Grass Residues Research Articles

Layer formation on quartz bed particles during fast pyrolysis of grass

Commercial fast pyrolysis technologies use bed materials, normally natural sand mainly consisting of quartz, acting as circulating heat carrier materials. Nowadays, the commercial conversion of biomass into fast pyrolysis bio-oil (FPBO) is still using ash-lean woody residues as a feedstock since the application of more abundant and possibly cheaper ash-rich agricultural biomass is currently at a significantly lower technology readiness level (TRL). To promote FPBO production from ash-rich biomass, the ash-related issues during the operation process need to be further studied. In the present investigation, the characteristics and formation process of layers formed on quartz bed particles, collected from a bench-scale fast pyrolysis unit based on the rotating cone technology, were studied. Two grass residues, representative of typical Si-K-rich agricultural biomass fuels, were used as feedstocks. Quartz bed particles at different sampling times from startup with fresh bed particles were collected. Scanning Electron Microscopy/Energy-Dispersive Spectroscopy (SEM/EDS) was employed to characterize the layer properties. Bed particle layers exhibited an uneven and discontinuous distribution on the quartz surface. This distribution over bed particles, as well as layer thickness, increased with the operational time. The dominating elements contained in layers were Si, K, Ca, and Cl (excluding O), which resembled that of individual bed ash particles found in the bed samples. In addition, the interpretation of the results was supported by thermodynamic equilibrium calculations. The findings suggest that the process of layer formation was governed by the direct adhesion of non-melted bed ash particles during the fast pyrolysis of grass.

Water vapor transport through bioenergy grass residues and its effects on soil water evaporation

AbstractMiscanthus is a productive perennial grass that is suitable as a bioenergy crop in “marginal” lands (e.g., eroded soils) with low water holding capacity. However, little is known about the impact of miscanthus residues on vapor transport and soil water budgets. Laboratory experiments were conducted to measure the vapor conductance through miscanthus residues and its effect on soil water evaporation. The ranges for the length, width, and thickness of residue elements were 0.5–9.0, 0.1–0.5, and 0.1–0.5 cm, respectively. Average residue areal, bulk, and skeletal densities were 0.88 kg m−2, 24 kg m−3, and 1006 kg m−3, respectively, giving a porosity of 0.98 m3 m−3. A power function described the decrease in conductance with increasing residue load. The corresponding conductance for a residue load of 0.88 kg m−2 was 1.6 mm s−1. During the first days of a 60‐day drying experiment, cumulative evaporation showed logarithmic decay with increasing residue load. Conversely, cumulative evaporation during the last days of the study showed little difference between treatments. Measurements indicated that there is a “critical” residue load (∼1.0 kg m−2) beyond which evaporation no longer decreases appreciably when the soil is under the stage 1 evaporation regime. Results suggest that soil water conservation in marginal lands may be accomplished by maintaining moderate amounts of bioenergy grass residue covering the soil. Determining “critical” loads for different residue types is a knowledge gap that merits further research.

Pemanfaatan Berbagai Jenis Limbah Pertanian Sebagai Media Tanam Jamur

Mushrooms are divided into two major groups, namely white rot fungi and brown rot fungi. White rot mushrooms are a group of fungi that easily grow on medium containing cellulose/simple sugars such as bagasse and grass residue, while brown rot mushrooms are a group of fungi that grow easily or well on medium containing complex cellulose such as residue from dead wood. Mushrooms are classified as heterotrophic living things, which means they live by processing food from organic compounds. In general, the substrate used for growing mushrooms is sawdust, but the problem found is the availability of sawdust which is difficult to obtain and costs a lot of money to procure. An alternative substrate that is easy to obtain and widely available is agricultural waste. The purpose of this research is to observe and examine from various sources what types of waste can be used as an alternative for cultivating mushrooms so as to save on production costs. This type of research is applied science research with the method used is the survey study method of literature. The results obtained are the types of waste that can be used as a mushroom growing medium are Sawdust, Coconut Fiber, Oil Palm Empty Bunches, Oil Palm Male Flowers, Palm Oil Stem Decomposite, Rice Husk, Rice Bran, Corn Cobs, Leftover Corn Seeds, Leftover Sorghum Seeds, Remaining Wheat Seeds, Sugar Cane Dregs, Dried Tea Powder, Dried Coffee Skins, Dried Peanut Shells. It is suggested that further research is needed on mixing the composition of mushroom growing media so that maximum results are obtained for the growth of both brown rot and white rot mushrooms

