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Biochar, Fertilizers and Microbes Interactions for Soil Health and Crop Productivity

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A special issue of Agronomy (ISSN 2073-4395). This special issue belongs to the section "Soil and Plant Nutrition".

Deadline for manuscript submissions: closed (30 June 2024) | Viewed by 20953

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Special Issue Editors

Dr. Spyridon Petropoulos

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Department of Agriculture Crop Production and Rural Environment, University of Thessaly, 38221 Volos, Greece
Interests: vegetable production; fruit production; essential oils; bioactive compounds; antioxidant activity; polyphenols
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Dr. Vasileios Antoniadis

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Department of Agriculture Crop Production and Rural Environment, University of Thessaly, Trikala, Greece
Interests: soil science; soil chemistry; heavy metals
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Dr. Maria Del Mar Alguacil

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CSIC-Centro de Edafología y Biología Aplicada del Segura, Department of Soil and Water Conservation, P.O. Box 164, Campus de Espinardo, 30100 Murcia, Spain
Interests: environmental science; agricultural plant science; agronomy
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Recent research on biochar has focused on enhancing soil fertility, carbon sequestration, microorganism activities, agricultural production, climate change mitigation, soil contamination and other related aspects. Given the ongoing interest in biochar, this Special Issue aims to collect original research as well as review articles exploring different aspects of biochar application for improving microbial activities, soil fertility and crop and pasture production. While research in this field has progressed considerably with significant key findings on agronomic benefits, carbon sequestration, greenhouse gas emissions, soil acidity, soil fertility, soil health, soil salinity, etc., more field-based research is required before definitive recommendations can be made to end-users regarding the effects of biochar application across a range of soils, climates and land management practices.

Soil constraints causing major problems for plant growth and crop production are categorised as chemical, physical and biological. Chemical constraints include acidity, salinity, sodicity and nutrient deficiencies, which impact crop and pasture production. A significant amount of fertiliser is needed in nutrient-deficient soil for crop production. Physically constrained soils have compacted soil layers with high bulk density and low water movement. Soils with low organic matter have poor biological activities with reduced microbial biomass and activity. Soil amendment with biochar along with appropriate combinations of fertilisers can improve soil by increasing organic carbon, soil fertility and agronomic benefits. This Special Issue will publish articles on how the application of biochar, fertilisers and microbes can increase soil health and crop yields and subsequently overcome soil constraints such as acidity, salinity, drought, low fertility, etc.

Dr. Spyridon Petropoulos
Dr. Vasileios Antoniadis
Dr. Maria Del Mar Alguacil
Guest Editors

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Keywords

arbuscular mycorrhizae
agronomic benefits
biochar
nutrient deficiency
soil quality
soil constraint
soil salinity
soil organic carbon
soil health
soil fertility
soil organisms
soil acidity

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Published Papers (11 papers)

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13 pages, 1075 KiB

Open AccessArticle

Effect of Biochar Using N, P, and K Fertilisers on Growth and Quality of Lithocarpus litseifolius

by Zelin Ye, Hang Zhang, Xiequan Lin, Siqi Huang, Shuangquan Zou and Xiaoxing Zou

