Ammonia Volatilization and Greenhouse Gases Emissions during Vermicomposting with Animal Manures and Biochar to Enhance Sustainability

Biochar Can Improve Absorption of Nitrogen in Chicken Manure by Black Soldier Fly

(1) Background: There is growing interest in using insects to treat nutrient-rich organic wastes, such as the black soldier fly (BSF), one of the most efficient organic waste recyclers for upcycling nutrients into the food system. Although biochar (BC) was shown to enhance nutrient retention and the final product quality during the composting of livestock and poultry manure in many previous studies, little information is available on the effect of BC on livestock manure bioconversion by black soldier fly larvae (BSFL). (2) Methods: This study investigated the effect of adding a small amount of BC to chicken manure (CM) on the bioconversion system of the black soldier fly (including N2O and NH3 emissions and the final distribution of nitrogen during the treatment process). (3) Results: The lowest N2O and NH3 emission and highest residual nitrogen in the substrate were observed in the 15% BC treatment. The highest bioconversion rate of CM (8.31%) and the peak of larval biomass was obtained in the 5% BC treatment. (4) Conclusions: The results demonstrate the feasibility of adding 5% BC to reduce pollution and achieve a satisfactory BSFL-based CM bioconversion efficiency.

Effect of addition of organic manures on basmati yield, nutrient content and soil fertility status in north-western India

Integrated use of chemical fertilizers with organic manure is becoming a quite promising practice to maintain higher crop productivity and to manage soil health, which is otherwise deteriorated due to intensive cultivation and imbalanced fertilizer use. Thus, the present experiment was conducted for combined application of inorganic fertilizers and organic manures for higher yield and nutrient uptake in basmati rice as well as to restore soil health. The treatments applied in the present study involve T1: control, T2: Farmyard manure (15 t ha^-1), T3: Poultry manure (6 t ha^-1), T4: Press mud (15 t ha^-1), T5: Rice straw compost (6 t ha^-1), T6: Farmyard manure (15 t ha^-1) + 50% N (recommended dose of nitrogen), T7: Poultry manure (6 t ha^-1) + 50% N, T8: Press mud (15 t ha^-1) + 50% N, T9: Rice straw compost (6 t ha^-1) + 50% N, T10: 75% N, T11: Farmyard manure (15 t ha¹) + 75% N, T12: Poultry manure (6 t ha^-1) + 75% N, T13: Press mud (15 t ha^-1) + 75% N, T14: Rice straw compost (6 t ha^-1) + 75% N, T15: 100% N. The integrated use of organic manures and inorganic fertilizers significantly increased the grain and straw yield, macronutrients as well as micronutrients uptake in basmati due to the release of nutrients from decomposition of organic manures. Among different treatments, the addition of PM+75% N showed maximum grain yield, straw yield and sustainability yield index (44.53 q ha^-1, 89.67 q ha^-1 and 0.91 respectively) as well as the highest uptake of nitrogen (58.29 and 65.39 kg ha^-1), phosphorus (25.04 and 23.24 kg ha^-1) and potassium (15.26 and 118.95 kg ha^-1) in grain and straw, respectively. Similar results were observed for zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn) uptake under treatment involving PM+75% N with values 183.9, 26.18, 339.3 and 355.8 g ha^-1 in grain and 205.3, 25.62, 2627.3 and 278 g ha^-1 in straw, respectively. Additionally, correlation studies showed that the grain and straw yield of basmati exhibited a significantly positive correlation with soil P, Cu and Fe. The study suggested that the partial substitution of inorganic fertilizers with organic manures did not lower crop yield and nutrient uptake. Thus, integrated application of organic and inorganic fertilizers can be used for the sustainability of basmati-wheat system and to retain the soil fertility which is otherwise deteriorated with sole use of inorganic fertilizers.