Production of commercial and Amazonian strains of Pleurotus ostreatus in plant waste / Produção de linhagens comerciais e amazônicas de Pleurotus ostreatus em resíduos de plantas

Pleurotus spp. have the ability to grow on a wide variety of lignocellulosic materials, which opens up a range of options to be explored. The use of locally available residues and native strains can reduce production costs, thus making fungiculture a potential economic activity in developing regions, such as northern Brazil. The aim of this research was to compare the production and nutritional characteristics of different strains of P. ostreatus, cultivated on lignocellulosic residues available in Amazonas state, Brazil. The native (474 and 1467) and commercial (542 and 885) strains were cultivated in marupá (Simarouba amara) and pine (Pinus sp.) sawdust, açaí (Euterpe oleracea) seeds and elephant grass (Pennisetum purpureum Schum.) straw. Productivity was evaluated according to biological efficiency, yield and loss of organic matter. Some physicochemical and nutritional parameters were also evaluated. In general, among the residues evaluated for mushroom cultivation, the elephant grass substrates (EG) showed better physicochemical properties in terms of moisture, ash content (minerals), hemicellulose and lignin. Additionally, the EG-based substrate resulted in the best productive parameters (yield and EB) for all strains studied, with emphasis on strain 1467, which is native to the Amazon. The basidiocarps of the native strains (474 and 1467) presented a nutritional composition that is similar to the commercial strains (885 and 542), and the mushrooms grown in EG-based residue, in general, presented the best nutritional compositions. Thus, strain 1467 of Pleurotus ostreatus, native to the Amazon, shows promise for commercial purposes, when cultivated in elephant grass residue.

Decomposition and Nutrient Release from Grass Residue in Tropical Conditions

ABSTRACT The use of grasses as ground cover in tropical climate guarantees soil protection against erosion processes, however, its capacity for nutrients mineralization is poorly understood. In this sense, the aim of the study was to evaluate the decomposition of vegetable residues from grasses and the mineralization of macronutrients in tropical conditions. The study was conducted in a randomized block design with four replications, in a 4 × 9 factorial scheme with four cultural residues: sorghum, millet, black oats, and fallow; and nine evaluation times: 0, 14, 28, 42, 56, 70, 84, 98, and 112 days after setting up the study (DAA), in the field. Vegetable residues were disposed on the soil surface for remaining dry matter (RDM), half-life (t1/2) and mineralization rates. Lower decomposition rates were observed in sorghum and millet residues, with RDMs of 40% and 31% when compared to oats and fallow (17% RDM). Thus, the waste mineralization rates decreased in the following order: fallow = oats > millet > sorghum. The mineralization of macronutrients was considered high and decreased in the following order: K > P > N > C > Mg > S > Ca, corresponding to 96, 88, 88, 80, 76, and 74%. The fallow, millet, oat, and sorghum residues released 84, 17, 225, and 17 kg t−1 of N, P, K, and S, with different mineralization rates. The largest fraction of these nutrients was mineralized in the first 30 DAA, what indicates its potential use in agriculture.

