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Energy sorghum [Sorghum bicolor (L). Moench] is potentially of great significance for bioethanol production because of its high biomass and wide adaptability. In this study, a field experiment was conducted on a semiarid marginal land in Inner Mongolia (39°10′N, 109°53′E), China, to assess the effects of genotypes with similar growth duration and biomass yield levels on chemical composition and theoretical ethanol yield (TEY) in both leaves and stems of four genotypes each of sweet and biomass sorghum in 2013 and 2014. Among all varieties, no significant variation was observed in the biomass yield of leaf (1.81–2.55 Mg ha−1) and stem (3.73–4.87 Mg ha−1), which was relatively low due to the marginal land with low temperature conditions. By contrast, considerable variation was detected in soluble sugars, ash and hexose contents of leaves and stems among the sweet sorghum varieties over two years. Compared with the sweet type, biomass sorghum varieties exhibited significantly lower soluble sugars content but higher cellulose, hemicellulose, and lignin contents in both leaf and stem tissues, resulting in significantly lower hexose and higher pentose contents. Moreover, stems exhibited significantly higher total content of hexose and pentose (725.4 g kg−1) than leaves (642.3 g kg−1) across all varieties, leading to significantly higher TEY of stems than that of leaves. Despite the slightly higher TEY of sweet sorghum, biomass sorghum varieties exhibited particularly stable chemical components and TEY across both experimental years, resulting in greater potential for industrial bioethanol production in this study. Overall, varietal selection was effective in improving the biomass feedstock quality of energy sorghum for biochemical conversion. The findings of this study will help to facilitate industrial bioethanol production from dedicated bioenergy crops.

Background High-throughput evaluation of lignocellulosic biomass feedstock quality is the key to the successful commercialization of bioethanol production. Currently, wet chemical methods for the determination of chemical composition and biomass digestibility are expensive and time-consuming, thus hindering comprehensive feedstock quality assessments based on these biomass specifications. To find the ideal bioethanol feedstock, we perform a near-infrared spectroscopic (NIRS) assay to rapidly and comprehensively analyze the chemical composition and biomass digestibility of 59 Jerusalem artichoke (Helianthus tuberosus L., abbreviated JA) clones collected from 24 provinces in six regions of China. Results The distinct geographical distribution of JA accessions generated varied chemical composition as well as related biomass digestibility (after soluble sugars extraction and mild alkali pretreatment). Notably, the soluble sugars, cellulose, hemicellulose, lignin, ash, and released hexoses, pentoses, and total carbohydrates were rapidly and perfectly predicted by partial least squares regression coupled with model population analyses (MPA), which exhibited significantly higher predictive performance than controls. Subsequently, grey relational grade analysis was employed to correlate chemical composition and biomass digestibility with feedstock quality score (FQS), resulting in the assignment of tested JA clones to five feedstock quality grades (FQGs). Ultimately, the FQGs of JA clones were successfully classified using partial least squares-discriminant analysis model coupled with MPA, attaining a significantly higher correct rate of 97.8% in the calibration subset and 91.1% in the validation subset. Conclusions Based on the diversity of JA clones, the present study has not only rapidly and precisely examined the biomass composition and digestibility with MPA-optimized NIRS models but has also selected the ideal JA clones according to FQS. This method provides a new insight into the selection of ideal bioethanol feedstock for high-efficiency bioethanol production. Electronic supplementary material The online version of this article (10.1186/s13068-018-1335-1) contains supplementary material, which is available to authorized users.