Agronomy 2024, 14(4), 728; https://doi.org/10.3390/agronomy14040728 - 1 Apr 2024

Cited by 1 | Viewed by 1047

Abstract

Objective: In this study, we aimed to investigate the effects of facile combinations of biochar and N, P, and K fertilisers on the growth and physiological characteristics of Lithocarpus litseifolius seedlings, and to optimise the biochar/NPK ratio of Lithocarpus litseifolius. Method: A four-factor three-level orthogonal method was used to conduct a field experiment using 2-year-old Lithocarpus litseifolius. Nine fertiliser treatments and one control treatment (CK, i.e., no fertiliser) were established in a completely randomised block group with six replications of ten treatments. The plants were planted in October 2020 and harvested in November 2021, and fertiliser was applied once in April 2021 and once in July 2021. Results: Rational application could effectively promote the growth of Lithocarpus litseifolius, and T4(C₂N₁P₂K₃) produced the highest increase in plant height growth (17.03 cm), diameter growth (5.47 mm), soluble sugar (94.60 mg/g), soluble protein (4.59 mg/g), and phlorizin (old leaf: 16.00%; tender leaf: 15.13%); T8(C₃N₂P₁K₃) resulted in the highest chlorophyll a content (1.46 mg/g), chlorophyll b content (0.62 mg/g), and total chlorophyll content (2.08 mg/g), and T1(C₁N₁P₁K₁) resulted in the highest contents of starch (11.60 mg/g) and trilobatin (old leaf: 0.29%; tender leaf: 2.28%). The indicators corresponding to the above three treatments were significantly higher than those under the other treatments (p < 0.05). The results as analysed by the affiliation function method show that the highest mean value of the affiliation function was 0.645 after T4(C₂N₁P₂K₃) treatment. Conclusions: The combination of biochar and nitrogen, phosphorus, and potassium fertilisers can effectively increase the biomass and active components of Lithocarpus litseifolius while reducing the amount of chemical fertiliser applied. A comprehensive analysis of the results showed that the T4 treatment (biochar: 20 g/plant; urea: 10 g/plant; superphosphate: 9 g/plant; potassium chloride: 12 g/plant) resulted in the highest comprehensive score, with the highest increase in plant height growth, ground diameter growth, root–crown ratio, soluble sugar, soluble protein, and phlorizin, as well as other indicators. Full article

(This article belongs to the Special Issue Biochar, Fertilizers and Microbes Interactions for Soil Health and Crop Productivity)

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15 pages, 1208 KiB

Open AccessArticle

Assaying the Use of a Leonardite-Suspension Concentrate-Based Product as a Potential Biostimulant to Enhance Growth, NPK Use Efficiency, and Antioxidant Capacity in Lactuca sativa L.

by Santiago Atero-Calvo, Francesco Magro, Giacomo Masetti, Eloy Navarro-León, Juan Jose Rios and Juan Manuel Ruiz

Agronomy 2024, 14(1), 64; https://doi.org/10.3390/agronomy14010064 - 26 Dec 2023

Cited by 3 | Viewed by 1506

Abstract

Biostimulants are presented as a potential tool to achieve the main objectives of modern agriculture: increase crop yield and nutritional quality while reducing chemical fertilizer use. Here, we investigated the use of a HS-based product (BLACKJAK^®, from Sofbey S.A., Mendrisio, Switzerland) as a biostimulant to enhance plant growth, nitrogen (N), phosphorus (P), and potassium (K) use efficiency, as well as antioxidant capacity. For this purpose, BLACKJAK^® was applied to lettuce (Lactuca sativa L.) as radicular (‘R’) and foliar (‘F’) at doses: 0.20 mL/L (R1), 0.40 mL/L (R2), 0.60 mL/L (R3), and 0.80 mL/L (R4), 5.00 mL/L (F1), 7.50 mL/L (F2), 10.00 mL/L (F3), and 12.50 mL/L (F4), along with a control. Shoot fresh weight (FW) and dry weight (DW), leaf area, NPK use efficiency parameters, and antioxidant capacity were evaluated. Our results showed that R1, R2, R3, F2, and F3 enhanced shoot FW and leaf area, while only R3 increased shoot DW. Furthermore, in general, most of the doses employed enhanced NPK use efficiency parameters such as apparent crop recovery, nutrient export, physiological efficiency, and internal utilization of applied nutrients. Similarly, HS also increased ascorbate, glutathione, and phenol concentrations, showing an improvement in antioxidant capacity measured through FRAP (Ferric Reducing Antioxidant Power) and TEAC (Trolox Equivalent Antioxidant Capacity) assays. Overall, root-HS offered better results than foliar-HS, especially at R3. Hence, our results indicate that BLACKJAK^® could be a good candidate to enhance crop productivity and nutritional quality while reducing the use of chemical NPK fertilizers. Full article

(This article belongs to the Special Issue Biochar, Fertilizers and Microbes Interactions for Soil Health and Crop Productivity)