Production of microbial protein from fermented grass

• Industrially relevant lactic acid productivity (9.9 g/L/h) was achieved at 45 °C. • Solid removal is essential for lactic acid extraction via membrane electrolysis. • Lactic acid can be extracted at 13 kWh/kg from solid-free fermentation broth. • The dried MP produced was superior to whole egg, raw chicken, tofu and soybean. • Methane was produced from grass residues at yield up to 0.53 g CODCH4 /g CODsubstrate . Grass is one of the most abundant plant families on Earth, however it has limited applications beyond the use as animal feed due to its low economic and nutritional value. Here we developed a concept for the increased valorization of grass to microbial protein (MP) for human food and biogas. We followed a four-step approach, starting with lactic acid (LA) fermentation of grass juice (GJ) using Bacillus coagulans , followed by LA extraction via membrane electrolysis, aerobic MP production using Cupriavidus necator and digestion of the side-products for biogas production. Temperature (28–55 °C) had a strong effect on the performance of batch GJ fermentations under axenic and non-axenic tests performed with B. coagulans , with the highest LA concentration (16–18 g LA /L) and productivity (0.45–0.56 g LA /L/h) achieved at 45 °C. Continuous non-axenic thermophilic (45 °C) GJ fermentation enabled the highest LA titers (23 g LA /L) at 6 h HRT while 1.5 h HRT enabled the highest productivity (9.9 g LA /L/h). The microbial community was dominated (77–97%, HRT < 6 h) by Lactobacillaceae, regardless of inoculating B. coagulans . LA extraction via membrane electrolysis was possible after removal of solids, achieving maximum LA recovery of 35%, while the lowest energy input was 13 kWh/kg LA . Microbial biomass produced in pH-stat mode using extracted LA contained 58% protein in cell dry weight, while the final product (dried MP) is superior to egg, chicken, tofu and soybean. The side-products of these processes ( i.e. fermentation effluent and unconverted solids) can be used for methane production with 0.085–0.53 g CODCH4 /g CODsubstrate yield. This research delivered a proof-of-concept for the use of grass within a biorefinery concept, allowing for recovery of products with a potentially large market such as MP, LA and biogas.

Yields and Nitrogen Dynamics in Ley-Arable Systems—Comparing Different Approaches in the APSIM Model

Nitrogen (N) dynamics in ley-arable cropping systems require better understanding in order to assess the potential of such systems to contribute to improved productivity and reduced nutrient losses in crop production. Large inputs of organic matter after termination of the ley phase result in increased mineralization and N availability to subsequent crops. The description and quantification of this residual N effect in ley-arable systems remains a major scientific challenge due to its variability and many influencing factors. Simulation modeling could contribute to improved understanding of N dynamics in ley-arable systems. The aim of this study was to evaluate the robustness of the Agricultural Production Systems Simulator (APSIM) to predict biomass yield, N yield, and N leaching of different forage maize systems in northwest Europe, while using two different approaches to predict the residual N effect. The evaluation was based on three field experiments covering plant phenology, biomass, N yield, and N leaching over several years. Model adjustments were necessary to describe mineralization of organic matter and release of N after ploughing of the grass leys. For this purpose, three scenarios were investigated by accounting for either (1) aboveground grass residues; (2) above- and belowground grass residues, both with the generic turnover approach in the model; or (3) N release depending on the carbon-to-N ratio of the residue compiled in a simple mineralization model (SMM). The results showed that APSIM-simulated biomass and N yield of maize were reasonable to poor across the different systems and sites, regardless of using the residue-related approach. The SMM performed more accurately compared to the generic turnover approach in predicting N leaching in a maize following a grass-clover ley. However, for all scenarios, APSIM had difficulties to predict a delay of N leaching observed in the experimental data after a pure ryegrass ley. In conclusion, the process description in APSIM related to organic matter mineralization in ley-arable systems under northwest European pedo-climatic conditions needs improved accounting of belowground grass residues, while the SMM is of added value to improve N mineralization patterns and leaching after a ley phase.

Bio-Crude Production from Protein-Extracted Grass Residue through Hydrothermal Liquefaction

