Sugarcane Crop Residues Research Articles

Use of sugarcane crop residue silage with different levels of inclusion in dual-purpose cow diets

In the sugar cane production chain, different byproducts are generated that can be used in animal feed. Their conservation in the form of silage is an important contribution towards improving animal production in tropical regions. The objective was to evaluate the inclusion of different levels of silage from sugarcane crop residues in the diet of dairy cows in a family farming system. Nine lactating cows were used in a 3x3 Latin square design in triplicate and means were compared using the Tukey test. The treatment sequences were randomly assigned with periods of 14 days. Three treatments were formulated that included feed of mixed native grasses, supplemented with sugarcane top silage with different inclusion levels (2 kg/DM for T1, 4 kg/DM for T2 and 6 kg/DM for T3), along with commercial concentrate and corn silage. Milk production, its chemical composition, and the efficiency of feed utilization were evaluated. The average milk production, fat content and crude protein were, respectively, 9.38kg/cow/day, 32.6 and 340.0 g/cow/day. No differences were detected (P>0.05) for any of the variables evaluated, but the inclusion of 6 kg of sugarcane residues silage improved the animals' feed efficiency. Therefore, sugarcane top silage is a viable alternative for feeding ruminants.

Dry Rot Caused by the Complex Colletotrichum falcatum and Thielaviopsis paradoxa Emerges as a Key Stalk Disorder in Newly Expanded Sugarcane Plantations from Northwestern São Paulo, Brazil

Sugarcane dry rot emerged as an important stalk disorder in newly expanded plantations in northwestern São Paulo, Brazil, under the current no-burning fully mechanical harvest policy gradually implemented in the past 20 years. This emergence was probably due to a considerable increase in both pathogen inocula and insect pest populations in sugarcane crop residues kept in the field. In this study, we surveyed the incidence of three stalk-related disorders in commercial sugarcane fields in six municipalities in northwestern São Paulo and the corresponding yield losses. The three stalk-related disorders surveyed were as follows: the red rot disease caused by the fungal pathogen Colletotricum falcatum, the spittlebug-induced shoot stunting, and the stem dry rot, which is associated with the simultaneous infection of C. falcatum and Thielaviopsis paradoxa, the pineapple set rot pathogen. Red rot disease was detected in 88.2% of the fields surveyed, while the spittlebug-induced shoot stunting disorder and the internal stem dry rot were found in 97.1% of the fields. Stem dry rot had the highest incidence and resulted in the highest yield losses. Total sugarcane yield losses were estimated at 20.1%, with an average of 14.2 (±3.8) t·ha−1 per field. The multiple regression model constructed to determine which of the three stem-related disorders contributed the most to total yield losses was not significant. Subsequently, the performance analyses of single-variable polynomial regression models indicated that the simple linear model was the best fit in terms of independently predicting sugarcane yield losses based on each stem-related disorder. Positive and significant correlations were only detected between sugarcane yield losses in t·ha−1 and the incidence of red rot disease or leafhopper-induced shoot stunting. We concluded that the stalk’s internal dry rot, as a disease complex associated with both C. falcatum and T. paradoxa, was the most important disorder in sugarcane fields in the northwest region of São Paulo state. A sustainable pest management program is needed to reduce the impact of all three stalk-associated disorders on regional sugarcane production.

Changes in water‐extractable organic matter in tropical forest and agricultural soils as detected by the DRIFT spectroscopy technique

AbstractWater‐extractable organic matter (WEOM) drives many fundamental functions which determine soil equilibria, acting as a useful probe to highlight the effect of land management on overall C cycling. The ecological importance of WEOM is emphasized in tropical environments characterized by humid climate and short OC turnover. The low OC concentration and the physical–chemical conditions associated to water dissolved compounds determine an analytical issue for the characterization of WEOM. The present experiment aimed to test the diffuse reflectance infrared Fourier transformation (DRIFT) spectroscopy as a rapid tool to evaluate the dynamic of WEOM in tropical soils under different soil organic matter (SOM) managements. The influence of SOM composition on WEOM fraction was evaluated in a laboratory incubation of two tropical soils treated with different organic amendments. The superficial layers of forest and sugarcane Ultisol were incubated for 1 year with 10 mg C g−1 soil of litter from either native tropical forest or sugarcane crop residues. The sugarcane residues promoted a fast increase of dissolved organic carbon (DOC) followed by a subsequent decrease in both soils, whereas the soils amended with forest litter showed DOC dynamics similar to control samples. The DRIFT analysis unveiled changes in the chemical profile of WEOM mainly reflected on the preservation of dissolved hydrophobic compounds. The results indicate the DRIFT technique as an efficient tool to monitor the chemical changes of WEOM f as related to soil use and organic inputs, and to support a comprehensive understanding of the interaction of WEOM in agro‐ecological and environmental processes.

