Semi-arid Soils Research Articles

Potential of biochar to restoration of microbial biomass and enzymatic activity in a highly degraded semiarid soil

Biochar is an effective material for enhancing soil ecosystem services. However, the specific impacts of biochar on microbial indicators, particularly in degraded soils, remain poorly understood. This study aimed to evaluate the effects of biochar produced from cashew residues and sewage sludge, in a highly degraded soil, on microbial indicators. We analyzed soil chemical composition and microbial biomass C and N, enzyme activity, and stoichiometry. Cashew biochar increased soil respiration, indicating a higher availability of C to microorganisms compared to sewage sludge biochar and a better adaptation of soil microbial communities to C-rich organic material obtained from a native plant. Although the biochar differentially impacted microbial biomass C, both significantly increased N in the microbial biomass. Arylsulphatase activity did not respond to biochar application, while β-glucosidase, urease, and phosphatases showed significant changes with biochar treatments. Importantly, stoichiometry and vector analysis revealed that both types of biochar increased P limitation for soil microbes. Conversely, both biochar alleviated C and N limitations for the soil microbes. Thus, biochar applications in highly degraded soils should be supplemented with external P sources to maintain soil functions, mainly for cashew residues. Our results provide evidence that biochar can restore soil biological properties and enhance the availability of C and N to microorganisms. These findings have significant implications for restoration practices in degraded lands of semiarid regions.

Application of Compositional Nutrient Diagnosis to Maize Cultivated in Tropical Soils in Brazilian Semi-Arid

ABSTRACT Nutritional diagnosis, a technique used to maximize the economic yield of agricultural holdings and to protect the environment, is the focus of this study. Nutrient availability is one of the critical limiting factors in maize grain yield. The study, which aimed to establish and compare the nutritional standards obtained by the Compositional Nutrient Diagnosis (CND) method in maize grown in tropical soils in a semi-arid region, is based on a thorough examination of a database containing information from 198 experimental plots collected between 2011 and 2019 in the semi-arid region of Ceará, Brazil. The evaluation methodology was the multivariate CND calculation method. The mathematical models used to analyze the relationship between the nutrient’s CND-r2 index and leaf concentrations revealed coefficients of determination (R2) for nitrogen (N) and magnesium (Mg) of 0.36 and 0.66, respectively. The other values exceeded 70% (R2 ≥ 0.70), while phosphurus (P), calcium (Ca), cupper (Cu), iron (Fe), and manganese (Mn) showed values above 90% (R2 ≥ 0.90). These results not only highlight the high accuracy of these models in studying the interactions between nutrient coefficients and their leaf concentrations but also reassure the reader about the reliability of the research. The study’s thoroughness instills confidence in the research’s validity.

Soil response in a Mediterranean forest ecosystem of Southeast Spain following early prescribed burning

The escalation of global warming, high temperatures, and wildfire frequency in dry ecosystems, including semi-arid landscapes, has resulted in increased wildfire regimes, compromising ecosystem resistance and resilience. To mitigate these risks, prescribed burning (PB) is being employed as a preventive measure to modify fuel loads in forest ecosystems. However, fire can also impact soil structure and microbiota, which play critical roles in nutrient cycling, biodiversity conservation, and overall ecosystem functioning. Therefore, understanding post-fire processes is essential for sustainable forest management. However, while previous studies have explored the effects of prescribed fire management on semi-arid soil properties in Mediterranean forest ecosystems, gaps remain in our understanding of its specific impact on the physical structure, chemical composition, and biological activities of soils.In this study, we conducted early spring PB in SE Spain in 2021 and assessed the ecological and temporal effects of PB on semi-arid soils. Soil respiration (SR) measurements using automatic CO2 flow chambers were employed to evaluate microbiota recovery. To examine impacts on soil structure we evaluated physicochemical characteristics, soil hydraulic conductivity (SHC), and soil water repellency (SWR). No significant differences were observed in any of the variables studied after one year. However, immediate effects were detected shortly after the PB. Our research specifically targeted soil structure and microbiota in a semi-arid landscape with poor soils, characterized by slower recovery and potentially fragile ecosystems. These results provide valuable insights for forest management practices, indicating that prescribed fire management strategies in similar ecosystems are unlikely to cause adverse effects on soil health. However, further research is warranted to explore the potential effects of prescribed fire intensity and seasonality. Future studies can focus on investigating these factors to provide more targeted recommendations for effective forest management strategies and wildfire prevention efforts.

