Concentrations Of Available Nitrogen Research Articles

Foundation and evaluation of a diagnosis and recommendation integrated system for star apple (Chrysophyllum cainito L.)

Diagnosis and recommendation integrated system (DRIS) is a greatly accurate and reliable mean of evaluating the exact nutrition status of crops via foliar analysis. DRIS has been applied to many types of crops, but DRIS has not been established for and applied to star apple, which is an important fruit in many countries. Therefore, this study aims to (i) detect soil obstacles in star apple cultivation, (ii) create a DRIS for star apple, and (iii) apply the created DRIS norms to evaluate the macro-nutrition status of star apple. In total, 90 leaf samples were obtained from 90 different star apple farms, where 90 soil samples were also collected. The soil analysis results revealed that concentrations of available nitrogen and soluble phosphorus were low and medium, indicating a high risk of reduction in star apple yield. The average yield of star apple was 200.0 kg plant−1. The high-yielding group had higher concentrations of N, K, and Mg in the leaf than the low-yielding group; however, the concentrations of Fe and Mn in the leaf were opposite, and the concentrations of P, Ca, Cu, and Zn were equivalent in the two groups. The DRIS norms have been established for star apple with 28 nutrient ratio pairs and consisted of means, coefficients of variation, variances (S2), and variance ratios (S2 l/S2 h), whose values were 0.136–182.6, 21.0–69.5%, 0.0024–10400.9, and 1.89–34.3, respectively. The results of applying the DRIS norms revealed that the nutrient status of star apple was deficient of N, K, and Mg.

Tillage systems affect soil nitrogen availability and interact growth parameters of different faba bean cultivars

Abstract. Al-Enezy AFM, Zaidan BA, Almehemdi AF, Hussein AA, Salih MAA. 2023. Tillage systems affect soil nitrogen availability and interact growth parameters of different faba bean cultivars. Biodiversitas 24: 5558-5564. A field trial was conducted during the winter season of 2021-2022 in one of the agricultural lands of Hamid Shaban village, which belongs to Abu Ghraib District of Baghdad Province (33°17'51.3"N, 44°04'55.0"E). The aim of the experiment was to investigate nitrogen availability in two different tillage systems and the growth characteristics of six broad bean varieties on clay-loamy soils. The field trial was triplicated using the Randomized Complete Block (RCBD) method. The first factor was the six broad bean varieties (Turkish, Dutch, Italian, Spanish, American and local), the second factor was the cultivation system Conservation Tiltage (no-till) and the traditional cultivation with a mouldboard plow. The results showed that the availability of nitrogen in the soil in the traditional tillage system corresponds to the superior to conservative tillage systems. Where this gives an average available nitrogen concentration of 23.3 mg kg-1, an increase of 21 in relation to conservation tillage, which resulted in an average concentration of available nitrogen of 19.1 mg kg-1. In addition, all the growth characteristics of the plants favored the traditional agricultural system. In the variety comparison, the Italian variety was characterized by the highest nitrogen content available in the soil of 26.10 mg kg-1 as well as the highest values ??of plant growth properties among the six varieties.

Biochar Prepared by Microwave-Assisted Co-Pyrolysis of Sewage Sludge and Cotton Stalk: A Potential Soil Conditioner

The reduction and safe disposal of sewage sludge remains an urgent problem worldwide. In this work, biochar prepared from co−pyrolysis of sewage sludge and cotton stalk at different mix ratios and different pyrolysis temperatures was prepared using a novel microwave-assisted auger reactor. The obtained biochar samples were mixed with selected soil samples at different mix ratios for a short−term plant−growing test to examine their abilities as a soil conditioner on nitrogen fixation and retention. The addition of biochar could increase the total nitrogen in the soil to 0.3951% compared to 0.0403% in the untreated soil, while the concentration of available nitrogen could be increased to 114.45 mg·kg−1 compared to 47.95 mg·kg−1 in the untreated soil. Moreover, the introduction of biochar to the soil also contributed to the growth of corn seedlings, which grew at a rate of 3.41 cm·d−1 compared to 3.03 cm·d−1 in untreated soil. The results show that the addition of biochar can enrich total soil nitrogen before and after incubation and promote the growth of corn seedlings, providing a potential route for the safe disposal and resource recovery of sewage sludge.

