Crop Residue Management Research Articles

Effect of Tillage, Crop Residue Management and Nutrient Levels on Energetics, Microbial Growth, Dehydrogenase Activity, Weed Parameters, Quality Parameters and Soil Physico-Chemical Properties of Maize (Zea mays L.)

The field experiment on “Effect of tillage, crop residue management and nutrient levels on energetics, microbial growth, dehydrogenase activity, weed parameters, quality parameters and soil physico-chemical properties of maize (Zea mays L.)” was conducted during rabi season of 2022-23 at Maize Research Centre, Professor Jayashankar Telangana State Agriculture University, Agricultural Research Institute, Rajendranagar, Hyderabad, Telangana. The experiment comprised of 12 treatment combinations laid out in a split–plot design with three replications. The main–plot treatments included four different tillage practices:M1-Conventional tillage (Plough + Cultivator + Rotovator), M2-Residue incorporation (After 10 days of spreading the haulms, only rotovator was run), M3- Residue incorporation (After spreading the haulms, microbial consortium was sprayed and after 10 days only rotovator was run) and M4- Zero-tillage (Only microbial consortium was sprayed on the haulms). Sub–plot treatments included three nutrient levels: N1- 100% RDF (240-80-80 N-P2O5-K2O kg ha-1), N2: 100% RDN & P and 50% RDK (240-80-40 N-P2O5-K2O kg ha-1), and N3: 87.5% of RDN, 75% RDP and 75% RDK (210-60-60 N-P2O5-K2O kg ha-1). Results revealed that, among the tillage practices, residue incorporation (M3) had recorded significantly higher total microbial population, dehydrogenase activity and post-harvest soil available NPK of maize and lowest weed density and weed dry matter and it was on par with zero-tillage (M4) whereas all the parameters were significantly lower in conventional tillage (M1). However, Energy indices viz., energy use efficiency, specific energy, net energy, energy productivity, energy intensiveness was found to be the best in M1 -conventional tillage. Among the different nutrient levels, N1 (100% RDF) had shown significantly higher total microbial population, dehydrogenase activity and post-harvest soil available NPK of maize. Energy indices viz., energy use efficiency, specific energy, net energy and energy productivity was found to be the best in N1- 100% RDF. Whereas energy intensiveness was found to be best with N3- 87.5% of RDN, 75% RDP and 75% RDK. However, energy indices like energy use efficiency, energy productivity and energy intensiveness indicated non-significant effect of different nutrient levels. Tillage as well as nutrient levels did not exert any significant effect on moisture content and bulk density at sowing, tasselling & silking and at harvest stages. Similar results were followed with quality parameters. The interaction effect due to tillage and nutrient levels on soil microbial studies, enzymatic activity, weed parameters, quality parameters, soil physico-chemical parameters, and energy indices was found non- significant.

Influence of crop establishment method and residue management practices on productivity and economics of soybean-based cropping systems

The field experiment was conducted during kharif, 2021 at ICAR-Indian Institute of Soybean Research, Indore (MP). This experiment was initiated in kharif season of 2017, to study the effect of different cropping systems, crop establishment method and residue management practices on productivity and soil health of soybeanbased cropping systems. Significantly higher yield of soybean was registered under soybean-chickpea. Among the crop establishment techniques, permanent broad bed and furrow (PBBF) + residue retention (R) followed by PBBF + without residue retention (WR) found superior as compared to conventional tillage as per farmer practices. The increase in seed yield was 13.0 to 19.0% under PBBF technology as compared to conventional tillage as per farmers’ practices (CTFP).

