Biomass Characteristics Research Articles

Thermal kinetic analysis and characterization of water hyacinth biomass for renewable energy application

Thermal kinetic analysis and characterization of water hyacinth biomass for renewable energy application

Chemical thermodynamics of biomass, cellulose, and cellulose derivatives: A review

This article provides a review of the research on the chemical thermodynamics and thermochemistry of biomass, cellulose, and its derivatives such as ethers, esters, and oxycelluloses. For diverse biomass types, gross and net heating values were studied. It has been established that these energetical characteristics of biomass can be calculated using a superposition of the energetical characteristics of the main components of biomass such as cellulose, hemicelluloses, lignin, lipids, proteins, etc. The pelletization of biomass improves its fuel performance. It was shown that, if the ultimate goal is to generate the maximum amount of thermal energy, then it is more profitable to directly burn the initial biomass in the form of pellets than to burn the amount of solid or liquid biofuel that can be extracted from this biomass. After the cellulose study, the direct and exact thermochemical method for determining the crystallinity degree of this biopolymer was proposed. In addition, the standard combustion and formation enthalpies of various cellulose samples were studied. As a result, the thermodynamic characteristics of four crystalline allomorphs of cellulose, CI, CII, CIII, and CIV, were obtained and their thermodynamic stability was evaluated. The thermochemistry of enzymatic hydrolysis of cellulose was studied. In addition. The thermodynamical characteristics of various cellulose derivatives were determined, and the thermochemistry of the reactions of cellulose alkalization, etherification, esterification, and oxidation was studied.

Elephant Grass Cultivar BRS Capiaçu as Sustainable Biomass for Energy Generation in the Amazon Biome of the Mato Grosso State

Sustainable biomasses are vital to ensure preservation of the Amazon biome within the Mato Grosso State whilst enabling energy generation for the region and its population. Here, the potential of the elephant grass cultivar BRS Capiaçu as an alternative to replace native forest wood as biomass for energy generation is investigated, considering the whole process from plant cultivation to biomass characterisation in terms of productivity of green and dry mass per hectare; density, moisture, ash, volatile and fixed carbon content, as well as higher heating value (HHV). MANOVA indicates that the effects of plant parts and age on density and proximate analysis parameters are influenced by the plant parts and age interaction, whereas HHV can be considered similar between them. The cultivar BRS Capiaçu showed suitable energetic values (17,922 < HHV < 18,918 kJ.kg−1) compared to that of native Amazon wood. Energetic results combined with cultivation outputs of high productivity (dry mass production of 44.1 tonnes.ha−1 at 180 days) with a short cutting interval (3 months), adaptation to the region’s climate and soil, and the possibility of cultivation in areas currently consolidated for agriculture demonstrate the potential of BRS Capiaçu as biomass to reduce native wood usage and deforestation rates.

Evaluating the role of feedstock composition and component interactions on biomass gasification

Biomass gasification offers a solution to waste concerns while generating clean energy. This study examines the gasification of pine sawdust (PS), used ground coffee (UGC), and wheat straw (WS) under identical conditions. The compositions of the biomass samples are determined, and the gasification of individual components (hemicellulose, cellulose, and lignin) are conducted to understand the process’ dependency on the biomass characteristics. The results suggest cellulose and cellulose-rich biomass (PS) produces more tar and less hydrogen than lignin and lignin-rich biomass (UGC and WS). High lignin and hemicellulose content leave more char. Gasification of PS, UGC, and WS yields 12.7, 15.7, and 17.2 vol% hydrogen, respectively. Additionally, cellulose, hemicellulose, and lignin gasification yield 10.5, 22.1, and 30.4 vol% hydrogen, respectively. Comparing experimental and theoretical values for the three biomass samples reveals significant differences due to component interactions. Thermogravimetry analysis (TGA) indicates significant degradation interactions between hemicellulose-lignin, cellulose-hemicellulose, and cellulose-lignin. It is concluded that high cellulose content biomass shows more predictable results, while high lignin and hemicellulose biomass increases secondary reactions or interactions, exacerbating predictability. These findings assist in estimating gasification performance for better biomass selection.