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15 pages, 2242 KiB

Open AccessArticle

Evaluation of Biochar and Inorganic Fertilizer on Soil Available Phosphorus and Bacterial Community Dynamics in Acidic Paddy Soils for Different Incubation Temperatures

by Rubab Sarfraz, Faisal Nadeem, Wenhao Yang, Muhammad Tayyab, Muhammad Israr Khan, Rashid Mahmood, Xingjie Guo, Shihe Xing and Gil Won Kim

Agronomy 2024, 14(1), 26; https://doi.org/10.3390/agronomy14010026 - 21 Dec 2023

Cited by 4 | Viewed by 1428

Abstract

The composition of microbial communities and the functioning of ecosystems are greatly influenced by the nutrient inputs. Despite this fact, our knowledge regarding the impact of phosphorus (P) inputs on soil P availability and microbial community structures in subtropical acidic soils remains limited. We hypothesized that diverse P inputs, incubation temperatures, and soil types could significantly alter soil P availability and microbial communities. To address this gap, we conducted a laboratory incubation experiment, investigating the effects of biochar and inorganic P amendments on soil available P, soil pH, acid phosphatase enzymes, and bacterial abundance. We employed two different incubation temperatures (15 °C and 25 °C) using acidic paddy soil and red soil from the subtropical Southern China region. Our results indicate a notable increase in soil pH, reaching 37% and 39% at 15 °C and 40% and 40.6% at 25 °C, respectively, following the application of biochar and inorganic P amendments in paddy soil. In the case of red soil, we observed pH increases of 41% and 43% at 15 °C and 44% and 45% at 25 °C after the application of biochar and inorganic P amendment, respectively. The addition of inorganic P amendment resulted in the highest available P contents in paddy soil, reaching 111.47 mg/kg at 15 °C and 100.17 mg/kg at 25 °C, respectively. However, Proteobacteria decreased after inorganic P addition, which showed that P might not be the only limiting nutrient for various bacterial communities. Bacterial diversity and richness indices were found to be higher after biochar application in both soils. Gemmatimonadetes, Acidobacteria, and Actinobacteria were found to be strongly influenced by incubation temperatures, whereas most of the top abundant bacterial phyla, such as Gemmatimonadetes, Actinobacteria, Chloroflexi, Acidobacteria, Planctomycetes, Firmicutes, Patescibacteria, and Bacteroidetes, were highly dependent on soil type. At the genus level, various important P solubilizing genera (Pseudomonas, Bradyrhizobium, Streptomyces jietaisiensis, Massilia) significantly increased after biochar and inorganic P addition in both soils. The correlation analysis proved that P-solubilizing genera were significantly associated with changes in soil pH, as well as soil available P after biochar and inorganic P addition. Conclusively, in a short-term incubation experiment, inorganic P amendment greatly increased the soil pH and available phosphorus contents compared to biochar and control treatments; however, the microbial community was observed to be strongly associated with biochar application, soil type, and incubation temperature. Full article

(This article belongs to the Special Issue Biochar, Fertilizers and Microbes Interactions for Soil Health and Crop Productivity)

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15 pages, 1089 KiB

Open AccessArticle

Can Soil Improvers (Biochar, Compost, Insect Frass, Lime, and Zeolite) Achieve Phytostabilization of Potentially Toxic Elements in Heavily Contaminated Soil with the Use of Purslane (Portulaca oleracea)?

by Giorgos Thalassinos, Efi Levizou and Vasileios Antoniadis

Agronomy 2023, 13(11), 2827; https://doi.org/10.3390/agronomy13112827 - 16 Nov 2023