Sugarcane straw effects on soil compaction susceptibility

Crop residues may buffer part of compressive stress applied over the soil surface. Thus, indiscriminate crop residue removal would magnify soil compaction in highly mechanized cultivation systems, such as sugarcane in Brazil. Nevertheless, the effect of different amounts of sugarcane crop residue (straw) on soil compaction mitigation still needs to be tested. We conducted a laboratory study to quantify the effects of sugarcane straw rates on soil compaction indicators in response to external applied stress. The experiment involved remolded soil cores with four initial bulk densities: 1.25, 1.35, 1.45 and 1.55 Mg m−3, and five amounts of straw were left on soil surface, equivalent to 0, 5, 10, 15 and 20 Mg ha−1. The soil cores were subjected to uniaxial compression test and seven successive vertical static loads (25, 50, 100, 200, 400, 800 and 1600 kPa) were applied over the soil surface using a pneumatic consolidometer. Soil displacement was measured after each applied load. Based on these values, apparent precompression stress (σp), apparent compression index (CI) and final bulk density were calculated as indications of soil deformation. Because, soil inherent properties should not change, we call the changes due to straw layer addition "apparent" in this study. Our results revealed that large amounts (>10 Mg ha−1) of straw increased subtly apparent soil load bearing capacity (i.e., increased up to 15 kPa in apparent σp; 7%). The bulk density change rate (soil deformation) decreased due to presence of straw under low stress (<100 kPa), and increased under high stress (>400 kPa) levels in loose soil. On the other hand, compaction was slightly reduced in compacted soil, with corresponding reduction on apparent CI values. Nevertheless, despite this buffer effect provided straw, we noticed that increases in surface straw amount are likely insufficient to reduce the risk of compaction (little gain in apparent load-bearing capacity), but a reduction of about 5% on the soil deformation (as apparent σp is overcome) could occurs in compacted soils. We advocate that benefits of leaving sugarcane straw covering the soil go beyond the direct “damper” effect, because straw is source of carbon, which is fundamental for enhancing soil structure stability and biological activity, and thus, reducing soil compaction risks or even alleviating soil compaction restrictions to plant growth. Finally, we encourage future studies to test the straw effects under machinery traffic in field conditions, which could involve the additional effect of shear stress over the tyre-straw-soil interface.

Trade-Offs between Sugarcane Straw Removal and Soil Organic Matter in Brazil

Environmental benefits from bioenergy production derived from sugarcane crop residues (straw) can be lost by soil organic matter depletion resulting from excessive straw removal rates from fields. Soil organic carbon stock is the core for sustaining soil health, supporting nutrient cycling, and sequestering carbon dioxide. To find out that how much sugarcane straw can be removed from the field to produce bioenergy without changes in soil C concentrations, we investigated effects of straw removal rates (total, moderate, and no removal of sugarcane straw) on soil carbon and nitrogen fractions in an Oxisol and an Ultisol in southeastern Brazil for two years. Soil C and N fractions were affected by increased rates of straw removal at the second year. In the Oxisol, total straw removal decreased labile and microbial-C by ~30% and soil C stock by 20% compared to no straw removal. No removal decreased microbial-N and total N stock by ~15% and ~20%, respectively. In the Ultisol, no straw removal resulted in increases in C stock by &gt;10% and labile and microbial-C by ~20% related to total straw removal. Total straw removal showed more microbial-N (~10%) and total-N stock (~25%) compared to no straw removal. The moderate straw removal intensity (i.e., 8 to 10 Mg ha−1 of straw) may control the straw-C release to soil by straw decomposition. This study suggests that excessive straw removal rates should be avoided, preventing SOM depletion and consequently, soil health degradation. Moderate straw removal seems to be a promising strategy, but long-term soil C monitoring is fundamental to design more sustainable straw management and bioenergy production systems.

