Microbial Response to Phytostabilization in Mining Impacted Soils Using Maize in Conjunction with Biochar and Compost

Even after remediation, mining impacted soils can leave behind a landscape inhospitable to plant growth and containing residual heavy metals. While phytostabilization can be used to restore such sites by limiting heavy metal spread, it is reliant on soil capable of supporting plant growth. Manure-based biochars, coupled with compost, have demonstrated the ability to improve soil growth conditions in mine impacted soils, however there is a paucity of information regarding their influence on resident microbial populations. The objective of this study was to elucidate the impact of these soil amendments on microbial community structure and function in mine impacted soils placed under phytostabilization management with maize. To this aim, a combination of phospholipid fatty acid (PLFA) and enzymatic analyses were performed. Results indicate that microbial biomass is significantly increased upon addition of biochar and compost, with maximal microbial biomass achieved with 5% poultry litter biochar and compost (62.82 nmol g−1 dry soil). Microbial community structure was impacted by biochar type, rate of application, and compost addition, and influenced by pH (r2 = 0.778), EC (r2 = 0.467), and Mg soil concentrations (r2 = 0.453). In three of the four enzymes analyzed, poultry litter biochar treatments were observed with increased activity rates that were often significantly greater than the unamended control. Overall, enzyme activities rates were influenced by biochar type and rate, and addition of compost. These results suggest that using a combination of biochar and compost can be utilized as a management tool to support phytostabilization strategies in mining impacted soils.

EFFECT OF POULTRY LITTER BIOCHAR ON THE NUTRITIONAL STATUS OF CORN1

ABSTRACT Corn, one of the main grain crops in Brazil, needs to have its nutritional requirements fully satisfied to achieve high biological productivity. Thus, the objective of this work was to evaluate the influence of increasing doses of poultry litter biochar on nutrient concentrations in the leaves of hybrid corn BRS 2022 and in the soil after harvest. The experiment was carried out in a completely randomized design, with four replicates, evaluating six doses of biochar (0; 2.02; 4.05; 6.07; 8.10 and 10.12 t ha-1) and the plots composed of one plant per pot with a volume of 20 dm3. The collection of leaves for leaf diagnosis was carried out at the time of flowering, removing the opposite leaf from the ear base in the middle third region. These leaves were dried in a forced air circulation oven, 65 °C, for a period of 48 hours, ground, sieved through 20 mesh and analyzed for the concentrations of macronutrients in the leaf tissue. At the end of the experiment, 83 days after corn sowing, soil samples were collected as a function of the treatments and then analyzed chemically. Biochar application promoted an increase in the leaf contents of N, P and K, resulting in improvements in the nutritional status of plants for these nutrients. The chemical characteristics of the soil, analyzed after the corn harvest, revealed that there was an influence of the doses of biochar on the levels of calcium, organic carbon, potassium and phosphorus.

Growth of papaya seedlings on substrate consisting of poultry litter biochar

The choice of a substrate that meets the nutritional and physical demands of papaya seedlings with the use of organic wastes is directly linked to increases in crop yield and is an important environmental and economic alternative. Aiming to produce good-quality papaya seedlings while considering the composition and availability of substrates, this study examined the influence of applying increasing rates of poultry litter biochar as a substrate component in the production of papaya seedlings. The study was developed in a protected environment belonging to the Federal University of Campina Grande (UFCG). The experiment was laid out in a completely randomized design with a 6 × 2 factorial arrangement consisting of six rates of biochar (4, 8, 12, 16 and 20 t ha-1 and the control) and two papaya cultivars (Formosa and Ouro), with four replicates. Plant height, stem diameter, number of leaves and leaf area were evaluated 90 days after sowing. The fresh and dry biomass of shoots and root system and the Dickson Quality Index were also evaluated. In conclusion, the rates that provided good development of papaya seedlings were 8 and 16 t ha-1, and papaya cultivar Ouro showed better growth results.

Development and production of maize as a function of biochar rates

Poultry litter biochar has shown to be promising in crop development and production. On this basis, this study was developed to investigate the influence of increasing rates of poultry litter biochar on the growth and production of maize hybrid BRS 2022. The experiment was laid out in a completely randomized design with six biochar rates (0, 2.0, 4.0, 6.1, 8.1 and 10.1 t ha-1) and four replicates. Plots consisted of pots with a volume of 20 dm3, with one plant each. The following variables were evaluated at 83 days after sowing: plant height; first-ear insertion height; stem diameter; number of leaves; leaf area; internode length and number; stem, leaf and total dry weights; ear weight; grain weight per plant; 1000-grain weight; and ear length and diameter. Biochar application influenced plant height; first-ear insertion height; stem diameter; leaf area; internode length; and stem, leaf and total dry weights, having a positive impact in increasing in ear weight, grain weight per plant, 1000-grain weight and ear length and diameter. For the conditions in which the experiment was conducted, the recommended biochar rate to obtain the best results is 6.4 t ha-1.