Effects of farmyard manure and chemical fertilizer application rates on soil biology, cotton and fiber yield

Organic and inorganic fertilizers have significant effect on plant physiology, yield per unit area, available plant nutrient contents and extracellular enzyme activities of soils. This study was carried out in field conditions in arid and semi-arid regions between 2020-2021 years, May 01. The effects of farmyard manure (FM) (20, 40, 60 Mg ha-1) and chemical (CF) (350 kg urea ha-1, 100, 200, 300 kg DAP ha-1) fertilizers applied at different rates on plant nutrient (N, P, K, Ca, Mg, Fe, Cu, Zn and Mn) contents, SPAD value and NDVI of cotton plants, seed cotton yield and soil enzymes (urease, catalase, dehydrogenase, alkaline phosphatase) were investigated. The results showed that FM applications significantly (p<0.01) increased the plant macro and micronutrients compared to CF applications, except for N (200 + 150 kg urea ha-1), Zn and Cu (300 kg DAP + 200 + 150 kg urea ha-1) in the 2021 cotton growing season. Mineralization of FM is slow under natural conditions; therefore, the use of FM alone is not sufficient to meet the nutrient needs of high yielding varieties. Urease and dehydrogenase activities increased significantly in FM treated soils compared to CF, while no significant (p<0.01) increase was recorded in alkaline phosphatase and catalase activities. Farmyard manure is a useful management practice for increasing soil biological activity. Physiological parameters of NDVI, SPAD and seed cotton yield significantly increased in FM treated soils compared to CF applications. The increase in cotton yield was 29.15%, in NDVI value was 22.38% and in SPAD value was 121.7%. The main issues with cotton in the area are the low organic carbon content of the soils, high clay content, arid and semi-arid soils, and their detrimental impact on the uptake of particular nutrients (N, P and B).

Classification of expansive soils among problematic soils in the brazilian semiarid from artificial neural networks

The climatological and geomorphological conditions of the Brazilian semiarid region favor the formation of potentially expansive soils. The development of neural networks to identify and classify expansive soils in Pernambuco, and the need to export to soils across the semiarid region of Brazil is investigated in this study using a Multi-Layer Perceptron (backpropagation). The neural network was developed using 87 experimental data points, divided into three groups. The Training Group, consisting of 53 samples, using data inputs: sand percentage, clay percentage, plasticity index, activity index, and geological, pedological, and climatological classification. Selection Group, made up of 17 samples, was used to select the best network architecture, genetics algorithms formed of 7 inputs and 3 hidden nodes. The Test Group used 17 samples to evaluate the predictive accuracy of the expansion potential, obtaining an accuracy rate of 88,2%. This network was validated by applying it to 67 samples of problematic soils of the collapsible, expansive, and soft type from the Brazilian semiarid region, reaching an accuracy of 76,1%. Probabilistic Neural Networks were found to be efficient in evaluating the behavior of expansive soils, with the ability to deal with the absence of sample input data, demonstrating the ability to capture movement trends in the expansion of the soil surface, indicating the functions that introduce the effects of the composition potential on the expansion behavior, and determining the limit values of each of the input variables for the samples from the database used.

Soil properties predict below-ground community structure, but not nematode microbiome patterns in semi-arid habitats.