Soil carbon characterization in a subtropical drained peatland

Peatlands store a significant portion of the global carbon (C) budget. Peatland drainage triggers soil subsidence and is a threat to soil conservation. Differences in C composition as soils get shallower in drained peatlands are not clearly understood. Soil C quality has been considered as one of the possible causes for changes in soil subsidence rates in drained peatlands. The purpose of this research was to characterize soil C in drained peats experiencing soils subsidence by using a fractionation procedure and 13C Nuclear Magnetic Resonance (13C NMR) spectroscopy. The study was done in the Everglades Agricultural Area (EAA), located south of Lake Okeechobee in south Florida, US. The EAA is a subtropical peatland that has been drained for more than 100 years. Subsidence rates at the EAA have shown a reduction in recent decades possibly due to higher water tables and increases in inorganic and recalcitrant C (Shih et al., 1998). Analyses were performed for the top and bottom of sampled peat soils collected from shallow and deep soil areas within the EAA. Hot water (80 °C) and acid extractions were used to determine operational C fractions with residues characterized by magic angle spinning (MAS) 13C NMR spectroscopy before and after extraction to quantify C compound classes. Recalcitrant C is the dominant C pool in EAA soils with 85% of total carbon (TC) on average, while acid extracted C, hot water extracted C, and inorganic C comprise 19%, 1%, and 0.7% of TC, respectively. Shallow soils had significantly less organic matter (OM), hot water extracted C, and recalcitrant C, and showed a reduction of OM and C fractions deeper in the soil profile. The 13C NMR spectra analyses indicate that average C compounds in EAA peats are O-alkyl C (36.9%), followed by alkyl C (28.2%), aromatic C (24%), and carboxyl C (10.8%), with shallow and deep soils having a similar distribution of these C compounds. Extracted recalcitrant C fractions of both shallow and deep soils showed an increase in aromatic C (34.3%) and a reduction in O-alkyl C (26.6%). Subsidence reduced OM in shallow soils and can reduce soil C, including the recalcitrant C pool, which might affect N cycling and nutrient availability. Addition of fresh biomass into the soil (e.g. sugarcane crop residue) might increase labile C reducing subsidence and improving soil conservation in the EAA and other drained peatlands.

Effect of in situ recycling of sugarcane crop residue and its industrial wastes on yield and quality of sugarcane and soil sustainability in Inceptisol

A field experiment was conducted at Central Sugarcane Research Station, Padegaon Farm Tal Phaltan Dist Satara (M.S.) during 2015-16 to 2018-19 as a one plant cane and its three successive ratoon with object of to assess the effect of recycling of sugarcane crop residues and it’s industrial wastes on yield, quality and nutrient uptake of sugarcane, study the soil properties as influenced by decomposition of sugarcane crop residues and it’s industrial wastes, to assess the changes in soil organic carbon as influenced by various treatments of in situ decomposition of sugarcane crop residues and industrial wastes and to assess the possibility of saving of chemical fertilizers.The experimental results recorded and mentioned during harvest of second ratoon. It consists of main plot treatment as sugarcane crop residue and industrial wastes management with sub plot treatment comprising fertilizer levels. In situ recycling of sugarcane crop residues + pressmud compost + Post biomethanated spent wash + bagasse ash recorded significantly higher cane yield, CCS yield and number of millable canes per hectare also improved physico chemical properties of soil. However, effect of fertilizer levels results showed that the fertilizer level receiving 100 % recommended dose of fertilizers recorded significantly higher cane yield, CCS yield and number of millable canes and it was at par with 75 % recommended dose of fertilizers. While in terms of soil chemical parameters showed significant results for organic carbon, available nitrogen, available phosphorus and available potassium as compared to soil initial status. The higher gross and net return were observed in the In situ recycling of sugarcane crop residues + pressmud compost + Post biomethanated spent wash + bagasse ash (Rs.2,72,857 and Rs.2,02,815) with higher benefit cost ratio (2.90). The 100 % recommended dose of fertilizer recorded significantly higher gross and net return (Rs.2,78,614 and Rs.2,00,093) with higher benefit cost ratio (2.55). Thus, result shows that recycling of sugarcane crop residue and industrial wastes along with 100% or 75 % recommended dose of fertilizers found to be better for enhance farmers income as well as improves soil health.