Impacts of vermicompost application on crop yield, ammonia volatilization and greenhouse gases emission on upland in Southwest China

Ammonia (NH₃) volatilization and greenhouse gas (GHG) emission are important environment pollution sources in upland agro-ecosystems. Vermicompost was used for amending purple soil and comparing NH₃ and GHG emissions. A field experiment was conducted with a comparison of organic and inorganic fertilizers in a wheat-maize rotation system in the Sichuan Basin, China. The five treatments were conventional inorganic fertilizers, NPK as control; vermicompost prepared with cow dung (VCM); and pig manure (VPM); cow dung and pig manure vermicompost, respectively (VCMNPK, VPMNPK). Total nitrogen rates of all treatments were the same. Soil NH₃ volatilization and GHG emissions were monitored with the static chamber method. The results showed that NH₃ volatilization occurred in the first two weeks following nitrogen (N) fertilization. The cumulative fluxes of NH₃ recorded in the NPK, VCM, VPM, VCMNPK, and VPMNPK treatments were 15.4, 5.7, 6.3, 10.32, and 10.29 kg N ha^-1 yr^-1, respectively, in the winter and 4.8, 5.5, 19.83, 12.8, and 11.9 kg N ha^-1 yr^-1 respectively, in the summer. The global warming potential (GWP) 773.6 and 803.9 g CO₂-eq m^-2 in VCM and VPM, respectively, during the wheat season 540.6 and 576.2 g CO₂-eq m^-2, respectively, during the maize season. The GWPs in NPK treatment were 1032.4 and 570.7 g CO₂-eq m^-2 during the wheat and maize seasons, respectively. The increasing effects of nutrient loops, particularly 18 % soil total nitrogen (TN) and 31 % soil organic carbon (SOC) in VCM, and crop productivity of vermicompost treatments during the wheat-maize rotation had been evaluated. This study recommends that VCM can be considered as a better organic amendment, promoting plant growth while decreasing the environmental costs of gas emissions.

Different ratios of Canna indica and maize-vermicompost as biofertilizers to improve soil fertility and plant growth: A case study from southwest China

Vermicomposting is recommended as an eco-friendly technology for an organic amendment to avoid the excessive use of inorganic fertilizers, which are causing environmental pollution. Here, this study evaluated soil fertility and plant growth after vermicompost amendment using reclaimed wetland plants and manure. A pot experiment was conducted to assess the seven treatments for nutrient recovery and plant growth: a control group without any fertilization (CK); four groups with vermicompost prepared from different ratios of ecological wetland plant residues, maize, and pig manure (V1, 4:6; V2, 5:5; V3, 6:6; and V4, 7:3); one group with only Canna indica (V5, Ci), and a group with synthetic fertilizers (NPK). The results showed the remarkable impacts of Ci-vermicompost and different ratios of organic fertilizer on soil fertility and plant height (28.8%) as major outcomes. In addition, vermicompost substantially increased soil total nitrogen (60.5%), soil organic matter (60.9%) including dissolved organic carbon (52.2%), and shoot biomass (V4, three-fold increase) compared with NPK and CK. Overall, the findings of this study suggest that vermicomposting combined with wetland plants is a feasible method for organic amendments and offers an innovative approach for recycling ecological waste to produce nutrient-rich organic fertilizers, reduce environmental damage, and improve crop production.

Biochar application ameliorated the nutrient content and fungal community structure in different yellow soil depths in the karst area of Southwest China