Cover crop characteristics modulate amount and timing of nitrogen supply of fertilized sugar beet (Beta vulgaris L.) in temperate climate

For temperate climate, there is little information on the effects cover crops grown in fall (CCs) on the nitrogen (N) supply for next year’s sugar beet (SB). Four field trials were conducted on silty soils to establish the CC N effect (Neff) compared to bare fallow separately for the periods sowing-summer and summer-autumn harvest. Biomass characteristics of radish (Raphanus sativus L.), spring vetch (Vicia sativa L.), saia oat (Avena strigosa Schreb.), and winter rye (Secale cereale L.) CCs before winter, soil mineral nitrogen in spring (SMN), and SB N accumulation and sugar yield (SY) were measured. In the period sowing-summer, characterized by a high SB N demand, Neff of overwintering, high biomass yielding rye CC was negative up to -50 kg N ha-1 at three site/years and varied around zero for the other CCs except vetch, for which Neff was positive. At SB autumn-harvest, Neff was negative up to -100 kg N ha-1 except for vetch in one trial. SY was lowest after rye CC. Regression analyses indicated a negative impact of CC biomass, C:N ratio and the difference in SMN between fallow (high SMN) and CCs (low SMN) on Neff. To conclude, if CCs yield a high amount of biomass surviving until spring and thus remove SMN from the soil which otherwise remains available for SB, early season mineralization of CC biomass N can be too low to ensure a N supply sufficient for maximum SB yield. Choosing leguminous CCs or early termination of CCs might alleviate this constraint.

Spatial and Temporal Patterns of Forest Biomass Carbon Sink in China from 1990 to 2021

China’s forests act as a large carbon sink and play a vital role in achieving the carbon neutrality goal by the 2060s. To achieve this goal, the magnitude and spatial patterns of forest carbon sinks must be accurately quantified. In this study, we aim to provide the longest estimate of forest biomass carbon storage and sinks in China at a 1 km spatial resolution from 1990 to 2021 by merging long-term observations from optical and microwave remote sensing datasets with a field-validated benchmark map. We explored the spatial characteristics of aboveground biomass (AGB) and belowground biomass (BGB) carbon in China’s forests, as well as variations in AGB carbon sinks. The average AGB and BGB carbon storage from 1990 to 2021 in China’s forests were 8.42 ± 0.96 Pg C and 1.9 ± 0.21 Pg C, respectively. The average annual AGB carbon sink during this period was approximately 0.083 ± 0.023 Pg C yr−1. Forests in the southwest region contributed 31.15% of the forest AGB carbon sink in China and contributed 41.01% of the forest AGB carbon storage. Our study presents an effective tool for assessing changes in forest biomass carbon by leveraging comprehensive multi-source remote sensing data and highlights the importance of obtaining large-scale, high-quality, consistent, and accessible plot survey data to validate the earth observation of biomass.

Machine learning assisted prediction of specific surface area and nitrogen content of biochar based on biomass type and pyrolysis conditions

Predicting and optimizing the physicochemical properties of biochar is crucial for its applications. The characteristics of biomass and pyrolysis conditions are the main factors influencing these properties. However, the numerous components of biomass and the pyrolysis conditions contribute to the substantial challenge in predicting the physicochemical properties, particularly the specific surface area and the nitrogen content of biochar. In this work, machine learning methods including random forest (RF), gradient boosting decision tree (GBDT) and extreme gradient boosting (XGB) (all with R2 exceeding 0.97) were used to predict and analyze specific surface area of biochar (SSA), N content of biochar (N-char), and yield of biochar (Yield-char). Compositions of biomass and pyrolysis conditions were selected as input variables. The partial dependence plot analysis showed the impact way of each influential factor on the target variable and the interactions among these factors in the pyrolysis process. The feature importance of these models indicated that the influencing factors toward predicting three targets (sorted by importance) were specified as follows: pyrolysis temperature, nitrogen content, and fixed carbon for Yield-char; N and ash for N-char; ash and pyrolysis temperature for SSA. This work provided new insights for understanding pyrolysis process of biomass.