Supply Chain Optimization for Energy Cogeneration Using Sugarcane Crop Residues (SCR)

Access to clean and non-polluting energy has been defined as a Sustainable Development Goal (SDG). In this context, countries such as Colombia have promoted policies and incentives for the implementation of energy projects with non-conventional sources of energy. One of the main energy alternatives available is related to the use of residual biomass left by agribusiness supply chains, such as sugarcane. In Colombia, sugar cane is grown and harvested all year round, due to the local tropical climate. The model we propose addresses the question of the selection of the plots whose crop residue will be transported for energy production on a given day. We built a Mixed-Integer Programming model to decide which plots to harvest on a given day. Although no additional energy is generated in the model, the results show that it is feasible to replace all coal used in the boilers with sugarcane crop residues (SCRs) for power cogeneration.

Does Sugarcane Straw Removal Change the Abundance of Soil Microbes?

Growing global demand for bioenergies has raised the interest in using sugarcane crop residues (straw) as feedstock to produce cellulosic ethanol and/or bioelectricity in Brazil. However, indiscriminate straw removal may deplete soil quality, particularly induced by its negative effects on soil microbial communities. A 2-year field study was conducted in soils classified as Oxisol (site 1) and Ultisol (site 2) in southeastern Brazil. The experiment started after plant cane cycle, establishing three straw removal rates (treatments), as follows: total removal, moderated removal, and no removal of sugarcane straw from the field. The amount of straw left on the soil surface and removed in the treatments varied according to the straw yield of each year and location. Soil samples were collected at 0–5- and 5–10-cm layers. The total abundance of bacteria, archaea, and fungi were analyzed by real-time quantitative polymerase chain reaction (qPCR). Bulk density, pH, base saturation, cation exchange capacity, phosphorus (P), and total organic C and soil microbial biomass C (MBC) were also measured. The soil chemical results indicate that the Oxisol presents higher inherent soil fertility compared with the Ultisol. In the first year, the straw had a different significant effect for bacterial and archaeal abundance in both soils and for fungi in the Oxisol site. In the second year, the numbers of gene copies of bacteria, archaea, and fungi in the 0–5-cm layer were higher under moderated and no removal when compared with those under total removal, regardless of site. The MBC decreased significantly under total removal of straw at the Ultisol site. Moderate straw removal has no significant effect on the abundance of soil microbes, but total straw removal may induce sharp reductions (from 23 to 54%) on microbial abundance. Soil microbes are a sensitive indicator to assess soil changes induced by crop residue management and should be taken into account for defining sugarcane straw management towards a sustainable bioenergy production.

Crop residue removal and nitrification inhibitor application as strategies to mitigate N2O emissions in sugarcane fields

Nitrous oxide (N2O) emission estimates are important to ascertain the greenhouse gas balance of ethanol produced from sugarcane. We quantified N2O emissions in the presence of sugarcane crop residues, N fertilizer (ammonium sulfate), and a nitrification inhibitor (NI, dicyandiamide). Two field experiments were conducted to evaluate the implications of N fertilizer application during dry and wet seasons at two locations in southeast Brazil. Treatments consisted of four levels of crop residue (0, 5, 10, and 15 Mg ha−1) and three of N fertilizer (0 and 120 kg ha−1 and 120 kg ha−1 plus NI). N2O emission was measured using the closed chamber method and sugarcane yield via mechanical harvest. N2O emissions were higher in wet than in dry seasons following N fertilizer application, albeit affected by crop residue and NI in both. Retaining crop residues on the soil increased N2O emission and sugarcane yield. The N2O emission factor from N fertilizer ranged from 0.12% to 1.44% of N applied. NI reduced N2O emissions (by 87% and 63% in dry and wet seasons, respectively). Sugarcane yield varied from 42 to 92 Mg ha−1 of fresh matter stalk and emission intensity from 3.7 to 22.9 kg of CO2eq. Mg of stalk−1. The lowest greenhouse gas intensity was recorded with 5 Mg ha−1 crop residue and 120 kg ha−1 N supplemented with NI. Therefore, partial crop residue removal and NI addition to N fertilizer may be effective strategies to improve the sustainability index of biofuel from sugarcane and reduce N2O emissions and intensity.