Sweet sorghum [Sorghum bicolor (L.) Moench] offers a sustainable and renewable bioenergy resource for feed and biomass production. Two separate field experiments were conducted on arable land at Shangzhuang Station and on saline-alkali land at Quzhou Station in the North China Plain. Three cultivars of sweet sorghum including early- (ZS1) (114 days), medium- (CT2) (138 days), and late-maturity (LN3) (160 days), were sole cropped on arable land in 2006–2007. Using the same cultivars, sweet sorghum based - double cropping systems with winter wheat rotation were analyzed on saline-alkali land in 2009–2011. This study aims to determine the planting potential of three sweet sorghum cultivars and develop an optimized sweet sorghum - based double cropping system on saline-alkali land to maximize the production outputs. The aboveground biomass yield, energy output, theoretical ethanol yield (TEY), and chemical composition of three sweet sorghum cultivars - based cropping systems were assessed. Results indicate that: (1) the annual average dry biomass yield and dry matter content of the three sweet sorghum cultivars showed an overall uptrend with the increasing crop growth length. The average dry biomass yield of three sorghum maturity groups on arable land were 48.9% higher than that on saline-alkali land. (2) Sweet sorghum cultivars of late- (LN3) and medium- maturity (CT2) displayed better chemical composition for both bioenergy utilization (higher starch, soluble sugar, cellulose and hemicellulose and lower ash) and forage quality (better relative feed value (RFV) and lower acid detergent fiber (ADF) and neutral detergent fiber (NDF)). (3) The double cropping system of medium-maturity sweet sorghum (CT2) and winter wheat presented the best total dry biomass yield (24.9 t ha−1), energy output (394.6 GJ ha−1), and theoretical ethanol yield (6857 L ha−1). Therefore, this double cropping system can be recommended for extensive planting in the North China Plain for bioenergy or forage production.

It is important to understand switchgrass (Panicum virgatum L.) productivity with relation to diverse nutrient deficiency conditions in order to optimize continuous biomass production in marginal lands. This study was conducted on a wasteland sandy soil (Aridosol) to assess biomass yield, nutrient uptake and nitrogen (N) recovery of switchgrass, and soil nitrate-N (NO3−-N) accumulation responses to N (120 kg N ha−1), phosphorus (P, 100 kg P2O5 ha−1), and potassium (K, 45 kg K2O ha−1) applications during 2015 and 2016 in Inner Mongolia, China. The experiment layout was a randomized complete block design with fertilizer mixture treatments of N, P, and K (NPK), P and K (PK), N and K (NK), N and P (NP), and a control with no fertilizer input (CK). Plant height and stem diameter remained unaffected by the different fertilizer treatments. Biomass yield with the NPK treatment in 2015 was 8.9 Mg ha−1 and in 2016 it was 7.3 Mg ha−1. In 2015, compared with the NPK treatment, a significant yield reduction of 33.7% was found with PK, 22.5% with NK, 28.1% with NP, and 40.5% with CK; however, in 2016, yield declined significantly only with CK compared to the rest of the fertilizer treatments, for which yields were statistically similar. Plant N content was reduced for the treatment PK (i.e. N omission); conversely, plant P and K content remained unaffected with P and K omission treatments. Plant nutrient uptake, particularly of N and K, was severely decreased by the nutrient omission treatments when averaged across 2 years. Apparent N recovery (ANR; quantity of N uptake per unit of N applied) was reduced for the NP and NK treatments, which led to an increase in soil NO3−-N accumulation in the top 0–20 cm layer, compared with the NPK treatment. However, ANR was the highest (37.2% in 2015) with the NPK treatment, which also reduced soil NO3−-N accumulation. A balanced N, P, and K fertilizer management approach is suggested to sustain switchgrass yield and stand persistence on semiarid, marginal, sandy wasteland.

An understanding of biomass yield and quality response to N supply is essential to breeding and cultivation of sorghum ( Sorghum bicolor (L.) Moench) for the production of bioethanol or forage. A two – year field experiment was conducted in 2013 and 2014 on semiarid marginal land in Inner Mongolia (39°10′N, 109°53′E) to determine the effects of N fertilizer rate (0, 60, 120, and 240 kg ha −1 ) on biomass yield and quality of sweet sorghum (GT-8) and biomass sorghum (GN-11), and on soil conditions. Results indicated that (1) biomass yield, leaf/stem ratio, and crude protein (CP), protein yield, theoretical ethanol yield (TEY), and soil net NO 3 − -N accumulation of both sorghum varieties in 2013 and 2014 significantly increased with the increasing N fertilizer rate from 0 to 240 kg ha −1 , whereas dry matter ratio and relative feed value (RFV) varied inversely with the N application rates. (2) Compared to biomass sorghum (GN-11), sweet sorghum (GT-8) demonstrated significant enhancement of forage quality components including CP, dry matter digestibility (DMD), dry matter intake (DMI), total digestible nutrients (TDN), net energy for lactation (NE L ), and RFV, with stems exhibiting higher forage quality than leaves. Biomass sorghum (GN-11) exhibited better performance for bioenergy production, with an average biomass yield of 7.9 t ha −1 and TEY of 3046.7 L ha −1 averaged across all N rates. (3) Annual average amount of net NO 3 − -N accumulation in 0–90 cm layers of two years significantly increased when fertilizer N exceeded 120 kg N ha −1 . In short, N fertilizer of 60 kg ha −1 is recommended to sweet sorghum for the forage production and 120 kg N ha −1 to biomass sorghum for bioenergy feedstock sustainability, respectively, meanwhile to prevent the soil degradation on semiarid marginal lands.