In the present study, the protein-extracted grass residue (press cake) was processed through hydrothermal liquefaction under sub and supercritical temperatures (300, 350 and 400 °C) with and without using a potassium carbonate catalyst. The results revealed that bio-crude yield was influenced by both temperature and the catalyst. The catalyst was found to be effective at 350 °C (350 Cat) for enhancing the bio-crude yield, whereas supercritical state in both catalytic and non-catalytic conditions improved the quality of bio-crude with reasonable HHVs (33 to 36 MJ/kg). The thermal behaviour of bio-crude was analysed and higher volatile contents (more than 50% under the range of 350 °C) were found at supercritical conditions. The overall TOC values in the residual aqueous phase varied from 22 to 38 g/L. Higher carbon loss was noticed in the aqueous phase in supercritical conditions. Furthermore, GCMS analysis showed ketones, acids and ester, aromatics and hydrocarbon with negligible nitrogen-containing compounds in bio-crude. In conclusion, the catalytic conversion of grass residue under subcritical conditions (350 Cat) is favourable in terms of high bio-crude yield, however, supercritical conditions promote the deoxygenation of oxygen-containing compounds in biomass and thus improve HHVs of bio-crude.

SOIL MICROBIAL ACTIVITY AS BIOINDICATORS DURING THE DECOMPOSITION OF GRASS RESIDUES IN SANDY CLAY LOAM SOIL

Assessing the quality of the soil is an important method in determining the sustainability and environmental impact of agricultural ecosystems. Soil microbial indices like microbial biomass and microbial activity are important criteria for the determination of soil quality. Laboratory incubation study was undertaken to examine the influence of 2 grass residues on changes in soil microbial indices {(microbial (Cmic: Corg), metabolic (qCO2), carbon mineralization (qM) and microbial biomass change rate (qC) quotients)} in a sandy clay loam soil. Both P.maximum and D.horizontalis amended soil showed maximum soil respiration rate (11.90 mgCO2-C g-1 soil) while P.maximum had maximum cumulative respiration rate (199.90 mgCO2-C g-1 soil) .Microbial biomass C was significantly improved by both P.maximum and D.horizontalis residues under study (158.08 and 162 mg/g respetively). The qCO2 among different grass residues ranged from 1.23 to 1.24μg CO2- C μg-biomass-C -1 on the 82nd day. The results showed that incorporation of both grass residues impacted a positive effect on microbial flora and their activity. The study suggests that the despite the high C:N ratio of grasses, its seems to be of advantage in the maintenance of soil quality in a sandy clay loam soil.

Microbial respiration and functional diversity of soil microbial community under treeline shifts in the Northwestern Caucasus

In mountain areas, one of the noticeable results of modern climate change is rapid shift of treelines to subalpine and alpine meadows. Such vegetation shifts is associated with a change in quality of the plant residues entering the soils, which in turn can affect the mineralization activity (basal respiration) and functional diversity of the soil microbial community. Therefore, the study was aimed at assessing the soil microbial (basal respiration and functional diversity) and chemical (C, N, C/N, pH) properties (0-10 cm) along the reserved and grazed forest-meadow transects of the Northwestern Caucasus (Karachay-Cherkess Republic), as well as evaluating an effect of vegetation type and land use on variation of these soil properties. It was found that the C and N contents (for both land usees), pH and basal respiration (reserved slope) significantly increase from forest to meadow soils. In contrary, the microbial functional diversity decreased from forest to meadow soils, which might be due to less diverse organic compounds entering the soil only with grass residues than their combination with forest litter. Two-way ANOVA showed that soil microbial functional diversity, pH, C and N along the studied forest-meadow transects was mostly associated with vegetation type (1439 % of the explained variation), and C/N and basal respiration - with land use (3336 % of the explained variation). Thus, a land use change will have a more significant effect on the mineralization activity of soil microbial community than a treeline shifts.

Effect of winter cereal sowing time on yield and nitrogen leaching based on experiments and modelling

AbstractEarly sowing of winter cereals has been promoted as an alternative to catch crops for reducing nitrogen (N) leaching in intensively managed cropping systems. Underlying data for this are, however, scarce and it is unclear how year‐to‐year variations affect potential reductions in N leaching. Well‐tested cropping system models can be used to assess the impact of early sowing on crop yield and N leaching. We tested the ability of the Agricultural Production System Simulator (APSIM) to simulate grain yield, biomass, phenology, N uptake and N leaching from timely and early‐sown winter cereals. The evaluation was based on two extensive field experiments carried out in Denmark in continuous winter cereals systems with different N fertilization applications, and a farm experiment in Germany with a grass ley/winter wheat crop sequence and two different N fertilization rates. Additionally, observations from growth stages throughout Denmark were used. After changing a few crop model parameters, APSIM reproduced the general effects of N fertilization and crop sequence on yields and N uptake, as well as N leaching. The model was then used to simulate the effect of sowing time on grain yield over a period of 10 years, to capture year‐to‐year variability and enable a better evaluation of the efficacy of early sowing for reducing N leaching. In the continuous winter cereal systems, early sowing reduced N leaching at both sites in Denmark. In contrast, in the grass ley/winter wheat system in Germany early sowing increased N leaching, due to enhanced mineralization of grass residues.