Using steam explosion or AFEX™ to produce animal feeds and biofuel feedstocks in a biorefinery based on sugarcane residues

AbstractSustainable integration of biofuel (primarily bioethanol) and highly digestible livestock feed in production systems is a potential way to increase the economic returns to agriculture and simultaneously promote energy security, particularly in developing countries. In this work we evaluated the efficacy of steam explosion (StEx) and ammonia fiber expansion (AFEX™) as potential processes for improving the in vitro rumen digestibility, metabolizable energy, and ethanol yields from sugarcane crop residues (bagasse and cane leaf matter, CLM). Ammonia fiber expansion pretreatment enhanced the in vitro true digestibility and metabolizable energy content of sugarcane crop residues by 69% and 26%, respectively compared to untreated controls. On the other hand, StEx increased the true digestibility and metabolizable energy content of the sugarcane residues by 54% and 7%, respectively. Ammonia fiber expansion also increased the total nitrogen content of both sugarcane bagasse and CLM to more than 20.2 g kg−1 dry forage, a more than 230% improvement relative to untreated controls. High solid‐loading enzymatic hydrolysis and fermentation of StEx‐ and AFEX™‐pretreated sugarcane crop residues generated yields of up to 3368 and 4360 L of ethanol per hectare of sugarcane cultivated, respectively, at a biomass‐degrading enzyme dosage of 20 mg protein per gram glucan. This research strongly suggests that the use of suitably pretreated sugarcane crop residues in integrated sugarcane biofuel‐livestock production systems can increase the total per hectare agricultural output without increasing the area of sugarcane cultivated. In effect, this integrated approach promotes more sustainable biofuel production and increased food production while avoiding the potential for indirect land use change. © 2018 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

Sugarcane Crop Residue and Bagasse Allelopathic Impact on Oat (Avena sative L.), Tall Morningglory (Ipomoea purpurea L. Roth), and Redroot Pigweed (Amaranthus retroflexus L.) Germination

Allelopathy, the chemical interaction between plants, may result in the inhibition of plant growth and development, and includes compounds released from a primary crop that adversely impact crop or weed species. The objective of this research was to observe the allelopathic impact of sugarcane (Saccharum sp.) post-harvest crop residue and mill bagasse leachate on seed germination of three other plant species. Oat (Avena sative L.) var. ‘Corral’, tall morningglory (Ipomoea purpurea L. Roth), and redroot pigweed (Amaranthus retroflexus L.) seeds were treated with 5 leachate concentrations (0, 12.5, 25, 50, and 100 g/L) from either sugarcane crop residue or sugarcane bagasse. Each experiment was repeated twice (Experiment 1 &amp; 2) with each plant species, leachate concentrations, and leachate source (sugarcane crop residue and mill bagasse). The impact of leachates from sugarcane variety ‘HoCP 96-540’ crop residue and sugarcane bagasse differed by the species evaluated (oat, morningglory, and redroot pigweed), the leachate source (crop residue vs. bagasse), and leachate concentration (0 to 100 g/L). Oat germination was not affected leachate source or concentration. Germination for both weed species, tall morningglory and redroot pigweed, were adversely affected by leachate source and concentration. In both cases, the sugarcane crop residue leachate had a greater deleterious impact on germination than did the bagasse leachate. The response to the leachates was more consistent and severe for tall morningglory germination than redroot pigweed germination. Averaged across experiments, the 12.5 g/L crop residue concentration decreased the tall morningglory germination to 17% compared to 34% germination for the bagasse leachate, and the 100 g/L residue concentration reduce germination to 6% compared to 19% for bagasse 100 g/L bagasse concentration. The 100 g/L concentration of crop residue reduced redroot pigweed germination by 13% (Experiment 1) and 27% (Experiment 2), while the bagasse leachate reduced germination by 5% (Experiment 1) and 15% (Experiment 2). Future research should investigate the allelopathic compounds present in the sugarcane crop residue and bagasse, determine if the same allelopathic compounds are present and in the same concentration among other sugarcane varieties, and further examine which weed and crop species may be vulnerable to the allelopathic compounds present in sugarcane crop residue and bagasse.

