Straw Treatment Research Articles

Dry biorefinery conversion of cadmium-contaminated rice grain and straw to ethanol with complete collection and recycling of cadmium

Cadmium contaminated rice should be carefully treated by considering two aspects: full recovery of cadmium without risks of emission to environment, and energy balance between input and consumption. Separate treatment of rice grain and rice straw not only generates cadmium contained wastewater but also produces solid residue with livestock feed potentials. This study investigated a dry biorefining treatment to convert whole rice biomass (both grain and straw) into bioethanol at a reasonable energy balance and without solids residue potentials. The cadmium contained wastewater was significantly reduced and further completely evaporated into cadmium-free steam for recycled use in the treatment. The cadmium contained lignin solids were completely burned to evaporate the wastewater. The final cadmium content in combustion ash was enriched by 5–7 folds compared to raw rice biomass. The simulation showed that the heat generation from lignin residue combustion compensated for the energy requirement of wastewater evaporation. This study provides a fully converged treatment method of cadmium contaminated rice biomass on both cadmium and energy consumption with value added bioethanol production.

Effect of Different Organic Amendments on Actual and Achievable Yields in a Cereal-Based Cropping System

Soil fertility is at risk in intensive cropping systems when using an exclusive regime of inorganic fertilisers without returning sufficient organic matter to the soil. Our objective was to evaluate the long-term effects of commonly used organic amendments interacting with different rates of inorganic nitrogen fertiliser on crop yields of winter wheat. Yield data from winter wheat were collected for five seasons between 2013 and 2019 from a continuous field trial based at Rothamsted Research, SE England. Organic amendments (anaerobic digestate, compost, farmyard manure, and straw at a rate of 0 and 2.5 ton C per hectare) and five rates of inorganic nitrogen fertiliser (NH4NO3 at 0, 80, 150, 190, 220 kg N ha−1) were applied to winter wheat grown in an arable rotation. At the same inorganic N rate, grain yields for the different organic amendment treatments (excluding the straw treatment) were statistically similar but significantly greater than the unamended control treatment. The nitrogen rate required for optimum yields tended to be lower in plots receiving a combination of organic amendments and mineral fertiliser. Based on the observed and modelled response functions, organic amendments excluding straw increased maximum achievable yields compared to non-amended controls. The size of the effect varied between seasons and amendments (+4.6 to +19.0% of the control yield), increasing the mean maximum achievable yield by 8.8% across four seasons. We conclude that the application of organic amendments can increase the yield potential in winter wheat substantially over what is achievable with inorganic fertiliser only.

Application of Different Wastes in Soil Improvement in Mining Area

The treatment and utilization of fly ash, coal gangue and straw has become one of the focus issues of social concern. Rational utilization of solid waste to improve agricultural soil is one of the important ways to improve its comprehensive utilization level. This paper summarizes the application of different solid wastes as soil conditioners in soil improvement, and discusses the main problems and countermeasures in soil improvement, in order to provide scientific basis for the utilization of solid wastes as resources.

Availability Changes in Different Exogenous Selenium Fertilizers in Soil and Their Effects on Selenium Accumulation in Wheat

In order to understand the differences in the uptake and accumulation of several common exogenous selenium fertilizers by crops, a wheat pot experiment was conducted to study the availability changes in different selenium fertilizers (potassium selenate, potassium selenite, EDTA-chelated selenium, selenium powder, fly ash, and selenium-enriched straw) in soil and their effects on wheat growth and selenium uptake and distribution. The results showed that the change in availability of different exogenous selenium types in soil was different. During the whole growth period of wheat, the soil available selenium proportion of selenate, selenite, and EDTA-chelated selenium treatment was significantly higher than that of the control (CK), respectively, but there was no significant difference between the other treatments and the CK treatment. In the early stage of wheat growth, the soil available selenium proportion of selenate, selenite, and selenium powder treatment decreased gradually and tended to be stable in the later growth stage of wheat; however, the soil available selenium proportion of other exogenous selenium treatments showed a dynamic change of decreasing in the early period and increasing in the late period. The available selenium content in soil significantly affected the selenium uptake by wheat, and there was a significant positive correlation between them. Selenate application significantly increased the grain and leaf biomass of wheat, but other selenium fertilizers had no significant effect on wheat growth. The accumulation capacity of different exogenous selenium fertilizers for wheat followed the order of selenate>selenite, EDTA-chelated selenium>selenium powder, fly ash, and selenium-enriched straw. There was no significant difference between the selenium powder, fly ash, and selenium-enriched straw treatments and the CK treatment. Selenium was more easily transferred to and accumulated in the stems and leaves of wheat after the application of selenate, whereas selenium was more easily transferred to and accumulated in grains after the application of selenite and EDTA-chelated selenium.

