Carbon sequestration potential and its main drivers in soils under alfalfa (Medicago sativa L.).

As a perennial forage crop, alfalfa (Medicago sativa L.) has been extensively utilized for the vegetation restoration of degraded soil and provides feedstock for forage. Its high usage can be attributed to its high yield potential and the increasing soil organic carbon (SOC) sequestration of alfalfa cultivation. However, the impact of land conversion to alfalfa on SOC content and its underlying drivers remain unclear. We performed a meta-analysis at the global scale to explore the quantified effects of alfalfa cultivation on SOC content and identify its controlling factors. We employed 1699 pairwise data points from 90 publications based on cropland/abandoned land conversion to alfalfa. Globally, cropland (cropland-alfalfa) and abandoned land (abandoned land-alfalfa) conversion to alfalfa enhanced SOC content by 12.1 % and 13.7 %, respectively. Alfalfa exhibited greater SOC content benefits in the surface soils (0-20 cm) with a lower level of initial SOC (<16 g kg-1), regardless of the land conversion type. Cropland-alfalfa was observed to increase SOC content with fertilization, irrigation, and conventional tillage in the long term (>5 years). Furthermore, abandoned land-alfalfa enhanced SOC content in the absence of alfalfa biomass removal and for longer cultivation durations (>5 years). Boosted regression tree analyses indicated variations in soil properties (75 % for cropland-alfalfa and 65 % for abandoned land-alfalfa) as the primary factors driving changes in SOC content. The dominant drivers were determined as the soil layer (51.6 %), cultivation duration (13.1 %), and initial SOC (12.9 %) for cropland-alfalfa, and initial SOC (43.7 %), soil layer (24.6 %) and cultivation duration (17.1 %) for abandoned land-alfalfa. Land conversion to alfalfa has great potential for SOC sequestration, particularly in low-fertility soils. Therefore, alfalfa cultivation is highly recommended for degraded lands due to its SOC sequestration benefits in vegetation restoration.

Unlocking the potential of Dongting Lake-grown Miscanthus lutarioriparius biomass: A comprehensive quality analysis and bioproduct application study.

Miscanthus lutarioriparius grown in Dongting Lake has an annual biomass yield potential of 1 million tons. However, with the shutdown of its previous utilization for paper-making, abandoning this huge amount of biomass has caused serious economic, ecological, and social problems. Constructing an industrial cluster to continuously convert biomass into various bioproducts is a win-win measure to address this dilemma. With the increasing confirmation of the importance of biomass quality affecting the conservation process, fully understanding the biomass characteristics of Dongting Lake-grown M. lutarioriparius is crucial for building a scientific industrial cluster. The present work is designed to explore the variation in biomass quality across the entire Dongting Lake area. Results show that the biomass contented with Cd, Mn, Zn, and Cr has significant geographical differences, with a general trend of Southern Dongting Lake-grown biomass having a higher concentration than that from Eastern and Western Dongting Lake areas. Moreover, significant differences are found in terms of biomass ash content, lignin content, and the degree of polymerization of cellulose (DP). The biomass with low ash content is generally from the entire Eastern Dongting Lake area and the northern part of the Western Dongting Lake area. Virtually all Western Dongting Lake-grown biomass has a low lignin content (approximately 18 %). Regarding the spatial variation of DP, Eastern Dongting Lake-grown biomass has a higher DP (average at 585.33) than that in Southern (575.15) and then Western Dongting Lake (529.16). Based on these quality indicators, the biomass production potentials for bioethanol, biochar, and xylo-oligosaccharide were calculated and visualized. Results show that biomass from almost the entire Western and Eastern Dongting Lake area is suitable for bioethanol and xylo-oligosaccharide production, while biomass from the Southern Dongting Lake area for biochar production. These results provide scientific guidance for the future utilization of Dongting Lake-grown M. lutarioriparius biomass.

[Definition and assessment of coefficients for the calculation of forestry residues].

Organic waste is an important biomass resource. In this study the definition of coefficients for the calculation of all the secondary 10 forestry residue categories was improved and established according to literature reviewing of previous reports between 1982 and 2017. The rationality of value-taking for each coefficient in previous literature was examined by tracing to its citation sources. The irrational, or unstudied coefficients were assessed using the data in previous reports or questionnaire surveys. Lastly, values of the coefficient for the calculation of woody nursery residue, forest woody pruning residue, wood logging residue, firewood, wood bucking residue, wood handling residue, waste wood, banana and pineapple plant residue, bamboo processing residue and waste bamboo were reasonably assessed in this study.

[Methods for assessing resources of forestry residues].

In this study, models for assessing resources of forestry residues were improved based on analysis of previous studies and current forest production in China. And novelties are highlighted: this study covered the models for the calculation of 10 secondary forestry residues from woody nursery, forest woody pruning, wood logging, firewood, wood bucking, wood handling, waste wood, banana and pineapple plants, bamboo processing and waste bamboo; the residues produced from fast-growing forest for logging and processing of imported wood were taken into consideration to calculate woody residue potential; the calculation of pruning residue included woody fruit trees, and herbaceous fruit plants from the management of orchard and other economic forest; the consistency of parameter terminology and definition which referred from their literature resources have been ensured; more studies focused on the coefficient values, industrial standard, forestry residue amount and spatial distribution are recommended for future researches.