Initial Soil Samples Research Articles

EFFECT OF SOME SOIL CONDITIONERS ON PHYSICAL AND CHEMICAL PROPERTIES OF NORTH SINAI SANDY SOILS

A pot experiment was carried out during the early winter of 2016-2017 at the Experimental Farm of Faculty of Environmental Agricultural Sciences, Arish University, to evaluate the use of some soil conditioners on physical and chemical properties of Arish sandy soil, Wheat (Triticum aestivum L.,CV Sakha 94) plants were grown in pots, A surface sandy soil sample (0-15cm) from the Experimental Farm of the Faculty was used in the study. Each conditioner was homogenously distributed on the soil surface and then were mixed with the upper 15 cm of soil surface. Grains of wheat were sown in each pot containing 20 Kg soil. NPK fertilizers were added as recommended. Vinasse, humic acid and polyacrylamide were added at three rates (0.5,1.0 and1.5(W/W)). The experimental design was complete randomized with four replicates for each treatment. Results of pH showed that the effect of applied both vinasse and humic acid to the soil in different rates led to slightly decrease on pH values gradually by increasing the rate of application. The result of acrylamide polymer show that the effect of the application to the soil led to increase pH values gradually by increasing the rate of application. Results of EC in soil show that the effect of applied vinasse, humic acid and acrylamide polymer to the soil in different rates led to increase on EC values gradually by increasing the rate of application. Also, data showed an increase in available N, P and K at all application, the higher value of N observed on application of vinasse on rates of V2 at the initial soil sampling periods, V3 at the mid-season and harvesting soil sampling periods. The higher value of P observed on application of vinasse on rates V3 at the initial soil sampling periods and HA3 at the mid-season and harvesting soil sampling periods and the higher value of K observed with application of V3 at all experiment periods. Except vinasse treatments, the mean values of organic matter, significantly increased with increasing the rates of the application the higher value HA3. Also, data indicate that for all studied levels of vinasse significantly increase soil organic matter values comparing to control treatments, HA3 achieve the highest increasing values of OM while application of PAM3 treatment was the superior for increasing soil OM. All studied levels of vinasse significantly increased soil bulk density. Apparently, HA2 and HA3 achieved the highest reducing values of BD. Such decreases represent about 8.05% and 7.89% lower than control treatment for the previously mentioned two HA rates and PAM3 treatment was the superior to other PAM3 for reducing soil BD, such decrease was 0.13 Mg m-3at the development stage of soil sampling and represent about 8.87% lower than control treatment. Results also revealed that there was a pronounced decreasing in soil Ks at the Initial period of soil sampling. Soil moisture content in both field capacity and witting point were increase along most of the studied soil sampling stages. The highest N, P and K content in grains was found for addition V3. Also, the highest grains yield was found for addition (vinasse)V3 while the control treatment had the lowest values.

Rehabilitation of Old and Moribund Cacao Soil Using Organic Amendments in Ibadan and Owena of South West Nigeria

Aims: To evaluate the effects of organic amendment in the rehabilitation of two moribund cacao plantations at Ibadan (Oyo State) and Owena (Ondo State) using organic materials that included Cocoa Pod Husk (CPH) and Neem Leaf powder (NL).
 Study Design: The experiment was laid out in a Randomized Complete Block Design in four replicates with four treatments which were CPH, CPH+NL (90:10), CPH+NL (80:20) and untreated.
 Place and Duration of Study: Cocoa plantations at Ibadan and Owena, Nigeria between May, 2014 and Dec 2017.
 Methodology: Initial soil sampling was done. Organic materials were applied to eight cacao trees in a ring at the base of trees in treated plots at the beginning of the rains in April/May and August/September. The treatments are: CPH Only @ 0.5 kg/tree, CPH Fortified with Neem Leaf (90:10) @ 0.45 kg + 0.05 kg/tree, respectively, CPH fortified with Neem Leaf (80:20) @ 0.40 kg + 0.10 kg/tree respectively. No application (control treatment).
 Results: Eleven fungi species assigned to seven genera were recovered across the treatments. Organic amendments significantly (p<0.05) increased soil mineralization, microbial populations and pod production. After the second year of applications, CPH had the highest percentage of pod production over the control (64%) in Ibadan, while in Owena, CPH, CPH+NL (80:20) and CPH+NL (90:10) had percentage pod increase of 68, 64 and 63%, respectively, over the control. Organic materials had significant (p≤0.05) effect in raising the soil pH in the two locations from 6.41 to 6.82 in Owena and from 6.50 to 6.89 in Ibadan, compared to untreated soil.
 Conclusion: The use of organic amendments in the rehabilitation of old and moribund cocoa (near death), improved soil nutrients as well as increased pod production and the microbial populations from the two plantations.

