Types Of Organic Amendments Research Articles

Humic balance of a rice plot located on the South Iazafo Plain, Vavatenina district, Analanjirofo region - Madagascar: Study of possible humic recovery through the contribution of leaf compost from the distillation activity of essential oils from the leav

Knowing the initial state of the soil, especially the amount of organic matter contained in the soil, is the basis of effective fertilization. A soil with too little organic matter will be difficult to cultivate, mainly because of problems of soil structure loss. Humus plays a central role in the quality of soils and the maintenance of their key functions. If the level of organic matter decreases further, soil fertility may be called into question. Therefore, this study consists of evaluating the stock of humus in a private paddy field located in the South Iazafo plain and considering the possible recovery in the event of a proven deficiency. The soil examination carried out on this private plot indeed shows the lack of organic matter (barely 2%). Consequently, a humus recovery in order to reach an optimal threshold of 3% ideal for rice cultivation will therefore be deemed necessary. This need for humus is amply compensated by the organic supply in the form of leaf molds from the residues of the essential oil distillation activity of clove leaves, around 20 to 40 years old. Note that this type of organic amendment is very abundant in the neighboring areas of the said Iazafo plain. Their agronomic enhancement is essential in order to promote agricultural yield, in particular paddy yield in this rice-growing area which is unfortunately constantly shrinking

Mobility of asbestos fibers below ground is enhanced by dissolved organic matter from soil amendments

To prevent exposure of millions of people living near thousands of contaminated sites to asbestos, the sites are typically capped with soil and amendments, assuming asbestos mobility underground is negligible in all conditions. Here, we disprove this long-standing assumption and showed that the presence of certain types of dissolved organic matter (DOM) can facilitate the transport of the asbestos fibers through packed sand or soil columns. The column scale simulates asbestos transport without and without DOM, although asbestos transport at a longer scale through aquifer may vary because of soil heterogeneity. Our data shows that the extent of fiber transport in soil is affected by DOM quality: fulvic acid > humic acid > natural organic matter isolated from Suwanee River, a model terrestrial organic carbon. We attribute the results to the ability of DOM to affect aggregation of asbestos fibers and limit their attachment on soil. Thus, types of organic amendments applied on asbestos-contaminated sites may have an unintended consequence: transport of asbestos fibers to shallow groundwater to receiving streams or rivers, from where they could be resuspended in the air via irrigation or drying of the riverbed.

Environmentally-friendly dewatering of sewage sludge: A novel strategy based on amphiphilic phase-transfer induced by recoverable organic solvent

This study proposed a novel strategy for sludge dewaterability improvement by eliminating the solid-liquid affinity through the polarity regulation of liquid phase. Initial screening experiments with different types of organic amendments (e.g., polar solvents, low-pole solvents, cytolytic reagents) found that acetonitrile and acetone could reduce specific resistance to filtration of sludge by 83.9% and 76.8%, respectively, at the solvent-sludge mass ratio of 1:1. The vacuum distillation and atmospheric distillation were both examined for the solvent recovery from filtered sludge cake and filtrate. Also, by considering the sensible heat for feedstock heating and enthalpy of solvent evaporation, the theoretical energy consumption of acetonitrile/acetone-enhanced sludge dewatering process was estimated to be at least 1/3 lower than that of the thermal drying process with the same treatment capacity, which indicated the energy saving potential of solvent-enhanced sludge dewatering process. Mechanism investigation was conducted by analyzing the surface functional groups of residual solid phase and the phase-transfer characteristics of amphiphilic compounds based on high-resolution Fourier transform-ion cyclotron resonance-mass spectrometry. It was found that the polarity of liquid phase dominated the phase-transfer of sludge compositions. The sufficient decrease in liquid polarity (dielectric constant < 55) would significantly eliminate the affinity of polar functional groups with the low-pole liquid phases, which induced the precipitation of amphiphilic proteins and substantially enhanced the solid-liquid separation. These findings suggest a promising technology for sludge dewaterability improvement by modifying the physical properties of liquid phase, which exhibits the obvious advantages in saving energy and material consumption.

