High Biomass Yield Research Articles

Exploring the potential of Salicornia: A halophyte’s impact on Agriculture, the Environment, and the Economy

Salicornia, a halophytic plant, garners attention for its environmental, energy, medicinal, and economic potential. It excels in environmental management through phytoremediation and carbon sequestration, thriving in saline environments to filter toxins and recycle nutrients. As a biofuel source, its oil-rich seeds and high biomass yield offer eco-friendly alternatives for biodiesel and bioethanol production, mitigating greenhouse gas emissions. Salicornia’s bioactive compounds exhibit significant potential in modulating the immune system and managing various diseases. Despite challenges such as production costs and regulatory barriers, Salicornia holds promise as a sustainable crop with diverse commercial applications. Scaling up Salicornia production and utilization requires addressing challenges related to cultivar development, production costs, and regulatory frameworks. However, with continued research and investment, Salicornia could emerge as a valuable resource for addressing food security, energy sustainability, and environmental restoration. Future research directions include exploring Salicornia’s nutritional composition, environmental sustainability, and epigenetic mechanisms, as well as optimizing extraction methods and intercropping systems. Understanding these aspects will contribute to unlocking Salicornia’s full potential as a versatile crop with wide-ranging benefits for human health, environmental conservation, and economic development.

In-vitro digestibility and methane gas emission of indigenous and introduced grasses in the rangeland ecosystems of south eastern Kenya

Various grass species with high biomass yield and low moisture demand have been introduced in the rangelands of Kenya to realize increased ruminant productivity that could not be achieved with the low quality of the indigenous grasses. However, this intervention ignores the different methane emission of the indigenous and introduced grasses, a necessary consideration for realizing increased productivity while minimizing greenhouse gas emissions. This study determined in-vitro digestibility and methane emission of three indigenous grasses: Eragrostis superba (E. superba), Cenchrus ciliaris (C. ciliaris), Enteropogon macrostachyus (E. macrostachyus) and two introduced grasses (two varieties of Chloris gayana; Boma rhodes and Extozi rhodes. Samples of these five grasses (whole plant above ground) were collected from established pasture plots in South Eastern rangelands of Kenya. The grass samples were collected at bloom stage using one-meter square quadrats for proximate analysis and determination of neutral detergent fiber (NDF), acid detergent lignin (ADL) and acid detergent fiber (ADF) using AOAC (1990) methods. On average, relative to the indigenous grasses, the introduced grasses were higher in crude protein (74.05 g Kg-1 dry matter (DM) vs. 52.11 g Kg-1 DM), organic matter digestibility 62.7% vs 53.6%) and in NDF (712.7 g Kg-1 DM vs. 708.0 g Kg-1 DM), metabolizable energy (16.35 vs 12.90 MJ/kg DM), methane emission (25.61 ml vs 15.93 ml) but with lower in-vitro-dry matter digestibility 54.24% vs 58.12%. Methane production positively correlated with crude protein, NDF, metabolizable energy, ADF and in-vitro organic matter digestibility. Hence, utilizing the introduced grasses to boost cattle production would achieve increased productivity but a point of concern are the higher methane emissions, not to mention the ecosystem change caused by the introduction of new species, which should affect the sustainability of the rangeland ecosystem.

Sensitivity-based economic analysis of Gracilaria dura cultivation: Comparison of bamboo raft and tube-net techniques along South-east and West Coast of India

The emerging niche applications make agar one of the sought-after seaweed-derived polysaccharides globally. This communication deals with a comprehensive sensitivity-based economic analysis of two farming methods of Gracilaria dura to bring out the best scenario for investors. The profitability assessment parameters under a 50 % increased revenue were favourable. A least payback period of 0.25 years was reported for tube-net method with a high biomass yield; while a breakeven point for the raft and tube-net in single-farmer model were found to be 144 kg and 400 kg respectively; and a net present value of USD 9518 was reported for tube-net based farming. The sensitivity analyses demonstrated that the raft method is not viable, while the tube net farming is economically feasible under scenarios such as 50 % increased revenue of average biomass yield, 25 % and 50 % increased revenues of one crop gain scenario and in all revenue impacts of high biomass yield for G. dura.