Viewed by 1307

Abstract

In soil with extremely high contents of Cd (101.87), Pb (26,526.44), and Zn (17,652.63 mg kg⁻¹), we aimed to test the phytostabilization capacity of purslane (Portulaca oleracea) with the use of various soil improvers, both organic (biochar, compost, insect frass) and inorganic (lime and zeolite). Thus, in a 60-day pot experiment, we amended this heavily contaminated soil with the five materials at two rates, 2% and 4%, resulting in 11 treatments (control plus five materials × two rates) replicated 10 times. We found that soil extractions of Cd with DTPA (diethylenetriaminepentaacetic acid) were not affected by any of the amendments, as there was no recorded significant reduction in soil Cd. In the case of Pb, there were even significant increases in its extractability with added biochar, and so was the case for compost at 4%. The reason may be the formation of organometallic complexes with organic substances of low molecular weight eluted by the organic amendments. Similarly, Zn extractability increased significantly compared to the control in the compost and frass treatments. As for purslane shoots, Cd decreased from 61 μg kg⁻¹ fresh weight (FW) at control to 39 at biochar 4%, but the reduction was non-significant. As for Pb, it decreased with biochar but not significantly, while it exhibited a significant decrease in all other treatments. However, in all cases the content of Pb in purslane was well above the European regulation limit of 0.100 mg kg⁻¹ FW (fresh weight) for vegetables and fresh herbs, while Cd fell below the regulation limit of 50 μg kg⁻¹ FW at biochar 4%, compost 4%, and frass 2% and 4% (with control being 62.5 μg kg⁻¹ FW). We conclude that in heavily contaminated soils, although biochar, along with compost and frass, was not entirely unsuccessful, the tested amendments did not reduce satisfactorily toxic elements to sufficiently low levels both in soil and in the test plant (here, purslane) in order to achieve phytostabilization. However, further research is necessary to identify exact mechanisms and to elucidate the role of different biochars. Full article

(This article belongs to the Special Issue Biochar, Fertilizers and Microbes Interactions for Soil Health and Crop Productivity)

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18 pages, 4712 KiB

Open AccessArticle

Effects of Combined Application of Biochar and Different Types of Nitrogen Fertilizers on Rapeseed Root Growth and Properties of Purple Soil in Southwest China

by Biao Li, Xiaoqin Tian, Sai Zhang, Meichun Duan and Longchang Wang

Agronomy 2023, 13(9), 2209; https://doi.org/10.3390/agronomy13092209 - 24 Aug 2023

Cited by 1 | Viewed by 1495

Abstract

To demonstrate the effects of combined application of biochar and different types of nitrogen fertilizers on the growth of plant roots and on purple soil properties such as soil nutrients, soil carbon content and soil respiration, a 206-day greenhouse pot experiment with rapeseed was conducted. Three types of nitrogen fertilizer were used: urea (UR), controlled-release urea (RU), a mixture of 60% urea and 40% controlled-release urea (40% RU), and biochar was added at mass fractions of 0% (C0), 2% (C1) and 4% (C2), with a control treatment (CK) without nitrogen fertilizer and biochar. The results showed that biochar significantly improved soil nutrient status, with the best effect observed when 40%RU was co-applied with biochar. The addition of biochar significantly increased soil total organic carbon (TOC) and particulate organic carbon (POC). Soil respiration increased with increasing biochar application, and the combination of 2% biochar and 40% RU showed a reduction in carbon emissions compared to the UR and RU treatments. The number of rapeseed root tips (NT), forks (NF) and crossings (NC) increased significantly with the addition of biochar, and the combination of biochar and 40% RU was more beneficial for root growth and development than RU and UR. Considering the improvement in soil nutrition, increased soil organic carbon content, reduced carbon emissions, and enhanced rapeseed growth and development, the co-application of 2% biochar and 40% RU is recommended for large-scale application in rapeseed cultivation in the hilly purple soil of southwest China. Full article

(This article belongs to the Special Issue Biochar, Fertilizers and Microbes Interactions for Soil Health and Crop Productivity)

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15 pages, 2783 KiB

Open AccessArticle

Enhancing Soil Nitrogen Retention Capacity by Biochar Incorporation in the Acidic Soil of Pomelo Orchards: The Crucial Role of pH

by Xiaojie Qian, Qinghua Li, Hongmei Chen, Lin Zhao, Fei Wang, Yushu Zhang, Jinbo Zhang, Christoph Müller and Zhigang Yi

Agronomy 2023, 13(8), 2110; https://doi.org/10.3390/agronomy13082110 - 11 Aug 2023