Combined intensive management of fertilization, tillage, and organic material mulching regulate soil bacterial communities and functional capacities by altering soil potassium and pH in a Moso bamboo forest.

Intensive management is a common practice in agricultural and forestry ecosystems to improve soil quality and crop yield by influencing nutrient supply and soil microbiota; however, the linkage between soil nutrients and bacterial community and functional capacities in intensively managed economic forests has not been well studied. In this study, we investigated the soil properties such as available potassium (AK), available nitrogen (AN), available phosphorus (AP), ammonium (NH), nitrate (NO), organic matter (OM), total nitrogen (TN), total phosphorus (TP), bacterial diversity and community composition, potential functions of rhizome roots, and soil microbiota across a chronosequence of intensively managed Moso bamboo (Phyllostachys edulis) forests. Our results demonstrated that the combined intensive management (deep tillage, fertilization, and organic material mulching) in this study caused a significant increase in the concentrations of AK, AN, AP, NH, NO, OM, TN, and TP (P < 0.05). However, they led to a remarkable decrease in pH (P < 0.05). Such changes lowered the Shannon diversity of the soil and rhizome root microbiota but did not significantly affect the community composition and functional capacity. Soil bacterial community variation was predominantly mediated by soil total potassium (TK) (15.02%), followed by pH (11.29%) and AK (11.13%). We further observed that Nitrospirae accounted for approximately 50% of the variation in soil pH, NO, NH, and AK, indicating its importance in soil nutrient cycling, especially nitrogen cycling. Accordingly, we propose that the management-induced changes in soil parameters reshaped the bacterial community structure and keystone bacterial assemblage, leading to the differentiation of microbial functions.

Effect of Bio-Inoculum, Compost, and Humic Acid on NPK Availability in Tomato Soils

The study aimed to determine the influence of biological inoculation and organic fertilizer on the availability of nitrogen, phosphorous, and potassium (N.P.K.) in protected tomato soil. During the 2021 agricultural season, the experiment was conducted in greenhouses in the Al-Azzawiya area / Babylon Governorate (longitude 44.5E and latitude 32.7N). Bacterial bio-inoculum was used and compared with the control (S0 and S1), three levels of compost (C0, C1, C2) tons.ha-1, and three levels of organic fertilizer Humus (H0, H1, H2) and the interaction between them in nitrogen, phosphorous, and potassium were used. The results of the statistical analysis resulted in higher values of the triple interaction treatment (S1 + H2 + C2) than the control by giving it the highest mean concentration of available nitrogen, phosphorous, and potassium in the soil (48.70, 19.71, 255.33) mg.kg-1.soil for each, respectively.

The Interaction Effect between Mycorrhiza (Glomus Mosseae), Organic and Mineral Fertilizers on Growth, Yield of Cauliflower (Brassica Oleracea) and Some Desert Soil Characteristics

