Land use change from permanent rice to alternating rice-shrimp or permanent shrimp in the coastal Mekong Delta, Vietnam: Changes in the nutrient status and binding forms

Saline water intrusion has become a severe threat in the coastal areas of Mekong delta of Vietnam, though offering farmers the option to diversify their land use, and switching, for instance, from permanent rice to alternating rice-shrimp systems or even to permanent shrimp systems. The objective of this study was to evaluate the respective impacts on soil salinity, nutrient status and their binding forms. Hence, we sampled the topsoils (cultivation layer, 0–15 cm) from 10 permanent rice systems and the rice platforms of 10 alternating riceshrimp systems. Furthermore, the sludges and the soils 10 cm underneath of the sludges from the ditches of the alternating rice-shrimp as well as from ponds of the permanent shrimp systems were sampled in Bến Tre and Sóc Trăng provinces, Vietnam, respectively. The samples were analyzed regarding their electric conductivity, total and plant-available nutrient contents. To reveal possible changes in nutrient binding forms, sequential P and S extraction, 31P-nuclear magnetic resonance spectroscopy, and S and P X-ray absorption near edge structure spectroscopy were applied. The results showed that permanent and alternating shrimp cultivation lead to elevated salt concentrations but also improved the overall nutrient status relative to the permanent rice management and especially in the sludges relative to the soils underneath. The continued deposition of shrimp and feed debris promoted the accrual of stable, Ca- and Mg-associated P forms as well as of P-monoesters, whereas the S forms were depleted in thiophene S groups but enriched in sulfides relative to permanent rice fields. As effects by alternating rice-shrimp management were intermediate, this management has more potential to serve as a no-regret strategy for farmers to remain flexible in their response to climate changes and concurrent salinity intrusion relative to permanent shrimp production, which requires strict maintenance of adequate salinity levels also during the rainy season.

Soil domestication by rice cultivation results in plant-soil feedback through shifts in soil microbiota

BackgroundSoils are a key component of agricultural productivity, and soil microbiota determine the availability of many essential plant nutrients. Agricultural domestication of soils, that is, the conversion of previously uncultivated soils to a cultivated state, is frequently accompanied by intensive monoculture, especially in the developing world. However, there is limited understanding of how continuous cultivation alters the structure of prokaryotic soil microbiota after soil domestication, including to what extent crop plants impact soil microbiota composition, and how changes in microbiota composition arising from cultivation affect crop performance.ResultsWe show here that continuous monoculture (> 8 growing seasons) of the major food crop rice under flooded conditions is associated with a pronounced shift in soil bacterial and archaeal microbiota structure towards a more consistent composition, thereby domesticating microbiota of previously uncultivated sites. Aside from the potential effects of agricultural cultivation practices, we provide evidence that rice plants themselves are important drivers of the domestication process, acting through selective enrichment of specific taxa, including methanogenic archaea, in their rhizosphere that differ from those of native plants growing in the same environment. Furthermore, we find that microbiota from soils domesticated by rice cultivation contribute to plant-soil feedback, by imparting a negative effect on rice seedling vigor.ConclusionsSoil domestication through continuous monoculture cultivation of rice results in compositional changes in the soil microbiota, which are in part driven by the rice plants. The consequences include a negative impact on plant performance and increases in greenhouse gas emitting microbes.

Aplikasi Jenis Pupuk organik terhadap Kadar Hara NPK dan Produksi Kedelai (Glycine max (L.) Merril) pada Jarak Tanam yang Berbeda di Lahan Pasang Surut

Marlina N, Aminah IS, Amir N, Rosmiah R. 2019. Application of organic fertilizer types to NPK nutrients levels and soybeans production (Glycine max (L.) Merril) at different planting spaces in tidal land. Jurnal Lahan Suboptimal: Journal of Suboptimal Lands. 8(2):148-158. Tidal lowlands flood type C is suboptimal land and very potential in cultivating soybean, but it has problems in soil fertility, macro and micro nutrient poor, therefore to increase soil fertility can be given various types of organic fertilizers, including cow manure organic fertilizer, chicken manure organic fertilizer and biofertilizer. All types of organic fertilizers are composted, and specifically biofertilizers are made with their own formula. It is expected that the organic fertilizer provided can increase soil fertility and nutrient availability for soybean plants. This study aimed to get the best type of organic fertilizer on the availability of nutrient levels of NPK and soybean production at different spacing in tidal land. This research was conducted in Jaya Agung Village, Lalan District, Musi Banyuasin Regency, South Sumatra Province, and was carried out in March 2018 - June 2018. The method used was the experimental method. The design used is a split-plot design. with 9 treatment combinations and repeated 3 times. As the main plot treatment is plant spacing (20 cm x 20 cm, 20 cm x 30 cm and 20 cm x 40 cm), and treatment of subplots are: types of cow manure organic fertilizers 10 ton/ha, chicken manure organic fertilizer 10 ton/ha, and biofertilizer 400 kg/ha. The results showed that the combination treatment of plant spacing of 20 cm x 30 cm with the type of biofertilizer 400 kg/ha could increase soybean production by 9.11 g/plot or equivalent to 2.43 ton/ha.

