Canola Residues Research Articles

Reducing flea-beetle feeding wounds on canola seedlings with foliar insecticide failed to improve blackleg control

In earlier studies, it was found that Leptosphaeria maculans could readily infect canola via fresh wounds but would require extended leaf wetness to infect intact tissues. We hypothesized that flea beetle feeding wounds might facilitate L. maculans infection under field conditions. Multi-year plot trials were conducted in western Canada to assess the effect of reducing flea beetle feeding wounds on canola seedlings with in-crop insecticide on subsequent blackleg infection. The experiment encompassed susceptible and resistant cultivars seeded into canola stubble from the previous year, with pyrethroid insecticide applied weekly commencing at trace feeding (<5%) to mitigate the insect damage. Fluopyram seed treatment was used as an additional treatment against early blackleg infection. Results from eight station years showed moderate feeding damage by flea beetles and generally high blackleg pressure, with the average disease incidence > 80%. Despite reduced feeding damage due to in-crop insecticide treatment, significant blackleg reduction was not observed. A greenhouse study revealed no correlation between puncture wounds on cotyledons and successful stem infection under high-inoculum conditions, suggesting that reduced insect feeding might not effectively counteract the heavy inoculum pressure resulting from canola residue in field trials. Fluopyram seed treatment did not reduce blackleg substantially, while resistant cultivars consistently exhibited effectiveness. Furthermore, harvested seed from plots with lighter blackleg often displayed lower levels of L. maculans inoculum contamination.

Hydrogen production from supercritical water gasification of canola residues

Canola hull, meal and straw are abundantly available as low-value agricultural residues in Canada. These lignocellulosic feedstocks have the potential for the generation of biofuels as alternatives to fossil fuels. Supercritical water gasification is an emerging hydrothermal process for the conversion of recalcitrant biomasses into value-added hydrogen with the application of water beyond its critical temperature and pressure. This study focuses on the comparative investigation of supercritical water gasification of canola residues for H2 production through optimization of process temperature (350–500 °C), reaction time (20–80 min) and feedstock concentration (10–25 wt%) at a constant pressure of 23–25 MPa. Supercritical water gasification of canola straw resulted in a high H2 yield of 7.1 mmol/g to 6.2 mmol/g of H2 from canola hull and 5.5 mmol/g of H2 from canola meal at a temperature, reaction time and feedstock concentration of 500 °C, 40 min and 20 wt%, respectively. Furthermore, H2 yield and total gas yield from canola straw were maximized to 8.1 mmol/g and 29.7 mmol/g at the optimized supercritical water gasification conditions of 500 °C, 60 min and 10 wt%. Hydrochar obtained at high gasification temperatures also revealed aromatic carbon structures and thermal stability due to dehydrogenation, decarboxylation, deamination and aromatization. The overall results demonstrated the potential of supercritical water gasification as an evolving hydrothermal process to convert lignocellulosic biomass into high-value H2-rich gas.

Effective Treatments for the Successful Establishment of Milkweed (Calotropis procera L.) under Water Deficit

The application of superabsorbents to soils and seed coatings is a pre-sowing seed treatment method that is commonly used to improve early vigor and establish stability and uniformity under water deficit conditions. To evaluate the interaction of seed coating and superabsorbent on Calotropisprocera L. (milkweed) under water deficit conditions, a greenhouse experiment was conducted. The experiment was conducted with four coating material levels (non-coated seeds and seeds coated with peat moss, vermicompost, and canola residue), four growth medium levels (soil, sand + soil, soil + 2 g superabsorbent, and soil + 4 g superabsorbent), and three field capacity regimes (25, 50%, and 100%) in a completely randomized design factorial arrangement with four replications. Reducing the field capacity from 100 to 25% led to decreased growth (shoot and root dry weights and leaf area) and chlorophyll content. The activities of SOD, CAT, APX antioxidant enzymes, and proline increased under drought stress. The use of superabsorbent polymers in growth media enhanced growth indices and chlorophyll content and decreased the activity of antioxidant enzymes and proline under water deficit conditions. The highest chlorophyll and growth indices were observed when 4 g of superabsorbent was added to the growth medium under drought stress. The application of 4 g of superabsorbent to the growth medium reduced the activity of antioxidant enzymes and proline. The use of seed coatings improved the growth indices, antioxidant enzyme activity, and chlorophyll content under drought stress. The most adaptive morphological and physiological responses to water stress were observed in the vermicompost-coated seeds. The vermicompost coating containing a superabsorbent polymer (4 g/kg soil) proved to be the best for establishing milkweed under mild (50% FC) and severe water deficits (25% FC).