The current study aimed to evaluate the effect of adding Mycorrhiza, local organic fertilizer, and biochar (seek) singly or in combination on some properties of desert soils from the Karbala governorate. Coupled with the growth and yield of cauliflower (Brassica Oleracea) under different levels of mineral fertilization. A Biological experiment was carried out to achieve the objectives of the study by placing 20 kg of desert soil that was transported from the Holy Karbala Governorate from the site of Imam Hussein Agricultural City. This soil was placed in environmentally friendly bags made of linen cloth 50 cm in diameter and 35 cm in height. The biological experiment included three factors: organic fertilizer (local organic fertilizer, biochar (Seek) and without adding organic fertilizer) and biofertilizer (inoculation with mycorrhiza and without mycorrhiza). On the other hand, the third factor represents mineral fertilizer addition at three levels (100%, 50%, and 0 %) of the fertilizer recommendation for cauliflower. Generally, 16 g of biochar (Seek) for every 20 kg of soil was added by mixing to 15 cm of depth from the soil surface, while 500 g of local organic fertilizer was added in the same way. The results showed the superiority of adding Mycorrhiza in the availability of nitrogen and phosphorous in the soil after planting. It gives values of 92.00 mg N kg-1 soil and 9.18 mg p kg-1 soil in the inoculated soil compared to their concentration in the uninoculated soil, which amounted to 87.69 mg N kg-1 and 8.65 mg p kg-1 soil nitrogen and phosphorous, respectively. The results analysis showed also the superiority of adding a mixture of local organic fertilizer with biochar (Seek) in increasing the nitrogen availability in the soil. It gave 91.72 mg N kg-1 of soil compared to the treatment of adding seek alone and the control treatment, which gave values of 88.94 and 87.28 mg N kg -1soil, respectively.The study showed the positive and significant resultsof the triple interaction between the addition of mycorrhiza and the combination of organic fertilizer with the addition of 100% of the mineral fertilizer recommendation for cauliflower in increasing the concentration of available nitrogen in the soil, as it gave 101.00 mg N kg-1 soil compared to the control treatment, which gave 67.67 mg N kg-1soil. The addition of mycorrhiza contributed to an increase in the weights and curd diameters, the leaves dry weight and gave values of 711.1 g, 15.44 cm, 36.33 g compared to the control treatment for the same traits, which amounted to 562.4 g, 14.69 cm, and 27.08 g, respectively. Besides, the 100% addition of the recommendation resulted in higher values for leaves, curd diameters, and leaf dry weight to reach 697.9 g and 15.71 g respectively compared to not adding mineral fertilizer which gave values of 581.2 g, 14.08 cm, and 28.96 g respectively. Finally, the study findings showed the significant effect of adding combined bio-organic fertilizer in increasing the concentration of organic matter in the soil after planting, which amounted to 7.14 and 7.63 g.kg-1, compared to the control treatment, which gave 6.91 and 6.31 g. kg-1, respectively.

Changes in soil carbon and nutrients and related extracellular enzymes in successive rotations of Japanese larch plantations

Extensive areas of secondary forests (SF) have been converted into larch plantations to meet the demand for timber and other forest products in northeast China since the early 1960s. However, the successive rotations of larch plantations may alter the understory vegetation and soil properties following reforestation. The aim of this study was to determine how soil carbon and nutrients and related extracellular enzymes changed after conversion from SF to larch plantations. Six larch plantations, including 16-, 30- and 47-year-old in the first rotation, 8-, 16-, and 30-year-old in the second rotation, and one adjacent SF as the 0-year site were selected using the space-for-time substitution (chronosequence) method. The results showed that most soil parameters [pH, soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN) and available potassium (AK) concentrations, and β-glucosidase, N-acetyl-glucosamine, cellobiohydrolase, and phenol oxidase activities] decreased initially from 16- to 30-year-old in the first rotation, and then increased from 30- to 47-year-old in the first rotation and 8-year-old in the second rotation, and were finally reduced from 8- to 30-year-old in the second rotation after conversion from SF, whereas soil bulk density (SBD) showed the inverse pattern. However, SOC (except at 0–10 cm) and nutrient stocks did not change significantly along the chronosequence. Redundancy analysis showed that litter biomass significantly affected most of the soil parameters, and correlated significantly and negatively with the concentrations of SOC, TN, AN and AK, and the activities of β-glucosidase, N-acetyl-glucosamine, cellobiohydrolase and phenol oxidase, while it had a significant positive relationship with SBD. Thus, rational thinning treatments should be conducted at earlier 16 years to create available space and favorable conditions for understory vegetation and litter decomposition. The appropriate rotation age of a larch plantation should be > 45 years with effective measures to maintain soil sustainability.

Long-term effects of sustainable management practices on soil properties and crop yields in rainfed Mediterranean almond agroecosystems

The long-term effects of conservation agriculture on soil physical and chemical properties and their relationship with crop yields are still relatively poorly understood. In addition, the effects of those practices ranged widely depending on climatic and edaphic conditions and so they cannot be generalized for all agro-ecological regions and crop types. This study evaluates the effects of three conservation agriculture practices - reduced tillage (RT), reduced tillage plus incorporation of green manure (RTG), and no-tillage (NT) - on the soil quality on almond orchards under semiarid conditions and the soil factors explaining crop yield under these management practices. The soil physical indicators used were bulk density, resistance to penetration, total porosity, air capacity, relative field capacity, available water content, infiltration rate and field plant-available water content. The chemical parameters evaluated were soil organic carbon, total nitrogen, nitrate, and available phosphorus. Changes in the soil physical properties with the incorporation of green manure and with no-tillage, relative to RT were, mainly detected in the 5−15 cm soil layer, where improvements in soil water availability were observed. In addition, there was a positive effect of both green manure and no-tillage on the infiltration rate relative to RT. The shift from RT to RTG led to an improvement in total soil organic carbon and nitrogen, resulting in a positive effect on crop yield after six years of implementation. No-tillage led to a decline of about 70 % in crop yield with respect to the tillage treatments, despite the improvement in the soil available water content from the first year of its adoption. However, a strong decrease in the concentrations of available nitrogen was the factor mainly responsible for the crop yield reductions under NT.