Standardised soil profile data to support global mapping and modelling (WoSIS snapshot 2019)

Abstract. The World Soil Information Service (WoSIS) provides quality-assessed and standardised soil profile data to support digital soil mapping and environmental applications at broadscale levels. Since the release of the first “WoSIS snapshot”, in July 2016, many new soil data were shared with us, registered in the ISRIC data repository and subsequently standardised in accordance with the licences specified by the data providers. Soil profile data managed in WoSIS were contributed by a wide range of data providers; therefore, special attention was paid to measures for soil data quality and the standardisation of soil property definitions, soil property values (and units of measurement) and soil analytical method descriptions. We presently consider the following soil chemical properties: organic carbon, total carbon, total carbonate equivalent, total nitrogen, phosphorus (extractable P, total P and P retention), soil pH, cation exchange capacity and electrical conductivity. We also consider the following physical properties: soil texture (sand, silt, and clay), bulk density, coarse fragments and water retention. Both of these sets of properties are grouped according to analytical procedures that are operationally comparable. Further, for each profile we provide the original soil classification (FAO, WRB, USDA), version and horizon designations, insofar as these have been specified in the source databases. Measures for geographical accuracy (i.e. location) of the point data, as well as a first approximation for the uncertainty associated with the operationally defined analytical methods, are presented for possible consideration in digital soil mapping and subsequent earth system modelling. The latest (dynamic) set of quality-assessed and standardised data, called “wosis_latest”, is freely accessible via an OGC-compliant WFS (web feature service). For consistent referencing, we also provide time-specific static “snapshots”. The present snapshot (September 2019) is comprised of 196 498 geo-referenced profiles originating from 173 countries. They represent over 832 000 soil layers (or horizons) and over 5.8 million records. The actual number of observations for each property varies (greatly) between profiles and with depth, generally depending on the objectives of the initial soil sampling programmes. In the coming years, we aim to fill gradually gaps in the geographic distribution and soil property data themselves, this subject to the sharing of a wider selection of soil profile data for so far under-represented areas and properties by our existing and prospective partners. Part of this work is foreseen in conjunction within the Global Soil Information System (GloSIS) being developed by the Global Soil Partnership (GSP). The “WoSIS snapshot – September 2019” is archived and freely accessible at https://doi.org/10.17027/isric-wdcsoils.20190901 (Batjes et al., 2019).

Converting Conventional Agriculture to Poplar Bioenergy Crops: Soil Chemistry

ABSTRACTWoody bioenergy is a viable source of alternative energy; however, questions remain on how purpose-grown bioenergy feedstock production management impact surface soil chemistry. In order to understand the soil processes under poplar (Populus spp.) trees and adjacent agricultural sites, surface (0–15 cm) soil samples were collected from four northwestern United States locations over a four-year period. Initial and final surface soil samples were analyzed for various soil chemical parameters, including organic matter, pH, cation exchange capacity and nutrient concentrations. Fields selected to compare poplar and agricultural management initially differed in some key soil chemical parameters. Many soil chemical parameters changed over time and the magnitude of change often depended on location; however, initial differences between management types within any one location did not change over time for most soil chemical variables. Consistent in-location differences between management types over time show poplar did not alter soil chemical parameters relative to agricultural management during the study period. Together all observations indicate that little of the overall soil chemistry was impacted by the introduction of poplar in the traditionally agricultural fields.