Effect of three crop rotations and four residue levels on canola and bean grain yield and residue production

AbstractCrop rotation in agriculture can lead to increased crop productivity in the rotation and improved soil fertility as a result of residue incorporation. Unfortunately, residue incorporation is not a common practice in crop production systems under the Mediterranean regime, largely due to the lack of information on the effect of the follow-up crops. Therefore, this study was conducted with six biannual rotations (bread wheat–canola, bread wheat–bean, durum wheat–canola, durum wheat–bean, corn–canola and corn–bean) using four residue incorporation levels (0, 50, 100 and 200%) in an Andisol in south central Chile. Grain yield and residue production were evaluated in the canola and bean crops 5 years after initiating crop rotation. The previous crop affected canola grain yield and residue production, which were both higher after corn. Meanwhile, the residue incorporation level had a slight effect on residue production after bread wheat. Only bean grain yield was affected by the previous crop, which was higher after the durum wheat and corn crops. The residue incorporation has marginally affected residue production after bread wheat. Finally, residue incorporation at different levels under the conditions of the present experiment had a minimal effect on bean and canola residue production following the bread wheat crop. The best crop rotation for canola grain yield was corn–canola, which produced 0.54 Mg/ha (18.3%) higher yield than the average of the other two rotations. The best crop rotation for achieving higher bean grain yield was corn–bean, which yielded 0.52 Mg/ha (12.3%) higher than the average of the other two rotations.

Nano-Organic Coatings Improve Early Vigor of Brassica napus L. Seeds in Water Deficit

Low emergence and vigor of canola seeds are common problems encountered by canola growers. Seed coating is a good way to solve this problem. The objective of this study was to find the best combination of nano-organic to be used as a coating for seeds for strengthening the absorption of water and emergence seed of low vigor canola. The treatments in the first experiment included six levels of organic coatings: 20% vermicompost with 80% bentonite, 30% vermicompost with 70% bentonite, 40% vermicompost with 60% bentonite, 40% residues of canola with 60% bentonite, 30% residues of canola with 70% bentonite, and 20% resides of canola with 80% bentonite. The results indicated that 20% residues of canola and 20% vermicompost had the highest moisture under the saturation conditions and kept moisture for a longer time. Subsequently, the factors of the second experiment included three levels of water stress (100, 75, and 50% field capacity (FC)), three levels of seed coating (control, vermicompost, and canola residues), and three levels of titanium dioxide nanoparticles (0, 0.5, and 1 mM). The results showed that nano-organic coating improved emergence percentage and seedling traits while increasing superoxide dismutase, peroxidase, and catalase activities and decreasing electrolyte leakage. The highest ratios for emergence percentage (74.67), seedling vigor index (264.58), and leaf area (418) were obtained at the highest level of nano-titanium (1 mM). The highest rates of superoxide dismutase (53.44), peroxidase (30.68), catalase (5.35), chlorophyll content (51.05), and lowest electrolyte leakage (42.39) were observed in the highest level of nano-titanium (1 mM). Based on the results, we suggest the use of rapeseed residues with nano titanium oxide for rapeseed coating. The use of nanoparticles in current seed coatings is useful for reducing stresses in the germination and emergence stages.

Partial Substitution of Chemical Fertilizers with Organic Supplements Increased Wheat Productivity and Profitability under Limited and Assured Irrigation Regimes