The influence of biochar on the change of nutrient content and fungal community structure is still not clear, especially in different yellow soil depths in karst areas. A soil column leaching simulation experiment was conducted to investigate the influence of biochar on soil content, enzymatic activity, and fungal community diversity and structural composition. Three biochar amounts were studied, namely, 0%(NB, no biochar), 1.0%(LB, low-application-rate biochar), and 4.0% (HB, high-application-rate biochar). The results showed that biochar increased the pH value and the contents of soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP), and available potassium (AK) but reduced the microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN). Furthermore, this effect was enhanced with increasing biochar amount. Biochar was conducive to improving the nutrient availability in topsoil (0-20 cm), especially TN, AK, and MBN. Meanwhile, biochar affected the enzymatic activity, especially the sucrase activity. Biochar affected the diversity and structure of the fungal community, of which HB treatment had the most obvious effect. Among these treatments, Aspergillus, unclassified_Chaetomiaceae, Mortierella, Spizellomyces, Penicillium, Fusarium, and unclassified_Chromista fungal genera were the highest. Moreover, biochar inhibited the growth of harmful pathogens and increased the abundance of beneficial fungi in soil, and the effect was enhanced with increasing biochar amount and soil depth. Redundancy analysis (RDA) showed that AK was an important factor in yellow soil, although the main environmental factors affecting the fungal community structure were different in different soil depths. Overall, biochar had a positive effect on improving the land productivity and micro-ecological environment of yellow soil in the karst area.

Everesting: cycling the elevation of the tallest mountain on Earth

Purpose

With few cycling races on the calendar in 2020 due to COVID-19, Everesting became a popular challenge: you select one hill and cycle up and down it until you reach the accumulated elevation of Mt. Everest (8,848 m or 29,029ft). With an almost infinite number of different hills across the world, the question arises what the optimal hill for Everesting would be. Here, we address the biomechanics and energetics of up- and downhill cycling to determine the characteristics of this optimal hill.

Methods

During uphill cycling, the mechanical power output equals the power necessary to overcome air resistance, rolling resistance, and work against gravity, and for a fast Everesting time, one should maximize this latter term. To determine the optimal section length (i.e., number of repetitions), we applied the critical power concept and assumed that the U-turn associated with an additional repetition comes with a 6 s time penalty.

Results

To use most mechanical power to overcoming gravity, slopes of at least 12% are most suitable, especially since gross efficiency seems only minimally diminished on steeper slopes. Next, we found 24 repetitions to be optimal, yet this number slightly depends on the assumptions made. Finally, we discuss other factors (fueling, altitude, fatigue) not incorporated in the model but also affecting Everesting performances.

Conclusion

For a fast Everesting time, our model suggests to select a hill climb which preferably starts at (or close to) sea level, with a slope of 12–20% and length of 2–3 km.

On-Farm Composting of Hop Plant Green Waste—Chemical and Biological Value of Compost

Green agro waste can be turned into compost, which can then be used as an organic fertilizer, thus reducing the environmental impact of food and feed production. This research is focused on finding a feasible on-farm composting treatment of plant biomass to produce high-quality compost. Three different composting treatments were prepared and followed (with different additives at the start—biochar (BC) and effective microorganisms (EM), no additive (CON); covering and not covering the pile; different start particles size). Samples were analysed for nutrient concentrations, phytotoxicity and bacterial and fungal presence after seven months of composting. In 100 g of dry matter, the average compost contained 2.7 g, 0.38 g and 1.08 g of N, P and K, respectively. All investigated treatments contained more than 2% of total nitrogen in dry mass, so they could be used as a fertilizer. The highest nutrient content was observed in compost of small particle size (˂5 cm) and added biochar (11 kg/t fresh biomass). However, this compost had the least bacteria and fungi due to very high temperatures in the thermophilic phase of this pile. According to the radish germination index, the prepared composts have no phytotoxic properties and are stable and ready to use in plant production. Taking the cress germination test into consideration, they provided a nutrient-rich and biostimulative soil amendment. All three final composts were stable in terms of respiration rate, growth and germination tests. Results have shown that hop biomass after harvest has great potential for composting.