Mechanistic insights into the (im)mobilization of arsenic, cadmium, lead, and zinc in a multi-contaminated soil treated with different biochars.

The effect and mechanistic evidence of biochar on the (im)mobilization of potentially toxic elements (PTEs) in multi-contaminated soils, with respect to the role of surface-functional groups and organic/inorganic compounds of biochar, are poorly understood. Herein, biochars produced from grass residues, rice straw, and wood were applied to a mining-soil contaminated with As, Cd, Pb, and Zn for 473-d. Biochars did not reduce the mobilization of Cd and Zn, whereas they simultaneously exhibited disparate effects on As and Pb mobilization. The phenolic hydroxyl and carboxylic groups on the wood biochar's surfaces promoted the conversion of Pb2+ into PbCO3/Pb(OH)2 and/or PbO, minimally by the rice and grass biochars. Rice and grass biochars led to the dissolution of scorodite and the formation of less stable forms of Fe-oxide-bound As (i.e., goethite and ferrihydrite); furthermore, it resulted in the reduction of As(V) to As(III). The PTEs mobilization and phytoavailability was mainly governed by the release of dissolved aliphatic- and aromatic-carbon, chloride, sulfur chemistry, phosphate competition, and the electrostatic repulsion in biochar-treated soils. In conclusion, pristine-biochar has a limited impact on the remediation of multi-contaminated soils, and the use of modified-biochar, possessing higher surface areas and functionality and active exchange sites, are preferred under such conditions.

Leaf mineral composition and noni fruit production under vegetal mulching and potassium fertilization

In the last 10 years, there has been an increasing demand for noni products, which has aroused interest for its cultivation and commercialization in several consumer markets in Brazil. In relation to this, studies on the nutritional requirements mineral and agronomical practices for noni production have been carried out. The objective of this study was to evaluate the effect of potassium fertilization and soil mulching with residue of Brachiaria grass (Brachiaria decumbens (Stapf)) on the nutritional and production aspects of noni crops. The study was conducted from July 2012 to November 2013 at the Agriculture Sector of the Center for Human, Social, and Agrarian Sciences, Federal University of Paraíba, Bananeiras county, Brazil. The experiment was carried out in a 2 × 5 factorial arrangement, with five potassium chloride levels of 0.0, 13.2, 37.5, 61.5, and 69.6 g per plant, applied in the soil with and without mulching using residues of B. decumbens. The fruit production and plant nutritional status with respect to P, K, Ca, Mg, S, Fe and Zn of noni crop were positively affected by soil mulching and KCl fertilization. The highest fruit yield was obtained in plants grown with 69.6 g of KCl per plant combined with soil mulching using B. decumbens grass residue.

Properties of humus-like substances isolated from organic wastes and their effects on structures of soil humus by Fourier transform infrared spectroscopy

ABSTRACT The structures of soil humus (HS) amended with organic wastes (OWs) were closely related to properties of OWs-derived humus-like substances (HSL). This work evaluated the properties of HSL isolated from mushroom residue (MR), chicken manure (CM), sheep manure (SM), tree leaves (TL), maize straw (MS) and fodder grass (FG) and studied the structures of soil humic acid (HA) and fulvic acid (FA) amended with these OW. FTIR results showed that the relative intensities at 1,640 cm−1 peaks of TL-, FG- and SM-derived HAL were higher than other CM-, MS- and MR-derived HAL (p < 0.05), while the 2,930/1,640 ratios were lower (p < 0.05). Relatively lower E4/E6 ratios and ΔlogK values of TL-, FG- and SM-derived HAL were recorded (p < 0.05). Relative intensities at 1,620 cm−1 peaks of soil HA and soil FA amended with TL, FG and SM were higher than other OWs, while the 2,930/1,620 ratios were significantly lower (p < 0.05). The 2,930/1,620 ratio of soil HA and soil FA amended with MS and CM was the highest, respectively. In conclusion, the properties of OWs-derived HSL play important roles in functional groups of soil HS amended with these OWs.