Microbial and microeukaryotic communities are extremely abundant and diverse in soil habitats where they play critical roles in ecosystem functioning and services that are essential to soil health. Soil biodiversity is influenced by above-ground (vegetation) and below-ground factors (soil properties), which together create habitat-specific conditions. However, the compound effects of vegetation and soil properties on soil communities are less studied or often focused on one component of the soil biota. Here, we integrate metabarcoding (16S and 18S rRNA genes) and nematode morphology to assess the effects of habitat and soil properties shaping microbial and microeukaryotic communities as well as nematode-associated microbiomes. We show that both vegetation and soil properties (soil bulk density) were major factors structuring microbial and microeukaryotic communities in semi-arid soil habitats. Despite having lower nutrients and lower pH, denser soils displayed significantly higher alpha diversity than less dense soils across datasets. Nematode-associated microbiomes have lower microbial diversity, strongly differ from soil microbes and are more likely to respond to microscale variations among samples than to vegetation or soil bulk density. Consequently, different nematode lineages and trophic groups are likely to display similar associated microbiomes when sharing the same microhabitat. Different microbiome taxa were enriched within specific nematode lineages (e.g. Mycobacterium, Candidatus Cardinium) highlighting potentially new species-specific associations that may confer benefits to their soil nematode hosts. Our findings highlight the importance of exploring above- and below-ground effects to assess community structure in terrestrial habitats, and how fine-scale analyses are critical for understanding patterns of host-associated microbiomes.

Hydro-meteorological aspects of soil fluorides in semi-arid soils using microwave remote sensing.

Soil fluoride is a critical determinant of soil fertility, human health and crop productivity. Soil fluoride can be increased by climatic conditions, irrigation water and anthropogenic activity, and it is important to control fluoride by understanding the complex relationships between atmospheric conditions and water systems. In this research, a detailed focus is on the hydrological and meteorological aspects of soil fluorides in semi-saturated and saturated soils to discuss the impact of irrigation, capillary rise and the combination of rainfall and anthropogenic activities such as fertilizer application on the soils in the dry spell and monsoon seasons of 2021 and 2022. A Sentinel-1 data can be used to estimate fluoride levels to the above soil conditions. In an effort to estimate fluoride levels in different hydro-meteorological scenarios, we have put forward a hypothesis that focuses on understanding the potential connections between hydro-meteorological factors (precipitation, groundwater levels, and temperature) and the levels of fluoride. The findings indicate that the extensive use of groundwater for irrigation leads to a rise in fluoride levels, posing a significant threat to crop health over time. Furthermore, the combined effects of irrigation and upheaval leaching on fluoride levels have shown strong statistical conformity (R2 > 0.85) with the relevant field-measured fluoride data for the year 2022. Importantly, areas affected by are more sensitive to the sand and clay percentage in the soil because potential and dispersion behaviour enlarge the capillaries to decelerate the upward movement. A region-based discussion details the factors contributing to the increase of fluoride in soil helpful in taking remedial measures and mitigation plans.

Effects of local farming practices on soil organic carbon content, enzymatic activities, and microbial community structure in semi-arid soils of Morocco

Soil organic carbon (SOC) is essential in semi-arid agricultural land for enhancing soil health, particularly through the promotion of microbial activities. This study assessed the impact of different agronomic practices on soil properties, microbial communities, and SOC levels in semi-arid Moroccan wheat fields. Three treatments were investigated: eucalyptus (Eucalyptus spp.) companion planting (EU), and fallowing with harvest residue mulching (FA), with the latter involving both short (3 months; FAS) and long (15 months; FAL) fallow periods. The study revealed significant variation in soil characteristics and microbial communities between these agronomic management regimes. Notably, soils managed with FAL contained elevated SOC levels (1.2%) compared to other treatments (FAS and EU) which show lower SOC range (0.62–0.86%). Both labile C (water-soluble carbon) and recalcitrant C (humic substances) were increased by FAL. Additionally, soil microbial biomass and dehydrogenase activity were observed to be high in FAL-managed soils, along with increased levels of extracellular enzymes related to nutrient cycling (β-glucosidase, alkaline phosphatase, and urease). Phospholipid fatty acid (PLFA) analysis indicated positive correlation between carbon content in soils and microbial populations. In contrast, soils managed with EU had significantly lower SOC levels, possibly due to differences in carbon fractionation. FAL increased soil enzymatic activities and enriched the microbial community when compared to EU management. In conclusion, this study indicated the importance of fallowing and fallowing period for conservation of SOC, and potential to mitigate negative effects of biophysical constraints on agricultural productivity in semi-arid soils of Northwest Africa.