Machine learning prediction and exploration of phosphorus migration and transformation during hydrothermal treatment of biomass waste

Hydrothermal treatment (HTT) held promise for phosphorus (P) recovery from high-moisture biomass. However, traditional experimental studies of P hydrothermal conversion were time-consuming and labor-intensive. Thus, based on biomass characteristics and HTT parameters, Random Forest (RF) and Gradient Boosting Regression machine learning (ML) models were constructed to predict HTT P migration between total P in hydrochar (TP_HC) and process water (TP_PW) and hydrochar P transformation among inorganic P (IP_HC), organic P (OP_HC), non-apatite inorganic P (NAIP_HC), and apatite P (AP_HC). Results demonstrated that the RF models (test R2 > 0.86) exhibited excellent performance in both single-target and multi-target predictions. Feature importance analysis identified TP_feed, O, C, and N as critical features influencing P distribution in hydrothermal products. TP_feed, NAIP_feed, temperature, and IP_feed were crucial factors affecting P form transformation in HC. This study provided valuable insights into understanding the migration and transformation of P and further guided experimental research.

Pretreated sugarcane bagasse matches performance of synthetic media for lipid production with Yarrowia lipolytica

Engineered strains of Yarrowia lipolytica with modified lipid profiles and other desirable properties for microbial oil production are widely reported but are almost exclusively characterized in synthetic laboratory-grade media. Ensuring translatable performance between synthetic media and industrially scalable lignocellulosic feedstocks is a critical challenge. Yarrowia lipolytica growth and lipid production were characterized in media derived from two-step acid-catalyzed glycerol pretreatment of sugarcane bagasse. Fermentation performance was benchmarked against laboratory-grade synthetic growth media, including detailed characterization of media composition, nitrogen utilization, biomass and lipid production, and fatty acid product profile. A Yarrowia lipolytica strain modified to enable xylose consumption consumed all sugars, glycerol, and acetic acid, accumulating lipids to 34–44 % of cell dry weight. Growth and lipid content when grown in sugarcane bagasse-derived media were equivalent to or better than that observed with synthetic media. These sugarcane bagasse-derived media are suitable for transferable development of Yarrowia lipolytica fermentations from synthetic media.

Characteristics of forest understory herbaceous vegetation and its influencing factors in biodiversity hotspots in China

Forest ecosystems, especially within biodiversity hotspots, heavily rely on the often-overlooked understory herbaceous communities (USHC) for their structural integrity and ecological functions. Because of their modest stature, these communities have garnered insufficient attention from researchers. Therefore, in this study attention is focused on USHC, which attempts to fill this research gap. To achieve this, we established 105 sample plots in 2022 within forest ecosystems situated in the biodiversity hotspot of southwest China. Our investigation unveiled a rich biodiversity tapestry, identifying 424 plant species from 108 families and 284 genera. Notable were the 217 herbaceous species identified in the understory layer, representing 67 families and 163 genera. These understory herbaceous species accounted for 51.2 % of the overall species count. Through a detailed analysis, the sample plots were categorized into eight distinct communities using a two-way indicator species analysis. These communities exhibited diverse variations in species composition, diversity, biomass, and nutrient characteristics. Notably, community I (Eucalyptus robusta Smith + Rubus corchorifolius L. f. + Alternanthera philoxeroides (Mart.) Griseb.), V (Camptotheca acuminata Decne + Rubus parkeri Hance + Iris tectorum Maxim), VIII (Platycladus orientalis (L.) Franco + Viburnum dilatatum Thunb. + Cyclosorus interruptus (Willd.) H. Ito) stood out for their exceptional species diversity and productivity. Moreover, correlation analyses highlighted the substantial impact of topographic and soil factors on USHC. Altitude, soil water content, and total carbon content emerged as the primary determinants of species diversity. Biomass demonstrated close associations with total soil carbon and nitrogen. Furthermore, the nutrient characteristics displayed significant correlations with soil nutrient contents. These findings underscore the critical importance of prioritizing USHC attention in forest conservation and management strategies within biodiversity hotspots. The implications strongly advocate for the inclusion of these communities in planning and decision-making processes, emphasizing their pivotal role in maintaining structural and functional diversity in ecosystems.

Adaptive strategies in architecture and allocation for the asymmetric growth of camphor tree (Cinnamomum camphora L.)