Сучасний стан популяції бабака степового (Marmota bobak) у Стрільцівському степу (схід України)

The Striltsivskyi Steppe Nature Reserve (with a total area of 522 hectares) was created in 1948 to preserve the steppe marmot population; however, according to the population state studies carried out in the course of the reserve operation, a decrease in the marmot population has been established. This article is aimed to provide current data related to the marmot population monitoring results. The author established the number of colonies as well as adult and this year’s individuals inhabiting the nature reserve territory in 2020. The author explored the structure of each colony’s site and studied their area, shape and number of permanent and temporary burrows to analyze the state of the population. Only a quarter of all colony sites located in the territory of the reserve can be characterized as permanent ones. According to the author, despite a slight increase in the number of colony sites in the northern part of the Kreydyanyi Ravine and slopes towards the Cherepakha River, the entire population tends to decline. A high level of age structure misbalance and pronounced population fragmentation are observed, which are more evident in the left-hand slope in the northern part of the Kreydyanyi Ravine and in the vicinity of the Zapovidna Balka, which characterizes the population state as unstable. Changes in the vegetation cover are the principal reasons for these processes: increased area occupied by bushes, high grass stand, dry grass residues and predators (foxes and domesticated dogs). It is possible to forecast that the number of steppe marmot will continue to fall due to the current state of the vegetation cover state and absence of large grazers. The state of colony sites improves in the territories of with cattle grazing and haymaking. The state of colony sites and number of individuals in the colonies improved to a certain degree in the slopes towards the Cherepakha River where cattle grazing was carried out. As many as four colonies were found there in 2018 while their number reached ten in 2020. Exclusively reserve status under the current steppe conditions without large grazers will fail to improve the marmot population. The author suggests carrying out such actions aimed to prevent the decrease in the number of marmot population in the nature reserve territory as introducing cattle grazing, haymaking in the territories of colony sites, removing high grass near permanent burrows and conducting ecology awareness-building campaigns among the local population to prevent illegal hunting.

Identifying indigenous practices for cultivation of wild saprophytic mushrooms: responding to the need for sustainable utilization of natural resources