Profiling Lignocellulose Degraders in the Microbiome of Rice Straw from Three Selected Lowland Farms in General Santos City, Philippines Using a High-Throughput Microarray Platform

Crop residues, such as rice straw, usually regarded as agricultural wastes recalcitrant to degradation, offer a myriad of services in the field, including reservoirs of valuable microorganisms and bioactive substances that are necessary for productive agroecosystems. However, very few studies report on the utilization of rice straw as a source of lignin-degrading microorganisms. This study probed into the taxonomic diversity of microorganisms associated with rice straw using metagenomic DNA obtained from samples collected in three lowland rice fields in General Santos City, Philippines for bioprospecting of microorganisms with ligninolytic potential and expanding the knowledge on prokaryotic lignin-degraders. Three samples collected from each site were pooled into one sample for the extraction of genomic DNA that was further subjected to the AxiomTM Microbiome Array (AMA) analysis, a relatively new high-throughput detection system, that can comprehensively identify a wide range of microorganisms at the species and strain levels. The sequences identified via AMA analysis were distributed across 3 superkingdoms, 7 phyla and 55 families. Our data showed that the samples contain a few fungi and some DNA viruses but are primarily composed of prokaryotic bacteria, with Actinomycetota, Bacillota, Bacteroidota, and Pseudomonadota being the dominant phyla in terms of the number of detected species. The rice straw microbiomes harbored several microbial species that have been widely reported elsewhere as lignocellulose degraders. Several noteworthy species detected by AMA were closely related to Bacteroides thetaiotaomicron, Cellvibrio japonicus, Pseudomonas putida, Flavobacterium rivuli, Fusarium graminearum, and Streptomyces sp. The results of this study provide molecular evidence that rice straw-associated microbiomes are rich sources of biological agents for crop residue management.

Generation and Management of Crop Residues in Punjab

Generation and Management of Crop Residues in Punjab

Impact of agro-geotextiles on soil aggregation and organic carbon sequestration under a conservation-tilled maize-based cropping system in the Indian Himalayas

Although agro-geotextile (AGT) emplacement shows potential to mitigate soil loss and, thus, increase carbon sequestration, comprehensive information is scanty on the impact of using agro-geotextiles on soil organic carbon (SOC) sequestration, aggregate-associated C, and soil loss in the foothills of the Indian Himalayan Region. We evaluated the impacts of Arundo donax AGT in different configurations on SOC sequestration, aggregate stability, and carbon management index (CMI) since 2017 under maize-based cropping systems on a 4% land slope, where eight treatment procedures were adopted. The results revealed that A. donax placement at 0.5-m vertical-interval pea–wheat (M + AD10G0.5-P-W) treatment had ∼23% increase in SOC stock (27.87 Mg·ha−1) compared to the maize–wheat (M-W) system in the 0–30-cm soil layer. M + AD10G0.5-P-W and maize–pea–wheat treatments under bench terracing (M-P-W)BT had similar impacts on SOC stocks in that layer after 5 years of cropping. The total SOC values in bulk soils, macroaggregates, and microaggregates were ∼24, 20, and 31% higher, respectively, in plots under M + AD10G0.5-P-W treatment than M-W in the topsoil (0–5 cm). The inclusion of post-rainy season vegetable pea in the maize–wheat cropping system, along with AGT application and crop residue management, generated additional biomass and enhanced CMI by ∼60% in the plots under M + AD10G0.5-P-W treatment over M-W, although M + AD10G0.5-P-W and (M-P-W)BT had similar effects in the topsoil. In the 5–15-cm layer, there was no significant effect of soil conservation practices on CMI values. Under the M + AD10G0.5-P-W treatment, the annual mean soil loss decreased by ∼92% over M-W treatment. We observed that CMI, proportion of macroaggregates, aggregate-associated C, labile C, total SOC concentration (thus, SOC accumulation rate), and mean annual C input were strongly correlated with the mean annual soil loss from 2017 to 2021. The study revealed that the emplacement of an A. donax mat and incorporation of a legume in a cropping system (M-W), conservation tillage, and crop residue retention not only prevented soil loss but also enhanced C sequestration compared to farmers’ practice (M-W) in the Indian Himalayas. The significance of this study is soil conservation, recycling of residues and weeds, and climate change adaptation and mitigation, as well as increasing farmers’ income.