A better understanding of the genetic basis that governs the inheritance of biomass quality traits may help to improve sorghum (Sorghum bicolor [L.] Moench) varieties for energy purposes. Here, combining ability studies were conducted using three restorer lines (male) and 60 cytoplasmic male sterile (CMS) lines (female), at two locations in China, during 2017 and 2018. Both entries and environments (i.e., site) significantly affected concentrations of soluble sugar, cellulose, hemicellulose, lignin, and ash of sorghum, in both stems and leaves. The coefficient of variation level was higher in stems than leaves for each chemical component investigated. The broad-sense and narrow-sense heritability indicated the predominance of an additive gene effect upon chemical components occurring in stems and leaves. This investigation is the first report to evaluate the combining ability effects on soluble sugar, cellulose, hemicellulose, lignin, and ash in stems and leaves of sorghum plants. Sorghum exhibited either significantly negative or positive general combining ability (GCA) effect for all chemical components in stems and leaves. Highly significant negative correlations were found between the GCA effect on soluble sugar and that on cellulose, hemicellulose, and lignin. Significant positive correlations were found among GCA effects of cellulose, hemicellulose, and lignin. The GCA effect on ash was significantly negatively correlated with that on soluble sugar but positively so with that on hemicellulose in stems, whereas it had significant negative correlations with that on soluble sugar, cellulose, and hemicellulose in leaves. Based on these findings, 11 and 6 female lines were selected for further development of biomass sorghum hybrids and sweet sorghum hybrids, respectively.

Background Due to its chemical composition and abundance, lignocellulosic biomass is an attractive feedstock source for global bioenergy production. However, chemical composition variations interfere with the success of any single methodology for efficient bioenergy extraction from diverse lignocellulosic biomass sources. Although chemical component distributions could guide process design, they are difficult to obtain and vary widely among lignocellulosic biomass types. Therefore, expensive and laborious “one-size-fits-all” processes are still widely used. Here, a non-destructive and rapid analytical technology, near-infrared spectroscopy (NIRS) coupled with multivariate calibration, shows promise for addressing these challenges. Recent advances in molecular spectroscopy analysis have led to methodologies for dual-optimized NIRS using sample subset partitioning and variable selection, which could significantly enhance the robustness and accuracy of partial least squares (PLS) calibration models. Using this methodology, chemical components and theoretical ethanol yield (TEY) values were determined for 70 sweet and 77 biomass sorghum samples from six sweet and six biomass sorghum varieties grown in 2013 and 2014 at two study sites in northern China. Results Chemical components and TEY of the 147 bioenergy sorghum samples were initially analyzed and compared using wet chemistry methods. Based on linear discriminant analysis, a correct classification assignment rate (either sweet or biomass type) of 99.3% was obtained using 20 principal components. Next, detailed statistical analysis demonstrated that partial optimization using sample set partitioning based on joint X–Y distances (SPXY) for sample subset partitioning enhanced the robustness and accuracy of PLS calibration models. Finally, comparisons between five dual-optimized strategies indicated that competitive adaptive reweighted sampling coupled with the SPXY (CARS-SPXY) was the most efficient and effective method for improving predictive performance of PLS multivariate calibrations. Conclusions As a dual-optimized methodology, sample subset partitioning combined with variable selection is an efficient and straightforward strategy to enhance the accuracy and robustness of NIRS models. This knowledge should facilitate generation of improved lignocellulosic biomass feedstocks for bioethanol production. Moreover, methods described here should have wider applicability for use with feedstocks incorporating multispecies biomass resource streams. Electronic supplementary material The online version of this article (doi:10.1186/s13068-017-0892-z) contains supplementary material, which is available to authorized users.