Crop wastes could be applied in conjunction with synthetic fertilizers to satisfy crop nutritional needs and enhance soil fertility. A field experiment was carried out during winter 2019–2020 at the AMK Research Farm (Palatoo) Mardan, KPK (Pakistan) to investigate the combined effect of phosphorous (PS) and organic sources (OSs) on wheat productivity under different irrigation regimes. The experimental factors were: two irrigation regimes (limited and full irrigation), three inorganic sources of phosphorus (triple super phosphate (TSP), single super phosphate (SSP) and di-ammonium phosphate (DAP)) applied at 90 kg ha−1, and three organic amendments (farmyard manure (FYM), mung bean residue (MBR), and canola residue (CR)) applied at a rate of 10 t ha−1. A control plot (no phosphorus or organic supply) was included. A randomized complete block design (RCBD) with three replications was adopted. Among the fertilization strategies, SSP + FYM outperformed all other P fertilizers combined with legume or nonlegume residues in terms of grains per spike−1 (52), thousand-grain weight (41.6 g), biological yield (9.7 t ha−1), and grain yield (4 t ha−1). Under full irrigation, improved yield, yield components, and profits were obtained compared to the limited irrigation regime. Three clusters were obtained after applying an Agglomerative Hierarchical Clustering (AHC), and Principal Component Analysis (PCA) conferred the positive effects of inorganic P with FYM on the wheat yield and its related parameters. This study indicated that the productivity of wheat under the SSP + FYM fertilization strategy was found to be more economical with respect to the benefit–cost ratio (BCR). The combined application of SSP + FYM was more profitable in terms of a higher BCR (3.25) than other treatments under the full irrigation regime.

Process optimization and investigating the effects of torrefaction and pelletization on steam gasification of canola residue

In this study, steam gasification of pellets prepared from canola residue was carried out at varying temperatures (650–850 °C) and equivalence ratio (0.2–0.4). The optimal gasification temperature and equivalence ratio, based on syngas yield and its fuel quality, were found to be 800 °C and 0.4, respectively. Torrefaction and densification of canola residue significantly improved syngas yield. Torrefied pellets were obtained from torrefaction of canola residue at a microwave power, residence time and feeding load of 250 W, 10 min and 90 g, respectively. Pellets prepared with different bio-based additives were gasified to compare the effects of binder in gas compositions. The highest total gas yield (24.4 mol/kg), syngas yield (22.1 mol/kg), carbon conversion efficiency (85.1%), lower heating value of gases (2396 kJ/Nm3) and gas energy recovery (29.2%) were reported from the gasification of torrefied canola residue pellet at optimal conditions. Tar yield decreased significantly when torrefied pellets were gasified. A comprehensive characterization of biochar and tar produced from gasification of raw and torrefied canola residue pellets was performed to determine their potential applications. The formation of aromatic carbon structures in biochar produced at higher gasification temperatures was noticed through FTIR spectroscopy. The aromaticity of biochar also resulted in its greater carbon content, heating value and thermal stability as evident from ultimate and thermogravimetric analyses. Tar obtained from gasification of canola residue pellets contained depolymerized products such as organic acids, phenolics, aldehydes, ketones, ethers and esters.

Pelletization of torrefied canola residue: Effects of microwave power, residence time and bio-additives on fuel pellet quality

This study involves a sequential torrefaction and pelletization process to produce high-quality fuel pellets from canola residue. Firstly, canola residue was torrefied via microwave irradiation at 250–450 W for 10–20 min with 70–110 g feed load and further pelletized under 3500 N load for a relaxation time of 15 s. The Box-Behnken design was employed to understand the interactions between torrefaction operating conditions for optimal relaxed density, durability, and hardness of the pellets. The optimal torrefaction as determined at 250 W for 10 min with 90 g feed load having the highest relaxed density (1090 kg/m3), durability (83%) and mechanical strength (0.55 MPa) of fuel pellets. The results show that torrefaction significantly improved the energy content as well as hydrophobicity due to the degradation of the lignocellulosic structure. The goal of this study was to investigate the effects of bio-additives (i.e., lignin, sawdust, mustard meal and pyrolysis-derived bio-oil) to further improve the relaxed density, durability, tensile strength, energy density and hydrophobicity of fuel pellets. The combination of the mustard meal, lignin with bio-oil improved the density, durability, tensile strength by 21%, 20% and 123%, respectively. The energy densities of raw, torrefied pellets and torrefied pellets with additives were found to be 15.6, 19.4 and 21.2 GJ/m3, respectively.