Impact of Biochar Application on Ammonia Volatilization from Paddy Fields under Controlled Irrigation

Ammonia volatilization is an important nitrogen loss pathway in the paddy field ecosystem which leads to low nitrogen-utilization efficiency and severe atmospheric pollution. To reveal the influence and the mechanism of biochar application on ammonia volatilization from paddy fields under controlled irrigation, field experiments were conducted in the Taihu Lake Basin in China. The experiment consisted of three levels of biochar application (0, 20, and 40 t·ha−1) and two types of irrigation management (controlled irrigation and flood irrigation). Increasing ammonia volatilization occurred after fertilization. Biochar application reduced the cumulative ammonia volatilization from controlled-irrigation paddy fields, compared with non-biochar treatment. The cumulative ammonia volatilization in controlled-irrigation paddy fields with 40 t·ha−1 biochar application was reduced by 12.27%. The decrease in ammonia volatilization was related to the change in soil physical and soil physical–chemical properties and soil microbial activities. The high biochar application (40 t·ha−1) increased the NH4+-N content in soil (p < 0.01) and soil solution (p <0.05), increased by 64.98% and 19.72%, respectively. The application also increased the soil urease activity (p < 0.01), and high biochar application (40 t·ha−1) increased soil urease activity by 33.70%. Ammonia volatilization from paddy fields was significantly correlated with the nitrogen concentration (p < 0.01) in the soil solution and soil urease activity (p < 0.05). Meanwhile, the abundance of ammonia monooxygenase subunit A (AOA) and ammonia-oxidizing bacteria (AOB) with biochar application under controlled irrigation showed an increasing trend with rice growth. The long-term application of biochar may have a relatively strong potential to inhibit ammonia volatilization. In general, the combined application of controlled irrigation and biochar provides an eco-friendly strategy for reducing farmland N loss and improving paddy field productivity.

Comparing the nutrient changes, heavy metals, and genotoxicity assessment before and after vermicomposting of thermal fly ash using Eisenia fetida

Fly ash (FA) is available in an unstable state and can be ameliorated by vermicomposting. The different ratios of FA viz (FA₁₀, FA₁₅, FA₂₀, FA₂₅, FA₅₀, FA₇₅) were mixed with another organic waste, i.e., cattle dung. Supportive effects of FA were seen on the reproductive parameters of the earthworms up to FA₂₅. Some beneficial changes have been reported in pH, EC, TOC, TKN, TAP, TNa, TK, and potentially toxic heavy metals (Zn, Cu, Cd, Co, Ni, Cr, Pb). The genotoxicity test was performed to assess the toxic effects of the fly ash which has not been done till now. Low genotoxicity potential and high onion root growth were observed in the post-vermicompost samples which were not even reported yet by any other study. These results clearly indicated that the vermicomposting process offers the best option to manage the FA by converting it into an ecofriendly, nutrient-rich, and properly detoxified manure with the help of earthworms which also indicate its economically best-fit applications for the large scale agricultural practices.

Differential Effects of Organic Amendments on Maize Biomass and Nutrient Availability in Upland Calcareous Soil

The current study is focuses on a sustainable agricultural ecosystem for soil fertility and human health improvement. To estimate the effects of applying organic amendments (compost, vermicompost, biochar, organic manure and rapeseed cake) on crop growth of maize and nutrient uptake in calcareous soil, eleven treatments were studied, which included compost (CM), cow manure vermicompost (CMV), pig manure vermicompost (PMV), biochar vermicompost (BCV), biochar (BC), conventional synthetic fertilizers (NPK), CMV in addition to NPK (CMV + NPK), and PMV in addition to NPK (PMV + NPK), organic manure (OM), rapeseed cake (RC) and control without any fertilization (CK). Maize above and belowground biomass were analyzed in glass greenhouse experiments. The results showed that nitrogen and carbon contents showed significant differences among treatments. Vermicompost significantly showed higher biomass as compared to inorganic fertilizers except for RC. All vermicompost treatments also showed better nutrient availability as compared to NPK and CK. In conclusion, vermicompost with all substrates are recommended for application as organic fertilizers. Our study will help promote the application of organic fertilizers alone or in combination with inorganic fertilizers rather than only inorganic fertilizers for environmental health and sustainability.