BackgroundDue to increasing pressure on natural resources, subsistence agriculture communities in Uganda and Sub-Saharan Africa are experiencing increasingly restricted access to diminishing natural resources that are a critical requirement of their livelihoods. Previously, common-pool resources like forests and grasslands have been either gazetted for conservation or leased for agriculture, the latter in particular for large-scale sugarcane production. Satisfying the increasing consumer demand for grassland or forestry products like wild mushrooms as food or medicine, requires innovative ethno-biological and industry development strategies to improve production capacity, while easing the pressure on diminishing natural resources and averting ecosystems degradation.MethodsThis case study addresses traditional knowledge systems for artisanal mycoculture to identify cultivation practices that enhance sustainable utilization of natural resources. Multi-scalar stakeholder engagement across government and community sectors identified artisanal mushroom producers across five districts in Uganda. Focus groups and semi-structured interviews characterized artisanal production methods and identified locally used substrates for cultivation of different mushroom species.ResultsArtisanal practices were characterized for the cultivation of six wild saprophytic mushroom species including Volvariella speciosa (akasukusuku), two Termitomyces sp. (obunegyere and another locally unnamed species), Agaricus sp. (ensyabire) and Agrocybe sp. (emponzira), and one exotic Pleurotus sp. (oyster) that are used as food or medicine. The substrates used for each species differed according to the mushroom’s mode of decomposition, those being the following: tertiary decomposers such as those growing under rotting tree stumps or logs from forestry activity like the Agrocybe sp. known as emponzira which grows in forests, thickets, or near homesteads where big logs of hardwood have been left to rot. Also pieces of firewood are chipped off whenever need arises thus providing fuel; secondary decomposers growing on naturally composted grass associated with termites like the Termitomyces sp. known as obunegyere growing in protected sites in gardens, composted cattle manure for Agaricus sp. known as ensyabire in the kraal area where cattle manure is plenty, composted maize cobs for a locally unnamed Agaricus sp. on heaped cobs placed near homesteads; and primary decomposers growing on waste sorghum from brewing the traditional alcoholic drink, muramba for Pleurotus sp. (oyster), and banana and spear grass residue from banana juice processing like the Volvariella speciosa known as akasukusuku because it is associated with the banana plantation locally known in the Luganda language as olusuku and is usually heaped under ficus trees. Management practices also varied based on mode of decomposition and other ecological requirements such as the following: zero tillage and minimal disturbance in areas where obunegyere grow, heaping banana and spear grass residues under the cool ficus trees which also keep them away from banana stump that may cause infestation with nematodes and insects. Even within the generic practices accessibility by the users is critical for example placing logs near homes where children can use them to play, they can be used as fire wood and to even get off-season mushroom as household waste water can make the mushrooms grow.ConclusionsOur description of artisanal mycoculture methods that respond to conservation and utilization pressures, demonstrates the value of addressing traditional knowledge to improve ethno-biology and mycoculture industry practice. Traditional communities engage in multiple technological and organizational innovations and practices for sustainability and in the case of mushroom production to conserve the environment and culture, ensure variety, food and nutrition security, and income. The results of this study present opportunities to preserve ecosystem quality while developing an artisanal mycoculture system. They have also identified aspects of artisanal mycoculture that most urgently require further ethno-biological study and industry development. Future research and industry development can utilize the result of this study to boost artisanal production of wild saprophytic mushrooms in Sub-Saharan countries, for food or medicinal consumption, and environment conservation. Further development of production efficiencies in context with sustainable natural resource management is recommended.

Soil nitrous oxide emissions associated with conversion of forage grass to annual crop receiving annual application of pig manure

The disruptive land-use change during forage grass conversion to annual crop can be critical for determining nitrous oxide (N2O) emissions, but this is an understudied period. We measured soil N2O fluxes (using closed static vented chambers) together with potential environmental drivers of these fluxes from liquid pig manure (LPM) and solid pig manure (SPM) applied to an annual crop (ANN) and perennial forages (FPP) that was converted to annual crop. Unamended plots were used as a control (CON). The results showed that in 2013, average soil nitrate-N was significantly higher on the recently converted FPP (ranging from 19 to 83 mg N kg−1) than the continuous ANN plots (from 16 to 35 mg N kg−1). The recently converted perennial forage system produced three times greater N2O than the continuous annual system, which is likely a result of accelerated N mineralization from the accumulated soil organic matter (over 4 yr) and grass residues of the recently killed forage grasses. However, during the second year of the study when the FPP plots were reseeded to perennial grasses, the system emitted 30% less N2O than the ANN system. These results suggest that including perennial forage grass in rotation with annual crops can provide N-saving and climate change mitigation benefits; however, some of the N stored in the soil would be lost when the perennial grass plots are cultivated to grow annual crops.

Biochar-induced metal immobilization and soil biogeochemical process: An integrated mechanistic approach