Effects of nitrogen supply on hydrogen-oxidizing bacterial enrichment to produce microbial protein: Comparing nitrogen fixation and ammonium assimilation

To investigate the effects of nitrogen source supply on microbial protein (MP) production by hydrogen-oxidizing bacteria (HOB) under continuous feed gas provision, a sequencing batch culture comparison (N2 fixation versus ammonium assimilation) was performed. The results confirmed that even under basic cultivation conditions, N2-fixing HOB (NF-HOB) communities showed higher levels of CO2 and N2 fixation (190.45 mg/L Δ CODt and 11.75 mg/L Δ TNbiomass) than previously known, with the highest biomass yield being 0.153 g CDW/g COD-H2. Rich ammonium stimulated MP synthesis and the biomass accumulation of communities (increased by 7.4 ～ 14.3 times), presumably through the enhancement of H2 and CO2 absorption. The micro mechanism may involve encouraging the enrichment of species like Xanthobacter and Acinetobacter then raising the abundance of nitrogenase and glutamate synthase to facilitate the nitrogen assimilation. This would provide NF-HOB with ideas for optimizing their MP synthesis activity.

Desho grass ( Pennisetum pedicellatum ) varieties adaptation trial in highland areas of the North Shewa Zone, Oromia region, Ethiopia.

Abstract The experiment was conducted in highland areas of the Kuyu site, Girar Jarso and Wachale districts of the North Shewa Zone, Oromia region. The objective of the experiment was to identify the adaptable and high biomass yield of Desho grass varieties. Accordingly, four Desho grass varieties, viz. Kindu Kosha DZF#591, Areka DZF#590, Kulumsa DZF#592 and Kindu Kosha DZF#589 were tested in a randomized complete block design (RCBD) with three replications. The results of the combined analysis revealed that plant height was significantly ( P < 0.05) different between treatments. The highest plant height was obtained from Kulumsa DZF#592 (85.73 cm), followed by the Areka DZF No# 590 (82.71 cm) and Kindu Kosha DZF#589 (81.74 cm) varieties, while the shortest plant height was recorded from the Kindu Kosha DZF#591 (80.34 cm) variety. However, the plant height of the Desho grass varieties was significant when combined over time, and it was significantly different among the production years. On the other hand, the number of tillers per plant, number of leaves per plant, survival rate and dry matter yield (DM) showed significant ( P < 0.05) differences between treatments. The maximum DM yield (13.85 ton ha -1 ) was obtained from Kindu Kosha DZF#591, followed by Kulumsa DZF#592 (12.81 ton ha -1 ). The number of nodes per plant, internodes length and leaf-to-stem ratio did not vary significantly among the Desho grass varieties. The chemical composition, crude protein yield, Ash, neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) contents were not significantly ( P > 0.05) different among the Desho grass varieties except for dry matter percent. Generally, the varieties Kindu Kosha DZF#591 and Kulumsa DZF#592 have comparable performances for most measured traits in the North Shewa Zone, Oromia. Therefore, Kindu Kosha DZF#591 and Kulumsa DZF#592 varieties of Desho grass were recommended for livestock producers in the North Shewa Zone, Oromia.

Purification of anaerobic fermentation digestate of dairy manure by Arthrospira biomass cultivated with biogas-CO2 fixation

Single Arthrospira strain was successfully used for synergistic bio-fixation of tail gas CO2 and digestate utilization generated from anaerobic fermentation project of dairy manure, establishing a new model of circular carbon bioeconomy. Digestate addition ratios (0.96–9.6 vol%) and frequency (once initially/in batches for 4 days) were investigated to improve Arthrospira growth rate, which maximizes at 0.58 g/L/d). Daily addition of digestate resulted in a higher biomass yield than addition once initially. Arthrospira biomass growth cultivated with 7.6 vol% ozone-pretreated digestate and 92.4% zarrouk culture medium first increased to a peak at 0.90 g-O3/g-COD, and then decreased with further enhanced ozone concentration. The digestate is confirmed and designed be used for microalgae cultivation without pretreatment based on actual engineering cases. As far as heavy metals and protein content are concerned, it is safe to cultivate Arthrospira biomass in zarrouk culture medium with appropriate digestate addition for animal feed production.

Indigenous microalgae strains characterization for a sustainable biodiesel production.