Oil palm cultivation enhances soil pH, electrical conductivity, concentrations of exchangeable calcium, magnesium, and available sulfur and soil organic carbon content

AbstractThe land area under oil palm (Elaeis guineensis Jacq.) cultivation (OPC) is increasing in different parts of world. Assessment of the soil parameters of oil palm plantations (OPP) is essential to judge the sustainability of land use for maintaining soil fertility and avoiding land degradation. The effects of OPC in India on soil parameters are poorly understood. Therefore, we evaluated the impact of OPC over the years (by considering oil palm plantations of 6, 12, and 18 years age) on soil properties, nutrient availability, soil organic carbon (SOC) pools, and SOC stock in comparison with those parameters in adjacent fallow land (FL) of southern India. Soils of OPP showed enhanced soil pH value, electrical conductivity, the concentrations of exchangeable calcium and magnesium and available sulfur, and SOC content in 0–20, 20–40, and 40–60 cm depths of soil compared with those parameters in FL. Available phosphorus concentration in soil increased with plantation age revealing the need for rational phosphorus management. However, the concentration of available nitrogen, potassium, exchangeable calcium and magnesium, and available sulfur and boron did not change with plantation age. The contents of SOC and very labile carbon were higher in surface soil layers of OPP than that in FL. Oil palm cultivation led to 20, 18, and 45% enhancement in SOC stock in 6, 12, and 18 years‐old OPP, respectively, compared with SOC stock in FL indicating C sequestration due to OPC. The very labile and less labile C stock in FL, 6 and 12 years‐old OPP were similar, whereas the values of these parameters were higher in 18 years‐old OPP. Positive correlation (p &amp;#60; .01) of SOC with very labile, labile, and less labile carbon pools indicated their inter‐relatedness. This information will be utilized in devising rational nutrient management options for the existing as well as ensuing OPP due to variations in soil properties and available nutrients.

The Naphthalene Catabolic Genes of Pseudomonas putida BS3701: Additional Regulatory Control.

Pseudomonas microorganisms are used for bioremediation of soils contaminated with petroleum hydrocarbons. The overall remediation efficiency is largely dependent on the presence of macro- and micronutrients. Widely varying concentrations of available nitrogen and iron (Fe) in soils were shown to affect residual hydrocarbons in the course of biodegradation. The regulatory mechanisms of expression of hydrocarbon catabolic genes in low nitrogen/low iron conditions remain unclear. The catabolism of naphthalene, a two-ring polycyclic aromatic hydrocarbon, has been well studied in pseudomonads in terms of the involvement of specific transcriptional activators, thus making it useful in revealing additional regulatory control of the adaptation of hydrocarbon destructors to a low level of the essential nutrients. The Pseudomonas putida strain BS3701 is a component of the “MicroBak” preparation for soil remediation. Previously, this strain was shown to contain genes encoding the key enzymes for naphthalene catabolism: naphthalene 1,2-dioxygenase, salicylate hydroxylase, catechol 2,3-dioxygenase, and catechol 1,2-dioxygenase. Our study aimed to clarify whether the naphthalene catabolic gene expression is dependent on the amount of nitrogen and iron in the growth culture medium, and if so, at exactly which stages the expression is regulated. We cultivated the strain in low nitrogen/low iron conditions with the concurrent evaluation of the activity of the key enzymes and the mRNA level of genes encoding these enzymes. We are the first to report that naphthalene catabolic genes are subject not only to transcriptional but also post-transcriptional regulation.