Tillage intensity and compost application effects on organically grown camelina productivity, seed and oil quality

The importance of Camelina sativa has lessened substantially over the last half century, however its unique oil composition and the beneficial agronomic attributes with regard to sustainable agriculture have recently reignited interest in this oilseed crop. Notwithstanding the great interest in camelina, the potential to be cultivated organically has not received prominent attention from researchers. The objective of this study was to evaluate the response of organic camelina to different tillage systems and compost types, based on differences in yield parameters, oil content, seed crude protein and fatty acid profile. The field experiments, conducted during the 2014, 2015 and 2016 growing seasons, were laid out in a split plot design with three replicates, two main plots (conventional tillage and minimum tillage) and three sub-plots (vermicompost, compost, unamended control). It is consequential from the results that the effect of the type of organic amendment was highly significant on camelina’s productivity. Particularly, compost treatment resulted in higher seed and oil yield (1132 and 446 kg ha-1, respectively) compared to the vermicompost (682 and 269 kg ha-1, respectively) and the unamended control (554 and 220 kg ha-1, respectively). Regarding the fatty acid profile, both organic amendments increased linoleic and palmitic acids, while they presented disparate effects on a-linolenic acid. Furthermore, tillage system influenced significantly only thousand seeds weight, protein content and gondoic acid, enabling the use of reduced tillage to be comparably effective on organically grown camelina performance. Further experimentation is needed to match crop needs with the appropriate cropping techniques in order to ensure an effective organic cultivation.

Soil phosphorus fractionation in calcareous soil as affected by organic amendments application

&lt;p&gt;Understanding of P transformations following organic amendments addition to highly calcareous soils is necessary for developing better management practices that can help enhance P fertilizer use efficiency. Phosphorus solubility and availability for plant uptake under the conditions of arid calcareous soil is very low, making P nutrient supply a critical issue under these conditions. The aim of this study was to evaluate the impact of various types of organic amendments (chicken compost, cow compost and a mixture of humic-fulvic acid) applied alone at different rates of KH2PO4 fertilizer on P fractions in calcareous soil using the sequential chemical extraction method. Amended calcareous soil was incubated under laboratory conditions and soil samples were collected at 0, 4, 8 and 16 weeks of the incubation periods. Soil was sequentially extracted and analyzed for P different fractions. The results indicated that the addition of chicken and cow compost increased soluble and exchangeable-P and Ca-P fractions in calcareous soil and the increases depend on application rates. The results indicated that combination of chicken and cow compost with different KH2PO4 fertilizer application rates increased the concentration of soluble and exchangeable-P in the soil compared to organic amendments or KH2PO4 fertilizer applied alone. The P associated with Ca was the dominant P fractions in soil, ranging between 51 to 59% regardless of the different treatment and the period of incubations. The Al- and Fe-associated P fractions varied between 2 and 9%, with the maximum value being observed at the eighth week of incubation. The residual-P fraction ranged between 5 and 22% at different incubation periods.&lt;/p&gt;