Microalgae have been widely recognized as a promising feedstock for sustainable biofuels production to tackle global warming and pollution issues related to fossil fuels uses. This study identified and analyzed indigenous microalgae strains for biodiesel production, specifically Chlorella vulgaris and Coelastrella thermophila var. globulina, from two distinct locations in Algeria. Molecular identification confirmed their identity, and the microalgae exhibited notable growth characteristics. Local Chlorella vulgaris and Coelastrella thermophila var. globulina showed good growth and high biomass yield, compared to Chlorella vulgaris CCAP211/11B reaching a weight of 1.48 gL-1 , 1.95 gL-1 , and 2.10 gL-1 , respectively. Lipids content of local Chlorella vulgaris, Coelastrella thermophila var. globulina, and Chlorella vulgaris CCAP211/11B, were found to be 31.39±3.3%, 17±2.26%, and 19±0.64%, respectively. Chlorella vulgaris stood out as a candidate for biodiesel production due to its equilibrium between SFA and PUFA (43.24% and 45.27%). FAs are predominated by SFA and MUFA for Coelastrella thermophila var. globulina with value of 81.49% (SFA+MUFA). Predicted biodiesel qualities comply with ASTM6751 and EN14214 standards. Studied microalgae have therefore a promising potential for biodiesel production. However, optimising cultivation conditions is necessary to enhance biomass and lipids yield at a large scale.

Şanlıurfa Ekolojik Koşullarında Farklı Tatlı Sorgum (Sorghum bicolor var. saccharatum (L.) Mohlenbr.) Genotiplerinin Lignoselülozik Biyoetanol Verimleri

The use of products with high biomass yield per unit area as a renewable energy source, which are not consumed primarily for food purposes or can be used for multi-purposes, is of great importance in terms of food safety. For this purpose, sweet sorghum plant, which can grow in salty-alkaline soils, tolerant to drought and short-term floods, and has wide adaptability, has gained importance as a lignocellulosic bioethanol raw material in recent years. The aim of this study is to theoretically determine the lignocellulosic bioethanol yield of 21 different sweet sorghum (Sorghum bicolor var. saccharatum (L.) Mohlenbr.) genotypes grown under second crop conditions in the ecology of Şanlıurfa province, obtained from domestic and foreign sources. In the study, sweet sorghum pulp from plant sap was used as lignocellulosic bioethanol raw material. The cellulose and hemicellulose contents of the pulp were determined and the amount of lignocellulosic bioethanol that could be obtained per decare was calculated by using the bioethanol conversion rates. According to the data obtained, the highest yield was obtained from UNL-Hybrid-3 (805.5 L/da), Theis (766.5 L/da), Smith (698.1 L/da) genotypes. In order to solve problems such as increasing the octane of gasoline, reducing greenhouse gas emissions and gasoline imports, it is recommended that these three genotypes be cultivated and disseminated for lignocellulosic bioethanol production in Şanlıurfa ecological conditions.

High-yield ramie derived carbon toward high-performance supercapacitors

Biomass porous carbon possesses prominent advantages of high specific surface area, appropriate pore distribution and excellent chemical stability, making them suitable for electrode materials of supercapacitor. However, achieving its high yield based on remarkably structural integrity of biomass derived carbon at the molecular level is extremely difficult due to the incompatibility between low-activity biomass chains and highly polymerized polymer chains. Here, we demonstrate a universal self-crosslinked strategy to effectively build the high-yield ramie derived carbon (hy-RDC) by molecularly regulating high-activity ramie precursor and hydroxy-protonated phenolic resin synergistically. Benefiting from the chemical compatibility between cellulose chain and phenolic chain and the structural integrity of ramie, this hy-RDC remarkably possesses a high yield of 31.33%, much higher than pure ramie carbon (3.56%) and pure phenolic carbon (15.22%) solely. These hy-RDC-based supercapacitors deliver an outstanding energy density of 35.58 Wh kg−1 at a high power density of 51.24 kW kg−1 than pure ramie carbon (34.29 Wh kg−1 at 51.22 kW kg−1) and pure phenolic carbon (14.08 Wh kg−1 at 46.09 kW kg−1). Evidently, this work may give a way to obtain high-yield biomass carbon with the effective electrochemical performance and the excellent structural stability, and dramatically promoting the energy storage application of biomass carbon.