Effect of Electron Acceptor on Hydrocarbon Pollution Degradation Rate Caused by Bacteria of the Genus Rhodococcus under Anaerobic Conditions

The effect of the concentration of an oxygen acceptor in the form of a nitrate-containing salt on the rate and mechanism of hydrocarbon degradation (HC) in actual soil samples extracted from wells of 1 to 5 m in depth from areas allocated for future urban development under the influence of bacterial strains belonging to the genus Rhodococcus (R. ruber Ac-1513 D and R. erythropolis Ac-1514 D) is studied. Initial soil samples containing up to 9.8% HC were capable of producing biogas for 59 years under anaerobic conditions, in the absence of an oxygen acceptor, under the influence of methane-forming indigenous microorganisms. At the same time, the content of fire-dangerous methane in gas products ranged from 8 to 36%, which makes housing development in such areas unacceptable without preliminary treatment. To accelerate hydrocarbon degradation by oil-oxidizing bacteria under non-specific oxygen-free conditions, it was proposed to use an electron acceptor, calcium nitrate. The mechanism of hydrocarbon degradation in the presence of Ca(NO3)2 through denitrification has been established. It is shown that effect of calcium nitrate studied in the presence of three concentrations (1.25, 2.5, and 5.0%) on denitrification and anaerobic HC degradation was reversely proportional, which may be associated with the inhibition of the denitrification process by high concentrations of Ca(NO3)2. In the presence of a minimum concentration of calcium nitrate (1.25%), maximum rates of anaerobic HC degradation in the soil are of k = 1.27 and 0.32 year–1 during warm and cold seasons, respectively. The content of the main non-flammable reaction product, carbon dioxide in the gas mixture was 99% by volume. Thus, the complete decomposition of the hydrocarbon and the gas generation phase may be completed within 1 year, which is 59 times faster than processes occurring in the absence of an oxygen acceptor.

Lime soil conditioner based on soda production sludge for reclamation of industry-disturbed soils in the impact zone of an oil refinery

The paper presents the results of a study on the use of soda production sludge (SPS) as a lime soil conditioner. SPS with a less than 0.1 mm fraction is the most suitable in terms of physical, chemical, and toxicological properties and meets the requirements of GOST-14050-93 «Limestone (dolomite) dust. Specifications» on the content of the active substance, the mass fraction of calcium and magnesium carbonates. Reclamative properties of SPS were studied on soil samples taken in the territory removed from the sanitary protection zone of the oil refinery. It was found that all soil samples have a phytotoxic effect on pea seedlings. The introduction of SPS in amount of 1-3 g per kg of soil stimulates the development of the ground part and roots of oats and peas, and also increases the germination energy of oat and pea seeds in the initial soil samples by 2÷10 times. The introduction of SPS into the samples of the studied soils at a dose of 1-3 g/kg stimulates the development of colonies of Azotobacter bacteria and leads to an increase in the total number of soil microorganisms. The introduction of SPS in an amount of 3 g per kilo of soil leads to a slight increase in the environment reaction and an increase in the content of water-soluble salts in the soil up to 2 times. In view of this, it is necessary to control that the content of water-soluble salts does not exceed the established standards. Based on the results obtained, we consider it expedient to use soda production sludge as a lime soil conditioner and for the reclamation of industry-disturbed soils.

Integrated Effects of Vermi-compost and NPS Fertilizer Rates on Soil Chemical Properties and Maize Production in Bedele District, Western Oromia

Integrated plant nutrient management is the application of inorganic fertilizer in combination with organic fertilizer to maintain soil fertility and balance nutrient supply in order to boost up the crop yield per unit area. A study was conducted in Bedele District on farmers' fields to find out the combined effects of vermi-compost (organic fertilizer) and NPS (inorganic fertilizer) rates on soil chemical properties and maize production. The treatments consisted of three levels of vermi-compost (0, 1.5 and 3 t ha-1) and three levels of NPS fertilizer (0, 100 and 200 kg ha-1). The experiment was laid out in RCBD design in factorial combination with three replications. laboratory analysis results of composite soil samples collected before sowing showed deficiency in soil chemical properties. However, analysis of variance of post harvest composite soil samples collected from each plot indicated significant differences on soil available P, OC, TN and CEC while, soil pH and exchangeable acidity showed positive improvement as compared to initial soil sample. The analysis of variance among the treatments showed significant differences (P ≤ 0.05) on almost all the maize characters tested. The highest and lowest maize grain yield (7932.1 kg ha-1) and (1944.4 kg ha-1) were obtained from the treatment combination of 3 t ha1 vermi-compost with 200 kg ha-1 NPS and 92 kg ha-1 N, and control plot, respectively. However this combination was statically at par with the treatment combination of 1.5 t ha-1 vermi-compost with 200 kg ha-1 NPS and 92 kg ha-1 N, which gave maize grain yield (7577.2 kg ha-1). Therefore, the present study showed that combined fertilization of vermi-compost and NPS fertilizer enhanced maize productivity and soil fertility status in the study area; indicated that maize productivity in the study sites were reduced due to high demand for external nutrient inputs. Hence combined fertilization of 1.5 t ha1 vermi-compost with 200 kg ha-1 NPS and 92 kg ha-1 N could improve maize productivity and soil chemical properties, and recommended for the study area (Bedele District) and similar agro-ecology. The result also showed that the soils of the study sites had poor chemical fertility and integrated soil fertility management practices can improve the current situation.