Water quality, nutrients, and stable isotopic signatures of particulates and vegetation in a mangrove ecosystem exposed to past anthropogenic perturbations

Water quality in mangrove estuaries within Caroni Swamp, Trinidad is impaired by a combination of recent increases in nitrogen loads and lingering effects of a series of reclamation efforts that reduced tidal exchanges and fostered low oxygen and high ammonium concentrations, conditions that are relatively unusual for estuaries. Concentrations of available nitrogen diminish down-estuary, with an overall within-estuary interception of about 25% of total dissolved nitrogen. Caroni Swamp remains a productive mangrove environment, and a tourist attraction, in spite of failed and continuing reclamation efforts and increased N loads, a demonstration of remarkable resilience. Developing ecosystem-based management to support that resilience will benefit from improved understanding of processes involved in nitrogen retention and losses, consideration of the consequences in intensifying land use on contributing watersheds and plans to ease tidal water exchanges and diminish extent of shallow and stagnant areas.

Impacts of different soil fertility improvement practices with film mulched ridge-furrow til-lage on soil nutrient content, maize yield, and water use efficiency in Northwest China.

Improvement of soil quality is one of the most important ways to enhance fertility for efficient dryland crop production. However, the effects of different fertilization measurements with film mulched ridge-furrow tillage on soil fertility, crop yield, and water use efficiency (WUE) of maize largely remain unknown. A three-year field experiment was conducted at the Zhuanglang Experimental Station, Gansu Academy of Agricultural Sciences, located in the semiarid region of the Loess Plateau, Northwest China during 2014-2016. Maize breed Funong No.1 was used during the study. There were four treatments, including: 1) conventional planting (CP, served as control), 2) film mulched ridge-furrow with straw incorporation (FS), 3) film mulched ridge-furrow with optimizing fertilization (FF), and 4) film mulched ridge-furrow with controlled fertilization (FC). Seasonal and yearly changes of soil water content, topsoil organic matter (SOM), soil available nitrogen (AN), phosphorus (AP) and potassium (AK) concentration and crop yield were measured. Nitrogen and phosphorus fertilizer partial factor productivity (PFPN and PFPP), soil profile water storage (WC), crop seasonal water consumption (ET) and water use efficiency (WUE) were calculated. The results showed that FS, FF and FC effectively improved soil fertility via synergistic regulation of soil hydrothermal and nutritional condition. Water-fertilizer interaction effect greatly enhanced incorporated straw decomposition and crop growth, resulting in more returning of straw nutrients and crop biomass to soil, thus significantly increased soil water and fertilizer supply capacity. Compared to CP, the three treatments of FS, FF and FC efficiently increased the concentrations of SOM, AN, AP, and AK by 0.27 g·kg-1, 4.44 mg·kg-1, 0.20 mg·kg-1 and 4.53 mg·kg-1 with an order of FC＞FF＞FS, but had no significant difference among them. Meanwhile, in contrast to pre-sowing WC200, the three year's sum of FS,FF and FC increased WC200 at the end of growing season by 107.41, 38.99 and 28.35 mm, respectively. On average, FS, FC and FF significantly reduced maize ET by 60.50, 37.7 and 34.15 mm to CP, with a relative decrease of 12.6%, 7.9% and 7.1% respectively. By the synergistic effect of modified water and fertilizer environment, the three soil fertility improvement strategies greatly enhanced maize growth from tasseling to maturity stages in the relatively dry year. They affected maize growth in relatively more rain and warmer year, resulting in significantly increased maize yield by improving the yield traits (double ear rate, grain number per ear and 100-grain mass), PFPN, PFPP and WUE. Compared to CP, the PFPN,PFPP of FS, FF and FC increased by 1.82, 1.65, 1.62 and 2.41, 1.69, 1.63 times respectively. Yield and WUE were increased by 5986.1, 4972.31, 4585.63 kg·hm-2 and 13.27, 12.65, 14.01 kg·mm-1·hm-2 correspondingly raised by 81.5%, 67.7%, 62.5% and 86.5%, 82.5%, 91.3%. In conclusion, FS was more effective in water harvesting and drought resistance, while FC and FF were effective for high yield.

Effects of microbial fertilizer on soil improvement and fruit quality of kiwifruit in old orchard.