Soil management and seasonality impact on soil properties and soil erosion in steep vineyards of north-western Croatia

Abstract In order to mitigate vineyard degradation, we study different soil management to obtain the most suitable practices. To study the effects of water erosion on vineyards, a rainfall experiment (58 mm h-1 for 30 min) was applied on Anthrosols in humid conditions to assess the impact of treatment (Tilled, Straw and Grass) and season (Spring and Summer). Higher bulk density (BD) and soil water content (SWC) were on the Straw treatment in the Spring period. Also, the Tilled and Grass treatment noticed higher mean weight diameter (MWD) and water-stable aggregates (WSA). In the Summer, BD, SWC and MWD were significantly higher on the Grass treatment. Higher values of time to ponding (TP) and time to runoff (TR) in Spring were recorded on the Grass treatment, Runoff was higher on the Straw treatment. Higher sediment concentration (SC) and soil loss (SL) were noticed during the Tilled treatment. In the Summer period, TP was higher on the Straw treatment, while TR and Runoff were higher on the Straw, SC and SL on the Tilled treatment. This study confirms the positive effects of grass cover and straw mulching as a sustainable agricultural practice in sloped vineyards of north-western Croatia.

Enhanced Rate of Enzymatic Saccharification with the Ionic Liquid Treatment of Corn Straw Activated by Metal Ion Solution

The aim of this paper was to effectively reduce environmental pollution and further improve the enzymatic hydrolysis rate of corn straw. Thus, a pretreatment method for activating cellulose by using ionic liquid to treat metal ion solution was developed. By investigating the effects of the three factors of substrate mass fraction, reaction temperature, and reaction time, and the interaction between the factors on the pretreatment effect, the response surface design method was used to optimize the conditions of ionic liquid (1-butyl-3-methylimidazolium chloride) treatment of corn straw after activation, and the physicochemical structure and enzymatic hydrolysis efficiency before and after treatment were compared and analyzed. The experimental results showed that the yield of reducing sugar was increased by 157.85% and 150.41%, respectively, compared with the untreated corn straw. The analysis of chemical composition and structure showed that the cellulose content of the material increased significantly by 68.11% and 60.54%, respectively, after ionic liquid treatment. The results of the scanning electron microscope (SEM) observation and X-ray diffraction (XRD) showed that the relative crystallinity of the material decreased after ionic liquid treatment, which was more conducive to the enzymatic hydrolysis of cellulose.

Experimental modeling design to study the effect of different soil treatments on the dissipation of metribuzin herbicide with effect on dehydrogenase activity

The dissipation and side-effect of metribuzin (MBZ) were studied with various factors; two soil types (clay loam and sandy loam), soil amendment (wheat straw and without amendment), two temperature levels (25 and 50°C), sterilization (sterilized and unsterilized soil) and time of incubation (15 and 30 days) and designed by Windows version of MINITAB software package to reduce the time and the cost as well as increased the precision. Determination of MBZ by HPLC with recoveries ranged from 50.85 to 108.09%. The MBZ residues were detected in all samples up to 60 days of storage, respectively with decline in their concentrations with the time of incubation. The clay loam soil showed higher dissipation than the sandy loam soil. The different factors in the present study confirmed that the wheat straw amendment, non-sterilization and incubation at 50°C caused higher dissipation of MBZ than without wheat straw, sterilization and incubation at 25°C. The dissipation was described mathematically by a first order equation with t0.5 was ranged from 9.62 to 16.82 days in clay loam soil and from 10.01 to 16.04 days in sandy loam soil. The side-effect of MBZ was tested on soil dehydrogenase activity that can be considered as an indicator of the biological activity and microbial degradation. The result proved that the enzyme activity was significantly decreased in all treatments compared with the controls at 1 and 3 days of incubation then it was gradually increased at 7, 10, 15 and 30 days of incubation. Treatments of wheat straw, non-sterilized and incubated at 25°C or 50°C showed the lowest enzyme inhibition among all treatments.