Energy and yield optimization of field and vegetable crops in heavy crop residue for Indian conditions-climate smart techniques for food security

In NW-India cereal and vegetable crops are sown in paddy, sugarcane, maize, cotton (P–S-M-C) residue and left over crop residue management is major energy intensive operation and is pre requisite for sowing and better establishment of next cereal, pulses, vegetables and oilseed crops, which needs to be completed in a window period of 15–20 days. The dehaulming operation involved in potato crop is done manually and is energy intensive (2562 MJ ha−1).The peas and canola are harvested manually and energy involved is 2744 MJ ha−1 and 343 MJ ha−1. The incorporation of previous crop residue resulted in higher yields and more profits. The highest energy was involved in incorporation technique used for crop residue management as 156.06 GJ ha−1 followed by baler + incorporation technique as 141.71 GJ ha−1. The energy involved in wheat seeders were 6.04 GJ ha−1 and 4.17 GJ ha−1 respectively. The maximum energy input was observed for Potato and sugarcane crop as 480955.65 MJ ha−1 and 808743.63 MJ ha−1 respectively. The maximum yield of potato crop was found as 22.58 t ha−1 with field shredder and mould board plough operation. The berseem crop recorded highest energy productivity as 0.36 kg MJ−1. The use of incorporation technique was mostly in potato crop, in-situ techniques for wheat, barley sowing and baler for vegetable, pulse, oilseed crops.

Climate-smart agriculture strategies for South Asia to address the challenges of climate change: Identification of climate-resilient agriculture practices for India, Bangladesh, and Afghanistan

In South Asia, agriculture is pivotal for food and nutritional security and the livelihood of more than 50% of the population. Food production and nutritional security pressures intensify as urbanisation decreases the agricultural land area amid population growth. Climate change complicates this scenario by introducing elevated temperatures, extreme climatic events, surging sea levels, and increased soil salinity. Identifying climate-resilient innovative technologies for farmer adoption becomes imperative to counter these adversities. An integrated approach to climate-smart agriculture, encompassing capacity building through practical training on innovative mitigation strategies, is needed. This study unites experts from Australia, India, Bangladesh, and Afghanistan in an Asia-Pacific Network project, fostering mutual learning and farmer training in climate-smart practices. Insights from workshops conducted at Amity University in February 2020 and June 2022, combined with country-specific technological advances in the past 15 years gleaned from the literature, revealed key technologies to combat climate change (e.g., zero tillage, raised bed planting, direct-seeded rice, crop residue management, crop diversification, site-specific nutrient management, laser levelling, micro-irrigation, seed/fodder banks, and ICT-based weather advisories). Widespread implementation of these technologies and practices will empower farmers to navigate climate change challenges, fostering resilience and sustainability.

Tillage and Crop Residue Management on Weed Dynamics and Productivity of Direct Seeded Rice

A field experiment was conducted during 2019 and 2020 to evaluate the effect of tillage and residue management on weed dynamics and productivity of direct seeded rice with four tillage systems; Conventional tillage in rice and wheat, Zero tillage in rice and wheat and two rotational tillage sequences that alternated between Conventional tillage and Zero tillage whereas four residue management practices; residue applied in both season, residue applied in kharif season only, residue applied in rabi season only and without residue in both season. The experiment was carried out at research farm of Birsa Agricultural University, Ranchi, Jharkhand. Results revealed that in direct seeded rice having highest grain yield (10%), straw yield (8%) and yield attributes (10-15%) as well as lesser weed density and weed dry matter found under Conventional tillage during both the seasons of experiment but performance of zero tillage was slightly better (3-4%) in second year as compared to all treatments. Whereas surface retention of residue @5 tonne/ha was significantly more effective in controlling different category of weeds, it decreased up to 60-75% weed population, resulting increment in grain yield up to 19% and 23% during first and second year, respectively, as compared to plot receiving no residue.

