Planted Soil Research Articles

Soil Acidification and Its Temporal Changes in Tea Plantations of Guizhou Province, Southwest China

ABSTRACTSoil acidification is a significant problem in intensive agricultural systems, particularly in tea plantations. Guizhou province, located in the center of the karst mountainous region of southwest China, has the largest tea plantation area in China. However, the soil acidification characteristics in the tea plantations of Guizhou province, as well as their temporal changes, have not yet been adequately studied. Therefore, soil acidification and associated soil properties in the major tea‐planting counties of Guizhou province were extensively assessed, and the temporal changes in soil acidity over the past 11 years were also evaluated through long‐term and short‐term experiments. The results showed that the average soil pH in the tea plantations in Guizhou province varied from 4.08 to 4.87, with a mean of 4.47. The average cation exchange capacity (CEC), TEA (total exchangeable acidity, TEA), EH (exchangeable H+), and EA (exchangeable Al3+) values were 9.6, 3.7, 5.8, and 19.0 cmol/kg, respectively. Seasonal changes in tea plantation soil pH were observed in low‐ and moderately acidic soils but not in highly acidic soils. The soil pH values did not significantly change during three consecutive years of in situ observations but significantly decreased over the past 11 years at an average of 0.03 yearly. Correlation analysis revealed that the soil pH in tea plantations was significantly positively correlated with the content of specific amino acids, such as glutamic acid, arginine, and valine, but was significantly negatively correlated with certain soil physicochemical properties. The findings of this study indicate that soil acidification in tea plantations of the Guizhou province is severe and possesses distinctive attributes that should be considered for its effective management.

Planting density effect on poplar growth traits and soil nutrient availability, and response of microbial community, assembly and function

BackgroundThe interaction between soil characteristics and microbial communities is crucial for poplar growth under different planting densities. Yet, little is understood about their relationships and how they respond to primary environmental drivers across varying planting densities.ResultsIn this study, we investigated poplar growth metrics, soil characteristics, and community assembly of soil bacterial and fungal communities in four poplar genotypes (M1316, BT17, S86, and B331) planted at low, medium, and high densities. Our findings reveal that planting density significantly influenced poplar growth, soil nutrients, and microbial communities (P < 0.05). Lower and medium planting densities supported superior poplar growth, higher soil nutrient levels, increased microbial diversity, and more stable microbial co-occurrence networks. The assembly of bacterial communities in plantation soils was predominantly deterministic (βNTI < -2), while fungal communities showed more stochastic assembly patterns (-2 < βNTI < 2). Soil available phosphorus (AP) and potassium (AK) emerged as pivotal factors shaping microbial communities and influencing bacterial and fungal community assembly. Elevated AP levels promoted the recruitment of beneficial bacteria such as Bacillus and Streptomyces, known for their phosphate-solubilizing abilities. This facilitated positive feedback regulation of soil AP, forming beneficial loops in soils with lower and medium planting densities.ConclusionsOur study underscores the critical role of planting density in shaping soil microbial communities and their interaction with poplar growth. This research carries significant implications for enhancing forest management practices by integrating microbiological factors to bolster forest resilience and productivity.

Post-Pyrogenic Restoration of the Biological Activity of Soils of Artificial Forest Plantations in the Arid Zone of the Shirinskaya Steppe in the Republic of Khakassia

Post-Pyrogenic Restoration of the Biological Activity of Soils of Artificial Forest Plantations in the Arid Zone of the Shirinskaya Steppe in the Republic of Khakassia

Assessment of Heavy Metals in Tea Plantation Soil and Their Uptake by Tieguanyin Tea Leaves and Potential Health Risk Assessment in Anxi County in Southeast China