THE EFFECT OF AGRICULTURAL WASTE COMPOST ON THE POPULATION OF AZOTOBACTER, AZOSPIRILLUM, AND PHOSPHATE SOLUBILIZING BACTERIA IN CORN PLANT MEDIA ON INCEPTISOLS JATINANGOR

Plants require nutrients in order to grow. One method is to provide organic fertilizer in the form of compost. rice straw, Oil Palm Empty Fruit Bunch (OPEFB), and sugarcane bagasse can all be used as compost material. The purpose of this study is to see how different types of agricultural waste compost affect the population of beneficial bacteria such as Azotobacter sp., Azospirillum sp., and Phosphate Solubilizing Bacteria (PSB) on maize planting media in Jatinangor. The study was carried out at the screen house of Ciparanje Experimental Garden in Jatinangor District, utilizing a Randomized Block Design with 9 treatments and three replications. The treatments included a control (no treatment) and three dose levels (5 tons.ha-1 , 10 tons.ha-1 , and 15 tons.ha-1 ) of each type of compost (oil palm empty fruit bunch, sugarcane bagasse, and rice straw). The findings revealed that the use of various types of agricultural waste compost influenced the population of Azotobacter sp., Azospirillum sp., and PSB. When compared to the compost treatment of rice straw and bagasse, the application of OPEFB compost at a dose of 15 tons.ha-1 produced a greater population of Azotobacter sp. 106.43 x 107 cfu.g-1 . While the population of Azospirillum sp. increased by 2.20 x 107 cfu.g-1 as a result of the 15 tons.ha-1 compost of OPEFB, the effect was similar to that of rice straw and bagasse compost. PSB population increased at 15 tons.ha-1 of rice straw compost to 3.73 x 104 cfu.g-1 but not different from 15 tons.ha-1 of OPEFB compost. Compost can be used as an environmentally friendly fertilizing alternative to enhance the population of beneficial bacteria in corn growth media and increasing nutrient availability for plants.

The effect of different types of mulch and different cultivation methods on the quantitative and qualitative traits of sunflower (Helianthus annuus L.) in Ahvaz climate

To investigate the effect of mulch and different cultivation methods on the quantitative and qualitative yield of oil sunflower (Helianthus annuus L.) in Ahvaz climate, a factorial experiment in randomized complete blocks with three replications in the 2017-2018 crop year was in the research farm of Agricultural Sciences and Natural Resources University of Khuzestan. The first factor includes different types of mulch in five levels (non-application, wheat straw, white plastic, live mulch (mung bean cultivation), and black plastic) and the second factor includes three-level cultivation method (on a flat surface, ridge cultivation, and inside the furrow cultivation). The results showed that in the flat surface and on the ridge, black plastic produced the highest amount of chlorophyll a, b, and In the inside the furrow, the highest chlorophyll a was obtained in the application of living mulch. The highest grain yield and oil yield were obtained from the interaction of wheat straw mulch × in the furrow and wheat straw mulch on the ridge. In addition, the highest harvest index was obtained in the treatment of white plastic mulch on a flat surface with an average of 51.85%. In general, it can be said that the treatment of wheat straw and straw × in the inside the furrow and wheat straw × on the ridge were superior in terms of quantitative and qualitative performance.

Experimental Study on the Compressive Strength of Concrete with Different Wheat Straw Treatment Techniques

Experimental Study on the Compressive Strength of Concrete with Different Wheat Straw Treatment Techniques

Determination of Organic Carbon Content of Corn Stalk: A Casestudy in Laiyuan County, Hebei Province

Organic carbon is an important component of straw, which plays an important role in the hydrothermal conditions, physical and chemical properties of straw. In order to discuss the transformation of corn straw in straw and the influence on straw fertility, this paper selects 6 villages in Laiyuan County, Hebei Province as the study area, and uses straw organic carbon analyzer to determine the organic carbon content of straw samples before and after corn straw treatment in the study area. The results show that: The organic carbon content of corn straw in Laiyuan County is 50.62%~55.01%, with an average of 53.46%. In Laiyuan County, the organic carbon content is high in the northern townships, low in the western townships and low in the southern townships. From the spatial distribution of organic carbon content of straw, the organic carbon content of corn straw in the northern area of Laiyuan County is high, while the organic carbon content in the western area is low. The conversion of corn straw in straw and its effect on straw fertility are related to the type of straw, the amount of straw and the planting method.