The stability-related asymmetry in roots, trunk, and crown is always found as a typical effect of biomechanical design under heterogeneous stimulus environment. However, it appears to be a conflict between the biomechanical principle and the source-sink distance of nutrient allocation strategies when the orientational asymmetry occurs. Adaptive growth strategies associated with biomass and nutrient allocation remain to be explored. This study used both the minirhizotron and harvest methods to test the effect of trunk inclination of camphor trees (Cinnamomum camphora) and found that the asymmetry coefficient of root biomass was − 0.29, showing more root biomass distributed on the other side of trunk inclination. This side had larger surface area and volume of fine roots, the smaller in diameter and the larger in length of the first level roots, higher leaf total nitrogen (TN) and slightly higher root TN content, higher activities of antioxidant enzymes SOD, POD, and CAT in leaves, and lower soluble sugar and protein. The biomass, morphological and physiological characteristics suggest that trees may follow both the biomechanical design and source-sink distance of nutrient allocation strategies. The research results expand the connotation of root-shoot balance in the orientational allocation of biomass and physiological responses.

Comparative Analysis of Optimal Reaction Conditions for Hydrothermal Carbonization and Liquid Hot-Water Processes in the Valorization of Peapods and Coffee Cherry Waste into Platform Chemicals

The management of coffee and peapod waste presents significant environmental challenges, with millions of tons generated annually, leading to disposal issues and resource inefficiencies. Hydrothermal processes offer a promising valorization method, though biomass characteristics significantly influence the resulting products. Biomass characterization revealed distinct profiles for coffee cherry waste (moisture: 10.94%, ashes: 7.79%, volatile matter: 79.91%, fixed carbon: 1.36%, cellulose: 27.6%, hemicellulose: 12.5%, and lignin: 13.7%) and peapods (moisture: 7.77%, ashes: 4.22%, volatile matter: 74.18%, fixed carbon: 13.0%, cellulose: 20.2%, hemicellulose: 17.4%, and lignin: 5.0%). Experiments were conducted in 100 mL and 500 mL hydrothermal reactors with varying conditions for temperature (120–260 °C), time (1–4 h), stirring (none and at 5000 and 8000 rpm), biomass/water ratio (1:5, 1:10, 1:20, and 1:40), particle size (0.5–5 mm), and catalysts (acids and bases). The results showed that peapods produced over 30 times more platform chemicals than coffee. High temperatures (over 180 °C) degraded peapods, whereas coffee yields increased. Both biomasses were influenced similarly by reaction conditions: lower biomass/water ratios, smaller particle sizes, acid catalysts, and no stirring increased yields. Peapods consistently had higher yields than coffee in all conditions. Biochar analysis revealed anthracite from coffee and coal from peapods.

Understanding the role of porous particle characteristics and water state distribution at multi-scale variation on cellulase hydrolysis of lignocellulosic biomass

Porous particle characteristics of lignocellulosic biomass and the water state distribution surrounding particles determine enzyme/solute transfer, while inherently affecting the liquefaction and hydrolysis reactions. For submillimeter biomass particles (<500 μm), deep eutectic solvent pretreatment tended to create additional macropores (∼4%, pore volume of 4.3 mL/g) and micropores (∼3%, pore area of 2.26 m2/g) at the extragranular and cell wall scales, simultaneously with reducing particle size by 15%. The pretreated biomass exhibited preferential rapid liquefaction over sugar production, leading to a ∼70% reduction in particle size only after 3 h hydrolysis. This further increased particle porosity (∼85% after 12 h hydrolysis) with the transition from large surface-pores to interior micropores. The increases in the tissue/cell-scale pore size and intraparticle area had greater significance for improving hydrolysis performance than particle size reduction. Additionally, particle liquefaction released constrained water in capillary pores and enhanced slurry fluidity; capillary water and free water became main transfer carriers during the hydrolysis. Free water activity was positively related to sugar production (r = 0.80–0.85), and integrating it with particle component and porosity allowed for accurate prediction of hydrolysis yields (R2 = 0.98–0.99). Inspired by particle liquefaction, a short-time feeding strategy was proposed to reconstruct high-solid hydrolysis.