Selenium enrichment, partitioning and leachability along semi-arid soils of NE Punjab, India

Selenium enrichment, partitioning and leachability along semi-arid soils of NE Punjab, India

Unraveling the Role of Capillarity in Arsenic Mobility: Insights from a Sedimentary–Karstic Aquifer in Semiarid Soil

Unraveling the Role of Capillarity in Arsenic Mobility: Insights from a Sedimentary–Karstic Aquifer in Semiarid Soil

Returning Different Organic Materials to the Field: Effects on Labile Soil Nitrogen Pool under Drip Irrigation with Film Mulching in a Semi-Arid Soil

The purpose of this study was to observe the changes in soil nitrogen pools (active organic and inorganic nitrogen fractions) after applying organic materials under drip irrigation with film mulching in a semi-arid soil. The two-year field experiment included four fertilization treatments: maize straw, fodder grass, sheep manure, and a control treatment with no organic material applied (CK). The results showed that the application of maize straw and sheep manure significantly increased the soil total nitrogen content by 9.02~13.33% and 11.02~17.27%, respectively, while no significant improvement was found with the use of fodder grass. Compared with CK, returning organic materials to the field increased the soil active nitrogen pools, except for ammonium nitrogen content. Meanwhile, the content of particulate organic nitrogen was significantly increased by 42.11~78.85% under the application of organic materials, which took the highest proportion of active nitrogen pools and was sensitive to fertilization treatments. Among the three organic materials, maize straw and sheep manure increased the soil active nitrogen content the most. In conclusion, both maize straw and sheep manure are the optimum organic materials, which could be applied for improving soil nitrogen storage under drip irrigation with film mulching within semi-arid areas.

Biogenic carbonates (queras) in loess-palaeosol sequences of the Ebro Basin and their potential use as a palaeoenvironmental proxy

Secondary carbonate accumulations are very common in arid and semi-arid soils but are often poorly described and classified. This is the case for queras that are observed in several loess-palaeosol sequences of the Ebro Basin. Micromorphologically, queras are complex pedogenic features basically consisting of infillings of calcified root cells in channels, surrounded by decarbonated hypocoatings. They apparently result from biologically mediated calcification/decalcification processes at a microscale. The aim of this study is to systematically characterize biocalcifications found in dated loess-palaeosol sequences, to determine the main factors of formation, and to discuss their possible use as a palaeoenvironmental proxy. Different queras show a similar number of biosparite layers (four to five) around a central channel, and a decarbonated hypocoating around the queras. This supports the hypothesis that queras originate from the calcification of root tips and are related to the acidification of surrounding soil for nutrient absorption. Under cathodoluminescence microscopy, biosparite has a different behaviour than non-biological calcite crystals: the latter appears reddish while biosparite remains black. The queras, with ages corresponding to Marine Isotope Stages 1–3, are younger than that of the loess where they are found in. The stable isotope values likely correspond to C3 plants, and the estimated temperatures of formation reflect a Mediterranean temperate climate. This suggests that the biocalcifications developed during short moist seasons amidst arid periods of the Quaternary.

Comparative genomics reveals the adaptation of ammonia-oxidising Thaumarchaeota to arid soils.