Soil CO2 emission in response to organic amendments, temperature, and rainfall

Vegetated land surfaces play an important role in determining the fate of carbon in the global carbon cycle. However, our understanding of the terrestrial biosphere on a global scale is subject to considerable uncertainty, especially concerning the impacts of climatic variables on the carbon cycle. Soil is a source and also a sink of CO2 exchange and helps in carbon sequestration. Agricultural management practices influence soil water dynamics, as well as carbon cycling by changing soil CO2 emission and uptake rates. The rate of soil CO2 emission varies for different crops and different organic amendments. The major goal of this study was to assess the impacts of the type and rate of organic amendment on soil CO2 emission in a collard greens crop grown in the southeast Texas environment. Thirty-six plots were developed to grow collard greens on Prairie View A&M University’s Research Farm. Three types of organic amendments (Chicken manure, Dairy manure, and Milorganite), at four levels of application (0, 168, 336, and 672 kg N/ha) were used and replicated three times. Each organic amendment type was applied to nine randomly selected plots. Three random plots were used as a control in each row. We measured daily soil CO2 emission for the first two weeks and every other day in a week during the experiment. We evaluated the effects of organic amendments and the application rates on soil CO2 emission for collard greens during two growing seasons. The results showed higher the application rates for each organic amendment, higher the CO2 emissions from the soil. The results also showed higher cumulative CO2 emissions for the soils amended with chicken manure and milorganite, but lowest for the soils amended with dairy manure. This field experiment and analyses help better understand the temporal and spatial variations of soil CO2 emission, and also help to develop best management practices to maximize carbon sequestration and to minimize soil CO2 emissions during the growth periods of collard greens under changing temperatures using different organic amendments, and application rates.

Organic carbon nature determines the capacity of organic amendments to adsorb pesticides in soil

The spread of organic pollutants from soil to other environments is one important source of environmental pollution. The addition of organic amendments to soil is an interesting strategy to control pollutants leaching. However, the contribution of different carbon types of organic amendments to organic pollutants adsorption is not clear. Hence, the objective of this work was to determine the role of carbon types of organic amendments into the adsorption of four herbicides. To this extent, organic amendments were characterized by elemental analysis and 13C-NMR and adsorption–desorption isotherms of herbicides by the organic amendments and two soils amended with them were obtained. Adsorption coefficients were correlated with the organic carbon content of the organic amendments and the adsorption process was enhanced by the hydrophobicity of herbicides and the aliphatic and aromatic carbon of amendments. Organic amendments increased the adsorption of herbicides by soils but it is not possible to extrapolate results from one soil to another because organo-mineral interactions between soils and organic amendments can modify this process. Desorption isotherms of herbicides from organic amendments and/or amended soils presented hysteresis indicating the irreversible adsorption of herbicides. Desorption results indicated, the abundance of O-alkyl and N-alkyl groups in organic amendments enhanced the hysteresis in amended soils.

Soil aggregation as affected by application of diverse organic materials

AbstractApplication of organic materials can amend soil for improved water infiltration and reduced erodibility with effects varying with soil properties and the organic amendment type and rate. The effects of four livestock manures, three municipal biosolids, and one industrial by‐product on dry and wet soil aggregate stability were evaluated at six sites in Nebraska. The amendments had similar C/N ratios but the biosolids had relatively high concentrations of lignin and cellulose. Soil organic matter (SOM) ranged from 21 to 65 g kg−1 and soils were silty clay loam, silt loam, or loamy sand. Soil was sampled for the 0‐ to 0.05‐m depth at physiological maturity of the second corn (Zea mays L.) crop following amendment application. Aggregation was high with no amendment applied as &gt;95% of the soil was in water stable aggregates (WSA) &gt; 0.053 mm and was not affected by amendments with a few exceptions such as an increase in dry aggregate size and WSA 0.25–2.0 mm at one location. Dry aggregate size was much less for the loamy sand than with other soils. With SOM &gt;60 g kg−1 compared with less SOM, there was 42% more WSA &gt;2 mm and 38% less WSA &lt;2 mm diam. It cannot be concluded that organic amendment application will improve aggregation if SOM &gt;20 g kg−1 but larger effects may have occurred with: sampling sooner after amendment application; a 0‐ to 0.025‐m sampling depth; or sampling at several months after harvest for reduced effect of the rhizosphere on aggregation.