Alfalfa Stem Cell Wall Digestibility: Current Knowledge and Future Research Directions

Alfalfa (Medicago sativa L.) is considered as the most important forage legume with high biomass yield and nutritional quality for ruminants. The alfalfa leaf cell walls are highly digestible, but stem cell walls of alfalfa are not readily digestible. The cell wall component of alfalfa has a large source of dietary energy, but ruminant animals can digest less than half of this component due to the presence of high lignin content. The main goal of this review is to make a summary of existing knowledge of alfalfa cell wall thickening and lignification patterns and suggest future directions for improving alfalfa stem cell wall digestibility. We describe alfalfa cell wall biochemistry, alfalfa stem morphology, stem tissue degradation, and existing methods to improve alfalfa digestibility, and discuss the potential future strategies for improving alfalfa cell wall digestibility. Information on these will help alfalfa breeders and producers identify superior alfalfa cultivars with improved stem cell wall digestibility. Concentrating future efforts on the selection and identification of traits and associated genes that affect cell wall digestibility could improve alfalfa cell wall digestibility.

High biomass yields of Chlorella protinosa with efficient nitrogen removal from secondary effluent in a membrane photobioreactor

Further treatment of secondary effluents before their discharge into the receiving water bodies could alleviate water eutrophication. In this study, the Chlorella proteinosa was cultured in a membrane photobioreactor to further remove nitrogen from the secondary effluents. The effect of hydraulic retention time (HRT) on microalgae biomass yields and nutrient removal was studied. The results showed that soluble algal products concentration reduced in the suspension at low HRT, thereby alleviating microalgal growth inhibition. In addition, the lower HRT reduced the nitrogen limitation for Chlorella proteinosa’s growth through the phase-out of nitrogen-related functional bacteria. As a result, the productivity for Chlorella proteinosa increased from 6.12 mg/L/day at an HRT of 24 hr to 20.18 mg/L/day at an HRT of 8 hr. The highest removal rates of 19.7 mg/L/day, 23.8 mg/L/day, and 105.4 mg/L/day were achieved at an HRT of 8 hr for total nitrogen (TN), ammonia, and chemical oxygen demand (COD), respectively. However, in terms of removal rate, TN and COD were the largest when HRT is 24 hr, which were 74.5% and 82.6% respectively. The maximum removal rate of ammonia nitrogen was 99.2% when HRT was 8 hr.

Potential of enriched phototrophic purple bacteria for H2 bioconversion into single cell protein

Single cell protein (SCP) has emerged as an alternative protein source, potentially based on the recovery of carbon and nutrients from waste-derived resources as part of the circular economy. From those resources, gaseous substrates have the advantage of an easy sterilization, allowing the production of pathogen-free SCP. Sterile gaseous substrates allow producing pathogen-free SCP. This study evaluated the use of an enriched phototrophic purple bacteria (PPB) consortium for SCP production using H2 and CO2 as electron and C sources. The influence of pH (6.0–8.5), temperature (15–50 °C) and light intensity (0–50 W·m−2) on the growth kinetics and biomass yields was investigated using batch tests. Optimal conditions were found at pH 7, 25 °C and light intensities over 30 W·m−2. High biomass and protein yields were achieved (~ 1 g CODbiomass·g CODH2consumed−1 and 3.9–4.4 g protein·g H2−1) regardless of the environmental conditions, being amongst the highest values reported from gaseous streams. These high yields were obtained thanks to the use of light as a sole energy source by the PPB consortium, allowing a total utilization of H2 for growth. Hydrogen uptake rates varied considerably, with values up to 61 ± 5 mg COD·d−1 for the overall H2 consumption rates and 2.00 ± 0.14 g COD·g COD−1·d−1 for the maximum specific uptake rates under optimal growth conditions. The latter value was estimated using a mechanistic model able to represent PPB growth on H2. The biomass exhibited high protein contents (>50 % w/w) and adequate amino acid profiles, showing its suitability as SCP for feed. PPB were the dominant bacteria during the experiments (relative abundance over 80 % in most tests), with a stable population dominated by Rhodobacter sp. and Rhodopseudomonas sp. This study demonstrates the potential of enriched PPB cultures for H2 bioconversion into SCP.