Evaluating heavy metal pollution in tea plantation soil and conducting potential health risk assessments are crucial for ensuring the safety of tea consumers. However, soil heavy metal pollution levels and dietary exposure risk remain poorly understood, and there is no consensus on how soil physicochemical properties affect heavy metal concentrations. In this study, seventy-three soil samples and corresponding tea leaves from main tea-producing regions in Anxi County were analyzed for arsenic (As), chromium (Cr), lead (Pb) and copper (Cu) concentrations. The results showed that mean concentrations of As, Cr, Cu and Pb in the soil did not exceed respective risk screening values in China (GB 15618-2018). The concentrations of As, Cr, Cu and Pb in the tea leaves were within limiting values of the Chinese National Food Safety Standard, and the bioaccumulation factor of heavy metals in descending order was Cu &gt; Pb &gt; As &gt; Cr. The hazard index values of heavy metals indicated no potential human health risk. Soil pH, EAl, EA and AP were the main controlling factors for heavy metal in soil and tea leaves. Cu and Pb concentrations in tea leaves were positively correlated with soil Cu and Pb concentrations. These results provide a scientific basis for effective monitoring and management in tea plantations and for controlling potential risks in tea leaves.

Synergistic organic manure treatment with Al/Fe/Ca-based fluoride-fixing agents promote soil formation and utilization of phosphate flotation tailings

Soil utilization of phosphate ore flotation tailings (PTs) was achieved using F-fixing agents combined with organic manure treatment to address issues related to inefficient stabilization of P-F, heavy metal solidification/stabilization, poor physicochemical properties, and ecological disruption. The formulation for PTs soil utilization included 1.75 % polyaluminum sulfate (PAS), 1.75 % FeSO4, and 0.25 % CaO, with PTs content at ≥86.75 %. This approach enhanced water retention and improved nutrient and biochemical conditions. Various nutrient indexes met general planting soil requirements: organic matter 24.93 g/kg, available K 252.26 mg/kg, available Ca 2048.67 mg/kg, available Mg 246.13 mg/kg, and ammonia-nitrogen 42.47 mg/kg. The water-soluble P content of PTs-based soil decreased to 6.96 mg/kg, while available P increased to 677.99 mg/kg. Mn leaching toxicity was less than 0.016 mg/L, with a stabilization efficiency of 96.86 %. Water-soluble F in PTs-based soil was reduced to 11.133 mg/kg. This study maximized phosphorus resource utilization and prevented the migration of water-soluble P, F, and Mn to the surrounding environment. Potting experiments showed PTs-based soil was more effective than red soil and PTs-based raw materials in cabbage plantation, achieving a maximum seedling emergence rate of 98.33 %. Microbial diversity increased, and community structure improved in 40-day soil formation experiments, with PTs-based soils developing microbial communities involved in carbon and nitrogen cycling, enhancing resistance to external environmental disturbances, and promoting ecological utilization. These findings offer practical insights into the ecological utilization of large quantities of PTs and present a cost-effective approach for producing planting soils or ecological mulches from similar solid wastes.

Abundance, Diversity, and Community Composition of Comammox Nitrospira in Tea (Camellia Sinensis) Plantation Soils

Abundance, Diversity, and Community Composition of Comammox Nitrospira in Tea (Camellia Sinensis) Plantation Soils

Draft genome sequence of Pseudomonas sp. ZS001 isolated from peanut plantation soil.

Pseudomonas sp. ZS001 is a bacterium potentially degrading soluble starch isolated from peanut plantation soil sprayed with starch-based material in Dasi Town, Tianjin. Reporting the genome sequence of strain ZS001 can help us understand the genome composition, potential functional characteristics, and application value of Pseudomonas members at the genetic level.