Study on biomass and polymer catalytic co-pyrolysis product characteristics using machine learning and shapley additive explanations (SHAP)

Biomass and polymer catalytic co-pyrolysis can convert waste into higher-quality fuels, thereby reducing the use of fossil fuels to some extent. However, this process is an extremely complex thermochemical conversion, influenced by numerous factors such as feedstock properties, operational variables, and catalyst. Currently, experimental methods require substantial time and resource investment. Machine learning (ML) can fit and match input and output features based on existing data, achieving extremely high accuracy in the co-pyrolysis process. This study applies advanced ML models to study the biomass and polymer catalytic co-pyrolysis process, with a focus on the yield of pyrolysis products and the variations of the oxygen-containing components in the pyrolysis oil. The best-performing model is used for feature analysis of the correlation between inputs and outputs, based on game theory SHAP analysis. The results indicate a significant negative correlation between the polymer addition ratio and the generation of oxygen-containing components during the co-pyrolysis process. The addition of catalysts promotes the generation of pyrolysis gas during co-pyrolysis but suppresses the yield of pyrolysis oil. Additionally, catalysts significantly inhibit the formation of oxygenates in the pyrolysis oil. The XGBR model shows the highest performance in predicting pyrolysis oil yield, achieving R2 values of 0.98 during training phase and 0.91 during testing phase. The GBR model performs well in predicting the oxygenate composition of pyrolysis oil from small datasets.

Nutrient balance for enhanced recovery of stressed Spirulina platensis.

The failure of mass production of Spirulina plateaus can be attributed to an imbalance of nutrients (C:N) and an increase in accumulated sodium ions, coupled with the traditional harvesting process. The current study aims at the recovery of stressed and red cultures of Spirulina platensis as well as enhanced phycocyanin accumulation. The stressed Spirulina platensis cultures were obtained from a local Egyptian Spirulina production farms, which were further subjected to water analyses after removing the Spirulina biomass. Optimization was performed within 300-ml water path photobioreactor. Spirulina platensis samples were incubated with Zarrouk medium comparing with those modified using ammonium bicarbonate or ammonium acetate instead of sodium bicarbonate. Continuous batching was performed every 12days during three sequenced batches. Growth measurements (dry weight and pigments) were performed along the incubation time. It was found that carbon content of the growth medium seems to be more effective in Spirulina growth and biomass characteristics. Under different carbon sources, acetate resulted in the maximum dry weight of 1.48g·l-1 and recovery percentage of 463.3%. Such effect was extended along the different incubation batches. Various carbon concentrations revealed that moderate concentration of carbon in the form of acetate (0.699g·l-1) leads to the maximum growth under the same nitrogen content. A similar trend was observed with chlorophyll and phycocyanin accumulation, while carotenoids showed the opposite manner.

Evaluating Flow Characteristics of Ground and Cut Biomass for Industrial Applications

Evaluating Flow Characteristics of Ground and Cut Biomass for Industrial Applications

Study on combustion characteristics of crustacean biomass derived fuel coupled with in-situ capture of SO2 based on pulsed microwave radiation

Crustacean waste has great potential as fossil fuel substitution and efficient desulfurization to reduce pollutant emissions, but high moisture and poor quality restrict broad-scale utilization. This study used microwave radiation on crayfish shell to investigate the combustion characteristics and desulfurization effect in different atmospheres/pulse microwave cycle. Meanwhile, the structure evolution mechanism and molecular reaction pathways were revealed. The results show that crayfish shell derived fuel has a pleasurable combustion performance and sulfur fixation ability after microwave radiation in flue gas. The heat release of derived fuel increased by 29.9 % after five microwave cycle in flue gas, and activation energy decreased by 3.7 %. By contrast, the heat release increased by 17.4 % after five microwave cycle in inert gas, and activation energy increased by 39.3 %. Subsequently, the effect of microwave cycle times in flue gas on crayfish shell combustion and desulfurization performance was studied. The results show that the heat release of derived fuel gradually increases with microwave cycle. After seven microwave cycle, the derived fuel heat release and SO2 removal efficiency increased by 34.9 % and 44.4 %, respectively. The results establish the foundation for expanding the utilization pathway of crustacean waste and realizing the low-carbon energy transition.

Effect of Pinus halepensis Mill. Reforestation on the Above-Ground Biomass and Internode Elongation and Leaf Size of Native Species in Morroco