Cited by 5 | Viewed by 2189

Abstract

Biochar is commonly used to improve acidic soil and reduce nitrogen loss. However, the impact of biochar on soil nitrogen retention, especially at varying pH levels, is not fully understood. Soil samples were obtained from an acidic red soil citrus orchard. The soil pH was adjusted using CaO, with five levels (4.0, 5.1, 5.8, 6.6, and 7.2), and two biochar doses (0% and 1%) were applied. The study used ¹⁵N-Tracer and Ntrace to investigate biochar’s influence on soil nitrogen retention at different pH levels. The results showed that soil amendment with biochar improved gross mineralization rates (TM) and gross NH₄⁺ immobilization rates (TI), except at pH 4.0 for TI. Biochar enhanced heterotrophic nitrification (O_Nrec) within pH 4.0–7.4, with a threshold for autotrophic nitrification (O_NH4) at pH 6.4. The findings revealed biochar’s positive effect on soil nitrogen retention within pH 4.5–6.4. Biochar had a greater impact on TI than TM and inhibited O_NH4, potentially enhancing nitrogen retention in this pH range. These results highlight the significance of considering biochar incorporation for improving nitrogen use efficiency and reducing NO₃⁻-N loss in subtropical pomelo orchards. Full article

(This article belongs to the Special Issue Biochar, Fertilizers and Microbes Interactions for Soil Health and Crop Productivity)

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13 pages, 2114 KiB

Open AccessEditor’s ChoiceArticle

Different Functional and Taxonomic Composition of the Microbiome in the Rhizosphere of Two Purslane Genotypes

by Angel Carrascosa, Jose Antonio Pascual, Alvaro López-García, Maria Romo-Vaquero, Margarita Ros, Spyridon A. Petropoulos and Maria del Mar Alguacil

Agronomy 2023, 13(7), 1795; https://doi.org/10.3390/agronomy13071795 - 4 Jul 2023

Cited by 1 | Viewed by 1561

Abstract

Soil microbial communities have an important role in plant establishment and health. Particularly, the role of the soil microbiome in agriculture is of current interest. The study of microbial communities associated with purslane could open questions about the rational exploitation of the microbiota for sustainable agricultural purposes. In this study, the composition of the fungal and bacterial communities and the bacterial metabolic functions, associated with the rhizospheres of two purslane genotypes (one commercially available and one collected from the wild in Spain) were evaluated. The results showed a clear effect of purslane genotype on fungal and bacterial community composition and functional profiles. The bacterial community of the commercial purslane rhizosphere was characterized by more numerous metabolic pathways, mainly pathways related to Terpenoids and Polyketides, Carbohydrate, Lipid, and Amino Acid metabolism. By contrast, the rhizosphere bacterial community of the Spanish (wild) genotype was characterized by the enrichment of functions related to cellular processes such as cell motility and transport. We hypothesize that these differences could be due to differential effects of root exudate composition on the microbial functional community composition. This finding points out the need to consider differences in the functional characteristics of plant genotypes when selecting the beneficial microorganisms to be used as biofertilizers aiming to maximize plant growth and resistance to environmental stressors. Full article

(This article belongs to the Special Issue Biochar, Fertilizers and Microbes Interactions for Soil Health and Crop Productivity)

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19 pages, 3977 KiB

Open AccessArticle

Chemical Fertilization Alters Soil Carbon in Paddy Soil through the Interaction of Labile Organic Carbon and Phosphorus Fractions

by Suphathida Aumtong, Chakrit Chotamonsak, Paweenuch Pongwongkam and Kanchana Cantiya

Agronomy 2023, 13(6), 1588; https://doi.org/10.3390/agronomy13061588 - 12 Jun 2023