Sorghum [Sorghum bicolor (L.) Moench] is a high-yielding C4 crop used not only to produce grains for food, feed, and industrial uses but also biomass (i.e., leaf and stem) for biofuel production. To take better advantage of its heterosis for both grain and biomass dual-purpose use, the combining ability of 34 cytoplasmic male sterile lines (female) were tested with 3 cytoplasmic male fertile restore lines (male) using the North Carolina design (NCⅡ) at Zhuozhou (Hebei province) and Jiexiu (Shanxi province) in northern China for two years (2017 and 2018). The hybrids exhibited a grain yield of 0.3 ∼ 14.0 t ha−1 and had an aboveground biomass yield (AGBY) of 9.6 ∼ 109.9 t ha−1 across both sites in 2017 and 2018. The genotype and site × genotype interactions significantly affected the yield and agronomic traits. With respect to their grain and biomass dual-purpose use, the tested 34 female lines revealed that plant height, gravity center height, productive tiller rate, and harvest index were strongly general combining ability (GCA) sensitive. Stem width, days to maturity, AGBY, and grain width were medium GCA-sensitive; and grain yield, 100-grain weight, days between heading and maturity, and grain bulk density were weakly GCA-sensitive. The GCA effect on grain yield was positive and significantly correlated with productive tiller rate, AGBY, and harvest index. The GCA effect on AGBY had a positive, significant correlation with plant height, gravity center height, productive tiller rate, and days to maturity; but the effect was negatively correlated with 100-grain weight and grain width. For tested traits, the additive gene effects strongly predominated over the non-additive genes for tested traits. Plant height was the most GCA-sensitive trait and the most important for biomass production. Female lines AMP418, AMP431, AMP434, AMP443, AMP495, AMP496 and the male line X097 were selected as being high-GCA effect germplasm. These selections from newly introduced cytoplasmic male sterile lines hold promise for accelerating the genetic improvement of sorghum for its dual-purpose use as grain for food and biomass for biofuel.

Jerusalem artichoke (Helianthus tuberosus L.) has been recognized as being a biomass crop for energy and livestock forage production. In this study, 26 Jerusalem artichoke clones previously collected from 24 provinces of China were grown under semiarid conditions in 2008 and 2011. At harvest, nitrogen (N), phosphorus (P) and potassium (K) concentrations and accumulations were measured for all clones and levels of both were higher overall for 2008 than 2011, with statistically reasonable results for both years. Notably, N and K concentrations in aboveground parts were higher than in tubers for most clones, yet the tuber P concentration was consistently higher than in aboveground parts. Comparing with other forage and energy plants, it demonstrates that under optimal conditions, diverse Jerusalem artichoke clones could meet the requirements of either energy production or livestock forage feed. Based on N, P and K accumulation and concentration profiles, the 26 Jerusalem artichoke clones clustered into six groups. Three clones of one cluster, CQ-1, GZ-1 and HUN-3, are recommended for use as biomass energy materials due to the lower N concentration level in aboveground parts and higher N concentration level in tubers, while 16 clones are recommended for use as forage due to the higher N concentration level in aboveground parts. The phenotypic traits described in this work should facilitate quantitative trait locus mapping and the subsequent use of clone germplasms for development of improved varieties suited to specific growth conditions and applications.