The continuous cropping obstacles caused by the increase of kiwifruit planting period resulted in imbalance of soil microbial community structure, and decrease of soil enzyme activity and physicochemical indicators, which substantially reduced both the quality and yield of kiwifruit. Under the field conditions, the traditional fertilization of fruit farmers was used as a control (CK) to study the effects of two different microbial fertilizers, JF and KF, which had been verified the growth promotion of kiwifruit aseptic seedlings test, on soil microbial community structure, soil enzyme activities, soil physicochemical characters during different growth periods of kiwifruit (germination period, florescence period, fruit enlargement period, fruit ripening period and next year germination period), as well as fruit quality. The results showed that both fertilizers significantly increased the ratio of bacteria with fungi and the ratio of actinomycetes with fungi in the kiwifruit orchard soil, indicating that they could improve and balance the soil microbial community structure. The enzymes activity in kiwifruit orchard soil with the addition of both fertilizers were significantly higher than that in CK, and among which sucrose, urease, phosphatase and polyphenol oxidase were increased by 17.9%-83.5%, 7.9%-83.0%, 7.3%-45.4% and 8.1%-140.3%, respectively. JF and KF increased soil fertility (the concentrations of available nitrogen, phosphorus, potassium, total nitrogen, total phosphorus, total potassium, and organic matter content significantly increased) and decreased soil pH (a decrease of 0.29 to 0.34). After application of microbial ferti-lizer, the content of vitamin C, soluble sugar, soluble protein and other contents of kiwifruit increased, and the titratable acid content decreased. Therefore, the application of both fertilizers could balance soil microbial community structure, enhance soil fertility, and improve the fruit quality of kiwifruit. Our results provide robust theoretical basis for the application of microbial fertilizers in the old-aged kiwifruit orchards.

Effects of Adding Nitrogen to Vermicompost on Tomato Seedlings Under Greenhouse Conditions

ABSTRACTVermicompost, a byproduct of earthworm digestion of organic solid waste is receiving attention as a peat substitute in the production of plug seedling media. We aimed to test the effects of adding nitrogen to vermicompost on the morphological development of tomato seedlings. Nursery experiments on tomato seedlings were carried out in the greenhouse. Urea at 0.00 kg/m3, 0.25 kg/m3, 0.50 kg/m3, and 1.00 kg/m3 was added to vermicompost and to the vermicompost-vermiculite (at a volume ratio of 4:1) mixture. Results showed that (1) Nitrogen application at different rates to the vermicompost significantly increased the strong seedling index (SSI) at the middle (T1) and late (T2) seedling growth stages. Besides, nitrogen application significantly increased concentrations of available nitrogen (available-N) at the beginning of seedling cultivation (T0) and nitrate nitrogen (NO3−-N) at T2 in vermicompost. (2) Adding nitrogen to vermicompost significantly increased the number of root tips at T1 and T2 and the root volume at T2. And it significantly decreased the electrical conductivity (EC), total N (TN), available N, ammonium N (NH4+-N), and NO3−-N at T1 and T2. (3) Adding nitrogen to the vermicompost-vermiculite mixture significantly increased the root/shoot ratio, and SSI at T1 and T2. And it significantly increased the pH and reduced the EC at T1 and the available-N, NH4+-N, and NO3−-N at T2. In short, adding nitrogen (0.5～1.0 kg/m3 urea) to vermicompost improved the shoot and root morphological development of tomato seedlings, as well as the biomass accumulation and allocation. Adding nitrogen to the vermicompost-vermiculite mixture further promoted the development of tomato seedlings.

Simultaneous addition of zero-valent iron and activated carbon on enhanced mesophilic anaerobic digestion of waste-activated sludge.

The performance of biogas generation and sludge degradation was studied under different zero-valent iron/activated carbon (ZVI/AC) ratios in detail in mesophilic anaerobic digestion of sludge. A good enhancement of methane production was obtained at the 10:1 ZVI/AC ratio, and the cumulative methane production was 132.1mL/g VS, 37.6% higher than the blank. The methane content at the 10:1 ZVI/AC ratio reached 68.8%, which was higher than the blank (55.2%) and the sludge-added AC alone (59.6%). For sludge degradation, the removal efficiencies of total chemical oxygen demand (TCOD), proteins, and polysaccharides were all the highest at the 10:1 ZVI/AC ratio. The concentration of available phosphorus (AP) decreased after anaerobic digestion process. On the other hand, the concentrations of available nitrogen (AN) and available potassium (AK) increased after the anaerobic digestion process and showed a gradually decreasing trend with increasing ZVI/AC ratio. The concentrations of AN and AK were 2303.1-4200.3 and 274.7-388.3mg/kg, showing a potential for land utilization.