The Influence of Organic Amendment Source on Carbon and Nitrogen Mineralization in Different Soils

Soil organic matter is one of the largest stores of carbon and nitrogen in various ecosystems that can crucially improve plant nutrition. The present study was conducted to investigate the effect of organic matter sources on carbon and nitrogen mineralization and also the contemporary comparison of carbon and nitrogen mineralization and nitrogen immobilization in soils amended with different organic treatments. Accordingly, six types of organic amendments were applied to three types of soils, under a constant temperature and moisture at the laboratory scale. The treated soils were incubated 60 and 120 days for nitrogen and carbon mineralization study, respectively. Results showed two decomposition stages, an initial rapid increase in decomposition in the first 20 days followed by a slower stage reaching a steady state condition. The amount of mineralized carbon ranged from 980 to 6860 mg/kg of dry soil for soils incorporating with different types of organic matters. The carbon mineralization kinetic data was well fitted to a second-order kinetic model showing the differences in microbial decomposition resistance of residues contents. The kinetic of carbon and nitrogen mineralization fluctuated similarly but in different scales. Net ammonification of fertilizer group, sheep manure, cow manure, and vermicompost was decreased, whereas in plant residue group, plane tree leaves, corn leaves, and wheat straw was increased. Two nitrification periods (first 10 days and 35 to 60 days) and an immobilization period (10 to 35 days) were observed. After 60 days of incubation of amended clayey soil, the nitrification values in plane tree leaves, corn leaves, wheat straw, municipal waste vermicompost, cow manure, and sheep manure were − 13.98, 14.06, 13.22, 34.88, − 12.25, and − 12.15 mg kg−1, respectively. The carbon and nitrogen mineralization trends fluctuated due to probably different resistance of substance components to microbial decomposition. Since the nitrate is the main part of inorganic N, therefore, net N mineralization had a similar trend as nitrification in different soils. Those organic residues with high ratios of C/N immobilized the mineral nitrogen, due to the presence of more carbon and a higher nitrogen decomposition rate, resulting in suppressed levels of nitrogen in the amended soil.

Tree water use strategies and soil type determine growth responses to biochar and compost organic amendments

Background and aimsOrganic matter is often used as an amendment to attempt restoration of degraded soils to improve tree establishment and growth. One key aim is to increase plant available water in the soil profile. The texture of the soil, the type of organic amendment (e.g. compost or biochar), and the native environment of the tree (mesic or xeric) will impact how successful restoration efforts are. We aimed to determine whether compost and biochar amendments, either individually or in combination, would improve plant available water (PAW) in both clay and sand soils. We then aimed to measure whether changes in PAW would translate into increased water use and plant growth of both mesic (Corymbia maculata) or xeric (Eucalyptus torquata) tree species under well-watered (WW) or water deficit (WD) conditions. MethodsClay and sand soils were amended with compost, biochar or a compost and biochar mix, whilst unamended soils acted as controls. Soil moisture characteristics of the soil mixes were determined with samples in the laboratory. Fifteen replicate pots (6 l) of each soil treatment were then planted with either mesic and xeric tree species. All pots and trees were subjected to either a WW or WD irrigation regime for 7 weeks. WD irrigation was a set percentage of the daily WW evapotranspiration (ET). ET was calculated as total pot mass one hour after irrigation (to allow for drainage) minus the total pre-dawn pot mass of the subsequent day. The tree biomass, biomass partitioning, ET, and tree water status were measured throughout the experiment to understand growth and stress responses. Key resultsThe xeric tree species (E. torquata) grown in sand soil had a significant increase in growth with all three OM amendments but did not when grown in clay soil. In contrast, we found no significant growth response for the mesic tree species (C. maculata) when grown in either clay or sand amended with any OM treatment. The ET of the xeric tree species was greater for all the OM amended soils for both WW and WD plants in the sand soil. ConclusionsThis study shows that OM amendments may improve the soil water properties of sand-based soils which in turn can increase the growth of xeric tree species. However, more expensive organic amendments may not be necessary, nor mixing of OM types, as we found no tree growth differences amongst the three different OM treatments.