Effect of Tillage, Crop Residue Management and Nutrient Levels on Growth and Yield of Maize (Zea mays L.)

A field study was conducted during rabi season of 2022 at Maize Research Centre, Professor Jayashankar Telangana State Agriculture University, Agricultural Research Institute, Rajendranagar, Hyderabad, Telangana. The experiment comprised of 12 treatment combinations laid out in a split–plot design with three replications. The main–plot treatments included four different tillage practices:M1-Conventional tillage (Plough + Cultivator + Rotovator), M2-Residue incorporation (After 10 days of spreading the haulms, only rotovator was run), M3- Residue incorporation (After spreading the haulms, microbial consortium was sprayed and after 10 days only rotovator was run) and M4- Zero-tillage (only microbial consortium was sprayed on the haulms). Sub–plot treatments included three nutrient levels: N1- 100% RDF (240-80-80 N-P2O5-K2O kg ha-1), N2: 100% RDN & P and 50% RDK (240-80-40 N-P2O5-K2O kg ha-1), and N3: 87.5% of RDN, 75% RDP and 75% RDK (210-60-60 N-P2O5-K2O kg ha-1). Results revealed that, among the tillage practices, residue incorporation (M3) had recorded significantly higher growth attributes like plant height, leaf area, dry matter production and chlorophyll content (SPAD) at 30, 60 DAS and at harvest stages and yield of maize and it was on par with zero-tillage (M4) whereas all the parameters were significantly lower in conventional tillage (M1). Among the different nutrient levels, N1(100% RDF) had shown significantly superior performance in terms of growth attributes and yield of maize and it was on par with N2 (100% RDN & P and 50% RDK) whereas N3(87.5% of RDN, 75% RDP and 75% RDK) recorded significantly lower growth attributes and yield of maize .The interaction effect due to tillage and nutrient levels on plant height, leaf area, dry matter production, chlorophyll content (SPAD) at 30, 60 DAS and at harvest and yield was non- significant.

The unusual stubble burning season of 2020 in northern India: a satellite perspective

ABSTRACT We analysed nine years (2012–2019) of fire observations from the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi-NPP satellite to assess the post-monsoon crop stubble burning activities over northern India. The 2020 fire season (September-November) was analysed extensively, and spatiotemporal trends were examined. Our analysis indicates that about 60% of post-monsoon fires occurred in the state of Punjab, followed by Madhya Pradesh (11%), Haryana (4%), and Uttar Pradesh (3%). The year 2020 saw the greatest fire activity in Punjab and across the country since 2016. Over the nine years, Punjab did not show any systematic trends in fire activities, whereas Haryana and Madhya Pradesh demonstrated an overall decreasing (45% lower in 2020 compared to the 2012–2019 mean) and increasing (185% more in 2020 compared to 2012–2019 mean) trends, respectively. The high fire occurance in the Punjab are related to high percentage of crop area with specific variety of rice, which produces high straw load and mature in shorter time. The increase in Madhya Pradesh is directly related to an increase in rice crop planting area over the years, whereas the decrease in Haryana is related to changes in crop residue management. The uncertainty analysis in this paper shows that over a given region, day-to-day variability in fire counts can have sampling biases due to changing satellite viewing geometry. Furthermore, long-term trends can also be impacted by the reduced sampling of satellite fire detections under cloudy conditions. However, large scale spatiotemporal analysis of fires in this area provides crucial and well sought-after information for crop fire control and air quality management in north India. The district level analysis for the four states signifies the critical information that satellites can provide for identifying hotspots and planning regionally focused mitigation strategies to curb pollution from crop burning fires.