Cited by 1 | Viewed by 1893

Abstract

The influence of long-term chemical fertilization in paddy soils is based on the interaction between labile carbon and phosphorus fractions and the manner in which this influences soil organic carbon (SOC). Four soil depths (0–30 cm) were analyzed in this study. Easily oxidized organic carbon components, such as permanganate oxidized carbon (POXC) and dissolved organic carbon (DOC), and other physicochemical soil factors were evaluated. The correlation and principal component analyses were used to examine the relationship between soil depth and the parameter dataset. The results showed that Fe-P concentrations were greater in the 0–5 cm soil layer. DOC, inorganic phosphate fraction, and other soil physiochemical characteristics interacted more strongly with SOC in the 0–5 cm soil layer, compared to interactions in the 10–15 cm layer, influencing soil acidity. An increase in DOC in the 0–5 cm soil layer had a considerable effect on lowering SOC, consistent with P being positively correlated with POXC, but negatively with SOC and water-soluble carbon (WSC). The changes in SOC could be attributed to the relationship between DOC and inorganic phosphate fractions (such as Fe-P) under specific soil pH conditions. An increase in soil DOC could be caused by changes in the P fraction and pH. The DOC:Avai. P ratio could serve as a compromise for the C and P dynamic indicators. The soil depth interval is a critical element that influences these interactions. Agricultural policy and decision-making may be influenced by the P from chemical fertilization practices, considering the yields and environmental effects. Full article

(This article belongs to the Special Issue Biochar, Fertilizers and Microbes Interactions for Soil Health and Crop Productivity)

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15 pages, 304 KiB

Open AccessArticle

Pine Chip and Poultry Litter Derived Biochars Affect C and N Dynamics in Two Georgia, USA, Ultisols

by Sharon L. Weyers, Keshav C. Das, Julia W. Gaskin and Amanda M. Liesch

Agronomy 2023, 13(2), 531; https://doi.org/10.3390/agronomy13020531 - 12 Feb 2023

Cited by 3 | Viewed by 1548

Abstract

Some biochars produced by pyrolysis of biomass have the potential to sequester C and enhance nutrient supplies in agricultural soils. A 28-day lab incubation was used to assess the potential effects of biochars derived from pine chips (PC) or poultry litter (PL) applied at five application rates (0, 22.5, 45.0, 67.5, and 90 Mg ha⁻¹ equivalent). Biochars were applied to two acidic Ultisols, a Cecil sandy loam and a Tifton loamy sand, found in Georgia, USA. Cumulative basal soil respiration was measured over the 28-day incubation. Other soil properties measured before and after incubation were soil pH, total soil organic carbon (SOC), total soil N, soluble organic C (OC), soil mineral nitrogen (NH₄⁺-N and NO₃⁻-N), and microbial biomass C (MBC). Before incubation, addition of both PC and PL biochars increased soil pH, total SOC, and C:N ratio in both soils. Addition of the PL biochar increased total soil N, soluble OC, and NO₃⁻-N in both soils, MBC in Tifton soil, and NH₄⁺-N in Cecil soil. Addition of the PC biochar decreased NO₃⁻-N in Cecil soil but increased it in Tifton soil. After the 28-day incubation, averaged across soils, pH increased in the 22.5 Mg ha⁻¹ PC and 22.5 and 67.5 Mg ha⁻¹ PL treatments, total SOC declined in the 45 and 67.5 Mg ha⁻¹ PC treatments, and the C:N increased in soil controls and decreased in the 67.5 Mg ha⁻¹ PC treatment. In Cecil soil, the MBC declined in PL treatments except at 90 Mg ha⁻¹, and NH₄⁺-N declined in the 90 Mg ha⁻¹ PC treatments. In Tifton soil, MBC increased in the 45 Mg ha⁻¹ PL treatment, and NH₄⁺-N increased in all but the 22.5 Mg ha⁻¹ PL treatments. Total N and NO₃⁻-N did not change with incubation. Basal respiration was not affected by biochar, thought it was generally greater in Cecil than Tifton soil. Net SOC loss and the initial increase in soluble OC and MBC indicated potential C priming from adding both biochars. Increased NH₄⁺-N with time in Tifton PL treatments indicated potential N priming. In Cecil soil, the PC biochar may have immobilized NH₄⁺-N, but PL biochar likely supplied it. In Tifton soil, PC biochar appeared to be generally inert, but PL biochar supplied soluble OC and NH₄⁺-N, although it might have inhibited nitrification. Full article