Chemical treatment of straw for ruminant feeding with NaOH or urea – investigative steps via practical application under current European Union conditions

Weather extremes in parts of Europe have led to a renewed search for alternative feeds for ruminants. Cereal straw presents one source of fibre, which is hard to digest due to its lignin-carbohydrate complexes. Chemical and biological treatments have been investigated to improve digestibility. Here, the applicability of alkaline treatments for farming conditions under EU legislation and their efficacy were checked. Thus, we tested caustic soda (60, 120 g kg-1straw) and urea (15, 30, 45, 60 g kg-1 straw without and with urease addition) applications both at laboratory scale and using a mixer-wagon. The nutritive value was evaluated analyzing chemical parameters including fibre components and estimating in vitro digestibility. The in vitro digestibility indicated by gas production, enzymatically soluble substrate and neutral detergent fibre digestibility (30h) was highest for the NaOH treatments, which did not differ by dose. Remoistening the straw to 600 g DM kg-1 was a precondition for the effectiveness of both treatments. Urease addition enhanced the intended ammonification when urea was applied at ≥ 30 g kg-1. An ambient temperature for urea treatment ≥ 25 °C was necessary and had to be maintained for at least 14 d post treatment. The determination of crude ash in NaOH treated feeds by the standard procedure and time overestimated the mineral fraction and had to be modified. This systematic approach provides guidance for feasible straw treatments for EU farmers. However, trials for feed acceptance and in vivo digestibility are needed to demonstrate the real effect in animals.

Characterizing corn-straw-degrading actinomycetes and evaluating application efficiency in straw-returning experiments.

Corn straw is an abundant lignocellulose resource and by-product of agricultural production. With the continuous increase in agricultural development, the output of corn straw is also increasing significantly. However, the inappropriate disposal of straw results in wasting of resources, and also causes a serious ecological crisis. Screening microorganisms with the capacity to degrade straw and understanding their mechanism of action is an efficient approach to solve such problems. For this purpose, our research group isolated three actinomycete strains with efficient lignocellulose degradation ability from soil in the cold region of China: Streptomyces sp. G1T, Streptomyces sp. G2T and Streptomyces sp. G3T. Their microbial properties and taxonomic status were assessed to improve our understanding of these strains. The three strains showed typical characteristics of the genus Streptomyces, and likely represent three different species. Genome functional annotation indicated that most of their genes were related to functions like carbohydrate transport and metabolism. In addition, a similar phenomenon also appeared in the COG and CAZyme analyses, with a large number of genes encoding carbohydrate-related hydrolases, such as cellulase, glycosidase and endoglucanase, which could effectively destroy the structure of lignocellulose in corn straw. This unambiguously demonstrated the potential of the three microorganisms to hydrolyze macromolecular polysaccharides at the molecular level. In addition, in the straw-returning test, the decomposing consortium composed of the three Streptomyces isolates (G123) effectively destroyed the recalcitrant bonds between the various components of straw, and significantly reduced the content of active components in corn straw. Furthermore, microbial diversity analysis indicated that the relative abundance of Proteobacteria, reportedly associated with soil antibiotic resistance and antibiotic degradation, was significantly improved with straw returning at both tested time points. The microbial diversity of each treatment was also dramatically changed by supplementing with G123. Taken together, G123 has important biological potential and should be further studied, which will provide new insights and strategies for appropriate treatment of corn straw.