Influence of crop residue and nitrogen management on nutrient uptake, yield, and economics of rice-wheat cropping system

The present investigation was conducted to find out optimize Nitrogen (N) dose and its scheduling to achieve nutrient uptake and higher productivity of ZT wheat with residue retention at the research farm of CCSHAU, Regional Research Station (RRS), Karnal during rabi seasons of 2019–2020 and 2020–2021. The field experiment comprised four main plot treatments viz., Zero tillage wheat-Happy seeder (ZTW-HS) with full residue (chopped), ZTW-HS with full residue (unchopped), ZTW-HS with partial residues (anchored stubbles), and conventional tillage wheat- drill sown (CTW-DS) with full residue (chopped); and six sub-plots having two N levels viz., 150 and 180 kg/ha applied into 2 and 3 splits, i.e. at sowing, before 1st irrigation, after 1st irrigation, and after 2nd irrigation. ZTW-HS with full residue (unchopped) in wheat increased the grain yield of wheat by 9.18% more than CTW-DS with full residue (chopped). Three N-splits, i.e. at sowing, before 1st irrigation and after 1st irrigation in wheat increased grain yield of wheat by 8.08% more than 2 splits, i.e. at sowing and after 1st irrigation. ZTW-HS with full residue (unchopped) with N@150 kg/ha with 3 splits, i.e. at sowing, before 1st irrigation and after 1st irrigation provides the best combination effect and improved the nutrient uptake in grain and straw, N, Phosphorus (P), Potassium (K), and yield of wheat and provide high economic returns.

Impact of Crop Residue and Green Manure Management in Rice Crop on Soil Nutrient Dynamics in Tarai Belt of Shivalik Himalaya, India

The study explores the effects of different soil management practices on various soil properties within the Tarai Belt of the Shivalik Himalaya region to assess the effects of different nutrient management strategies on various soil properties in the context of rice cultivation. Ten treatments were employed, T1 (100% recommended dose of NPK fertilizers), T2 (50% crop residue + 50% recommended NPK dose), T3 (50% crop residue + 50% recommended NPK dose with the addition of Pusa decomposer), T4 (50% crop residue + 50% Green Manure (GM), T5 (50% crop residue + 50% GM with Pusa decomposer), T6 (Crop residue at 2.5 tons per hectare + Pusa decomposer), T7 (Crop residue at 2.5 tons per hectare without Pusa decomposer), T8 (Absolute control group with no fertilizer application), T9 (150% recommended NPK dose), and T10 (100% recommended NPK dose with the addition of Farm Yard Manure at a rate of 5 tons per hectare, along with Zinc and Boron supplementation). including varying combinations of crop residues, organic and inorganic fertilizers, and green manure. Soil properties examined included soil organic carbon, available nitrogen, available phosphorus, available potassium, pH, and electrical conductivity (EC) at two different soil depths (0-15 cm and 15-30 cm. Organic sources enhanced soil organic carbon, while inorganic sources notably improved the availability of nitrogen, phosphorus, and potassium. The results showed that treatments incorporating both organic and inorganic nutrient sources demonstrated improved soil health and nutrient availability, with treatment T9 (150% recommended dose of fertilizer, RDF) showing the best results, particularly in terms of available nitrogen, phosphorus, and potassium. However, the sustainability of this approach over the long term may be a concern. Treatment T10, which combined 100% RDF with farmyard manure, zinc, and boron supplementation, emerged as a promising alternative for sustainable soil management. Treatment T3, with the incorporation of crop residues and the application of Pusa decomposer, also showed potential for maintaining soil health. These findings emphasize the importance of a balanced approach to nutrient management that combines readily available nutrients from inorganic sources with the long-term benefits of organic matter.
 In summary, this study emphasizes the importance of integrated nutrient management and sustainable agricultural practices for enhancing soil fertility and overall soil health, thereby contributing to sustainable crop production. These findings hold significance for addressing soil nutrient imbalances and ensuring the well-being of farmers and environmental sustainability.