Thaumarchaeota are predominant in oligotrophic habitats such as deserts and arid soils, but their adaptations to these arid conditions are not well understood. In this study, we assembled 23 Thaumarchaeota genomes from arid and semi-arid soils collected from the Inner Mongolia Steppe and the Qinghai-Tibet Plateau. Using a comparative genomics approach, integrated with 614 Thaumarchaeota genomes from public databases, we identified the traits and evolutionary forces that contribute to their adaptations to aridity. Our results showed that the newly assembled genomes represent an early diverging group within the lineage of ammonia-oxidising Thaumarchaeota. While the genomic functions previously identified in arid soil lineages were conserved across terrestrial, shallow-ocean and deep-ocean lineages, several traits likely contribute to Thaumarchaeota's adaptation to aridity. These include chlorite dismutase, arsenate reductase, V-type ATPase and genes dealing with oxidative stresses. The acquisition and loss of traits at the last common ancestor of arid soil lineages may have facilitated the specialisation of Thaumarchaeota in arid soils. Additionally, the acquisition of unique adaptive traits, such as a urea transporter, Ca2+ :H+ antiporter, mannosyl-3-phosphoglycerate synthase and phosphatase, DNA end-binding protein Ku and phage shock protein A, further distinguishes arid soil Thaumarchaeota. This study provides evidence for the adaptations of Thaumarchaeota to arid soil, enhancing our understanding of the nitrogen and carbon cycling driven by Thaumarchaeota in drylands.

Microbial impact on initial soil formation in arid and semiarid environments under simulated climate change.

The microbiota is attributed to be important for initial soil formation under extreme climate conditions, but experimental evidence for its relevance is scarce. To fill this gap, we investigated the impact of in situ microbial communities and their interrelationship with biocrust and plants compared to abiotic controls on soil formation in initial arid and semiarid soils. Additionally, we assessed the response of bacterial communities to climate change. Topsoil and subsoil samples from arid and semiarid sites in the Chilean Coastal Cordillera were incubated for 16 weeks under diurnal temperature and moisture variations to simulate humid climate conditions as part of a climate change scenario. Our findings indicate that microorganism-plant interaction intensified aggregate formation and stabilized soil structure, facilitating initial soil formation. Interestingly, microorganisms alone or in conjunction with biocrust showed no discernible patterns compared to abiotic controls, potentially due to water-masking effects. Arid soils displayed reduced bacterial diversity and developed a new community structure dominated by Proteobacteria, Actinobacteriota, and Planctomycetota, while semiarid soils maintained a consistently dominant community of Acidobacteriota and Proteobacteria. This highlighted a sensitive and specialized bacterial community in arid soils, while semiarid soils exhibited a more complex and stable community. We conclude that microorganism-plant interaction has measurable impacts on initial soil formation in arid and semiarid regions on short time scales under climate change. Additionally, we propose that soil and climate legacies are decisive for the present soil microbial community structure and interactions, future soil development, and microbial responses.

Ionomic analysis of Prosopis laevigata response to heavy metals: phytoremediation potential determined by wavelength-dispersive X-ray fluorescence

Prosopis laevigata (mesquite) plants can tolerate drought, thermal stress, alkalinity, salinity, and toxicity of heavy metals, making them attractive for phytoremediation. Nonetheless, most of these features have been studied under controlled laboratory conditions. In this work, the bioaccumulation of heavy metals in a free-living population of P. laevigata trees growing in a heavily metal-contaminated site (aluminum, chromium, iron, titanium, copper, and zinc) was analyzed. Furthermore, crystal phases of mineral nutrients and trace elements found in P. laevigata tissues were determined by X-ray diffraction. P. laevigata trees accumulated 705 (± 17), 47,064 (± 1459), 14,800 (± 401) and 30,000 (± 1719) mg/kg of Cu, Zn, Fe and Al, confirming the potential of these plants to hyper-accumulate metals. The X-ray diffraction analysis showed that P. laevigata trees can chelate Al3+ with phosphates to form orthorhombic crystals of aluminum phosphate (AlPO4) in the tissues. This aluminum chelation was probably a mechanism of tolerance used by the plant. The inoculation of seedlings with the endophytic Bacillus cereus MH778713 did not prevent Cr-accumulation in the plant but increased metal tolerance and seedling development. These results highlight the use of P. laevigata and B. cereus MH778713 together as tools for heavy metal bioremediation, particularly on arid and semiarid soils.