Enhancement of fuel and physicochemical properties of canola residues via microwave torrefaction

Conversion of low value agricultural residues to better-quality products e.g. biofuel, bioproducts can solve the issues related to energy crisis as well as environmental challenges. Torrefaction, a thermochemical pretreatment was employed on canola residue (CR) to augment the physicochemical properties of biomass for heat and energy applications. In the present study, the effects of microwave torrefaction on canola residue have been investigated for the following operating parameters: microwave power (250–450 W), residence time (10–20 min), and feeding load (70–110 g). Box Behnken design method was used to design the experiments and find the interaction between process parameters. Both mass and energy yields diminished with rise in microwave power and torrefaction reaction time. The results show that the carbon content significantly increased with degree of torrefaction while oxygen content had a reverse trend, therefore the atomic ratio of torrefied biomass reduced remarkably. Torrefied biomass shows higher carbon percentages than that for the bituminous coal. In addition, a noticeable decrease in volatile matter was observed with growth in torrefaction severity and thus increased fixed carbon content. The higher heating value (HHV) was boosted up by 26% (promoted from 17.8 MJ/kg to 22.4 MJ/kg). HHV of highly torrefied canola residue is very close to bituminous coal. Fourier transform infrared spectroscopy (FTIR) analysis showed that surface functional groups for example OH, CH, and CO decreased with torrefaction severity indicating the improvement of hydrophobicity of torrefied biomass. Scanning electron microscopy (SEM) results represent a more porous structure at highest torrefaction conditions which happened due to thermal cracking and decomposition of lignin and decreased the grinding energy by 89% compared to that for raw biomass. Moreover, inductively coupled plasma-mass spectrometry (ICP) analysis data showed that concentrations of minerals, alkaline and other essential element amplified with degree of torrefaction. The influence of microwave power was the highest on properties of torrefied biomass, followed by residence time and feeding load. The optimum torrefaction conditions were found at 450W with 90 g feeding load for residence time of 20 min.

The Optimization of Canola Crop Production through Wheat Residue Management within a Western Canadian Context—A Case Study of Saint-Front, Saskatchewan

In this study, the processes of wheat residue degradation in combination with various tillage treatments were explored to determine the ideal management prescription for maximizing canola crop production. A field experiment within a western Canadian context (near Saint-Front, Saskatchewan), consisting of a 2 × 3 factorial design, was conducted to determine the fate of crop residue under different harvest and treatment scenarios. ATR-Fourier transform infrared (FTIR) spectroscopy, FTIR spectromicroscopy, and synchrotron-based X-ray fluorescence imaging (SR-XFI) were used to explore wheat residue degradation mechanisms. The results indicated maximum canola yields and residue degradation occurred in combination with a combine outfitted with an aftermarket chopper and post-harvest treatment by harrow. Crop residue degradation was attributed to cellulose/linen hydrolysis and supramolecular structure changes from high crystalline to amorphous cellulose. Multi-element loss usually accompanied crop residue degradation. An important aspect of this study is the adoption of field-scale analysis to accurately portray real-world sustainable management techniques within a western Canadian context. The findings provided an optimal combination of crop residue treatment and tillage treatment to increase canola production, which had the potential ability to be applied in other countries. It is also an initial attempt to develop a technical composite of FTIR spectromicroscopy and SR-XFI for examining the mechanism of residue decomposition.

Crop rotation can be used to manipulate residue levels under no-tillage in a rainfed Mediterranean-type environment

Fields with low residue levels (<∼2 t ha−1) are prone to erosion and reduced water conservation in semi-arid environments, and high residue amounts (>∼4 t ha−1) can reduce crop establishment and herbicide efficacy. Furthermore, increasing herbicide resistance in southern Australia has resulted in an increase in non-herbicide control measures like ‘windrow burning’, which reduces residue levels. Therefore, it is important to understand crop residue dynamics in this Mediterranean-type environment and any management factors that can be used to regulate amounts of residue. This paper reports on the residue dynamics in a 12-year experiment (2007–2018) in the Wheatbelt of Western Australia, comparing rotations that included: cereal (cereal/cereal/cereal); diverse (wheat/legume/canola); farmer (wheat/barley/break – legume or fallow); and wheat monoculture. Crop residue was either spread behind the harvester (retain) or windrowed at harvest and burnt before seeding (windrow burn). Residue quantity was measured shortly after harvest (usually in December), prior to seeding (usually April), and around anthesis (September).Crop residue amounts were highest after harvest each year and then declined over the next 12 months, until the next harvest. Residue quantity was greatest following years of high rainfall and good crop growth. Within rotations, residue quantity was highest with retained residue in the cereal rotation and wheat monoculture, averaging 5.0 t ha−1 prior to seeding, which could present management problems at seeding time in some years. Residue amounts were lower in the diverse rotation, and levels declined after wheat (4.5 t ha−1) through to legume and canola residue at 3.8 t ha−1. Lowest residue occurred with windrow burning in the farmer rotation, which included one fallow every three years from 2013, with quantities averaging ∼1 t ha−1. Overall, windrow burning before seeding reduced residue amount by ∼50 % compared with retaining the residue.Retaining all residue in a cereal-dominant rotation produced highest residue quantities in this Mediterranean-type environment, but may lead to problems with crop establishment. Residue quantity was reduced to optimal levels by including legume crops or canola in the rotation, as these residues were more rapidly broken down than cereal residues, whilst maintaining residue retention practices.