Mitigation of Salinity Stress in Soybean Using Organic Amendments

A pot experiment was carried out in semi-controlled condition at the Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur from November 2015 to March 2016 to assess the effect of organic amendments to mitigate salinity stress in Soybean var. BARI soybean 5. Two types of organic amendments i) water hyacinth compost and ii) rice husk biochar were mixed in soil @ 5 and 10 t ha-1 of both. Saline solution was prepared by adding tap water in seawater to make 5 and 10 dS m-1 salinity respectively. Plants were irrigated with the salt solution from 14th day after sowing (DAS) to maturity and the control plants were irrigated with tap water. Data on different parameters like plant height, leaf, stem, root dry matter and yield contributing parameters were recorded at harvest. Experimental results revealed that salinity decreased plant height, dry weight of leaf, stem and root as well as yield of soybean plant-1. Application of water hyacinth compost and rice husk biochar had positive effects on mitigating the negative effects of salinity stress on all those parameters studied. However, rice husk biochar at the rate of 5 t ha-1 showed best result to mitigate salinity stress at low salinity (5 dSmdS m-1 condition.&#x0D; Bangladesh Agron. J. 2018, 21(1): 39-50

Chlorophyll content, water relation traits and mineral ions accumulation in soybean as influenced by organic amendments under salinity stress

The pot experiment was conducted to assess the effect of organic amendments to improve leaf chlorophyll and water content as well as mineral ions accumulation in BARI soybean 5 under saline condition. Two types of organic amendments i. water hyacinth compost ii. rice husk biochar were mixed in soil at 5 tha-1 and 10 tha-1 of both. Irrigation was done with 50 and 100 mM saline solution from 14th days after sowing (DAS) to maturity, where control plants were irrigated with tap water. Data on chlorophyll content, exudation rate, relative water content (RWC), water retention capacity (WRC) in leaf were measured at flowering stage as well as Na, K, Ca, Mg and Na: K ratio in leaf and stem were also recorded at harvest. Results revealed that salinity decreased chlorophyll content, exudation rate, relative water content, water retention capacity and K, Ca, Mg content in leaf and stem of soybean plant. Water hyacinth compost and rice husk biochar had positive effects to mitigate negative effects of salinity on soybean plant. However, rice husk biochar at 5 tha-1 showed best result to mitigate salinity stress on soybean at low salinity (50 mM) condition.

Water-stable aggregates and carbon accumulation in barren sandy soil depend on organic amendment method: A three-year field study

Organic amendment has proven to reduce resource waste and environmental pollution, in addition to increasing soil quality. However, the effect of different organic amendment methods on water-stable aggregates and soil organic carbon (SOC) accumulation is unknown, especially in barren sandy soil. A field experiment with four organic amendment methods, straw (ST, local practice), biogas residue (BR), manure (PM), and biochar (BC), was designed with the equal amount of nitrogen (N) input in the North China Plain. Soil aggregate distribution, stability, and aggregate-associated C at two depths (0–10 cm and 10–20 cm) were analyzed after a treatment was applied to evaluate soil quality improvement. The main results were as follows: compared to ST treatment, BC treatment enhanced SOC in the 0–10 cm and 10–20 cm layers by 143.8% and 156.5%, respectively (P < 0.05). The mean weight diameter (MWD) of soil aggregates in BR, PM, and BC treatments decreased by 16.2%–31.8%, 10.0%–24.7% (except the 2015 0–10 cm layer), and 18.9%–43.2% compared with ST treatment from 2014 to 2016. BC treatment increased C concentrations in all aggregate fractions compared to ST treatment in 2015–2016 (P < 0.05). The correlations between soil microbial biomass C and MWD (R = 0.7185, P < 0.001) and dissolved organic C and MWD (R = 0.5600, P < 0.001) indicated that soil aggregation is mainly affected by labile organic C in barren sandy soil. All four types of organic amendments increased SOC content; additionally, ST amendment had the highest capacity for aggregate formation. The results indicated that ST amendment is more appropriate for barren sandy soil than BR, PM or BC amendments, and improves soil quality for sustainable soil management.