Essentiality of Micronutrients in Soil: A Review

Micronutrients are very abundant in soil but plants normally absorb only a little amount of them, giving them the name "trace elements". Boron (B), Copper (Cu), Iron (Fe), Manganese (Mn), Zinc (Zn), Molybdenum (Mo), and Nickel (Ni) are the essential micronutrients that are required in smaller amounts but crucial for plant growth and development. Besides providing essentiality in fruits and seeds formation, they are helpful in performing various metabolic processes, nutritional management, reproductive growth, chlorophyll synthesis, and other key plant activities. Among all the essential micronutrients, two particular elements, zinc (Zn) and boron (B) are deficit in acidic soils and zinc (Zn) and iron (Fe)are insufficient in semi-arid soils, which have become a rising problem in a variety of cropping systems thereby, raising alarms for the future. Our understanding of difficulties relating to micronutrients might be improved by the production of detailed soil micronutrient maps that cover wide geographic regions, making relevant judgments about the delivery and distribution of fertilizers supplemented with micronutrients to areas that are deficient in these particular micronutrients. The outcomes of these delineation efforts would also be very helpful in developing site-specific suggestions to increase the micronutrient content of food crops. It's important to note that soil micronutrient availability directly affects plant growth.

Effects of Selected Properties of Semi-Arid Soil of Dutse, Jigawa State on Adsorption of Pb and Cd Ions

This study determined the effects of some selected physical and chemical properties of semi-arid soil on heavy metal sorption. Soil samples were collected randomly from Federal University Dutse within Nigeria's Sudan Savannah agroecological zone. Nitrate salts were used to prepare three different concentrations (10, 20, 30 mg/kg) of CdCl2 and PbCl2. The equilibrium sorption of the study soil was determined. The equilibrium sorption data were fitted into Langmuir and Freundlich isotherms. Langmuir and Freundlich isotherm model's r2 values (1) were at par. The boundary energy b (1 mg-1) from the Langmuir isotherm model was determined to be -110.0 and 47 for Pb and Cd, respectively. Freundlich isotherm sorption intensity (n) of 1.92 and 1.67 indicated a favorable sorption, revealing physical adsorption rather than chemical adsorption. Correlation analysis established the relationship between the heavy metal sorption capacity and soil properties. The R values of 0.92 and 0.72 showed a positive relationship between Pb and Cd adsorption with soil silt content. Positive relationships (R) were obtained from the organic matter (0.68), Total Nitrogen (0.99 and 0.60), as well as particle size on adsorption of both metals. Adsorption of heavy metals was positively affected by the physical and chemical properties of the semi-arid soil.

English

Lack of water is the main problem facing agriculture and crop production in arid and semi-arid regions. Deficit irrigation is widely used to optimize water application efficiency under drought conditions in arid areas. The purpose of the work is to estimate the efficiency of SALTMAD model for simulating soil moisture dynamics, water application efficiency, and seed yield under three Deficit Irrigation Strategies (DIS) [DIS1 (100% Full Irrigation (FI)), DIS2 (80% FI), and DIS3 (60% FI)] with six treatments of Integrated Nitrogen-Fertilization (INF) including [INF1 (100% MN + 0% ON), INF2 (80% MN + 20% ON), INF3 (60% MN + 40% ON), INF4 (40% MN+ 60% ON), INF5 (20% MN + 80% ON) and INF6 (0% MN + 100% ON)]. Moreover, the best strategy of deficit irrigation with the best treatment of integrated nitrogen fertilizer will be selected for improving soil hydro-physical properties, water productivity, and seed yield in semi-arid soil regions without any water stress. Field experiment was conducted during 2020/2021 and 2021/2022 at the Research Farm of National Research Center (NRC) at Nubaryia Region, Al Buhayrah Governorate, Egypt. Soil hydro-physical properties including infiltration rate (IR), and soil moisture dynamics were measured in the field. In addition, soil moisture dynamics, water application efficiency, seed yield, and water productivity of bean were simulated using the SALTMAD model and compared with thatmeasured in the field under the above conditions. The results observed that the best treatment that led to increased water application efficiency and seed yield was at DIS2 (80% FI) with INF4 (40% MN+ 60% ON) compared to DIS1 (100% FI), and DIS3 (60% FI). In this strategy, seed yield productivity increased by 43.4% in the first season, and 34.7% in the second season as well as saving irrigation water by up to 20% for cultivated faba bean in sandy soil without any water stress. The usage of balance a combination of mineral and organic fertilizers can be used to compensate for deficit irrigation by improving infiltration rate, water holding capacity, water application efficiency, and seed yield. The SALTMAD model can be used to simulate soil moisture dynamics, water application efficiency, seed yield, and water productivity with little calculation error under different deficit irrigation strategies and integrated nitrogen fertilization in arid and semi-arid areas with sandy soil.