Evaluation of different methods for efficient extraction of hemicelluloses leaves and tops of sugarcane

En Colombia se producen alrededor de 9 millones de toneladas de residuos de la cosecha de la caña de azúcar por hectárea cada año, que no han sido valorizados hacia ningún tipo de producto. Es necesario conocer su composición, en especial el contenido de hemicelulosas, para dilucidar el proceso para obtener los monosacáridos de éstas y aislarlos eficientemente. Para separar las hemicelulosas puras, se estudiaron cinco procesos de extracción a partir de las hojas y cogollos de las variedades de caña de azúcar CC 8592, CC 8475 y V 7151. Después de evaluar la eliminación de ceras con etanol y mezclas de cloroformo-metanol, los residuos se expusieron a diferentes concentraciones de peróxido de hidrógeno y clorito de sodio acidificado para lograr su deslignificación. Adicionalmente, se desarrollaron procedimientos de extracción con hidróxido de sodio e hidróxido de potasio, y de precipitación. El método que logró el mayor rendimiento fue el de desceración con metanol-cloroformo y deslignificación con clorito de sodio y borohidruro de sodio, con un rango de recuperación entre 0.20-0.34 g hemicelulosas /g residuo seco en las variedades estudiadas.

Green-Cane Harvested Sugarcane Crop Residue Decomposition as a Function of Temperature, Soil Moisture, and Particle Size

Sugarcane, a complex hybrid of Saccharum species, is grown on over 170,000 ha in the state of Louisiana. In 2016, the crop was worth $750 million US. Green-cane harvest, widely used in sugarcane producing countries, deposits up to 20 Mg ha−1 of crop residue annually. Green cane harvesting of sugarcane is recognized to be a more sustainable management opportunity than burning residue, or standing or heaped stalks. In Louisiana, cool, wet winters coupled with the crop residue left on the field reduce ratoon yields by as much as 10% year−1. However, the residue represents an important opportunity to improve degraded, low organic matter soils to facilitate sustainable sugarcane production. Our objective was to evaluate how temperature, soil moisture, and particle size influence sugarcane residue decomposition rates. In laboratory experiments, we observed rapid residue carbon (C) mineralization rates at temperatures of ≥ 23 °C across all soil moisture levels tested, and calculated the residue decomposed by 71–95% over the course of the 155 days experiment. Particle size also increased decomposition, with 61, 72, and 91% decomposition observed for the > 2.0, 0.25–2.0, and < 0.25 mm particle size fractions, respectively. The results indicate that earlier cut cane fields have the best chance to decompose green-cane harvested residue by taking advantage of warmer October temperatures, and that shredding the residue further increases its susceptibility to microbial decomposition. Future experiments will study field decomposition of residue in situ as well as incorporation of residue C into soil organic matter.

Effect of in-situ recycling of sugarcane crop residues and its industrial wastes on different soil carbon pools under soybean (Glycine max) - maize (Zea mays) system