Patterns and Drivers of Greenhouse Gas Emissions in a Tropical Rubber Plantation from Hainan, Danzhou

The intensification of global climate change has made the study of greenhouse gas (GHG) emissions increasingly important. To gain a deeper understanding of the emission characteristics and driving factors of nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) from rubber plantation soils, this study conducted a 16-month continuous observation in a rubber plantation in Danzhou, Hainan, employing the static chamber method for the monthly sampling and measurement of GHG emissions while analyzing the soil’s physical and chemical properties. The results indicated that the N2O flux exhibited no significant diurnal variation between the dry and rainy seasons, with an average emission rate of 0.03 ± 0.002 mg·m−2·h−1. A clear seasonal trend was observed, with higher emissions in summer than in winter, resulting in an annual flux of 3 kg·hm−2·a−1 (equivalent to 1.9 kg N·hm−2·a−1). N2O emissions were significantly correlated with soil temperature and moisture, explaining 46% and 40% of the variations, respectively, while soil ammonium nitrogen content also significantly influenced N2O and CO2 emissions. The rubber plantation soil acted as a source of N2O and CO2 emissions and a sink for CH2, with lower emissions of N2O and CO2 during the daytime compared to nighttime, and higher CH4 uptake during the daytime. In the dry season, there was a significant positive correlation between N2O and CO2 emissions (R2 = 0.74, p &lt; 0.001). This study reveals the diurnal and seasonal patterns of GHG emissions from rubber plantation soils in Hainan and their interrelationships, providing a scientific basis for the low-carbon management of rubber plantations and GHG mitigation strategies, thereby contributing to attempts to reduce the impact of rubber cultivation on climate change.

Successive monoculture of Eucalyptus spp. alters the structure and network connectivity, rather than the assembly pattern of rhizosphere and bulk soil bacteria

Eucalyptus as a fast-growing timber tree plays a crucial role in maintaining wood supplication and ecosystem balance worldwide. Nonetheless, the management practices of Eucalyptus plantation in southern China have resulted in productivity decline and soil degradation due to high-intensity successive cultivation. Soil bacteria is a sensitive indicator of soil quality, how does the successive planting of Eucalyptus regulate the soil bacterial community structure for instance the abundance of oligotrophic bacteria, network complexity, and soil bacteria assembly remain ambiguity. To explicate the underlying influencing mechanisms of successive cultivation of Eucalyptus plantations on soil bacterial community structure. Four harvests of Eucalyptus plantations that underwent 0, 1, 2, and 3 times of harvesting were conducted to examine variations in the bacterial community between rhizosphere and bulk soils after successive planting of Eucalyptus. An adjacent evergreen broadleaf forest was employed as control. The present study revealed that successive planting of Eucalyptus increased and reduced the relative abundance of Chloroflexi (oligotrophic bacteria) and Proteobacteria (copiotrophic bacteria), respectively. Continuous planting of Eucalyptus did not modify the assembly pattern of soil bacterial communities, which was governed by stochastic processes. Successive planting of Eucalyptus decreased co-occurrence network complexity, and elevated the proportion of rare microorganisms in the keystone bacterial taxa. Soil particle size composition (clay, silt, sand) indirectly influenced the structure of soil bacterial communities by directly affecting pH, carbon, nutrients, and their stoichiometric ratios. Improving soil physical structure, increasing the input of soil carbon, nitrogen, and other nutrient resources, and maintaining a balanced resource allocation may be effective strategies for ensuring enhanced productivity and sustainable utilization of soil in successive Eucalyptus plantations.

Biochar affects organic carbon composition and stability in highly acidic tea plantation soil