Changes in soil properties for 6 years of using the freshwater snail (Ampullaria tischbeini Dohrn) in a reclaimed sodic soil

PURPOSE: A field experiment was carried out to assess the effects of using the freshwater snail (Ampullaria tischbeini Dohrn) in a reclaimed sodic soil that contains low salt concentrations for 6 years. MATERIALS AND METHODS: A field experiment was conducted during 2010–2015 at the experimental station located in Yomju County, North Phyongan Province, DPR Korea. Initial soil sampling was performed at random from the plots after rice harvest just before the start of the experiment in the early November 2009; these were analyzed for basic soil properties such as pH, macronutrients, exchangeable cations, bulk density, and water infiltration. Soil sampling for the present study was performed after the rice harvest each year for 6 years, to determine the effect of using A. tischbeini on soil properties. RESULTS AND DISCUSSION: The bulk density and infiltration rate in the experimental plots with snails were significantly improved as compared to the control plot without snails at 0–10, 10–20, and 20–30 cm soil depths. Compared to controls, the experimental plots had significantly higher pH (average 5.6 vs. 4.6, P < 0.01) and organic matter content (average 3.5 vs. 1.9%, P < 0.01). Calculations for 0–10 cm soil depth showed that the experimental plots with snails contained 38.3 and 33.1 mg kg⁻¹ more N and P contents than control plots without snails, respectively. Like N and P, the soil in the experimental plots had significantly higher available K contents compared with control plots. The soil also showed a dissimilar pattern of change in the concentration of exchangeable ions (Na⁺, Ca²⁺, and Mg²⁺) with a decrease in the Mg²⁺ to Ca²⁺ ratios. CONCLUSIONS: A. tischbeini plays an important role in the improvement of soil physical-chemical properties, although our field experiment with the snail has not been carried out under different conditions of soil, climate, distribution of crops, fertilizer application, and agricultural management. Further work now needs to assess the direct effects of the use A. tischbeini on soil microbes and micronutrients under different field conditions.

The abundance of arbuscular mycorrhizal fungal species in symbiosis with okra plants is affected by induced drought conditions in a calcareous substrate

Here we examined the effect of soil drought conditions on the community and abundance of arbuscular mycorrhizal fungi (AMF) in symbiosis with okra (Abelmoschus esculentus), where the inoculated AMF community was originally obtained from the rhizosphere of an okra crop grown in the Sudan. Okra seedlings were cultivated in a calcareous pot substrate, where the water content was either maintained at 20% for the well-watered (W) or reduced to 10% for the drought treatment (D). At harvest, in both irrigation treatments the root length was highly AMF colonised and compared with treatment W, the drought condition (D) significantly limited the uptake of phosphorus but not that of nitrogen, potassium, iron or zinc. The AMF DNA sequences recovered from the initial field soil, substrate and root samples identified twelve AMF taxa in total belonging to the two Glomeromycotina families Glomeraceae (91%) and Claroideoglomeraceae (9%). The number of operational taxonomic units (OTUs) in root tissue and pot substrate samples was unaffected by the stress treatment D. However, while certain AMF taxa (notably Glomus hoi) were likewise present in samples recovered from both the water treatments, there was a shift of abundance for other taxa. The abundance of Rhizophagus aff. arabicus was significantly higher in D than in W, mainly at the expense of Dominikia sp. The results suggested that, within a few weeks of root colonisation, soil drought together with low P availability imposes a major shift in the relative abundance of some AMF taxa. Moreover, under the given dry substrate conditions, R. aff. arabicus appeared to comprise a high competitiveness within the Glomeraceae - dominated AMF community.