A field experiment was conducted during summer 2011-12 at MPKV Farm, Rahuri to evaluate the effect of in-situ recycling of sugarcane crop residues and its industrial wastes on soil organic C fractions like labile carbon, microbial biomass C, particulate organic C, KMnO4 extractable C, physically protected particulate organic matter carbon (POMC) and significantly improved water stable aggregates in the cultivated soil under maize (Zea mays L.)-soybean [Glycine max (L.) Merr.] system. The active carbon pools like soil microbial biomass carbon (SMBC), water soluble carbohydrates (WHC) and acid hydrolysable carbon (AHC) was significantly improved in the treatment receiving 100% recommended dose of fertilizer along with in-situ compost of crop residues, press mud cake and methanated spent wash compost compared to burning of residues. Application of in-situ sugarcane residues with pressmud incorporation retainedabout19.6%, 38.8% and 33% more amount of total organic carbon (TOC), SMBC, AHC respectively, over burning of sugarcane crop residues and removal of stubbles after harvest of maize. The mean values of WSC (43 mg/kg) and the physically protected carbon, i.e. POMC (2014 mg/kg) were greater by 47% and 6.6% respectively, in the treatment (T7) receiving in-situ residue decomposition of sugarcane crop residues in combination with equal proportion (50%) of press mud cake and biomethanated spent wash over the burning of sugarcane crop residues and removal of stubbles after harvest of maize. After harvest of maize the maximum recalcitrant fraction (humic acid) of carbon was observed in the treatment T7 (in-situ decomposition of sugarcane crop residues + 50% press-mud cake + 50% biomethenated spent wash). This study clearly indicated that resistant fraction of carbon might be accumulated more where decomposed organic matter was applied regularly. It clearly indicated that application of in-situ decomposed residues and by-products of industrial waste in combination with NPK enhanced the below and above ground biomass production, SOC stock and carbon pools.

Long Term Sugarcane Crop Residue Retention Offers Limited Potential to Reduce Nitrogen Fertilizer Rates in Australian Wet Tropical Environments.

The warming of world climate systems is driving interest in the mitigation of greenhouse gas (GHG) emissions. In the agricultural sector, practices that mitigate GHG emissions include those that (1) reduce emissions [e.g., those that reduce nitrous oxide (N2O) emissions by avoiding excess nitrogen (N) fertilizer application], and (2) increase soil organic carbon (SOC) stocks (e.g., by retaining instead of burning crop residues). Sugarcane is a globally important crop that can have substantial inputs of N fertilizer and which produces large amounts of crop residues (‘trash’). Management of N fertilizer and trash affects soil carbon and nitrogen cycling, and hence GHG emissions. Trash has historically been burned at harvest, but increasingly is being retained on the soil surface as a ‘trash blanket’ in many countries. The potential for trash retention to alter N fertilizer requirements and sequester SOC was investigated in this study. The APSIM model was calibrated with data from field and laboratory studies of trash decomposition in the wet tropics of northern Australia. APSIM was then validated against four independent data sets, before simulating location × soil × fertilizer × trash management scenarios. Soil carbon increased in trash blanketed soils relative to SOC in soils with burnt trash. However, further increases in SOC for the study region may be limited because the SOC in trash blanketed soils could be approaching equilibrium; future GHG mitigation efforts in this region should therefore focus on N fertilizer management. Simulated N fertilizer rates were able to be reduced from conventional rates regardless of trash management, because of low yield potential in the wet tropics. For crops subjected to continuous trash blanketing, there was substantial immobilization of N in decomposing trash so conventional N fertilizer rates were required for up to 24 years after trash blanketing commenced. After this period, there was potential to reduce N fertilizer rates for crops when trash was retained (≤20 kg N ha–1 per plant or ratoon crop) while maintaining ≥95% of maximum yields. While these savings in N fertilizer use were modest at the field scale, they were potentially important when aggregated at the regional level.

Bioconversion of sugarcane crop residue for value added products – An overview

Sugarcane is a major crop cultivated globally and the residue left over after the crop harvest and extraction of juice is a good biomass source that can be used for the production of several useful chemicals. The sugarcane bagasse is an excellent substrate for the production of various biochemicals and enzymes through fermentation. Now major interest is focused on the utilization of these residue for biofuel production. The sugarcane crop residue is rich in cellulose and hemicellulose, hence it can be used for the production of bioethanol and other liquid transportation fuels. The present review gives a detailed account of the availability of sugarcane residue and various commercially important products that can be produced from this residue. It also provides recent developments in R&D on the bioconversion of sugarcane crop residue for value added products.