Biochar amendments are effective in stabilizing soil aggregates and improving soil organic carbon (SOC) content. However, the effects of biochar on highly acidic soil and their relation with soil SOC stability remain understudied. The study aimed to investigate the impact of biochar on changes of aggregate distribution and SOC stability in a highly acidic tea plantation soils over an eight-year period. Soil samples were collected from plots with varying biochar application amounts (0, 2.5 t ha−1, 5 t ha−1, 10 t ha−1, 20 t ha−1 and 40 t ha−1). The content of SOC, iron bound organic carbon (OC-Fe), particulate organic carbon (POC), mineral-associated organic carbon (MAOC) and the functional group composition of SOC was analyzed. The results indicated that in the biochar application treatments, the value of soil pH, SOC, POC and MAOC contents were increased from 3.92 to 4.28, 6.68%–187.02%, 8.31%–66.78% and 13.07%–236.47% respectively, compared with CK, while the content of macro-aggregate (particle size>0.25 mm) and soil aggregates mean weight diameter (MWD) significantly increased with higher biochar application amounts. But dissolved organic carbon (DOC) and OC-Fe content exhibited downward trend, decreased from 2.43% to 6.97% and 4.18%–19.91%. Furthermore, aromatic-C levels increased, with increased biochar application amounts. The integration of biochar not only bolstered soil aggregate stability but also amplified the presence of aromatic-C, thereby enhancing the resilience of organic carbon in highly acidic tea garden soil (BC40 > BC20 > BC5>BC2.5 > BC10 > CK), with increases ranging from 6% to 47%. The principal component analysis and structural equation modeling identified soil pH, TN, SOC, POC, MAOC, R > 0.25 and MWD as key factors of soil organic carbon stability. These findings provide crucial insights into the mechanism underlying biochar's efficiency in fortifying organic carbon stability, particularly in the context of highly acidic soil.

Assembly and co-occurrence pattern of microbial communities in bulk and rhizosphere soils of Pinus elliottii plantations on sandy lands in China

Assembly and co-occurrence pattern of microbial communities in bulk and rhizosphere soils of Pinus elliottii plantations on sandy lands in China

Changes in soil organic carbon stocks and mineralization following the replacement of secondary evergreen broadleaf forests with tea (Camellia sinensis L.) plantations

AbstractTea plantation ecosystems have a strong potential to sequester carbon (C) and reduce CO2 emissions. However, the effects of different tea planting periods on soil organic carbon (SOC) stocks and mineralization and related mechanisms are unclear. To address this knowledge gap, we investigated the effects of replacing evergreen broadleaf forests with tea plantations on SOC stocks and mineralization rates by examining alterations in SOC pools and composition, microbial community composition, functional genes related to C‐cycling and enzyme activities. The SOC content in forest, 30‐, 50‐ and 100‐year‐old tea plantations were 1.91%, 2.37%, 2.87% and 3.69%, respectively, in the 0–20 cm soil depth (100‐year‐old &gt; 50‐year‐old &gt; 30‐year‐old &gt; forest). Cumulative CO2–C emissions increased by 38.1% (114 mg C kg−1 soil), 49.9% (157 mg C kg−1 soil), and 100.2% (171 mg C kg−1 soil) compared to forest soil (228 mg C kg−1 soil) after tea had been grown for 30, 50 and 100 years, respectively; however, cumulative CO2 emissions did not differ significantly between the 30‐ and 50‐year‐old plantations. The rate of SOC mineralization was positively related to particulate organic carbon (POC), water‐soluble organic carbon (WSOC), microbial biomass C (MBC), and O‐alkyl C contents, as well as β‐glucosidase/cellobiohydrolase activities and GH48/cbhI abundance; by contrast, the SOC mineralization rate was negatively correlated with the aromatic C content. More importantly, bacteria and fungi related to SOC mineralization, such as WPS‐2 and Acidobacteria, and Sordariomycetes, Tremellomycetes, Mortierellomycetes and Agaricomycetes, respectively, had high relative abundances. Our results indicate that replacing forests with tea plantations enhanced both SOC stocks and mineralization rates and that this effect was positively correlated with tea cultivation time. We reveal that an increased length of the tea planting period was conducive to increasing SOC stocks, and mitigating C losses in tea plantation soils is crucial for establishing an ecologically low‐C tea plantation system.

Effects of Fertilization and Planting Modes on Soil Organic Carbon and Microbial Community Formation of Tree Seedlings.