The Effect of Crop Residue Management and Nitrogen Supply on Canopy Light Interception and N Distribution

The Effect of Crop Residue Management and Nitrogen Supply on Canopy Light Interception and N Distribution

Crop yields under no-till in Canada: implications for soil organic carbon change

Crop yields directly affect carbon (C) inputs into soils. Tillage management can influence crop performance, and as such should be considered when quantifying soil organic carbon (SOC) change, and thus net greenhouse gas emissions from croplands for national greenhouse gas inventory reporting. We conducted a meta-analysis of the effects of no-tillage (NT) and conventional tillage (CT) on crop yields for multiple crop species, soil types, and climatic regions of Canada. Yield response to NT varied between western and eastern Canada. Regardless of crop type, experiment duration, soil texture, and residue management, experiments in eastern Canada showed an average of 6% lower yields ( p ≤ 0.005) under NT compared to CT. In western Canada, crop type had an important effect on yields between NT and CT with wheat, canola, and legumes exhibiting 10% ( p ≤ 0.001), 7% ( p ≤ 0.05), and 9% ( p ≤ 0.05) higher yields on average under NT compared to CT, respectively. In western Canada, higher yields would be reflected in a similar scale of higher C inputs to NT systems. A recent meta-analysis of the effects of tillage management on SOC in Canada showed an 8% higher storage of SOC under NT systems compared to CT, a difference limited to western Canadian soils. Incorporating the effect of tillage on C inputs will lead to improvements in the accuracy of the effects of tillage management on SOC change in Canadian cropland. The activity data can be improved by applying weightings to the yield data by site-specific assessment of tillage practices across Canada.

A global dataset for the production and usage of cereal residues in the period 1997–2021

Crop residue management plays an important role in determining agricultural greenhouse gas emissions and related changes in soil carbon stocks. However, no publicly-available global dataset currently exists for how crop residues are managed. Here we present such a dataset, covering the period 1997–2021, on a 0.5° resolution grid. For each grid cell we estimate the total production of residues from cereal crops, and determine the fraction of residues (i) used for livestock feed/bedding, (ii) burnt on the field, (iii) used for other off-field purposes (e.g. domestic fuel, construction or industry), and (iv) left on the field. This dataset is the first of its kind, and can be used for multiple purposes, such as global crop modelling, including the calculation of greenhouse gas inventories, estimating crop-residue availability for biofuel production or modelling livestock feed availability.

Economics of Crop Residue Management

More than five billion metric tons of agricultural residues are produced annually worldwide. Despite having multiple uses and significant potential to augment crop and livestock production, a large share of crop residues is burned, especially in Asian countries. This unsustainable practice causes tremendous air pollution and health hazards while restricting soil nutrient recycling. In this review, we examine the economic rationale for unsustainable residue management. The sustainability of residue utilization is determined by several economic factors, such as local demand for and quantity of residue production, development and dissemination of technologies to absorb excess residue, and market and policy instruments to internalize the social costs of residue burning. The intervention strategy to ensure sustainable residue management depends on public awareness of the private and societal costs of open residue burning.

Influence on Crop Health and Yields as Affected by Soil Organic Matter and Crop Residue Management: An Overview

For growth of plants and crop productivity, soil is a crucial component. However, just a very small portion of the soil is genuinely fertile for farming these days, and if we managed it incorrectly, it could be depleted. It has been demonstrated that organic nutrients increase crop production, quality, and yield, which in turn improves the quality as well as richness of the soil's characteristics and creates a more favorable environment for the soil's beneficial microorganisms. According to reports, organic carbon in the soil and soil matter are the most significant indicators of soil quality and soil health. They are also advantageous for the sustainability of agriculture. Crop residue can be used effectively to improve soil quality and increase or maintain SOM's physical and chemical qualities.

Organic soil fertility management practices for the management of fall armyworm, Spodoptera frugiperda (J.E. Smith), in maize.