Effect of Biochar on Peat Soil Fertility and NPK Uptake by Corn

This study aimed to investigate the biochar effect on peat soil fertility and uptake of nitrogen, phosphor, and potassium by corn plants. The experiment was conducted at a greenhouse in the Indonesian Swampland Agriculture Research Institute (ISARI), Banjarbaru, South Kalimantan, from June to September 2014. The peat soil sample was collected from the village of Kalampangan, Palangkaraya, Central Kalimantan. The treatment consisted of four types of biochar, namely coconut shell, palm midrib, Galam stem ( Melaleuca leucadendron ), rice husk and five rates of biochar i.e. 0, 2, 4, 8 and 16 t ha -1 . Biochar was analyzed in total C, P, K, Ca, Mg, Fe, Si, ash content, pH and CEC, also initial soil sample was analyzed pH, EC, organic C, total N, P, available P, exchangeable K, Ca, Mg, H, Cu, Zn, and total acidity were measured. The application of biochar changed peat soil properties including pH, available P, exchangeable K, nutrient uptake and the dry weight (i.e root and shoot). The type of biochar significantly affect the exchangeable K in peat soil and nutrient uptake. The highest exchangeable K and NPK uptake by corn showed by the coconut shell biochar at dose 4 t/ha.

A comprehensive data set demonstrating the spatial variability of soil properties and crop growth conditions at field scale

A four-year (1999-2002) multivariable data set for one specific agricultural used field located in North Rhine-Westphalia is documented in detailed. The data set focusses on the small-scale heterogeneity of soil properties varying in the spatial and temporal dimension. Initial soil sampling was conducted at altogether 80 sampling points arranged in a regular and a nested grid along the 20 ha large field. Information about the soil inventory (soil texture, soil organic carbon) exists for three subsequent soil layers to a total depth of 90 cm and for every sampling point. Subsequently, the same points and layers were examined for the soil variables soil moisture and soil nitrogen biannually. Additional information about crop rotation, tillage, site-specific fertilization, yield performance and weather complete the data set was that used for model inter-comparison within the crop modelling part (CropM) of the international FACCE JPI MACSUR2 project.

Can sustainability of maize-mustard cropping system be achieved through balanced nutrient management?

Information on optimization of nutrient management (NM) protocols for maize-mustard cropping system to achieve sustainability with regards to crop yield, nutrient use efficiency, soil quality, energy balance and profitability is limited. We evaluated NM practices for maize-mustard cropping system in a comprehensive manner using five criteria such as i) crop yield response, ii) recovery efficiency of plant nutrients, iii) soil quality index, iv) energy efficiency, and v) profitability of cultivation for acidic soils under subtropical conditions of northeast India. Eight NM treatments comprising of organic [farmyard manure (FYM)], inorganic fertilizers including micronutrients (Zn, B) and some of their combinations were tested using randomized complete block design with three replications for five consecutive maize-mustard cropping sequences during 2010–2015. Yield and yield related characters of the crops were recorded and nutrient concentration in representative plant parts was analysed for determination of their uptake, harvest index and use efficiency at each harvest. The initial and post-harvest (after fifth cropping sequence) soil samples were collected at 0-0.20 m depth from each of the experimental plots and analysed for physical, chemical and biological soil quality attributes. Energy and economic efficiency of the cropping systems was computed using fertilizers, seeds, plant protection chemicals, farm machineries for tillage and irrigation and human labor inputs and crop yield outputs. Yield and yield related characters, plant nutrient uptake and use efficiency, energy and economic variables of cultivation and soil properties were subjected to analysis of variance. Balanced supply of nutrients including micronutrients (Zn, B) through integration of organic and inorganic sources was proved to be sustainable in respect of crop productivity, economic viability and maintenance of environmental health. This helped improve recovery efficiency of applied nutrients as well as soil quality by increasing soil organic C, microbial biomass C and plant available nutrient content. Integrated use of 120-35-50-5-1 kg N-P-K-Zn-B with 10 Mg FYM ha−1 was proved to be the best due to significantly higher crop yield (5.80 Mg kernel and 1.22 Mg grain ha−1 for maize and mustard, respectively), recovery efficiency of applied nutrients (average recovery efficiency 64.5%), soil quality index (2.0), energy efficiency (energy gain 234,530 MJ ha−1) and economic return (marginal rate of return 3.5) as compared to the other NM treatments. Application of 120-35-50-5-1 kg N-P-K-Zn-B ha−1 or its combination with reduced rate of organic manure (5 Mg FYM ha−1) can also achieve sustainability with minimum conciliation with yield, nutrient recovery, environmental quality and economic benefit. Supply of nutrients only through organic sources (e.g., FYM) will not be sustainable for maize-mustard cropping system.