Assessment of Soil Nutrient Status under Different Cropping Systems in Khotang, Nepal

Availability of plant nutrients in rhizosphere is directly influenced by types of crop grown and land use pattern. The experiment was conducted in Diktel Rupakot Majhuwagadhi Municipality, Khotang, Nepal to assess the soil nutrients dynamics as influenced by different cropping system. Five different cropping systems (Rice – Wheat, Maize – Millet, Maize – Vegetables, Ginger and Cardamom) were selected as treatments and all treatments were replicated for five times for blocking in Randomized Complete Block Design. Soil samples from 0-15 cm depth were collected from each site and evaluated for soil pH, soil organic carbon (SOC), total nitrogen (N), available phosphorus (P), and available potassium (K). All the tested parameters except N were found to be significantly affected by cropping system. Soil in all five cropping systems were found acidic (pH<6.5) in nature with pH ranging from 5.180-6.640. The SOC was recorded highest (3.102%) from Cardamom based system and lowest amount of SOC was observed in Ginger based system. The highest amount of P (32.14 mg/kg) was reported in Maize – Vegetables cropping system and lowest P content (5.72 mg/kg) was recorded from Cardamom based system. P content in Ginger based system (31.51 mg/kg) was statistically at par with that of Rice – Wheat system. The highest K content (306.50 mg/kg) was recorded from Maize – Vegetable cropping system and lowest K content (34.80 mg/kg) was observed in Cardamom based system which is statistically similar to Rice –Wheat (35.70 mg/kg) and Maize –Millet systems (77.20 mg/kg). The result indicated that cropping systems have huge impact on plant nutrient dynamics in soil.
 Int. J. Appl. Sci. Biotechnol. Vol 7(3): 341-346

Effect of salinity on fungal diversity in the rhizosphere of the halophyte Avicennia germinans from a semi-arid mangrove

Abstract This study aimed to inventory fungal populations associated with the rhizosphere of Avicennia germinans in different salinity levels in a semi-arid mangrove in the Colombian tropics. Targeting the ITS1 and ITS2 regions provided complementary information, allowing a better approach to inventorying the fungal biodiversity. Amorosia and Aspergillus were the most abundant ascomycete genera, while Cystobasidium was the most abundant basidiomycete genus. Only five genera showed significant differences in abundance among the three salinity levels. Nevertheless, 65.4% of the genera were classified as exclusive for a specific salt content. Saprotrophs were the most abundant functional group and symbiotrophs were detected as mycorrhizas, fungi with biocontrol activity and entomopathogenic activity. These ecological groups play an important role in the cycling of organic matter and the availability of nutrients for mangrove plants and their tolerance to environmental and biotic stresses. This study highlights soil salinity as a determining factor in the composition of the fungal community in mangroves.

Modeling variability in the fire response of an endangered bird to improve fire-management.

Conservation managers regularly burn vegetation to regenerate habitat for fire-dependent species. When determining the time since fire at which to burn, managers model change in a species' occurrence over time, post-fire (fire-response curve) and identify the time since fire associated with decline in occurrence. However, where species exhibit variability in their fire response across space, using a single fire-response curve to determine the timing of burns may lead to burning habitat at an inappropriate time since fire. We tested if elevation, local topography, soil properties, vegetation type or evapotranspiration affect the fire response of the endangered Mallee Emu-wren Stipiturus mallee and its hummock-grass habitat Triodia scariosa in southeastern Australia (n=217). Previous work on the Mallee Emu-wren found a unimodal fire response with decline in occurrence at ~30-50yr since fire and a time window of occurrence of ~30yr. We found that time since fire and elevation interact to affect the Mallee Emu-wren fire response. At high elevations (55-98m), Mallee Emu-wrens declined in occurrence at ~50yr since fire, with a time window of occurrence of 20-40yr. However, at low elevations (28-55m), Mallee Emu-wrens showed no decline in occurrence with increasing time since fire with a time window of occurrence of up to 107yr. Extent cover of Tall T. scariosa showed similar patterns to the Mallee Emu-wren, indicating that vegetation structure is a likely driver of variability in the Mallee Emu-wren fire response. We speculate that the effect of low elevation is mediated by increased soil nutrient and water availability for key plants. We used our findings to map the appropriate time since fire at which to burn to regenerate habitat for the Mallee Emu-wren across the study region. We recommend no burning for regeneration across one-third of potential habitat, because the Mallee Emu-wren showed no decline in occurrence in these areas. We recommend managers model variability in species' fire responses across space to improve the timing of burns for regeneration.