Microbial inoculation of seeds characteristically shapes the rhizosphere microbiome in desi and kabuli chickpea types

Chickpea is generally cultivated after seed treatment with host-specific Mesorhizobium ciceri, the nitrogen-fixing bacterium forming root nodules. Some species of free-living cyanobacteria are capable of nitrogen fixation. We examined the rhizosphere microbiota changes and the potential for plant growth promotion by applying a free-living, nitrogen-fixing cyanobacterium and the biofilm formulation of cyanobacterium with M. ciceri, relative to M. ciceri applied singly, to two each of desi and kabuli varieties of chickpea. Denaturing gradient gel electrophoresis (DGGE) profiles of archaeal, bacterial and cyanobacterial communities and those of phospholipid fatty acids (PLFAs) were obtained to evaluate the changes of the microbial communities in the chickpea rhizosphere. Plant growth attributes, including the pod yields and the availabilities of soil macronutrients and micronutrients, were monitored. The DGGE profiles showed distinct and characteristic changes due to the microbial inoculation; varietal differences exerted a marked influence on the archaeal and cyanobacterial communities. However, bacterial communities were modulated more by the type of microbial inoculants. Abundance of Gram-negative bacteria (in terms of notional PLFAs) differed between the desi and the kabuli varieties inoculated with M. ciceri alone, and the principal component analysis of PLFA profiles confirmed the characteristic effect of microbial inoculants tested. Microbial inoculation led to increases in the 100-seed weight and differential effects on the concentrations of available nitrogen and phosphorus, and those of iron, zinc and copper, suggesting their increased cycling in the rhizosphere. Microbial inoculation of chickpea brought out the characteristic changes in rhizosphere microbiota. Consequently, the growth promotion of chickpea and nutrient cycling in its rhizosphere distinctively differed. Further studies are needed to analyse the association and dynamic changes in the microbial communities to define the subset of microorganisms selected by chickpea in its rhizosphere and the influence of microbial inoculation.

The Relative Concentrations of Nutrients and Toxins Dictate Feeding by a Vertebrate Browser, the Greater Glider Petauroides volans.

Although ecologists believe that vertebrate herbivores must select a diet that allows them to meet their nutritional requirements, while avoiding intoxication by plant secondary metabolites, this is remarkably difficult to show. A long series of field and laboratory experiments means that we have a good understanding of the factors that affect feeding by leaf-eating marsupials. This knowledge and the natural intraspecific variation in Eucalyptus chemistry allowed us to test the hypothesis that the feeding decisions of greater gliders (Petauroides volans) depend on the concentrations of available nitrogen (incorporating total nitrogen, dry matter digestibility and tannins) and of formylated phloroglucinol compounds (FPCs), potent antifeedants unique to Eucalyptus. We offered captive greater gliders foliage from two species of Eucalyptus, E. viminalis and E. melliodora, which vary naturally in their concentrations of available nitrogen and FPCs. We then measured the amount of foliage eaten by each glider and compared this with our laboratory analyses of foliar total nitrogen, available nitrogen and FPCs for each tree offered. The concentration of FPCs was the main factor that determined how much gliders ate of E. viminalis and E. melliodora, but in gliders fed E. viminalis the concentration of available nitrogen was also a significant influence. In other words, greater gliders ate E. viminalis leaves with a particular combination of FPCs and available nitrogen that maximised the nutritional gain but minimised their ingestion of toxins. In contrast, the concentration of total nitrogen was not correlated with feeding. This study is among the first to empirically show that browsing herbivores select a diet that balances the potential gain (available nutrients) and the potential costs (plant secondary chemicals) of eating leaves. The major implication of the study is that it is essential to identify the limiting nutrients and relevant toxins in a system in order to understand feeding behaviour.

Maize varieties released in different eras have similar root length density distributions in the soil, which are negatively correlated with local concentrations of soil mineral nitrogen.