Agronomy and chemical composition of sunflower (Helianthus annuus L.) as a forage option in a warm-humid intertropical environment

Objective: To determine the phenology of sunflower and its potential as forage for ruminants in a humid-warm environment. Design/Methodology/Approach: Six treatments were evaluated during the 2016 dry season, according to the number of cutting days after sowing (DAS): 65 (T1), 72 (T2), 79 (T3), 86 (T4), 93 (T5), and 100 (T6). The SYN3950 HO hybrid was planted in 5 × 40 m plots with a completely randomized block design and three replications. The following variables were measured: days to reach reproductive stages (Ri), plant height (PH) in cm, stem perimeter (SPM) in cm, flower diameter (FD) in cm, and dry matter production in stem, peduncle, leaf, flower, and total (DM t ha-1), as well as the content of dry matter (DM), crude protein (CP), ash (A), neutral detergent fiber (NDF), and acid detergent fiber (ADF). Analysis of variance were carried out, as well as correlation between variables, mean comparison tests (Tukey, P<0.05), and regression between variables and DAS. Results: There were significant differences (P<0.05) between PH, FD, and DM production in stem, peduncle, flower, and total DM (t ha-1), as well as in DM, CP, NDF, and ADF. The highest biomass yields were obtained at 100 DAS (16 t ha1 DM) with 26% DM, 12.7% CP, 21.9% A, 44.2% NDF, and 30.9% ADF. It is concluded that sunflower is an option for feeding ruminants in the study area.

The use of mix ration corn-silage based for dairy cattle: A systematic review on methane emission and milk quality

In subtropical countries, corn silage is the primary ration for dairy cattle. Corn silage is often chosen in mixed rations because of its higher biomass yield, superior palatability, homogeneous yield quality, and simple silage preparation due to its higher soluble sugar content. The review aimed to (i) compile a list of the different feed components that may be combined with corn silage and (ii) compare the results of their effects on methane gas emissions, milk quality, and feed efficiency as determined by an in vivo approach. Relevant papers indexed in the computerized Scopus database and published in a variety of scientific publications were found. This systematic review was based on the PRISMA. Records included in review from databases (n = 10). This method has been applied by the authors in the articles that have been reviewed. In general, the content of CP and EE in the study was almost the same. CH4 (g/d) is lowest at 315-329, and for CH4 (g/kg of DMI) is 15.7-15.9. Substituting ordinary corn silage with Enogen corn silage (ECS) in TMR can increase milk production (38.8-40.8 kg/d) and milk quality (fat 3.82-4%, protein 3.07-3.11% and lactose 4.86-4.92%). The present literature review confirms that all mixed feeds with corn silage base used have nutrient content in accordance with the daily nutrient requirements of dairy cattle. Mixed feed that produces the lowest CH4 emissions (g/kg of DMI) and good milk quality is by giving ECS (Enogen corn silage).

Sugar accumulation enhancement in sorghum stem is associated with reduced reproductive sink strength and increased phloem unloading activity.

Sweet sorghum has emerged as a promising source of bioenergy mainly due to its high biomass and high soluble sugar yield in stems. Studies have shown that loss-of-function Dry locus alleles have been selected during sweet sorghum domestication, and decapitation can further boost sugar accumulation in sweet sorghum, indicating that the potential for improving sugar yields is yet to be fully realized. To maximize sugar accumulation, it is essential to gain a better understanding of the mechanism underlying the massive accumulation of soluble sugars in sweet sorghum stems in addition to the Dry locus. We performed a transcriptomic analysis upon decapitation of near-isogenic lines for mutant (d, juicy stems, and green leaf midrib) and functional (D, dry stems and white leaf midrib) alleles at the Dry locus. Our analysis revealed that decapitation suppressed photosynthesis in leaves, but accelerated starch metabolic processes in stems. SbbHLH093 negatively correlates with sugar levels supported by genotypes (DD vs. dd), treatments (control vs. decapitation), and developmental stages post anthesis (3d vs.10d). D locus gene SbNAC074A and other programmed cell death-related genes were downregulated by decapitation, while sugar transporter-encoding gene SbSWEET1A was induced. Both SbSWEET1A and Invertase 5 were detected in phloem companion cells by RNA in situ assay. Loss of the SbbHLH093 homolog, AtbHLH093, in Arabidopsis led to a sugar accumulation increase. This study provides new insights into sugar accumulation enhancement in bioenergy crops, which can be potentially achieved by reducing reproductive sink strength and enhancing phloem unloading.