Altered leaf elemental composition with climate change is linked to reductions in photosynthesis, growth and survival in a semi‐arid shrubland

Abstract Climate change will increase heat and drought stress in many dryland areas, which could reduce soil nutrient availability for plants and aggravate nutrient limitation of primary productivity. Any negative impacts of climate change on foliar nutrient contents would be expected to negatively affect the photosynthetic capacity, water use efficiency and overall fitness of dryland vegetation. We conducted a 4‐year manipulative experiment using open top chambers and rainout shelters to assess the impacts of warming (~2°C, W), rainfall reduction (~30%, RR) and their combination (W + RR) on the nutrient status and ecophysiological performance of six native shrub species of contrasting phylogeny in a semi‐arid ecosystem. Leaf nutrient status and gas exchange were assessed yearly, whereas biomass production and survival were measured at the end of the study. Warming (W and W + RR) advanced shoot growth phenology and reduced foliar macro‐ (N, P, K) and micronutrient (Cu, Fe, Zn) concentrations (by 8%–18% and 14%–56% respectively), net photosynthetic rate (32%), above‐ground biomass production (28%–39%) and survival (23%–46%). Decreased photosynthesis and growth in W and W + RR plants were primarily linked to enhanced nutritional constraints on carbon fixation. Poor leaf nutrient status in W and W + RR plants partly decoupled carbon assimilation from water flux and led to drastic reductions in water use efficiency (WUEi; ~41%) across species. The RR treatment moderately decreased foliar macro‐ and micronutrients (6%–17%, except for Zn) and biomass production (22%). The interactive impacts of warming and rainfall reduction (W + RR treatment) on plant performance were generally smaller than expected from additive single‐factor effects. Synthesis. Large decreases in plant nutrient pool size and productivity combined with increased mortality during hotter droughts will reduce vegetation cover and nutrient retention capacity, thereby disrupting biogeochemical processes and accelerating dryland degradation with impending climate change. Increased macro‐ and micronutrient co‐limitation of photosynthesis with forecasted climate change conditions may offset any gains in WUEi and productivity derived from anthropogenic CO2 elevation, thereby increasing dryland vegetation vulnerability to drought stress in a warmer and drier climate. The generalized reduction in leaf nutrient contents with warming compromises plant nutritional quality for herbivores, with potential cascading negative effects across trophic levels.

Vermicompost Influences Soil P Pools and Available N—Effect of Placement and Combination with Inorganic Fertiliser

Compost application can increase plant nutrient availability. But the effect of compost on nutrient availability may depend on a number of factors. In this study, the effect of application method (mulch layer or mixed into the soil) and combination with inorganic fertiliser on soil P pools and available N was investigated. Soil was filled in microcosm with six treatments, including control, vermicompost layer with or without fertilisers (CL, CL/F), bulk soil mixed with inorganic fertiliser alone (F), vermicompost alone (CM) and both of inorganic fertiliser and vermicompost (CM/F). The microcosms were incubated in the dark for 3 weeks. Citrate P, HCl P and resin P were the highest in F, but MBP was higher in CM and CM/F. Citrate P and HCl P were about three- and six-fold higher in CM and CM/F than in CL and CL/F. Available N was the highest in CL/F and 20% higher in CL than in CM. Vermicompost mixed into soil slightly increased soil nutrient availability compared to unamended soil but had little effect when placed on the soil surface. Vermicompost mixed into soil with inorganic N and P could be used to minimise loss of N and P after inorganic fertiliser addition and thereby provide a longer-lasting nutrient supply for plants.