The nature of biochar-derived dissolved organic matter (DOM) has a crucial role in the interactions between biochar and metal immobilization, carbon dynamics, and microbial communities in soil. This study utilized excitation–emission matrix coupled with parallel factor analysis (EEM-PARAFAC) modeling to provide mechanistic evidence of biochar-induced influences on main soil biogeochemical processes. Three biochars produced from rice straw, wood, and grass residues were added to sandy and sandy loam soils and incubated for 473 d. Microbial and terrestrial humic-like fluorescent components were identified in the soils after incubation. The sandy loam soil exhibited a higher DOM with microbial sources than did the sandy soil. All biochars reduced Pb bioavailability, whereas the rice straw biochar enhanced the As bioavailability in the sandy loam soil. The biochar-derived aliphatic-DOM positively correlated with As bioavailability (r = 0.82) in the sandy loam soil and enhanced the cumulative CO2-C (r = 0.59) in the sandy soil. The promoted cumulative CO2-C in the sandy soil with all biochars correlated with the enhanced microbial communities, in particular, gram-positive (r = 0.59) and gram-negative (r = 0.59) bacteria. Our results suggest that the integration of EEM-PARAFAC with spectroscopic indices could be useful for a comprehensive interpretation of the soil quality changes in response to the application of biochar.

Green biomass to biogas – A study on anaerobic digestion of residue grass

Sustainable management in the biogas production via anaerobic digestion process intents the use of alternative biomass sources that are not competitive with food production. The aim of this study is to investigate the application of the abundant-quantity residue in more sustainable production of heat and electricity along with the production of the digested substrate as a fertiliser. The study has been divided into several sequential steps. First, the grass samples have been collected at the following locations: uncultivated land, river embankment and highway verge. The greatest grass yield has been determined for the riverbank grass, with an average value of 19 t/ha of fresh mass and 2.6 t/ha of dry mass. Next, the chemical characterisation of the collected residue grass and the laboratory batch mono and co-digestion tests with maize silage and cattle slurry have been conducted. The results show that all grass samples have satisfying digestive parameters (C/N ratio between 16.6:1 to 22.8:1) with the low presence of impurities, which makes them suitable for biogas production. The following biochemical methane potential in mono-digestion of residue grass has been recorded: uncultivated land (0.275 Nm3/kgTS), riverbank (0.192 Nm3/kgTS) and highway verge (0.255 Nm3/kgTS). The control of the process has been improved in co-digestion tests, by avoiding acidification in the first days of the operation. The estimation of kinetic parameters in mathematical modelling has shown that the degradation of residue grass shows some different parameters compared to the previous study. The model results for the gas phase show some small deviations compared to the experimental data. Based on the life cycle analysis results it can be concluded that there are perspectives in the use of residual grass compared to maize silage in the production of heat and electricity, especially in the improvement of ecosystem quality.

Impact of arbuscular mycorrhizal fungi and earthworms on soil aggregate stability, glomalin, and performance of pigeonpea, Cajanus cajan

Earthworms and arbuscular mycorrhizal fungi (AMF) modify soil physical and chemical properties. However, little is known about how their interactions affect water-stable aggregation, glomalin and crop performance. A greenhouse experiment was run for 9 months to test the effects of earthworms (endogeic, Pontoscolex corethrurus; and epigeic, Dichogaster bolaui) and AMF (none, Glomus etunicatum and Scutellospora verrucosa) on water-stable aggregation, glomalin levels in aggregate size classes and crop performance. The test crop was pigeonpea (Cajanus cajan (L.) Millsp.). The soil material used for the experiment was a humic nitisol from central Kenya mixed with sand (ratio 1:1). Grass residue (equivalent to 20tha–1) was placed on top. The AMF root colonisation and external hyphal length, water-stable macroaggregates and microaggregates, total and easily-extractable glomalin in aggregate size classes, plant biomass and plant N and P uptake were measured. Earthworms were a major source of variation for soil aggregation, glomalin content and crop performance. The epigeic earthworms (D. bolaui) increased the amount of water-stable macroaggregates (by 10%) and glomalin in microaggregates and improved crop (growth and biomass) performance. The endogeic earthworms (P. corethrurus) reduced external hyphal length, root colonisation and crop performance but had no effect on water-stable aggregates and glomalin levels in in aggregate size classes. A significant AMF×earthworm interaction was observed for plant biomass and concentrations of nitrogen (N) and phosphorus (P). The AMF species together with epigeic earthworms increased plant biomass and N and P concentrations. Our results contribute to the understanding of interactions between AMF and earthworms in relation to soil aggregation, plant productivity and nutrient uptake.