Bioethanol potential of switchgrass cultivars for rainfed and irrigated conditions in marginal lands

ABSTRACT Bioethanol is a climate-friendly alternative to conventional energy sources. This study was conducted to determine bioenergy potential of switchgrass cultivation in Central Anatolia where water scarcity limits the agricultural production. Field trials were conducted in a randomized blocks design with three replications under irrigated and rainfed conditions for three growing seasons (2019, 2020 and 2021). Biomass yield (BY), theoretical cellulosic ethanol yield (TEY), theoretical ethanol potential (TEP) with several quality parameters of 10 switchgrass cultivars were evaluated. Highest BY averages were obtained from Boomaster cultivar with 5.28 (rainfed) and 18.45 t ha−1 (irrigated) when Dacotah had the lowest BY averages of 1.55 (rainfed) and 5.29 t ha−1 (irrigated). ANOVA and Genotype Trait Biplot results revealed higher BY, TEY and TEP with lower ADF, NDF and ADL of lowland ecotype cultivars. Lowland ecotypes provided superior results in both rainfed and irrigated conditions with a higher response to irrigation. TEY of switchgrass were found as positively associated with BY, plant height and stem weight which could be used as indicators of TEY for genotype selection. In conclusion, lowland ecotype cultivars of switchgrass were recommended for bioethanol production in water limited environments.

Effect of Different Concentrations of NaCl on Growth and Biochemical Characteristics of Red Microalga Porphyridium cruentum

The red microalga Porphyridium cruentum is a potential source of valuable biologically active compounds. This microalga is easily cultivated and could change its growth and biochemical composition in response to environmental variations. The effect of growth medium content, especially salinity (15, 20, and 27 gL -1 NaCl) on P. cruentum cell growth, biomass composition, and extracellular polysaccharides production was investigated in this study. The results showed that the highest biomass yield and phycoerythrin content was achieved when NaCl in a concentration of 20 gL -1 was introduced into the culture medium. The measured biomass was equal to 4.3±0.1 gL -1 compared to 3.3±0.1 gL -1 for the control sample at the end of the cultivation process. The amount of chlorophyll „a“ was also 1.33 times greater in the sample with 20 gL -1 NaCl compared to the control sample with 27 gL -1 , where the carotenoid content was higher. The highest amount of extracellular polysaccharide was accumulated by the microalga at 27 gL -1 NaCl. The measured viscosity was 3.35 mPa.sec - 1.4 times more than the sample with 20 gL -1 NaCl. The investigations conveyed lead to the conclusion that with only slight changes in the salt concentration, a targeted biosynthesis could be achieved, nevertheless, all other conditions remained the same. The study provides an opportunity to optimize growth and metabolite production using optimization in the cultivation process of the microalgae.

Performance of fish sludge solubilization and phototrophic bioconversion by purple phototrophic bacteria for nutrient recovery in aquaponic system

Nutrient recovery from fish sludge in aquaponics is crucial to improve the economic output of a system sustainably and hygienically. Currently, fish sludge is treated using conventional anaerobic and aerobic mineralization, which does not allow the recovery of valuable nutrients in fish wastes. In this study, a two-stage approach (named as solubilization process and phototrophic bioconversion) is proposed to convert fish sludge into mineral nutrients and biomass nutrients using purple phototrophic bacteria (PPB), thereby promoting the growth of plants and fish simultaneously in aquaponics. Anaerobic and aerobic solubilization methods are tested to pretreat the fish sludge, generating substrates for PPB. Anaerobic solubilization yields 2.1 times more soluble chemical oxygen demand (SCOD) and 3.7 times more total volatile fatty acid (t-VFA) from fish sludge compared with aerobic solubilization. The anaerobic solubilization effluent indicates a CODt-VFA/SCOD of 60% and a VFA comprising 13.3% acetate and 49.0% propionate for PPB. The phototrophic bioconversion using anaerobic solubilization effluent under the light-anaerobic condition results in the highest biomass yield (0.94 g CODbiomass/g CODremoved) and the highest PPB dominance (Ectothiorhodospira, 58.7%). The anaerobic solubilization and light-anaerobic phototrophic bioconversion achieves 54.1% of carbon recovery efficiency (CRE) (in terms of COD), as well as 44.8% and 91.3% of nutrient recovery efficiency (NRE) for N and P. A novel multiloop aquaponic system combined with PPB-based nutrient recovery is proposed for the reuse of mineral nutrients and PPB biomass generated from fish sludge.