Reducing The Soil Erosion by Improving Infiltration Rate of Sprinkler Irrigation Under Laboratory Conditions

The soil under arid and semi-arid conditions is subject to erosion by irrigation. Polyacrylamide (PAM) significantly reduces erosion from irrigation. The PAM applied with sprinklers will provide erosion control and benefit the water infiltration rate, Soil was sieved by (6.2 mm) and placed in (0.75 * 0.60 * 0.15 m) steel boxes, a slope gradient of (6%), a median drop size of (1.2) mm was sprayed by a hanging oscillating nozzle on a height of (3 m). It used (0, 3, and 6 kg ha-1) PAM sprayed by (80 mmh-1) of water intensity for irrigation, followed by the two other-only irrigations. At (PAM=0) runoff mm, soil loss kgha-1 decreased (40%, 73.15%) respectively in the wheat straw treatments compared with bare flumes, in the time infiltration rate mmh-1 increased by (24.52% )in the same condition, It was shown that a significant difference between the mean of runoff at W. straw and bare treatment at (P <0.05), also a runoff was highly significantly affected (P >0.01) by using (PAM), the result shown that there was a nonlinear relationship between soil loss and runoff. with a coefficient of determination R2=0.95. The costs of (polyacrylamide), are between (40-50 $ ha-1) it depending on the type and the company, W. straw residue can be obtained cheaply after the domestic harvesting season.

Growth and Influence of White-Rot Fungi on the Chemical Composition of Wheat Straw Inoculated under Varying Pre-Conditions

Solid-state fermentation with white-rot fungi is an interesting alternative to chemical straw treatment for ruminant nutrition. However, for practical implementation on farms, feasible handling and its effect on nutritional characteristics have to be tested beforehand. Chopped wheat straw was either soaked and drained or just remoistened to about 24% dry matter without subsequent sterilization. Moist straw was inoculated with Pleurotus ostreatus, Ceriporiopsis subvermispora, or Volvariella volvacea. Fermentation lasted up to 42 d with weekly or shorter sampling intervals. Fiber fractions, minerals and elements, and non-starch polysaccharides were analyzed, and microflora was plate counted. Lactic acid bacteria of selected samples were identified by MALDI-TOF. All inoculated fungi grew well under the selected conditions expressed by the visible mycelium and specific smell. P. ostreatus developed fruiting bodies in the given time. Initial numbers of lactic acid bacteria were &gt;8.0 log cfu/g. In the beginning, Weissella confusa/cibaria dominated. However, neither decrease in lignin nor cellulose concentration was observed during the period in either of the treatments, thus seeming to be inappropriate for ruminant nutrition purposes. Some elements and minerals peaked, especially towards the second and third week (Na, Cl, Mg, Fe, and Mn). Growth conditions for mushrooms were optimized by remoistening the straw with a defined amount of water.

Physicochemical characterisation of barley straw treated with sodium hydroxide or urea and its digestibility and in vitro fermentability in ruminants