Assessment of Irrigation Quality of Disposal Water of Ashuganj-Polash Agro-Irrigation Project, Brahmanbaria Bangladesh

The study was conducted at Ashuganj-Polash agro-irrigation project (APAIP), Brahmanbaria,aim to determine the chemical properties of power plant disposal water and to assess its suitability for irrigation. Initial soil samples (before irrigating crop field) and final soil samples (after crop harvesting) were collected. During irrigation ten water samples (six from crop field and four from irrigation canals) were collected for analysis. All soil samples were analyzed in Humboldt soil testing laboratory and water samples in bio-chemistry laboratory of Bangladesh Agricultural University and compared to FAO irrigation standard. Results show thatthe sodium absorption ratio (SAR) (0.53 to 0.88), residual sodium bi-carbonate (0.8 to 1.3meq L-1), Kelly’s ratio (0.31 to 0.6) and total hardness (85 to 150) found in normal range and largely suitable for irrigation. Soluble sodium percentage values found in satisfactory (20.26 to 41.1) level and magnesium absorption (57.1 to 76.4) found unsuitable for irrigation. Statistically similar value of pH, EC, total nitrogen, organic carbon, calcium, magnesium and phosphorus in initial and final soil sample were observed. But potassium and sulfur value reduced in final soil sample from initial soil. The water samples fall within the permissible limit and found suitable for crop production

Effect of Potassium Dichromate on Properties and Biodegradation of Gum Arabic Based Bioplastic Membranes

Gum Arabic (GA) collected from Acacia senegal trees was used with polyvinyl alcohol (PVA) to prepare of a series of biodegradable membranes doped and non-doped with potassium dichromate (K2Cr2O7). Adding the K2Cr2O7 to the GA/PVA blends slightly decreased their crystallinity index (CI) by about 2 %. Increasing the PVA concentration in the chromated GA/PVA blends was responsible for increasing the CI. Adding the K2Cr2O7 to the pure GA solution modified its differential thermal behavior whereby the exothermic reactions occurred between 321°C and 433°C were disappeared. The K2Cr2O7 increased the heat change drastically for all the bioplastic blends with the highest increase for the pure GA. Adding K2Cr2O7 to the pure PVA increased the nanometric particle size (NPS) significantly. Increasing the PVA concentration in a blend had a greater effect than did the K2Cr2O7 on the NPS. The buried bioplastic membranes in the control soil had different count and species of microbial communities. The numbers of bacteria and fungi in the initial soil sample were lower than those for chromated GA membranes and were greater than those for the chromated PVA. All bacterial and fungi species had growth ability and are expected to be detoxification tools of chromium ion-doped blends of GA and PVA leading to a green environment.

Test Study on Consolidation Character of Unsaturated Loess

To calculate accurately settlement of loess foundation in filled area as the main goal, disturbed loess of filled project in Yan’an new district engineering construction in China as the research object, Q3 disturbed loess samples were made indoor for consolidation test by the reference of geotechnical engineering design parameters of filled project loess in actual practical project. Four groups of unsaturated consolidation tests were carried out with matric suction ranging from 100kPa to 500kPa. Compressive curve of the unsaturated and undisturbed loess sample were obtained. The influence of matric suction to consolidation characteristics of disturbed loess was analyzed. Results show: (1) For same initial state disturbed loess soil samples, when matric suction increases from 100kPa to 500kPa, the compressibility coefficient reduces from 0.151MPa-1 to 0.095MPa-1. Compressibility coefficient reduces with increasing the matric suction; (2) Compression index of unsaturated and disturbed loess sample was influenced not only by vertical pressure but also by matric suction. Compressibility index reduces when the matric suction increase; (3) The total vertical strain of disturbed loess sample which control parameters referred to the actual geotechnical engineering design plan was small under the 2MPa vertical stress. The biggest vertical strain was 0.7%.