Biochar and organic fertilizer can significantly increase soil organic carbon (SOC) and promote agricultural production, but it is still unclear how they affect forest SOC after. Here, low-quality plantation soil was subjected to four distinct fertilization treatments: (CK, without fertilization; BC, tea seed shell biochar alone; OF, tea meal organic fertilizer alone; BCF, tea seed shell biochar plus tea meal organic fertilizer). Cunninghamia lanceolata (Lamb.) Hook and Cyclobalanopsis glauca (Thunb.) Oersted seedlings were then planted in pots at the ratios of 2:0, 1:1, and 0:2 (SS, SQ, QQ) and grown for one year. The results showed that the BCF treatment had the best effect on promoting seedling growth and increasing SOC content. BCF changed soil pH and available nutrient content, resulting in the downregulation of certain oligotrophic groups (Acidobacteria and Basidiomycetes) and the upregulation of eutrophic groups (Ascomycota and Proteobacteria). Key bacterial groups, which were identified by Line Discriminant Analysis Effect Size analysis, were closely associated with microbial biomass carbon (MBC) and SOC. Pearson correlation analysis showed that bacterial community composition exhibited a positive correlation with SOC, MBC, available phosphorus, seedling biomass, and plant height, whereas fungal community composition was predominantly positively correlated with seedling underground biomass. It suggested that environmental differences arising from fertilization and planting patterns selectively promote microbial communities that contribute to organic carbon formation. In summary, the combination of biochar and organic fertilizers would enhance the improvement and adaptation of soil microbial communities, playing a crucial role in increasing forest soil organic carbon and promoting tree growth.

Threshold and interaction effects of environmental variables affecting the spatial distribution of Pb

Understanding the spatial distribution of soil Pb and its potential influence mechanism is significant for controlling Pb pollution in tea plantations and guaranteeing food safety. The linear and nonlinear relationships between Pb and environmental variables have been widely studied, but the threshold and interaction effects of its environmental variables are often neglected. In this study, 81 tea plantation soils were collected and determined the thresholds and interaction effects of environmental variables on Pb through the GBDT model. The results revealed that the 10 selected environmental variables together explained 71.01 % of the variation in Pb content, with the top three factors being pH, total phosphorus (TP), and distance from roads (dis_road). Most environmental variable had threshold effects on Pb. By visualizing the interaction of pH, TP, and dis_road on Pb concentration, we show that both two-way and three-way interactions are able to further explain its variation. The interaction between TP and dis_road alone accounts for 5.70 %, between pH and dis_road alone accounts for 7.92 %, and between pH and TP alone accounts for 5.83 % of the variation in Pb concentration. However, the three-way interaction between pH, TP, and dis_road alone explains 11.85 % of the variation in Pb concentration. Understanding these interactions is important for gaining insight into the underlying processes leading to Pb pollution and promoting the tea industry’s sustainable development in China and abroad.

Carbon accumulation in the soil and biomass of macauba palm commercial plantations

Commercial cultivation of the Macauba palm is growing due to its agro-energy potential. This study quantified carbon stock in two macauba plantations (4.8 and 9.0 years old), considering carbon stored in soil and biomass. We assessed total organic carbon (TOC) stocks in labile (EOC and LF-C) and non-labile (NL-C) soil fractions, comparing these with a forest regenerating for over 30 years. Soil samples were collected within the palm plantation (rows and inter-rows) and the forest area at five depths (0–10, 10–20, 20–40, 40–60, and 60–100 cm). The impact of plantation age and sampling position on TOC stocks and organic matter fractions across different soil layers (0–100 cm) was assessed. The Carbon Management Index (CMI) was calculated to evaluate carbon recovery. Plantation age and sampling position influenced soil TOC stocks across all depths up to 1 m. Higher TOC and NL-C soil stocks were observed in the older plantation (9.0 years) and inter-row. EOC and LF-C fractions varied by soil layer. The inter-row region of the 9.0-year-old plantation exhibited higher carbon recovery based on the CMI. Over 4.2 years of palm cultivation (between 4.8 and 9.0 years), carbon accumulation in biomass and soil reached 75.36 Mg C ha−1. These findings underscore the potential of commercial macauba plantations to enhance soil carbon stocks rapidly, particularly in inter-row areas. Plantations younger than a decade surpassed the soil carbon stock of a forest regenerating for over 30 years, highlighting significant environmental benefits of macauba cultivation, including soil and biomass carbon sequestration.