Larger, and deeper, root systems of new maize varieties, compared to older varieties, are thought to have enabled improved acquisition of soil resources and, consequently, greater grain yields. To compare the spatial distributions of the root systems of new and old maize varieties and their relationships with spatial variations in soil concentrations of available nitrogen (N), phosphorus (P) and potassium (K), two years of field experiments were performed using six Chinese maize varieties released in different eras. Vertical distributions of roots, and available N, P and K in the 0–60 cm soil profile were determined in excavated soil monoliths at silking and maturity. The results demonstrated that new maize varieties had larger root dry weight, higher grain yield and greater nutrient accumulation than older varieties. All varieties had similar total root length and vertical root distribution at silking, but newer varieties maintained greater total root length and had more roots in the 30–60 cm soil layers at maturity. The spatial variation of soil mineral N (Nmin) in each soil horizon was larger than that of Olsen-P and ammonium-acetate-extractable K, and was inversely correlated with root length density (RLD), especially in the 0–20 cm soil layer. It was concluded that greater acquisition of mineral nutrients and higher yields of newer varieties were associated with greater total root length at maturity. The negative relationship between RLD and soil Nmin at harvest for all varieties suggests the importance of the spatial distribution of the root system for N uptake by maize.

Nutritional Value of Habitat for Moose on Urban and Military Lands

Abstract Moose Alces alces are large and conspicuous animals valued for wildlife watching and hunting opportunities. However, near urban areas they can cause collisions with vehicles and damage to garden and ornamental plants. We studied a population of adult female moose that lives in and around both urban and industrial development on an active Army and Air Force base adjacent to Anchorage, Alaska, to evaluate nutrition and diet, map habitat quality, and model how habitat development affects the number of moose the landscape can support. Population density was moderate and hunter harvest was high in our study area, so we hypothesized that moose in our study area would be in similar condition to other healthy populations in Alaska. We also hypothesized that, in our study area, shrublands would support more moose than any other habitat type and that areas disturbed for urban development would be crucial to maintaining the local moose population. Rump fat depths, blood chemistries, and pregnancy rates in November and March for moose in our study area were consistent with populations in good to moderate condition. Microhistology of composite fecal samples indicated that willows Salix spp. dominated the summer diet, whereas the winter diet was divided among willows, birch Betula spp., and cottonwood Populus balsamifera. Low concentrations of available nitrogen in winter stems limited the number of moose that could be supported in our study area. Shrublands were the most valuable habitat type for moose, theoretically supporting 11–81 times more moose per hectare than any other habitat type. Shrublands were more concentrated within the developed portion of our study area than the surrounding undeveloped portions of the military base; and the access to shrublands in clearings, greenbelts, and parks sustains the productivity of this moose population despite the many disturbances of an urbanized landscape. Our habitat values can be used to model potential impacts of habitat modification on the number of moose the landscape can support.

Nutritional correlates of koala persistence in a low-density population.

It is widely postulated that nutritional factors drive bottom-up, resource-based patterns in herbivore ecology and distribution. There is, however, much controversy over the roles of different plant constituents and how these influence individual herbivores and herbivore populations. The density of koala (Phascolarctos cinereus) populations varies widely and many attribute population trends to variation in the nutritional quality of the eucalypt leaves of their diet, but there is little evidence to support this hypothesis. We used a nested design that involved sampling of trees at two spatial scales to investigate how leaf chemistry influences free-living koalas from a low-density population in south east New South Wales, Australia. Using koala faecal pellets as a proxy for koala visitation to trees, we found an interaction between toxins and nutrients in leaves at a small spatial scale, whereby koalas preferred trees with leaves of higher concentrations of available nitrogen but lower concentrations of sideroxylonals (secondary metabolites found exclusively in eucalypts) compared to neighbouring trees of the same species. We argue that taxonomic and phenotypic diversity is likely to be important when foraging in habitats of low nutritional quality in providing diet choice to tradeoff nutrients and toxins and minimise movement costs. Our findings suggest that immediate nutritional concerns are an important priority of folivores in low-quality habitats and imply that nutritional limitations play an important role in constraining folivore populations. We show that, with a careful experimental design, it is possible to make inferences about populations of herbivores that exist at extremely low densities and thus achieve a better understanding about how plant composition influences herbivore ecology and persistence.