The metabolic pathway of metamifop degradation by consortium ME-1 and its bacterial community structure.

Metamifop is universally used in agriculture as a post-emergence aryloxyphenoxy propionate herbicide (AOPP), however its microbial degradation mechanism remains unclear. Consortium ME-1 isolated from AOPP-contaminated soil can degrade metamifop completely after 6days and utilize it as the carbon source for bacterial growth. Meanwhile, consortium ME-1 possessed the ability to degrade metamifop stably under a wide range of pH (6.0-10.0) or temperature (20-42°C). HPLC-MS analysis shows that N-(2-fluorophenyl)-2-(4-hydroxyphenoxy)-N-methyl propionamide, 2-(4-hydroxyphenoxy)-propionic acid, 6-chloro-2-benzoxazolinone and N-methyl-2-fluoroaniline, were detected and identified as four intermediate metabolites. Based on the metabolites identified, a putative metabolic pathway of metamifop was proposed for the first time. In addition, the consortium ME-1 was also able to transform or degrade other AOPP such as fenoxaprop-p-ethyl, clodinafop-propargyl, quizalofop-p-ethyl and cyhalofop-butyl. Moreover, the community structure of ME-1 with lower microbial diversity compared with the initial soil sample was investigated by high throughput sequencing. β-Proteobacteria and Sphingobacteria were the largest class with sequence percentages of 46.6% and 27.55% at the class level. In addition, 50genera were classified in consortium ME-1, of which Methylobacillus, Sphingobacterium, Bordetella and Flavobacterium were the dominant genera with sequence percentages of 25.79, 25.61, 14.68 and 9.55%, respectively.

Effects of straw incorporated to different locations in soil profile on straw humification coefficient and maize yield.

Tillage and straw incorporation are important agricultural practices that can break plough layer and improve black soil fertility. The effects of tillage and straw incorporation on straw humification coefficient, soil organic carbon (SOC), and maize yield were investigated in a field experiment. Subsoil combined with straw incorporation in 20-35 cm soil layer (ST+S) could break plough layer and decrease the bulk density by 5.7%, 3.3% and 5.7% compared with traditional til-lage (TT), subsoil (ST) and traditional tillage combined with straw incorporation (TT+S) in six experimental years, respectively, and the best effects were observed in ST and ST+S treatments in the first expe-rimental year. The rate of straw decomposition was higher in 0-20 cm (72.0%) than in 20-35 cm (59.2%), and the straw humification coefficient in 0-20 cm and 20-35 cm soil la-yers reached the peak in first experimental year with 15.9% and 12.7%, respectively. Compared with initial soil sample, SOC and light fraction organic carbon (LFOC) of TT, ST and ST+S treatments in 0-20 cm soil layer was decreased in experimental years, but was increased by 2.9% and 12.4% within TT+S, respectively. SOC and light fraction organic carbon (LFOC) of ST+S in 20-35 cm soil layer was increased by 9.2% and 9.9%, respectively. The effect of field treatments on maize yield showed in a decreasing trend of ST+S>TT+S>ST>TT, effects of tillage and straw incorporation on maize yield could continue 3 and 6 years, respectively, indicating that tillage and straw incorporation had time effect. Therefore, straw incorporated into 20-35 cm soil layer based on tillage was an effective, sustainable agricultural practice of improving black soil quality.