Biochar Improves Soil Fertility and Crop Performance: A Case Study of Nigeria

Africa, specifically Nigeria, has witnessed a dramatic increase in population over the last century, prompting efforts to ensure sustainable food production and quality. Concerns for soil sustainability and food security have led to the exploration of cost-effective methods, such as biochar, to enhance soil quality. Researchers in Nigeria and Africa as a whole have investigated biochar’s potential to improve soil fertility and crop performance across various agroecological zones. This paper aims to review recent biochar research priorities on soil fertility and crop performance with an emphasis on various sole biochar applications and combinations with fertilizers to determine the research gaps that need to be developed more in biochar research in Nigeria. From the papers reviewed, sole biochar applications and biochar + macronutrients and biochar + manure combinations were studied more dominantly, while biochar + micronutrients research projects were scanty despite their low content in the semi-arid soils of Nigeria. The studies were spread across the country with the majority taking place in derived savanna and humid forest, while Sudan savanna and Sahel savanna received less research attention despite being characterized by a low-fertile soil and vast area of land. Research involving BC in the context of Sahel savanna (SLS) and Sudan savanna (SS) soils is strongly encouraged in Nigeria. This research should encompass a wide range of investigations, including sole BC applications and combinations of BC with macronutrients, micronutrients, and manure, as well as exploring its potential as a slow-release fertilizer. Incorporating exclusive biochar in substantial amounts appears economically unfeasible within the context of local biochar production. However, it can be utilized in the synthesis of slow-release fertilizers, requiring smaller quantities and potentially offering cost-effectiveness. This approach enhances soil condition and crop productivity. Challenges are faced due to less commercial production as a result of inadequate power and structural facilities. Exploring the modification of local biochar for slow-release fertilizers through future research offers potential profitability.

Semi-arid soil bacterial communities are refined by altered plant selection pressure under conservation management practices

Plants' ability to select for, and refine, their microbiome over time is well known. In soil, the strength of plant selection pressure on microbial composition can result in distinct rhizosphere, and root-zone communities, but may be masked in soils with lower native diversity such as semi-arid soils. Semi-arid soils are also known for their high potential for wind erosion, which may be mitigated by the implementation of cover crops. These cover crops may also alter the microbial composition of the semi-arid soils, but the strength of this effect, and the resulting changes in the composition of the microbiome, are less well known. This study aimed to address whether the implementation of a single-species wheat cover crop in semi-arid agricultural soils would impact the bacterial composition of the cash crop. We investigated three tillage regimes—no-tillage with a winter wheat cover crop, no-tillage winter fallow, and conventional tillage winter fallow—to determine the effects of tillage removal, and cover crop implementation on the soil bacterial community present in the root zone of the cash crop. It was determined that the composition of the bacterial microbiome was similar between cover cropped and non-cover cropped treatments. The similarity of bacterial composition was likely due to the strong effect of environmental selection reducing overall biodiversity in these soils. However, the variability of bacterial community composition was strongly reduced for the cover cropped treatment compared to the two non-cover cropped treatments. The similarity of bacterial communities with cover cropping, without significant soil physicochemical changes, suggests that plant-selection pressure, rather than management-induced changes in soil physicochemical properties, drove the refinement (decreased dissimilarity compared to non-cover cropped treatments) of the bacterial community. The composition of this refined community under cover cropping was determined to contain an enrichment of several genera of interest including N cycling and potential plant-growth promoting bacteria. In summary, the introduction of cover cropping in the nutrient and microbial-poor soil of the semi-arid Southern High Plains strongly refined the bacterial community and selected for organisms with the potential to improve soil functions associated with greater agronomic sustainability.