Effect of Irrigation with Diluted Seawater on Coriander Growth and Soil Properties of Sandy Soil Amended by Chicken Manure and Biochar

Salt stress is abiotic stress that limits plant growth, crop productivityas well as the main factor contributing to land degradation. This study was conducted to evaluate the ameliorative effect of chicken manure and biochar applications used as soil amendments inalleviating the adverse effects of saline water irrigation on plant attributes and macro nutrients uptake by coriander (Coriandrum sativum) plant grown on a sandy textured soil. The ameliorative effect of soil amendments was also evaluated on the properties of the soil and nutrients availability for the plant. For this purpose, a pot experiment was conducted on coriander plant at The Experimental Farm of the Faculty of Agriculture, Mansoura University, Dakahlia Governorate, Egypt. A split plot design with three replications was used during the spring season of 2016. Treatments were the combination of two types of organic amendments (chicken manure and biochar) and three saline irrigation water treatments, .i.e. non-saline water (control) (S0 = 0.45 dS m-1) and saline water (S1= 3.12 dS m-1, 5% and S2 = 6.25 dS m-1, 10%) irrigation. Obtained results showed that soil productivity, as indicated by the vegetative growth and physiological aspects (plant height, leaves fresh and dry weight, no. of leaves/plant and total chlorophyll) for coriander plant were adversely and significantly affected by saline water irrigation. Addition of chicken manure and biochar significant increased the vegetative growth and physiological parameters due to their ameliorative effect. It had been observed a significantly increased in plant N, P and K contents and uptake by plant due to the addition of chicken manure and biochar amendments under saline and non-saline water irrigation compared to unamended one. The contents and uptake of N, P and K in coriander leaves decreased significantly as salinity of irrigation water increased from (S0) to (S2). Soil pH and EC values increased significantly in saline water irrigation treatments (S1 and S2) compared to non-saline water (S0). Soil pH and EC values decreased in soil amended with chicken manure and biochar application under three water types. The reduction in EC values in soil amended with biochar was higher than those in soil amended with chicken manure under all salinity levels. While, the reduction in soil pH values in soil amended with chicken manure was higher than those in soil amended with biochar. Soil available Na+, K+, Ca2+ and Mg2+ concentrations increased with increases in irrigation water salinity, while available P and Zn concentrations were decreased. Soluble Na+ significantly decreased but K+, Ca2+ and Mg2+ increased as a result of amendments application under three water types used. Soil P and Zn availability increased after applying different soil amendments, the concentration of available P in chicken manure amended soil was higher than those in biochar amended soil. While, available Zn concentration in biochar amended soil was higher than unamended one. In conclusion, chicken manure and biochar added to soil as amendments have the potential to mitigate the negative effects of salt stress mainly related to their ability to improve soil physio-chemical properties, promote vegetative growth of coriander plant, increases soil content of organic matter and available nutrient uptake.

Contribution of organic amendments to soil organic matter detected by thermogravimetry

AbstractSustainable soil management requires reliable and accurate monitoring of changes in soil organic matter (SOM). However, despite the development of improved analytical techniques during the last decades, there are still limits in the detection of small changes in soil organic carbon content and SOM composition. This study focused on the detection of such changes under laboratory conditions by adding different organic amendments to soils. The model experiments consisted of artificially mixing soil samples from non‐fertilized plots of three German long‐term agricultural experiments in Bad Lauchstädt (silty loam), Grossbeeren (silty sand), and Müncheberg (loamy sand) with straw, farmyard manure, sheep faeces, and charcoal in quantities from 3 to 180 t ha−1each. In these mixtures we determined the organic carbon contents by elemental analysis and by thermal mass losses (TML) determined by thermogravimetry. The results confirmed the higher reliability of elemental analysis compared to TML for organic carbon content determination. The sensitivity of both methods was not sufficient to detect the changes in organic carbon content caused by small quantities of organic amendments (3 t ha−1or 0.1–0.4 g C kg−1soil). In the case of elemental analysis, the detectability of changes in carbon content increased with quantities of added amendments, but the method could not distinguish different types of organic amendments. On the contrary, the based on analysis of degradation temperatures, the TML allowed this discrimination together with their quantitative analysis. For example, added charcoal was not visible in TML from 320 to 330°C, which is used for carbon content determination. However, increasing quantities of charcoal were reflected in a higher TML around 520°C. Furthermore, differences between measured (with TML110–550) and predicted mass loss on ignition using both organic carbon (with TML330) and clay contents (with TML140) were confirmed as a suitable indicator for detection of organic amendments in different types of soils. We conclude that thermogravimetry enables the sensitive detection of organic fertilizers and organic amendments in soils under arable land use.