Boron Fertilization and Its Fate: Maize - Sunflower Cropping System

A field experiment was conducted in B deficient soil (0.37 mg kg-1) to assess the frequency and level of B application for increasing crop yields in maize - sunflower cropping system, fate of B pools in soils system and to monitor the changes in soil fertility and productivity due to different levels and frequency of B application under continuous cropping system at Tamil Nadu Agricultural University, Coimbatore since 2012. The analysis of initial soil samples indicated that experimental soil was neutral in soil pH and free from salinity with sandy clay in texture. The grain and stover yield of maize crop varied from 5.51-8.38 and 5.16 to 8.00 t ha-1 , respectively and significantly differed with rate of B application. Among the B levels application of B @ 1.0 kg ha-1 registered the maximum grain and stover yield of 7.55 and 7.00 t ha-1 , respectively and was followed by application of 1.5 kg ha-1, however they were on par with each other. After the harvest of maize crop, sunflower was raised and harvested and the grain and stalk yields were recorded. Among the B levels, application of B @ 1.0 kg ha-1 registered the maximum seed yield of 2.33 t ha-1 respectively and was followed by application of 0.5 kg ha-1. The interaction between the rate of B application and frequency significantly differed with grain and stalk yield. Among the frequency levels, application of B to maize crop alone every year (F3) registered the maximum seed yield as compared to others. The interaction effect revealed that application of B @ 0.5 kg ha-1 to all crop registered the highest seed yield of 2.79 t ha-1 respectively. Boron fractions like available boron, specifically adsorbed B, oxide B, organically bound B, residual B status and total boron contents were analysed after the harvest of second crop. The results revealed that the available B status varied from 0.277 to 1.940 mg kg-1,specifically adsorbed B ranged from 0.190 to 1.332,oxide bound B status in soil varied from 0.127 to 0.89 mg kg-1, organically bound B status in soil varied from 0.235 to 1.644 mg kg-1, residual fraction of B varied from 41.61 to 291.8 and total boron varied from 42.44 to 297.6 mg kg-1. Boron application resulted in significant increase in maize yield as first crop and sunflower as residual crop, respectively. Among the B fractions the order was residual B &gt;organically bound &gt; specifically adsorbed &gt; oxide bound B. Application of B @ 2.0 kg ha-1 significantly registered the highest available B in soil (1.038 mg kg-1) and among the frequencies, application of B to all crops registered the highest available B (1.32 mg kg-1). The actual fraction of B fertilizer removed by the crops is only 1-2 % of the total applied fertilizer through soil.

Growth and yield response of cowpea to multiaction bioinoculants

Studies were taken up to estimate the morpho-physiological changes in cowpea due to a multiaction bioinoculants (TagTeam) as seed treatment. Seed treatment with TagTeam @ 8.1g/kg showed significant increase in plant height, root length and number of nodules as compared to control. Physiological parameters such as leaf area, total dry matter accumulation, photosynthetic rate and chlorophyll index were also found higher in seed treatment with TagTeam @ 8.1g/kg. Co-inocultion of Rhizobium and Penicillium (TagTeam) @ 8.1g/kg enhanced the uptake of NPK in cowpea. Available NPK was found non significant with initial soil sample and found maximum with control and lower content in TagTeam seed treatment @ 8.1g/kg. Seed treatment with TagTeam @ 8.1g/kg increased the yield by 13.36 per cent over control and improved yield components and seed protein content in cowpea.

Enrichment of Desulfitobacterium spp. from forest and grassland soil using the O-demethylation of phenyl methyl ethers as a growth-selective process.

The O-demethylation of phenyl methyl ethers under anaerobic conditions is a metabolic feature of acetogens and Desulfitobacterium spp. Desulfitobacteria as well as most acetogens are Gram-positive bacteria with a low GC content and belong to the phylum Firmicutes. The consumption of the phenyl methyl ether syringate was studied in enrichment cultures originating from five different topsoils. Desulfitobacterium spp. were detected in all topsoils via quantitative PCR. Desulfitobacteria could be enriched using the O-demethylation of syringate as a growth-selective process. The enrichment was significantly favoured by an external electron acceptor such as 3-chloro-4-hydroxyphenylacetate or thiosulfate. Upon cultivation in the presence of syringate and thiosulfate, which naturally occur in soil, a maximum number of 16S rRNA gene copies of Desulfitobacterium spp. was reached within the first three subcultivation steps and accounted for 3-10% of the total microbial community depending on the soil type. Afterwards, a loss of Desulfitobacterium gene copies was observed. Community analyses revealed that Proteobacteria, Acidobacteria, Actinobacteria and Bacteroidetes were the main phyla in the initial soil samples. Upon addition of syringate and thiosulfate as growth substrates, these phyla were rapidly outcompeted by Firmicutes, which were under-represented in soil. The main Firmicutes genera identified were Alkalibaculum, Clostridium, Sporobacterium, Sporomusa and Tissierella, which might be responsible for outcompeting the desulfitobacteria. Most of these organisms belong to the acetogens, which have previously been described to demethylate phenyl methyl ethers. The shift of the native community structure to almost exclusively Firmicutes supports the participation of members of this phylum in environmental demethylation processes.