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a polyphagous pest native to the Americas. It attacks several crops but in particular causes significant damage to maize, which is a staple crop in Africa. Organic soil amendments have an impact on the physical, chemical, and biological properties of soil, which enhance plant resistance to or tolerance of insect pests and also promote a diverse population of natural enemies of the pest. However, the practices followed for the management of crop residue and animal manure affect their use as organic soil amendments. A field experiment was conducted to evaluate the effect of maize residue and cattle manure incorporation into soil on FAW in the Mana and Omo Nada districts of the Jimma zone, southwest Ethiopia, during the 2018/19 cropping season. Treatment involved three factors: five different levels of maize residue retention (0%, 25%, 50%, 75%, and 100%), different cattle manure storage systems (control, open, steel roof, and grass roof), and two different districts (Mana and Omo Nada). These variables were organized in a randomized complete block design and replicated three times. The infestation and damage ratings were collected from 30 days after planting at 20-day intervals. The results indicated that maize plots with retained crop residue had a significant reduction in FAW infestation compared with plots without maize residue (control) in both study districts. Furthermore, manure-fertilized plants had a lower percentage of FAW infestation when compared with maize plots without cattle manure in both study districts. The lowest severity of FAW infestation was recorded in a plot with 100% of residue incorporated and treated with cattle manure stored under a grass roof in the Mana district. Therefore, conventional tillage with 100% maize residue incorporation and the application of cattle manure stored under a grass roof showed the best result for reducing FAW infestation in maize. However, further studies are important to determine the effect of treatments over seasons and locations on FAW infestation and maize yields.

Revalorisation of broccoli crop surpluses and field residues: novel ingredients for food industry uses

Research on the management of broccoli crop residues and surpluses is critical for improving agricultural practices, optimizing food industrial manufacture, and contributing to better human nutrition. The objective of this study was to obtain novel ingredients based on these residues and surpluses for a wide range of applications in the food industry. The effect of air-drying (60 °C or 80 °C) applied to field residues (broccoli stalks), mimicking industrial conditions, was compared with dehydration by freeze-drying applied to these same field residues and to crop surpluses (broccoli whole plant). Thus, different broccoli flours were obtained and characterised for technological and biological properties including colour, antioxidant activity, nutrients, total polyphenol content, and content of glucosinolates. Flours from field residues showed high levels of dietary fibre (≈ 22% dry weight). Broccoli crop surpluses flours had relevant contents of glucosinolates (≈ 13 mg/g dry weight). Therefore, within the framework of the circular economy, these flours are proposed to revalorise the two main broccoli crop discarded fractions. Such flours could be used in a realistic and simple way by the agri-food industries interested in the development of healthy and conscience foodstuffs, in a cost-efficient manner.Graphical abstract

Ruminal content biochar supplementation for enhanced biomethanation of rice straw: Focusing on biochar characterization and dose optimization

Anaerobic digestion (AD) of agricultural wastes is a promising approach for energy recovery and crop residue management. However, its recalcitrant chemical structure hinders microbial hydrolysis and reduces biomethane production under AD. Biochar supplementation has been proven to promote the digestibility and biomethanation of lignocellulosic substrates. Therefore, this study investigated the influence of different pyrolysis temperatures (450 °C, 550 °C, and 650 °C) on the physicochemical properties of biochar. Furthermore, the impact of ruminal content biochar supplementation (1 %, 2 %, and 3 %) on the AD of rice straw with rumen fluid as inoculum has been investigated. The ruminal content biochar (RUCB) supplemented reactors showed an increment in biomethane yield and the highest cumulative biomethane yield 243.11 mL/g volatile solids (VS)) was recorded at 2 % RUCB supplementation, followed by 227.12 mL/g VS at 1 % RUCB supplementation and 162.86 mL/g VS at 3 % RUCB supplementation (P > 0.05). Compared to the control reactors (128.68 mL/g VS), RUCB supplemented reactors exhibited 1.88-fold, 1.76-fold, and 1.26-fold increments in biomethane yield due to pH stabilization and facilitation of microbial biofilm formation on the biochar. The correlation analysis showed that biomethane production is positively correlated with VS reduction (R2 = 0.9852). This study proposed a potential strategy to utilize ruminal content waste as a feedstock for biochar production and its application in AD for accelerating the biomethanation of rice straw.