Changes in sorghum production, soil P forms and P use efficiency following long-term application of manure, compost and straw in a Ferric Lixisol

ABSTRACTLow phosphorus availability in cultivated soils limits sustainable crop production in sub‐Saharan Africa. This study aimed at evaluating the effect of long‐term application of different types of organic amendments on soil P forms, P use efficiency and sorghum yields. A long term experiment established in 1980 at Saria in Burkina Faso, comparing the effects of manure, compost and sorghum straw was used. Manure and compost significantly increased organic P and resin‐P by about 35% and 64%, respectively after 10 and 32 years of sorghum cultivation, and HCl‐P after 32 years of cultivation compared to the control. Manure significantly increased NaHCO3-Pi and NaOH-Pi by 63% and 26%, respectively compared to the control. Sorghum straw had little effect on measured soil P forms. Manure and compost were the best in increasing sorghum grain yield, which effect were strongly correlated to soil pH, carbon and nitrogen. The partial factors productivities of P resulting from the application of studied organic amendments were similar and low, but significantly higher than that of the control treatment. Organic amendments with high P content, maintaining soil carbon and pH could be used to improve soil P availability, sorghum yield and reduce the demand for mineral phosphorus fertilizers.

Impacts of integrated nutrient management on methane emission, global warming potential and carbon storage capacity in rice grown in a northeast India soil.

Rice soil is a source of emission of two major greenhouse gases (methane (CH4) and nitrous oxide (N2O)) and a sink of carbon dioxide (CO2). The effect of inorganic fertilizers in combination with various organics (cow dung, green manure (Sesbania aculeata) Azolla compost, rice husk) on CH4 emission, global warming potential, and soil carbon storage along with crop productivity were studied at university farm under field conditions. The experiment was conducted in a randomized block design for 2years in a monsoon rice (cv. Ranjit) ecosystem (June-November, 2014 and 2015). Combined application of inorganic (NPK) with Sesbania aculeata resulted in high global warming potential (GWP) of 887.4kg CO2 ha-1 and low GWP of 540.6kg CO2 ha-1 was recordedfrom inorganic fertilizer applied field. Irrespective of the type of organic amendments, flag leaf photosynthesis of the rice crop increased over NPK application (control). There was an increase in CH4 emission from the organic amended fields compared to NPK alone. The combined application of NPK and Azolla compost was effective in the buildup of soil carbon (16.93gkg-1) and capacity of soil carbon storage (28.1Mg C ha-1) with high carbon efficiency ratio (16.9). Azolla compost application along with NPK recorded 15.66% higher CH4 emission with 27.43% yield increment over control. Azolla compost application significantly enhanced carbon storage of soil and improved the yielding ability of grain (6.55Mgha-1) over other treatments.