This study aims to determine the effect of the reforestation of Pinus halepensis Mill. on the above-ground biomass and morphological characteristics of native species (internode elongation and leaf size) in the Beni Sohane forest. Plant biomass of the herbaceous layer was harvested on randomly selected 2 m2 quadrats in reforested plots of ± 12, ± 25, and ± 45-year-old, and native forest controls. The internode length and leaf size (length and width) were measured on plants randomly selected belonging to four native species Quercus ilex L., Pistacia lentiscus L., Phillyrea angustifolia L., and Cistus creticus L.. The results showed that P. halepensis reforestation had no significant effect on the above-ground biomass and the leaves and internodes dimensions in the young plantations ± 12-year-old. However, as the pine trees mature, the average dry matter weight decreases, especially in stands 45 years old, where this weight was significantly lower than that of natural forests. This fact has led to herders abandoning important pastures previously used by their cattle. In addition, the fast growth of P. halepensis trees formed a canopy above all indigenous species resulting in changes in the dimensions of internodes and leaves. For the two oldest plantations, the internode length, leaf width, and length of the 4 species have been significantly increased. However, the leaf length-to-width ratio decreased significantly, with leaves in reforested plots being larger rather than longer compared to control samples in native forests. Planting P. halepensis can negatively impact the long-term growth of native plants, so we recommend periodically removing some of the pines (thinning) to restore the balance of these ecosystems. Thus, species selection for reforestation should consider maximizing rather than destroying ecological and socioeconomic services.

Effect of Pinus halepensis Mill. Reforestation on the Above-Ground Biomass and Internode Elongation and Leaf Size of Native Species in Morroco

This study aims to determine the effect of the reforestation of Pinus halepensis Mill. on the above-ground biomass and morphological characteristics of native species (internode elongation and leaf size) in the Beni Sohane forest. Plant biomass of the herbaceous layer was harvested on randomly selected 2 m2 quadrats in reforested plots of ± 12, ± 25, and ± 45-year-old, and native forest controls. The internode length and leaf size (length and width) were measured on plants randomly selected belonging to four native species Quercus ilex L., Pistacia lentiscus L., Phillyrea angustifolia L., and Cistus creticus L.. The results showed that P. halepensis reforestation had no significant effect on the above-ground biomass and the leaves and internodes dimensions in the young plantations ± 12-year-old. However, as the pine trees mature, the average dry matter weight decreases, especially in stands 45 years old, where this weight was significantly lower than that of natural forests. This fact has led to herders abandoning important pastures previously used by their cattle. In addition, the fast growth of P. halepensis trees formed a canopy above all indigenous species resulting in changes in the dimensions of internodes and leaves. For the two oldest plantations, the internode length, leaf width, and length of the 4 species have been significantly increased. However, the leaf length-to-width ratio decreased significantly, with leaves in reforested plots being larger rather than longer compared to control samples in native forests. Planting P. halepensis can negatively impact the long-term growth of native plants, so we recommend periodically removing some of the pines (thinning) to restore the balance of these ecosystems. Thus, species selection for reforestation should consider maximizing rather than destroying ecological and socioeconomic services.

N supply and yield of sugar beet after cover cropping: effects of cover crop species and management

Despite long-time practice, the effect of cover crop (CC) cultivation on N supply and yield of subsequent sugar beet (SB) is not clear for the temperate climate of Central Europe. To elucidate, four field trials with oil radish, spring vetch, saia oat, and winter rye CCs were conducted on typical loessial soil in Germany. Mineral fertilizer N dose was varied as second factor: zero (N0) and optimum dose (Nopt). Biomass characteristics before winter, soil mineral nitrogen content in spring (SMN), and sugar yield and total plant N content of SB were measured. The CC N effect (Neff), calculated as the difference in SB N uptake after CC minus bare fallow, was computed for the periods sowing-summer (July/August) and summer-harvest. On average, sugar yield was decreased after rye and increased after vetch CC compared to bare fallow which was more pronounced under N0 than Nopt. In the period sowing-summer, characterized by a high SB N demand, Neff was close to 0 kg N ha–1 after rye and up to +30 kg N ha–1 after vetch. In contrast, Neff in summer-harvest was negative, amounting up to –80 kg N ha–1 after radish and rye. Regression analysis revealed a significant relationship between Neff in the period sowing-summer and the sugar yield difference between the cover crop treatments and bare fallow (R2 = 0.29). A multiple regression analysis (R2 = 0.68) indicated that high CC biomass combined with a large negative spring SMN difference between CC treatment and fallow caused a large yield penalty, which can be compensated for by elevated N fertilization. Moreover, CC management ensuring either a limited CC biomass or low SMN difference of CCs compared to fallow by e.g., later sowing, less vital CC species or early CC termination, will likely secure higher SB yield after CCs than fallow.