Patterns of carbon, nitrogen and phosphorus dynamics during decomposition of fern leaf and fine root in a subtropical forest

Litter decomposition is a major driver of carbon and nutrient cycles and has major implications for carbon sequestration and plant nutrient availability in terrestrial ecosystems. The vast majority of litter decomposition studies have focused on the tree component in forest ecosystems, while little attention has been paid to understory components. Ferns, one ancient and diverse group of vascular plants, comprise a significant part of most forest understory layer. However, empirical study regarding decomposition rate and carbon, nitrogen and phosphorus release patterns of fern leaves and fine roots remains rare. Therefore, it is difficult to predict the ecological consequences of fern community changes resulting from forest management practices or other environmental changes. In this study, we examined the patterns of mass loss and carbon, nitrogen, and phosphorus gain, retention or loss during the decomposition of leaves and fine roots ( 2 mm) of 12 herbaceous fern species in a subtropical evergreen broad-leaved forest in Jinyun Mountain, Southwest China. We measured the initial carbon, nitrogen, and phosphorus concentrations of leaves and fine roots, and monitored the changes in carbon, nitrogen, and phosphorus after 113, 198, 386 and 586 day’ decomposition in the field. We hypothesized that: (H1) fern leaves would decompose faster than fine roots; (H2) nitrogen and phosphorus release patterns would be affected by the initial tissue nitrogen and phosphorus concentrations; and (H3) carbon, nitrogen and phosphorus release patterns of leaves and fine roots would coordinate across different fern species. The results showed that: (1) Initial carbon concentration of fern leaves were similar to fine roots, while initial nitrogen and phosphorus concentrations of leaves were significantly higher than those of fine roots. Litter mass, carbon, nitrogen and phosphorus remains of fern leaves were generally significantly lower than those of fine roots, supporting our first hypothesis (H1). (2) Carbon, nitrogen and phosphorus of fern leaves and roots exhibited different loss patterns. Leaf carbon, nitrogen and phosphorus generally directly lost during the entire decomposition process. By contrast, carbon, nitrogen and phosphorus of fine roots showed more complicated patterns such as direct loss, gain-loss, gain-loss-gain and always gain. In support of our second hypothesis (H2), we found that nitrogen or phosphorus release patterns were influenced by the initial tissue nitrogen or phosphorus concentrations, respectively. (3) Carbon remains between leaves and fine roots were significantly correlated after 113, 198 and 386 day’ decomposition in the field, but not after 586 d. Phosphorus remains between leaves and fine roots were significantly correlated after 198, 386 and 586 day’ decomposition in the field, but not after 113 d. By contrast, there was no significant relationship of the nitrogen remains between leaves and fine roots during the entire decomposition process. Thus, our third hypothesis (H3) was only partly supported. This result suggests that the above- and below-ground covariation patterns depend on specific element and the duration of decomposition. Our study improves our understanding of how fern species influence the carbon and nutrient cycling in subtropical forest.

Soil amendment with nanoresidues from water treatment increases P adsorption in saline soils

Soil salinity is a major food issue in Egypt because salinity modifies P nutrient availability for crop plants. Residues from wastewater treatment can be added to soils for fertilization, but there is actually little knowledge on the effect of nanoresidues on P availability. Here, we mixed nanoresidues, obtained by grinding raw residues of water treatment, with soils of increasing salinity. We studied P adsorption and nanoresidue morphology. Results show that the addition of 0.5% of nanoresidues increases P adsorption from 9.43 to 93.46 µg g−1 for non-saline soils and from 12.02 to 153.85 µg g−1 for saline soils. Accordingly, the P Freundlich constant (KF) increased from 64.60 to 515.94 mL g−1 in the saline soil. Fourier transform infrared and X-ray diffraction data suggest that ligand exchange and precipitation are the main mechanisms.

Biochar incorporation increased nitrogen and carbon retention in a waste-derived soil.

The synthesis of manufactured soils converts waste materials to value-added products, alleviating pressures on both waste disposal infrastructure and topsoils. For manufactured soils to be effective media for plant growth, they must retain and store plant-available nutrients, including nitrogen. In this study, biochar applications were tested for their ability to retain nitrogen in a soil manufactured from waste materials. A biochar, produced from horticultural green waste, was added to a manufactured soil at 2, 5 and 10 % (by weight), then maintained at 15 °C and irrigated with water (0.84 mL m-2 d-1) over 6 weeks. Total dissolved nitrogen concentrations in soil leachate decreased by 25.2, 30.6 and 44.0 % at biochar concentrations of 2, 5 and 10 %, respectively. Biochar also changed the proportions of each nitrogen-fraction in collected samples. Three mechanisms for biochar-induced nitrogen retention were possible: i) increased cation and anion exchange capacity of the substrate; ii) retention of molecules within the biochar pore spaces; iii) immobilisation of nitrogen through microbial utilisation of labile carbon further supported by increased soil moisture content, surface area, and pH. Dissolved organic carbon concentrations in leachate were reduced (-34.7 %, -28.9 %, and -16.7 %) in the substrate with 2, 5 and 10 % biochar additions, respectively. Fluorescein diacetate hydrolysis data showed increased microbial metabolic activity with biochar application (14.7 ± 0.5, 25.4 ± 5.3, 27.0 ± 0.1, 46.1 ± 6.1 µg FL g-1 h-1 for applications at 0, 2, 5, and 10 %, respectively), linking biochar addition to enhanced microbial activity. These data highlight the potential for biochar to suppress the long-term turnover of SOM and promote carbon sequestration, and a long-term sustainable growth substrate provided by the reuse of waste materials diverted from landfill.