Canola production and effect on soil chemical properties in response to different residue levels from three biannual crop rotations

ABSTRACT Conservation agriculture using crop rotations and residue management is increasingly accepted in conventional agricultural systems. However, the effects on crop productivity and soil properties of different rotations, levels of use, and residue management have yet to be fully understood. Our study considered the effect of three previous crops (bread wheat, durum wheat, and corn) and four levels of residue incorporation (0%, 50%, 100%, and 200%) in a split plot design with four replicates on canola production parameters and soil chemical properties at the end of this crop. Production parameters and soil chemical properties were mostly affected by the previous crop and less by the residue incorporation rates under the conditions of this experiment; however, neither of these factors affected grain yield (ranging from 4.0 to 4.8 Mg ha−1). Canola residue production was higher (9.7%) after the corn crop, regardless of the residue incorporation rate, but the harvest index was lower after this crop. Most of the soil chemical properties were also affected, revealing increased organic matter and exchangeable K when the previous crop was corn and decreased concentrations of the cations with basic reaction when the previous crop was durum wheat.

Changes in some chemical properties of saline-sodic soils over time as affected by organic residues: An incubation study

&lt;p&gt;Salinization and sodification of agricultural lands in arid and semi-arid regions of the world are two limiting factors in the crop production. This study was conducted to evaluate the effect of readily available agricultural residues on changing some chemical properties of saline-sodic soils. Wheat, potato, sunflower, and canola residues were separately added into three saline-sodic soils at a rate of 2% by weight and thoroughly mixed with soils. Control and treated soils were incubated for 168 days at a constant moisture and temperature. The pH, electrical conductivity (EC), soluble cations, available nitrate (NO3-) and phosphorous (P), cation exchange capacity (CEC), and exchangeable sodium percentage (ESP) were measured during the incubation. The EC increased in the response to the incorporation of plant residues, whereas the pH was reduced. The application of organic components in soils increased CEC and decreased ESP. The results showed that the maximum reduction in ESP was observed in the potato treatment because of the highest Ca2+ concentration. The average reduction in ESP of treated soil samples at the end of incubation followed this order: 16.1% (potato residue-treated soil) &amp;gt;12.7% (canola residue-treated soil) &amp;gt;11.1% (wheat residue-treated soil) &amp;gt;9.6% (sunflwer residue-treated soil). The potato residue was the most effective amendment in changing the chemical properties of saline-sodic soils in comparison with other organic residues. The results indicated that the application of organic residues had a positive impact on reducing the soil sodicity and improving the soil fertility depending on their chemical composition.&lt;/p&gt;

Critical standing crop residue amounts for wind erosion control in the inland Pacific Northwest, USA

Crop residue is an important factor influencing wind erosion of cultivated soils. Establishing soil surface protection afforded by standing crop residue is critical for land managers seeking to reduce or prevent soil loss by wind erosion and the impacts of blowing dust from agricultural lands. The objectives of this study were to evaluate the effect of standing residue on soil wind erosion in the inland Pacific Northwest (iPNW), USA, and test the performance of the plant factor algorithm of the Agricultural Policy/Environmental eXtender (APEX) and Revised Wind Erosion Equation (RWEQ) models in influencing soil loss. The effect of standing winter wheat (Triticum aestivum L.), spring canola (Brassica napus L.), and chickpea (Cicer arietinum) residue on wind erosion, remaining from major commodity crops in the region, was tested in a laboratory wind tunnel using four levels of residue density. The impact of standing residue in controlling wind erosion was compared and analyzed in terms of residue density and their respective frontal area index. Our results show that residue at a density characteristic of the production environment (110 standing residue elements m−1 for winter wheat, 20 standing elements m−1 for canola, and 16 standing elements m−1 for chickpea) provided significant protection to the soil surface from wind erosion. Soil loss at this level of residue density was reduced by 73.3, 53.4, and 60.9% for respectively winter wheat, spring canola, and chickpea (frontal area indexes are 0.172, 0.104, and 0.026 respectively) compared with a surface without residue. The soil surface was found to be at significant risk from wind erosion when residue densities of the three crop types were <50% of the typical production amounts. Although not consistently significant, soil loss decreased as wind direction shifted from parallel to perpendicular with the standing residue row. The APEX model adequately simulated winter wheat and spring canola residue protection but had low accuracy in representing chickpea residue effects relative to the wind tunnel experiments. In contrast, the RWEQ model appeared inadequate in simulating soil loss for the winter wheat and canola treatments but adequately represented chickpea residue effects. Differences in model accuracy for different crop types must be considered by producers and managers to determine whether model information used to select practices to control wind erosion are likely to result in under- or over-protection of soil resources.