Organic amendment type and application frequency affect crop yields, soil fertility and microbiome composition

Vegetable cultivation under plastic tunnels provides high-quality crop yields but negatively affects soil fertility, especially when conventional agricultural system (e.g., use of synthetic mineral fertilizer and agrochemicals) was adopted. In this regard, the use of organic amendments has been proposed as a reliable and effective approach for soil fertility recovery. The aim of this study was to assess the effects of different organic amendments and application frequency on crop yield, soil fertility and soil microbial communities. A 1-year long mesocosm experiment was performed by conditioning a soil with different organic amendment types and frequency of application, compared with the ordinary soil management based on mineral fertilizers and fumigation. Soil fertility was assessed by determining physical and chemical soil parameters, whereas microbial community functioning and structure were assessed by high-throughput sequencing of bacterial and eukaryotic rRNA gene markers and BIOLOG EcoPlates™. Compared to the organic amendment, the use of synthetic fertilizer had a higher crop production but negatively affected pH, soil organic carbon content and soil aggregation. Diversity and richness of bacteria and eukaryotic were lower in the synthetic than in the organic amendments. The addition of organic amendments promoted the growth of Acidobacteria and Gemmatimonadetes bacteria. On the contrary, members of Actinobacteria and Proteobacteria were more abundant in the soil treated with synthetic fertilizer. This study increases our current knowledge on the effect of the synthetic and organic amendment applications on crop yield, soil fertility and soil microbial community functionality.

Producción y calidad de forraje con enmiendas orgánicas en pastura (Brachiaria Brizantha), en la Costa Caribe Sur de Nicaragua

Esta investigación se ha aplicado diferentes alternativas orgánicas para determinar sus efectos en la producción y calidad de forraje en Brachiaria brizantha. En el estudio se evaluaron tres tipos de enmiendas orgánicas (Lombrihumus, Bokashi y EM) en el pasto Brachiaria brizantha, las que fueron comparados con un tratamiento testigo (sin enmienda orgánica). Se empleó un diseño de bloque completamente al azar (BCA), 4 réplicas por tratamiento para un total de 16 parcelas, evaluado en pasturas ya establecidas. La mayor producción de biomasa verde es de 17,325 kg/ha al aplicar lombrihumus, en producción de materia seca el lombrihumus obtuvo el mayor rendimiento (3,383 kg/ha). La mayor longitud de raíces primarias se obtuvo al aplicar lombrihumus (17.25 cm). En la variable relación hoja/tallo los mayores resultados se obtuvieron con Lombrihumus. Con bokashi se obtuvieron los mayores porcentajes de digestibilidad de la materia seca (62%), proteína bruta (9.8%) y cenizas (9.52%). El lombrihumus y bokashi ejercieron los mayores efectos en las variables evaluadas en Brachiaria brizantha. Se recomienda el uso de alternativas orgánicas para optimizar la producción y calidad de la pastura Brachiaria brizantha. Abstract

Control of Fusarium wilt of carnation using organic amendments combined with soil solarization, and report of associated Fusarium species in southern Spain

Fusarium wilt is a disease that restricts carnation (Dianthus caryophyllus L.) yield worldwide. Efficacies in reducing the Fusarium wilt of carnation (FWC), of various types of organic amendments (fresh or pelletized poultry manure, pelletized Brassica carinata and olive residue compost) combined with soil solarization, were compared in two biennial field trials conducted in a greenhouse with a history of carnation monoculture over 8 years. Soil treatments combining organic amendments and soil solarization significantly reduced disease incidence (86–99%) and increased the number of commercial carnation stems by 5–9 times compared to non-treated plots. Twenty-one Fusarium spp. isolates, with different colony morphologies were recovered from soil samples taken in the greenhouse, before the application of treatments in June 2013. Nineteen of them were morphological and molecularly characterized. Additionally, two pathogenicity tests with 17 isolates recovered from greenhouse soils and two isolates recovered from organic amendments were performed. Fusarium species associated with carnation cultivation were identified as Fusarium oxysporum (43%), Fusarium proliferatum (24%), and Fusarium solani (33%). The phylogenetic analysis of the translation elongation factor 1 alpha (EF-1α) region distinguished highly aggressive isolates of F. oxysporum f. sp. dianthi, from low aggressive isolates. The pathogenicity tests showed that FWC has a complex etiology, with several Fusarium spp. identified as causal agents. F. proliferatum and F. solani are associated with carnation wilt for the first time in Spain.