The cassava stem is found to be one of few crop residues containing starch (up to 42% of dry mass) that may be converted to fuel ethanol. The current study was to evaluate the influence of parameters genotype, growth location and harvest time on cassava stem starch contents and yields as well as consequences in ethanol production (non-cellulosic process), based on 180 samples from a full factorial design experiment (3 varieties × 3 locations × 5 harvest times) in Guangxi, China. The potential utilization of stem starch and soluble sugar that varied 14–42% and 3–12.1% of dry mass, respectively, can correspond to an increase of 26% in ethanol production compared to that produced by roots only. The cassava stem starch content was significantly affected by all three studied parameters and location had the largest effect followed by variety and harvest time, while the stem starch yield was significantly affected by location only. The starch and soluble sugar content were significantly correlated with soil properties, e.g., soil pH and organic carbon, S and P contents. A general and positive correlation was also found between the stem and root starch, suggesting a promising potential of using stem starch without reducing root starch production.

Based on a factorial experimental design (three locations × three cultivars × five harvest times × four replicates) conducted with the objective of investigating variations in fuel characteristics of cassava stem, a multivariate data matrix was formed which was composed of 180 samples and 10 biomass properties for each sample. The properties included as responses were two different calorific values and ash, N, S, Cl, P, K, Ca, and Mg content. Overall principal component analysis (PCA) revealed a strong clustering for the growing locations, but overlapping clusters for the cultivar types and almost no useful information about harvest times. PCA using a partitioned data set (60 × 10) for each location revealed a clustering of cultivars. This was confirmed by soft independent modelling of class analogy (SIMCA) and partial-least-squares discriminant analysis (PLS-DA), and indicated that the locations gave meaningful information about the differences in cultivar, whereas harvest time was not found to be a differentiating factor. Using the PLS technique, it was revealed that ash, K, and Cl content were the most important responses for PLS-DA models. Furthermore, using PLS regression of fuel and soil variables it was also revealed that fuel K and ash content were correlated with the soil P, Si, Ca, and K content, whereas fuel Cl content was correlated with soil pH and content of organic carbon, N, S, and Mg in the soil. Thus, the multivariate modelling used in this study reveals the possibility of performing rigorous analysis of a complex data set when an analysis of variance may not be successful.

The study was aimed to evaluate the potential of existing genotypes of Jerusalem artichoke (Helianthus tuberosus L.) as biomass feedstock for ethanol production. We investigated the biomass productivity and chemical composition of twenty-six Jerusalem artichoke clones grown in a semi-arid region of China. Jerusalem artichoke was demonstrated to be a sustainable feedstock for bioethanol production. All structural and non-structural carbohydrates in whole plant of Jerusalem artichoke could be 5000 L/ha. The above-ground biomass of Jerusalem artichoke could be a promising feedstock for cellulosic ethanol. The ethanol potential yield from cellulose and hemicellulose in aboveground biomass were 1821 to 5930 L/ha, contributing 29.8-66.4% of the total ethanol yield, which could be as high as that from switchgrass and sweet sorghum stem. Large variation among the investigated genotypes for carbohydrates makes it possible to select suitable clones to be used in bioethanol production in semiarid regions. Clones HB-3, HEN-3, IM-1, SC-1, SHX-3, SX-2 and ZJ-2 yielded tuber total soluble sugar higher than 4.0 t/ha. Clones BJ-4, HUB-2, HUN-2, QH-1, SD-2 and SHH-1 produced more than 5.0 t/ha cellulose and hemicellulose in above-ground biomass. Clones BJ-4 and HUB-2 have the highest ethanol potential based on structural carbohydrates. These clones were promising material if used as biofuel feedstock in this growth condition.

With ongoing economic development and population growth in China, large quantities of wastewater are discharged and substantial amounts of sewage sludge are generated, which is a potential biomass resource for methane production. This study used data from statistics yearbooks and literatures to evaluate the spatio-temporal distribution of sludge generation, potential and distribution of methane production from sludge, and the potential of greenhouse gas (GHG) emissions reduction (PGER) from sludge treatment and disposal in provinces in mainland China. The results showed that a total of 6.03 Mt of dry solids in 2015. The eastern part of the country produced more sludge than that the western part. The standard coal equivalence of sludge was 3.5 Mt, ranged from 0.7 to 399.8 Kt, among the 31 provinces of mainland China. Total sludge could produce 1.27 billion m3 of methane per year through anaerobic digestion (AD). The distribution of methane density exhibited that the east part was higher than the west part in China. The GHG emissions totaled 18.82 Mt CO2-eq as a baseline for the current sludge disposal methods without AD technology. The PGER was 10.77 Mt CO2-eq for the sludge disposal routes with AD technology. The sludge disposal for the project route of building material exhibited the highest PGER of 4.24 Mt CO2-eq among the disposal methods. As the least GHG emissions method, sludge treated by AD and the residue disposed for land using as fertilizer should be recommended. Our findings provide a sludge disposal reference for the government and industries. For further study, it is suggested to take the co-digestion technology into consideration for sewage sludge to produce methane, which would perform a higher methane production and GHG emissions reduction potential.