Mulching techniques: An approach for offsetting soil moisture deficit and enhancing manure mineralization during maize cultivation

Mulching is an effective technique for soil moisture conservation and increasing mineralization. Four mulching practices (i.e. no-mulch, canola residue, transparent and blue plastic) and five nitrogen (N) treatments (i.e. no-N, 100, 70, 50, 0 % from farmyard manure (FYM) with remaining from urea) to supply a total of 250 kg N ha−1 were assessed under field and lab conditions for soil moisture conservation and quantification of soil organic matter (SOM), total nitrogen (TN) and mineral nitrogen (min-N) contents in 2013-14. A total of 40 % added water to the soil was lost in no-mulching compared to 7 % been lost in plastic mulching during first week in open shed. Based on moisture losses, three moisture regimes were developed and used in a 56 days incubation experiment. The 60 % relative water holding capacity (RWHC) corresponding to plastic mulching had lowered SOM (1.0 %), and TN (1.6 %) but increased min-N (5.9%) than 40% RWHC (corresponding to no-mulch). Among the nitrogen treatments, 100% FYM had improved SOM and TN, but mineralization was higher in 50% FYM/urea. In field studies, the canola residue mulching had increased the SOM (8.4%), TN (1.2%), min-N (5.2%) and moisture contents (5.7%) over no-mulching. The 100% FYM had higher SOM (2.25 folds), TN (2.79 folds) and moisture content (11.3%) than control. In conclusion, soil fertility was improved with 100% FYM and mineral N with 50% FYM/urea. Thus, 100% FYM or 50 %FYM + 50 % urea sources to provide 250 kg N ha-1 should be used with plastic mulching in weed infested area or residue mulch in weeds free field conditions for improving mineralization and water conservation.

Maize grain production, plant nutrient concentration and soil chemical properties in response to different residue levels from two previous crops

ABSTRACTThe incorporation of previous crop residues in agricultural management benefits soil fertility, crop production, and environment. However, there is no enough information about maximum residue application level without negative effect over next crop yield. To evaluate maize (Zea mays L.) yield under short-time conservation management with incorporation and/or importation of different residue levels, a biannual rotation experiment was conducted in ash volcanic soil in south-central Chile. The experiment consisted of two previous crops, canola (Brassica napus L.) and bean (Phaseolus vulgaris L.), and four levels of residue incorporation (0%, 50%, 100%, and 200% of generated residue; from 0 to 21.4 Mg ha−1 for canola and from 0 to 19.0 Mg ha−1 for bean). Previous crop species and residue level affected some nutrients concentrations in grain and plant and some soil chemical properties, without effect in maize yield, which averaged 16.6 Mg ha−1. Bean residue increased Ca and reduced S in maize plant, increasing soil P, Ca, Mg and K (P < 0.05). Maize grain Ca content was positively and proportionally affected by canola residue level and negatively and proportionally affected by bean residue level. All canola residue levels increased soil pH and Mg, but the highest level reduced soil S; soil P concentration increased proportionally with bean residue level. The highest bean residue level increased soil S. Different crop and levels of residue did not affect maize yield but did some plant nutrient concentration, and also affected some soil chemical properties.