GERMINACIÓN Y EMERGENCIA DE Megathyrsus maximus VAR.maximus

RESUMEN Se estudió la germinación de semillas de Megathyrsus maximus al exponerlas a altas temperaturas y el efecto de diferentes profundidades de siembra y cantidades de residuos de cosecha en la emergencia de las plántulas. En laboratorio, se determinó la germinación y biomasa de semillas con y sin glumas y glumelas, expuestas a 0, 40, 60, 80 y 100 oC durante cinco minutos. Se realizaron dos experimentos en invernáculo para evaluar la emergencia de la maleza, primero a diferentes profundidades de siembra: 0, 0.5, 1, 2, 3, 4, 5, 7 y 8 cm. Posteriormente, se evaluó emergencia con diferentes cantidades de residuos de cosecha: 0, 5, 8, 11, 13, 15 y 18 t ha-1. Los resultados de los ensayos de temperatura se analizaron mediante análisis de covarianza y los datos de los ensayos de invernáculo mediante regresión. Los máximos porcentajes de germinación para semillas con y sin glumas y glumelas se obtuvieron a 40 oC y fueron del 35 y 48%, respectivamente; los mínimos valores se registraron a los 80 oC y fueron del 7 y 28%, respectivamente. La profundidad de siembra afectó la emergencia: un 51% se registró en el testigo, valor que disminuyó al 23,3% a los 7 cm y a 0% a los 8 cm. Los residuos de cosecha también afectaron la emergencia: con 0 a 18 t ha-1, esta disminuyó del 64,8 al 0%. Puede concluirse que las estrategias implementadas en el manejo del cultivo de caña de azúcar afectarán la germinación y emergencia de M. maximus

Agricultural and agro-industrial residues-to-energy: Techno-economic and environmental assessment in Brazil

This study aims to quantify the environmentally sustainable and economically feasible potentials of agricultural and agro-industrial residues to generate electricity via direct combustion in centralised power plants in Brazil. Further, the energy savings and greenhouse gas (GHG) reduction potential of replacing natural gas-based electricity by bioenergy have been assessed. To this end, a methodology has been developed based on an integrated evaluation, incorporating statistical and geographical information system (GIS)-based analysis, and a life-cycle-assessment approach. Results reveal that the environmentally sustainable generation potential is nearly 141 TWh/year, mainly concentrated in the South, Southeast, and Midwest regions of the country. Sugarcane, soybean and maize crop residues are the major feedstocks for available bioenergy. On the other hand, the economic potential is far lower, accounting to 39 TWh/year. The total GHG mitigation is nearly 18 million tonne CO2e and could reach 64 million tonne CO2e yearly, if the technical potential is considered. The gap between technical and economic potentials implies that constraints to bioenergy are not related to a lack of resources, but rather associated to economic, logistical, regulatory and political barriers.

Fundamental and molecular composition characteristics of biochars produced from sugarcane and rice crop residues and by-products

Biochar conversion of sugarcane and rice harvest residues provides an alternative for managing these crop residues that are traditionally burned in open field. Sugarcane leaves, bagasse, rice straw and husk were converted to biochar at four pyrolysis temperatures (PTs) of 450°C, 550°C, 650°C, and 750°C and evaluated for various elemental, molecular and surface properties. The carbon content of biochars was highest for those produced at 650–750°C. Biochars produced at 550°C showed the characteristics of biochar that are commonly interpreted as being stable in soil, with low H/C and O/C ratios and pyrolysis fingerprints dominated by aromatic and polyaromatic hydrocarbons. At 550°C, all biochars also exhibited maximum CEC values with sugarcane leaves biochar (SLB) > sugarcane bagasse biochar (SBB) > rice straw biochar (RSB) > rice husk biochar (RHB). The pore size distribution of biochars was dominated by pores of 20nm and high PT increased both smaller and larger than 50nm pores. Water holding capacity of biochars increased with PT but the magnitude of the increase was limited by feedstock types, likely related to the hydrophobicity of biochars as evident by molecular composition, besides pore volume properties of biochars. Py-GC/MS analysis revealed a clear destruction of lignin with decarboxylation and demethoxylation at 450°C and dehydroxylation at above 550°C. Overall, biochar molecular compositions became similar as PT increased, and the biochars produced at 550°C demonstrated characteristics that have potential benefit as soil amendment for improving both C sequestration and nutrient dynamics.