Exploitation of crop residue biomass resources will improve soil quality, future energy security, global carbon balance, and sustainable crop production. The present study was performed in order to evaluate residue quantities and distribution of field crops in the 31 provinces of China mainland with the latest residue indices, based on a province or a region. The annual average total residue in China (750.36 Mt) was composed of 660.76 Mt field residues (88.1%) and 89.60 Mt process residues (11.9%) on an air dried basis, in 2008 and 2009. Grain cereals of rice (200.56 Mt, 30.35%), wheat (145.91 Mt, 19.45%), and maize (153.85 Mt, 23.28%) were the major crops which produced 500.32 Mt field residue, accounting for 73.08% of the total field residue. The annual field residues produced in the 31 provinces varied between 1.26 Mt (Beijing) and 71.59 Mt (Henan). The field residue was distributed in regions according to the order: Northwest China (54.23 Mt, 8.21%)oNorth China (75.66 Mt, 11.45%)oSouthwest China (80.67 Mt, 12.21%)oNortheast China (89.61 Mt, 13.56%)oCentral-South China (179.11 Mt, 27.11%)oEast China (181.47 Mt, 27.46%). The SCE of the total crop residue was distributed in the top three regions: Central-South China (112.04 Mt)>East China (104.36 Mt)>Northeast China (55.02 Mt). The average residue yield was between 4.14 t ha � 1 and 8.65 t ha � 1 and the residue density was between

This study investigated the N and P uptake and yield performances of winter wheat (Triticum aestivum) and maize (Zea mays) upon intercropping with 1- to 2-year-old poplar (Populus × euramericana cl. “74/76”) trees compared to a sole wheat and maize rotation in fertilized and unfertilized subplots. Aboveground biomass, grain yield, yield components, and N and P contents of wheat and maize were measured in each plot, in addition to soil available N and P. No significant differences in biomass, grain yield, and N and P uptake of wheat were found between the intercropping and sole-crop systems within the same fertilization treatment. Maize biomass and grain yield decreased by 37% and 31%, and 28% and 34% for the fertilized and unfertilized treatment at maize maturity in the same order. The N and P contents in maize intercropped with poplar were found to be significantly lower than in the sole-maize. For the fertilized treatment, intercropping with poplar led to significantly lower soil NO3-N and Olsen-P in th...

Jerusalem artichoke (JA) has been known as a potential nonfood feedstock for biofuels. Based on systems analysis of total 59 accessions, both soluble sugar and ash could positively affect biomass digestibility after dilute sodium hydroxide pretreatment (A). In this study, one representative accession (HEN-3) was used to illustrate its enzymatic digestibility with pretreatments of ultrasonic-assisted dilute sodium hydroxide (B), alkaline peroxide (C), and ultrasonic-assisted alkaline peroxide (D). Pretreatment D exhibited the highest hexose release rate (79.4%) and total sugar yield (10.4 g/L), which were 2.4 and 2.6 times higher, respectively, than those of the control. The analysis of cellulose crystalline index (CrI), cellulose degree of polymerization (DP), thermal behavior and SEM suggested that alkali-based pretreatments could distinctively extract lignin and pectin polymers, leading to significant alterations of cellulose CrI and DP for high biomass saccharification. Additionally, hydrogen peroxide (H2O2) could significant reduce the generation of fermentation inhibitors during alkali-based pretreatments.