Growth and yield parameters of white oat and wheat as affected by canola residues

ABSTRACT Despite being an important crop option for Brazilian agriculture, canola has some characteristics that may limit its insertion in some cropping systems, such as its allelopathic effects. Thus, the present work aimed to study the effect of canola crop residues on the seed germination, growth and grain yield of white oat and wheat plants. In laboratory conditions, white oat (Milton) and wheat (Tbio Pioneiro) seeds were germinated in the presence of aqueous extracts of (i) aboveground part, (ii) root system, (iii) whole plant and (iv) twice the concentration of the whole plant extract, besides a control. In green house conditions, the same oat and wheat cultivars were grown until harvest, on soil mixed with fresh canola crop residues (whole plant residues, aboveground residues and root residues) and a control. Aqueous extract of the whole canola plant reduced the germination and increased abnormal seedlings of white oat and wheat, mainly in high concentration. For soil crop, the presence of canola residues did not affect the white oat emergence, growth and grain yield. For wheat, plant emergence was lower in the presence of canola residues, but growth and yield were not affected.

Enhanced humification of maize straw and canola residue during composting by inoculating Phanerochaete chrysosporium in the cooling period

To enhance the humification process, Phanerochaete chrysosporium (P. chrysosporium) was inoculated during different fermentation phases of the co-composting of maize straw and canola residue. The humification process was determined by evaluating cellulose and lignin contents and key enzyme activities during composting. Results showed that the cellulose and lignin degradation efficiency and humification degree of compost were significantly enhanced in the treatment that inoculated P. chrysosporium in the cooling period (T2). At the end of composting, compared with that in T1 (no inoculation), the content of cellulose and lignin in T2 decreased significantly by 40.00% and 64.30%, respectively, and compared with that in T1 and T3 (inoculation in the initial stage of composting) the content of humus in T2 increased significantly by 55.40% and 75.20%, respectively. This study confirms that inoculating P. chrysosporium during the cooling period promoted the degradation of cellulose and lignin, and therefore enhanced the compost humification.

Demonstrating the suitability of canola residue biomass to biofuel conversion via pyrolysis through reaction kinetics, thermodynamics and evolved gas analyses

The identification of biomasses for pyrolytic conversion to biofuels depends on many factors, including: moisture content, elemental and volatile matter composition, thermo-kinetic parameters, and evolved gases. The present work illustrates how canola residue may be a suitable biofuel feedstock for low-temperature (<450 °C) slow pyrolysis with energetically favorable conversions of up to 70 wt% of volatile matter. Beyond this point, thermo-kinetic parameters and activation energies, which increase from 154.3 to 400 kJ/mol from 65 to 80% conversion, suggest that the energy required to initiate conversion is thermodynamically unfavorable. This is likely due to its higher elemental carbon content than similar residues, leading to enhanced carbonization rather than devolatilization at higher temperatures. Evolved gas analysis supports limiting pyrolysis temperature; ethanol and methane conversions are maximized below 500 °C with ∼6% water content. Carbon dioxide is the dominant evolved gas beyond this temperature.

Elevated CO2 alters the rhizosphere effect on crop residue decomposition

Elevated atmospheric CO2 (eCO2) can affect microbial decomposition of native soil organic carbon (SOC) via enhanced root exudation and rhizosphere activity. Few studies have examined the effect of eCO2 on the decomposition of newly-added crop residues, which are important to understand below-ground C changes. A soil microcosm experiment was conducted to examine whether eCO2 would enhance the rhizosphere effects on the decomposition of crop residues. White lupin (Lupinus albus L. cv. Kiev) was grown for 34 or 62 days under ambient CO2 (aCO2, 400 μmol mol−1) or eCO2 (800 μmol mol−1) in a low-C (2.0 mg g−1) soil which was amended with or without dual 13C and 15N labelled wheat, field pea or canola crop residues. An isotopic tracing technique was adopted to partition residue-derived CO2 from total below-ground CO2 efflux. Two independent groups of data were analysed statistically at either Day 34 or 62. The presence of white lupin increased the decomposition of all residues at Day 34. This positive rhizosphere effect on residue decomposition decreased and was even reversed at Day 62, probably due to depletion of labile C, or microbial N limitation, or rhizosphere acidification. The eCO2-induced decomposition depended on residue type at Day 34. Specifically, when compared to aCO2, eCO2 did not affect the decomposition of canola residue, increased that of field pea residue by 13.5% but decreased wheat straw decomposition by 7.4%. However, residue decomposition was, on average, 13% higher under eCO2 at Day 62, which was correlated positively with the increase in rhizosphere extractable C (P < 0.01). Elevated CO2 generally increased residue decomposition in the rhizosphere, but this effect was mediated by residue type at Day 34. Enhanced residue decomposition under legumes at eCO2 may favour C turnover and the release of residue N.