(This article belongs to the Special Issue Biochar, Fertilizers and Microbes Interactions for Soil Health and Crop Productivity)

19 pages, 1341 KiB

Open AccessArticle

Biochar-Compost Additions Have Strong Short-Term Effects on Carbon and Nitrogen Emissions from an Agricultural Soil

by Regine Maier, Gerhard Soja, Wolfgang Friesl-Hanl, Sophie Zechmeister-Boltenstern, Kerstin Michel, Michael Tatzber and Barbara Kitzler

Agronomy 2022, 12(12), 2959; https://doi.org/10.3390/agronomy12122959 - 25 Nov 2022

Cited by 1 | Viewed by 4171

Abstract

Biochar (BC) application to agricultural soils has become a promising strategy for mitigation of soil-borne greenhouse gas (GHG) emissions, i.e., carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), but little is known about the effects on nitric oxide (NO) and dinitrogen (N₂) fluxes. We conducted a short-term field experiment to evaluate the effects of BC with compost and additional fertilizer on different soil GHG fluxes. Application of 1% BC-compost showed no significant effect on CH₄ and CO₂ fluxes but lowered NO and N₂O fluxes compared to the control without BC-compost. The addition of N to BC-compost (0.5% BC-compost + 175 kg N) showed a small mitigation potential for CH₄ whereas N₂O and NO fluxes significantly increased for one week after the application. The N₂:N₂O ratio shifted towards N₂O production after the application of N-enriched BC-compost. During storage of pure N-enriched BC-compost, high gaseous losses in the form of NO (71.2 ± 2 µg N g⁻¹ h⁻¹), N₂O (1319 ± 101 µg N g⁻¹ h⁻¹), and N₂ (337.8 ± 93 µg N g⁻¹ h⁻¹) were measured. Approximately 31% of applied N was lost in gaseous form even in the presence of BC. To avoid this, an optimized strategy to balance easily available N from compost and fertilizer with the amount of BC should be developed. Full article

(This article belongs to the Special Issue Biochar, Fertilizers and Microbes Interactions for Soil Health and Crop Productivity)

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25 pages, 366 KiB

Open AccessReview

Assessing the Potential of Biochar as a Viable Alternative to Synthetic Fertilizers in Sub-Saharan Africa Smallholder Farming: A Review

by Chuene Victor Mashamaite, Hamond Motsi, Alen Manyevere and Sanele Briged Poswa

Agronomy 2024, 14(6), 1215; https://doi.org/10.3390/agronomy14061215 - 4 Jun 2024

Cited by 2 | Viewed by 1350

Abstract

The adverse effects of long-term usage of synthetic fertilizers such as eutrophication, weed infestation, opportunistic diseases, and declining yields have been established. However, the fact that soil fertility declines because of continuous cropping to meet the demand for feeding the ever-growing population, coupled with the high cost of chemical fertilizers, has left little option. This mainly affects resource-poor smallholder farmers, who heavily depend on their production for sustenance and economic well-being. Current research efforts have underscored the urgency of mitigating this trend by seeking a cost-effective and eco-friendly alternative to avert impending global food crises. Biochar has gained attention as a possible alternative to meet the soil requirements on many fronts, such as improving soil functioning and restoring degraded lands. Biochar is also known to reduce heavy metal mobility and inorganic contaminants, mitigating salinity and drought stress as well as greenhouse gas emissions associated with agriculture. However, these studies need to be harmonized to draft a more pragmatic approach to policy formulation and establish an enhanced paradigm. In this paper, we review several studies on biochar and synthesize its possible use as an alternative or supplement to synthetic fertilizers to enhance crop productivity under standard and stressful growing conditions. The ability of biochar to sequester carbon and its impact on soil properties are highlighted. We emphasize its potential for soil nutrient management and the possibility of adopting it as an alternative to synthetic fertilizer in smallholder farming. We also point out several critical research gaps that call for attention and serve as pointers for future research. Full article

(This article belongs to the Special Issue Biochar, Fertilizers and Microbes Interactions for Soil Health and Crop Productivity)

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