The development of strategies to overcome the shortage of forage due to persistently low rainfall is becoming a central task for animal nutrition in research and practice. In this study, it was investigated how the treatment of straw with NaOH or feed urea in a practicable procedure for modern farms affects rumen fermentation (gas production and greenhouse gas concentration) as well as the digestibility of feed energy and nutrients. For this purpose, the treatments were tested individually and in different proportions in a total mixed ration (TMR) in ruminal batch cultures in vitro and in a digestibility trial with sheep. In order to explain the observed effects at the molecular level, descriptive data from 13C solid state nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopy were obtained. NaOH treatment of straw increased crude ash (CA), non-fibrous carbohydrates, digestible energy (DE), and metabolizable energy (ME) concentration, whereas the proportion of neutral detergent fibre (aNDFom) and hemicellulose decreased. In urea treated straw, NH3–N and crude protein increased, whereas acid detergent lignin (ADL), DE, and ME decreased. The physically effective fibre (peNDF8) concentration increased in TMR containing 18% of NaOH or urea treated straw (p < 0.01). The application of straw treatments as pure substrates (not as part of a TMR) increased gas production and decelerated ruminal fermentation (p < 0.05). In vitro organic matter digestibility (IVOMD) of the straw (0.31) increased after NaOH (0.51; p < 0.05) and urea treatment (0.41; p > 0.05). As part of a TMR, straw treatments had no distinct effect on gas production or IVOMD. Concentrations of CH4 and CO2 were likewise not affected. Apparent total tract digestibility of aNDFom, acid detergent fibre (ADFom), hemicellulose, and cellulose increased in the TMR by approximately 10% points following NaOH treatment (p < 0.05). The inclusion of urea treated straw did not affect apparent digestibility. Calculated true digestibility of aNDFom was 0.68, 0.74, and 0.79, of ADFom 0.58, 0.57, and 0.65, and of ADL 0.02, 0.13, and 0.08 in TMR including untreated, NaOH treated, and urea treated straw, respectively. 13C NMR and FTIR analyses consistently revealed that the global structure and crystallinity of the carbohydrates (cellulose and hemicellulose) was not altered by treatment and the concentration of lignin was likewise not affected. Depolymerisation of lignin did not occur. However, NMR signals assigned to acetyl groups were significantly altered indicating that straw treatments disrupted linkages between hemicelluloses and lignin. Moreover, the acetates signal was affected. This signal can be assigned to linkages between ferulic acids and hemicelluloses (arabinoxylans). FTIR spectra of straw treatments mainly differed at a wavelength of 1730 cm−1 and 1240 cm−1. Disappearance of the 1730 cm−1 peak suggests removal of hemicelluloses or lignin related compounds by treatment. The disappearance of the lignin peak at 1240 cm−1 could be due to conjugated ketone (phenyl-carbonyl) removal or the removal of ferulic and p-coumaric acid acetyl groups. Both treatments are supposed to release fermentable cell wall components (hemicelluloses) from lignin-associated bonds and as a result, straw fibre can be better fermented in the rumen. This contributes to energy supply and increased fibre digestibility at least in the TMR that contained NaOH treated straw. The alkaline straw treatments probably induced a release of phenolics such as ferulic acid and p-coumaric acid, which can be metabolised in the gut and the liver and metabolites might be excreted with the urine. This could notably contribute to metabolic energy losses.

Straw Management and Slurry Application Affect the Soil Microbial Community Composition and Its Activity

In low-input farming systems, where plant nutrition strongly depends on either organic matter inputs or nitrogen fixation by legumes, it is crucial to understand the effects of different crop residue management strategies on microbially mediated processes that influence nutrient dynamics. To evaluate different straw management options, we conducted a pot experiment with the following treatments: (1) control with no straw added (CON), (2) applying straw to the soil surface (SRF), simulating no-till, and (3) straw incorporating straw to the top 10 cm (INC), simulating minimum tillage. Another factor was slurry fertilization (with 3.2 t d.m. ha−1 or without). Throughout the experiment, CO2 efflux (µmol/m2/s) was measured regularly over a period of four months. Soil sampling was performed to monitor the abundance of the total bacterial, crenarchaeal and fungal communities, as well as nitrogen cycle microbial guilds and the dynamics of labile N and C fractions in the soils at different depths. Among straw treatments, significantly higher soil respiration was observed in INC and SRF compared to CON. Slurry fertilization increased soil respiration in all straw treatments. In the top 10 cm soil layer, the fungal abundance increased in INC compared to SRF and CON, whereas bacteria and crenarchaea did not respond. This effect was even more pronounced with slurry addition. The slurry also stimulated the abundance of certain N-cycle guilds, with the greatest increase in bacterial amoA-bearing nitrifiers and nirS, nosZI and nozII-bearing denitrifiers, particularly in the uppermost 0–1 cm soil layer. Straw treatment effects on N-cycle microbial guilds were less pronounced, while the coupled effect of straw incorporation and slurry was beneficial mostly for nosZ, again mainly in the top 1 cm soil layer. Compared to straw management, slurry fertilization had more potent effects on the abundance and performance of the investigated microbial communities.

Chemiresistive NH Sensor of Cotton-Stalk- Based Carbon@MoS Composites Promoted by Heterojunction

Under the background of the global low carbon development, in order to prevent the carbon in cotton stalks from returning to the atmospheric environment in the form of greenhouse gas, cotton stalks were used as a carbon source to prepare cotton straw-based carbon (CSC). Furthermore, CSC@MoS2 composites were prepared by hydrothermal reaction and used as a gas sensor for the first time. The structure and morphology of the CSC and CSC@MoS2 composites were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy. The CSC@MoS2 sensor exhibits a high sensitivity to NH3, fast response (< 26 s), and recovery (< 2.2 s). No matter whether after three months or in different humidity environments, the response fluctuation of the CSC@MoS2 sensor to NH3 is less than 5%, showing good long-term stability and antihumidity interference ability. Good repeatability is also shown between the different CSC@MoS2 sensors. This study not only provides a new reference for the low-carbon treatment and resource utilization of crop straw represented by cotton stalk but also provides a new path for the development of the gas sensor.