Optimal fertilizer rates towards the improvement of nitrogen use efficiency and reduction of nitrogen export in paddy rice-wheat intensive farming

Introduction: Fertilizer application above plant nitrogen (N) requirements, leading to N use inefficiency, has become the primary source of N surplus, posing nonpoint pollution threats. Chao Lake has received N loadings, primarily from the agroecosystem that surrounds it. Based on 10 years of field monitoring and experiment, this study used optimum fertilizer rates (30% N reduction) to evaluate nitrogen use efficiency (NUE) and N export in the Chao Lake watershed of paddy rice-wheat rotational farming.Methods: Five treatments were tested, namely, the Blank Treatment (CK), Conventional Fertilization Treatment (CFT), High Fertilization Treatment (HFT), Reduced Fertilization Treatment (CFT), Reduced Fertilization Treatment plus Straw addition (RFTS). The parameters employed to measure NUE were 1) by calculating NUE indicators; Agronomic efficiency (kg kg-1), recovery efficiency (%), and partial factor productivity (kg kg-1) 2) using the European Union NUE framework as a comparison tool. N export was measured using N export parameters, namely, nitrogen loading (kg ha-1yr-1), nitrogen runoff loss ratio (%), and net nitrogen runoff loss ratio (%).Results and discussion: Results revealed that optimum N fertilizer input levels maintained high crop and biomass yields. The empirical model of y = y0 + a * exp (−0.5 * (x-x0)/b2) explains the relationships between input N fertilizer and corresponding yield returns. Low yield responses to increased N input beyond certain limits were observed, which may lead to N accumulations. N export was much lower from the reduced fertilization treatments than other treatments. N export increased in 10 years for both paddy rice and wheat seasons. Runoff volume influenced N export more than any other environmental factor studied.Conclusion: Overall, optimal fertilizer levels produced high NUE, maintained high economic yield, and produced lesser N exports; NUE was in the order of reduced > high > conventional fertilization treatments, while it decreased in 10 years (2008–2018) across all treatments. Such strategies that further reduce fertilizer levels by accounting for excess supplies are vital for consolidating effective N control measures.

Leaf Area Duration and Crop Radiation Use Efficiency Determine Biomass Yield of Lignocellulosic Perennial Grasses under Different Soil Water Content

The aim of the present work was to assess the leaf area duration (LAD) and the radiation use efficiency (RUE) of six warm-season perennial biomass grasses (PBGs) in a two-year field trial in the semiarid Mediterranean climate under different soil water availability. Two ecotypes of giant reed (Arundo donax L., ARCT and ARMO), one ecotype of African fodder cane (Saccharum spontaneum L. subsp. aegyptiacum (Willd.) Hack., SAC) and three hybrids of Miscanthus (the commercial M. × giganteus J.M. Greef, Deuter ex Hodk., Renvoize, M × G, and two new seed-based hybrids, GNT9 and GNT10) were compared under three levels of soil water availability: rainfed, 50% and 100% of maximum crop evapotranspiration (ETm) restoration. The determination of RUE of perennial plants is controversial and has led to contrasting results in past studies. In the present work, LAD and RUE differed among crops and irrigation regimes, being positively affected by supplemental water inputs. SAC, ARCT and ARMO showed both high LAD and RUE, which determined the high biomass yield than both the commercial M × G and the improved Miscanthus hybrids GNT9 and GNT10. RUE was particularly high and less affected by soil water availability during the mid-season, while the effect of irrigation and the differences among the genotypes were larger during the late season. Adequate biomass yield can be achieved by sub-optimal soil water availability, thus reducing the water footprint and increasing the sustainability of these biomass perennial grasses selected for the Mediterranean climate.