This paper analyzes the rural Chinese biomass supply system and models supply chain operations according to U.S. concepts of logistical unit operations: harvest and collection, storage, transportation, preprocessing, and handling and queuing. In this paper, we quantify the logistics cost of corn stover and sweet sorghum in China under different scenarios. We analyze three scenarios of corn stover logistics from northeast China and three scenarios of sweet sorghum stalks logistics from Inner Mongolia in China. The case study estimates that the logistics cost of corn stover and sweet sorghum stalk to be $52.95/dry metric ton and $52.64/dry metric ton, respectively, for the current labor-based biomass logistics system. However, if the feedstock logistics operation is mechanized, the cost of corn stover and sweet sorghum stalk decreases to $36.01/dry metric ton and $35.76/dry metric ton, respectively. The study also includes a sensitivity analysis to identify the cost factors that cause logistics cost variation. Results of the sensitivity analysis show that labor price has the most influence on the logistics cost of corn stover and sweet sorghum stalk, with a variation of $6 to $12/dry metric ton.

Crop residue is recognized as a potential feedstock for biofuels and a sustainable substitute for fossil energy sources. Expanding the acreage of biofuel crops, it is important to establish a crop residue retention regime to conserve soil fertility and prevent soil erosion. This paper presents simple linear and power equations between stubble biomass ratio (SBR, i. e. percentage of stubble biomass to whole plant biomass) and stubble height ratio (SHR, i. e. percentage of stubble height to maximum plant height) for a wide range of field crops of rice, wheat, oat, corn, sorghum, sunflower, canola, soybean and cotton, using data collected from 15 sites in production fields in 11 provinces across China from 2009 to 2012. Simple linear regressions for the crops were associated with highly significant coefficients of determination (R2) for all crops. Validation with independent datasets also showed high R2 values, indicating model goodness-of-fit. Mean relative error (MRE) and root mean square error (RMSE) values showed good fit for the two allometric relationships for each field crop studied. These results could be used to assess stubble mass for sustainable residue removal in bio-based energy systems.

This study investigated biomass yield and growth characteristics of 26 Jerusalem artichoke (Helianthus tuberosus L.) clones and assessed it as a bioenergy crop for a semiarid region of the Loess Plateau in China. Genotype, year, and genotype ´ year interaction contributed to differences in crop development, growth characteristics, and biomass yields (dry matter). Generally, biomass yields in 2011 were lower than in 2008, mainly due to a more severe soil moisture deficit in 2011. Shoot and tuber biomass yields (STBY) ranged from 18.9 to 35.0 Mg ha–1 in 2008 and from 16.1 to 24.8 Mg ha–1 in 2011. Clones HUB-2 and BJ-4 produced the highest shoot biomass yield (SBY), amounting to 31.3 and 25.6 Mg ha–1, respectively, in the wetter year but higher drought sensitivity. Clones HUN-2, SD-2, and SHH-1 produced the second highest SBY, which varied between 14.3 and 20.1 Mg ha–1. Clones GZ-1, HEN-1, HUB-1, IM-1, and SX-2 are recommended for tuber production and produced tuber yields >8 Mg ha–1 in both seasons. Clones SD-2 and SHH-1 exhibited drought sensitivity indices

The objective of this investigate is to evaluate the variation in yield and fuel quality of corn stover under different harvest time and to determine appropriate harvest time. Using Zhengdan 958 as research material, the effect of harvest time on yield and fuel quality of corn stover was studied under field conditions in Baicheng Academy of Agricultural Sciences, during 2007-2008. Results showed that with the delayed harvest time, yield of corn stover decreased, and the proportion of leaves reduced gradually, reduction of leaf biomass was the main reason for lower yield. With the delayed harvest time, moisture, ash, and mineral elements contents of corn stover significantly decreased, cellulose and lignin contents increased, but hemicellulose content decreased. Heating value of corn stover was maximum at filling stage and minimum at maturity, it was slightly higher after maturity. Heating value was significantly correlated with cellulose and lignin contents; ash content was significantly positively correlated with mineral elements contents, and was significantly negatively correlated with Si/K ratio. Delayed harvest reduced the yield of corn stover, but significantly improved its fuel quality. Fuel quality of corn stover was better when harvested in winter and spring.