Optimization of ultrasound pretreatment and enzymatic hydrolysis of wheat straw: From lab to semi-industrial scale

In this paper, the dominance of the physical effects of ultrasound (US) pretreatment in improving the delignification of wheat straw at a 1:20 solid/liquid (biomass/water) ratio is reported showing low-frequency/high power (25 kHz, 2 or 3 kW) as preferred conditions. The sonochemical pretreatment with alkali was identified as an optimal method to make the cellulose more susceptible to further enzymatic hydrolysis, thereby increasing the yield of soluble sugars. Previous bench-scale studies have shown that US pretreatment has a positive effect on delignification, nevertheless this has not yet been demonstrated on a larger scale. The objective of this study was to demonstrate the effectiveness of US pretreatment for wheat straw delignification from lab to semi-industrial scale (40 kg biomass) in terms of sugar yield and energy efficiency. A 59.2% of lignin removal was recorded after the cavitational treatment of wheat straw with a subsequent 68 ± 5.7% yield in terms of enzymatic hydrolysis (52.6% glucose, 42.9% xylose and 4.5% arabinose).It was demonstrated that the positive effect of US alkali pretreatment of wheat straw on sugar yield was due to a combination of factors, including (i) an easier accessibility of the biomass carbohydrate network to enzymes due to the increased wheat straw porosity, (ii) the partial removal of lignin, which increases the relative proportion of carbohydrates in the treated biomass, and (iii) the disordering (amorphization) of the cellulose structure, which promotes carbohydrate hydrolysis as well as saponification of the acetyl groups in the hemicellulose. With respect to the Life Cycle Assessment (LCA) and the Cost Benefit Analysis the US pretreatment process herein reported was compared to an alternative Steam Explosion pretreatment. The results of the LCA analysis showed, that for all five environmental categories (energy consumption, global warming potential, water and fossil depletion, and the land occupation) the US pretreatment has advantages in comparison with the standard industrial Steam Explosion pretreatment.

Changes in soil silicon forms and availability as affected by rice straw and its biochar

AbstractPhytogenic silica (PhSi) is suggested to control silicon (Si) cycling in soil–plant systems in tropical and subtropical regions. However, the role of crop residues and its biochar as a source of available Si has not been well investigated in agricultural soils. In our study, we determined and compared the effects of rice straw and its biochar on soil Si forms and Si availability. Soil Si forms were characterised by a sequential extraction method, and soil Si availability was assessed by rice growth and soil Si extraction methods. A soil incubation experiment showed that the addition of rice straw and biochar increased plant‐available Si in soil (including mobile Si and adsorbed Si), as well as soil amorphous Si (especially in rice straw treatments). Moreover, this increase was more significant when higher Si (e.g., Si added at the rates of 1.6 and 2.0 g kg−1 soil) was added via rice straw and its biochar, which is most likely a result of PhSi dissolution. Rice‐straw biochar, particularly at higher Si addition rates, tended to have a higher efficiency in increasing soil Si availability than rice straw, mainly due to its greater proportion of readily labile Si. A rice growth pot experiment showed that it is difficult to determine the extent of Si dissolution from PhSi in rice straw using a short‐term experiment with a normal single‐season straw return rate, where the increased pH played a more crucial role in regulating soil Si availability. Our results imply that, in terms of enhancing Si availability, long‐term biochar application with abundant Si input is more effective than straw retention for improving soil fertility in subtropical and tropical regions with highly weathered soils.Highlights Effect of phytolith‐rich rice straw and its biochar on soil Si availability was studied. Biochar had greater efficiency in increasing plant‐available Si in soil than rice straw. Over the short term, Si dissolution from PhSi is insignificant with a typical single‐season straw return rate. Increased pH played a crucial role in regulating soil Si availability in a short‐term study.