Quality Evaluation of Poultry Litter Biochar Produced at Different Pyrolysis Temperatures as a Sustainable Management Approach and Its Impact on Soil Carbon Mineralization

Poultry litter biochar (PLB) is a value-adding soil amendment and an economically sustainable approach that is used to enhance food safety and reduce environmental harm. Poultry litter biochar has promising potential but has been under-examined in regards to carbon (C) sequestration in relation to its type and application rate. The objective of this study was to investigate the effectiveness of PLB in enhancing the C sequestration of acid soils through a short-term incubation experiment. The soil was amended with different materials: PLB (1%, 5%, and 10%) and a control (non-amended). The results indicated that PLB application increased soil C mineralization relative to the control (19–1562%), it significantly increased with an increasing application rate (e.g., increased addition 29, 99, and 172% for 1, 5, and 10% of 400 °C PLB), and the soil C mineralization and applied carbon mineralized (ACM) significantly decreased with temperature (e.g., the cumulative C pool ranges of ACM with 1% PLB, added at pyrolysis temperatures of 200, 300, 400, 500, and 600 °C, were 42.0, 34.4, 19.6, 6.16, and 4.04%, respectively). To assist sustainable soil management and to aid the achievement of multiple sustainable development goals (SDGs), as well as to maximize the benefits of PLB applications and minimize the potential environmental risk, it is suggested that application of PLB, pyrolyzed within 400–600 °C at a rate between 1% to 5%, should be adopted in acidic soils in Taiwan.

Organic Wastes Amended with Sorbents Reduce N2O Emissions from Sugarcane Cropping

Nutrient-rich organic wastes and soil ameliorants can benefit crop performance and soil health but can also prevent crop nutrient sufficiency or increase greenhouse gas emissions. We hypothesised that nitrogen (N)-rich agricultural waste (poultry litter) amended with sorbents (bentonite clay or biochar) or compost (high C/N ratio) attenuates the concentration of inorganic nitrogen (N) in soil and reduces emissions of nitrous oxide (N2O). We tested this hypothesis with a field experiment conducted on a commercial sugarcane farm, using in vitro incubations. Treatments received 160 kg N ha−1, either from mineral fertiliser or poultry litter, with additional N (2–60 kg N ha−1) supplied by the sorbents and compost. Crop yield was similar in all N treatments, indicating N sufficiency, with the poultry litter + biochar treatment statistically matching the yield of the no-N control. Confirming our hypothesis, mineral N fertiliser resulted in the highest concentrations of soil inorganic N, followed by poultry litter and the amended poultry formulations. Reflecting the soil inorganic N concentrations, the average N2O emission factors ranked as per the following: mineral fertiliser 8.02% > poultry litter 6.77% > poultry litter + compost 6.75% > poultry litter + bentonite 5.5% > poultry litter + biochar 3.4%. All emission factors exceeded the IPCC Tier 1 default for managed soils (1%) and the Australian Government default for sugarcane soil (1.25%). Our findings reinforce concerns that current default emissions factors underestimate N2O emissions. The laboratory incubations broadly matched the field N2O emissions, indicating that in vitro testing is a cost-effective first step to guide the blending of organic wastes in a way that ensures N sufficiency for crops but minimises N losses. We conclude that suitable sorbent-waste formulations that attenuate N release will advance N efficiency and the circular nutrient economy.

Combined application of poultry litter biochar and NPK fertilizer improves cabbage yield and soil chemical properties

Low soil fertility is a major problem limiting peri-urban vegetable production in the Kumasi metropolis. This study was conducted to assess the effects of poultry litter biochar (PLB) and NPK fertilizer application on soil chemical properties and the yield of cabbage. Twelve treatments (control, 100% NPK, 50% NPK, 2.5 t ha−1 PLB, 2.5 t ha−1 PLB + 50% NPK, 2.5 t ha−1 PLB + 100% NPK, 5 t ha−1 PLB, 5 t ha−1 PLB + 50% NPK, 5 t ha−1 PLB + 100% NPK, 7.5 t ha−1 PLB, 7.5 t ha−1 PLB + 50% NPK, and 7.5 t ha−1 PLB + 100% NPK) were evaluated under field conditions in a randomized block design with three replications. Combined application of PLB and NPK fertilizer improved the soil chemical properties, growth, and yield of cabbage relative to the control and sole PLB treatments. Application of 5 t ha−1 PLB + 50% NPK increased the soil pH, soil organic carbon, available phosphorus, and cation exchange capacity by 26.6, 41.4, 296, and 78.7%, respectively, relative to the control. Moreover, 5 t ha−1 PLB + 50% NPK increased the cabbage yield by 73% compared with the control. This study concludes that PLB and NPK fertilizers can be applied to improve the soil chemical properties and yield of cabbage.