The Role of Soil Fungi in K+ Plant Nutrition

K+ is an essential cation and the most abundant in plant cells. After N, its corresponding element, K, is the nutrient required in the largest amounts by plants. Despite the numerous roles of K in crop production, improvements in the uptake and efficiency of use of K have not been major focuses in conventional or transgenic breeding studies in the past. In research on the mineral nutrition of plants in general, and K in particular, this nutrient has been shown to be essential to soil-dwelling-microorganisms (fungi, bacteria, protozoa, nematodes, etc.) that form mutualistic associations and that can influence the availability of mineral nutrients for plants. Therefore, this article aims to provide an overview of the role of soil microorganisms in supplying K+ to plants, considering both the potassium-solubilizing microorganisms and the potassium-facilitating microorganisms that are in close contact with the roots of plants. These microorganisms can influence the active transporter-mediated transfer of K+. Regarding the latter group of microorganisms, special focus is placed on the role of endophytic fungus. This review also includes a discussion on productivity through sustainable agriculture.

Metabolic Profiling of Water-Soluble Compounds from the Extracts of Dark Septate Endophytic Fungi (DSE) Isolated from Scots Pine (Pinus sylvestris L.) Seedlings Using UPLC-Orbitrap-MS.

Endophytes are microorganisms living inside plant hosts and are known to be beneficial for the host plant vitality. In this study, we isolated three endophytic fungus species from the roots of Scots pine seedlings growing on Finnish drained peatland setting. The isolated fungi belonged to dark septate endophytes (DSE). The metabolic profiles of the hot water extracts of the fungi were investigated using Ultrahigh Performance Liquid Chromatography with Diode Array Detection and Electron Spray Ionization source Mass Spectrometry with Orbitrap analyzer (UPLC–DAD–ESI–MS–Orbitrap). Out of 318 metabolites, we were able to identify 220, of which a majority was amino acids and peptides. Additionally, opine amino acids, amino acid quinones, Amadori compounds, cholines, nucleobases, nucleosides, nucleotides, siderophores, sugars, sugar alcohols and disaccharides were found, as well as other previously reported metabolites from plants or endophytes. Some differences of the metabolic profiles, regarding the amount and identity of the found metabolites, were observed even though the fungi were isolated from the same host. Many of the discovered metabolites have been described possessing biological activities and properties, which may make a favorable contribution to the host plant nutrient availability or abiotic and biotic stress tolerance.

Why nonconventional materials are answers for sustainable agriculture

ABSTRACT

Biochar engineered to enhance the potential performance of soil in the Mediterranean region of Turkey

Biochar (BC) is a carbon-rich pyrolyzed material widely used in agriculture for soil amendment in order to enhance crop production and improve soil quality, carbon sequestration (C-sequestration), and mitigation of atmospheric C. Various functions of BC make it valuable; however, the heterogenic properties of BC raise questions regarding its suitability in a particular environment. The present study explored the heterogenic properties of BC with the aim of aligning its uses for soil and the environment. Different types of BC were prepared from feedstocks (FS) of sludge (S), animal waste (AW), and plants originating in the Mediterranean region. Physical and chemical characterization of BC was performed to evaluate its suitability for use in the Mediterranean region with regard to plant nutrient availability. To achieve this, pH, electrical conductivity (EC), and proximate, ultimate, and nutrient analyses were performed. Moreover, scanning electron microscopy (SEM) was also undertaken, and the C-stability of BC was observed using thermogravimetric analysis. Plant FS–derived BC exhibits a high moisture content, volatile matrix, and fixed and total carbon (TC) compared with sludge biochar (SBC) and AW-derived BC. A high calcium carbonate (CaCO3) content was observed in AW-derived BC. Furthermore, the porosity of BC revealed that soil microbes may be sustained inside the porous structure if used for soil amendment. The different FS-oriented BC studied here could potentially be used to amend soil. The AW-derived BC and plant FS–derived BC could be a good source of immediate nutrient release for plant growth in agriculture and C-sequestration, respectively.