Enhanced soil microbial stability is associated with soil organic carbon storage under high-altitude forestation

The potential of forestation to mitigate climate warming depends largely on whether it can improve terrestrial carbon (C) storage. Changes in soil microbial stability can cause ecosystem C fluctuations. Unfortunately, it remains unclear whether forestation alters soil microbial stability with cascading effects on C storage in high-altitude ecosystems. In this study, a total of 14 typical planted forests were selected on the Tibetan Plateau. We showed that high-altitude forestation, particularly with poplars, altered the microbial diversity and potentially improved the stability of soil microbial communities. These changes were associated with soil C accumulation and potentially positive feedback on soil organic C storage. Variations in the microbial community stability were mostly caused by changes in soil bulk density and dissolved organic C. Superior network stability was found in fungal community rather than bacterial community. Additionally, there were strong interactions between bacterial and fungal communities that influenced soil C storage. These findings contribute to understand the differences and relationships between bacteria and fungi in plantation soils. This work reveals the potential of high-altitude forestation to mitigate climate warming through insights into the microbial-mediated mechanisms responsible for soil C storage in high-altitude ecosystems.

Comparative research on monitoring methods for nitrate nitrogen leaching in tea plantation soils

Great concern has long been raised about nitrate leaching in cropland due to its possible environmental side effects in ground water contamination. Here we employed two common techniques to measure nitrate leaching in tea plantation soils in subtropical China. Using drainage lysimeter as a reference method, the adaptability of estimating drainage and nitrate leaching by combining the water balance equation with the suction cup technique was investigated. Results showed that the final cumulative leachate volume for the calculated and measured method was 721.43 mm and 729.92 mm respectively during the study period. However, nitrate concentration exerted great influence in the estimation of nitrate leaching from the suction cup-based method. The cumulative nitrate leaching loss from the lysimeter and suction cup-based method was 47.45 kg ha−1 and 43.58 kg ha−1 under lysimeter nitrate concentrations ranging from 7 mg L−1 to 13 mg L−1, 156.28 kg ha−1 and 79.95 kg ha−1 under lysimeter nitrate concentrations exceeding 13 mg L−1. Therefore, the suction cup-based method could be an alternative way of monitoring nitrate leaching loss within a range of 7–13 mg L−1 of nitrate concentrations in leachate. Besides, lower results occurred in suction cup samplers due to lack of representative samples which mainly leached via preferential flow when in strong leaching events. Thus, it is advisable to increase sampling frequency under such special conditions. The results of this experiment can serve as a reference and guidance for the application of ceramic cups in monitoring nitrogen and other nutrient-ion leaching in tea plantation soils.

Characterization of Silver Nanoparticles Synthesized With Fungi Isolated From Cocoa and Orange Plantation Soils

Green synthesis of nanoparticles with various metals is being interested among researchers globally attention for due to their safety, environmental friendliness and non-toxicity in contrast to chemical synthesis. Here, fungi were isolated from rhizosphere of cocoa and orange obtained from Federal University of Technology, Akure using standard mycological techniques with the aim of synthesizing silver nanoparticles. The silver nanoparticles synthesized by these fungal isolates were characterized using Ultraviolet-Visible (UV-Vis) and Fourier Transmission Infra- Red (FTIR) spectroscopy. Seven fungi isolated from the soil samples viz. Nigrospora sphaerica, Penicillium discolor, P. digitatum, Neurospora crassa, Alternarium infectoria, Trichophyton verrucosum and Mucor mucedo. The colour transformation from yellow to brown indicated the formation of silver nanoparticles. All the isolates showed an intense peak in the wavelength range of 410-440 nm. The FTIR analysis of silver nanoparticles synthesized by N. sphaerica, P. discolor, P. digitatum, N. crassa, A. infectoria, T. verrucosum and M. mucedo revealed the existence of a band at different stretches of bonds at different peaks of 3314.36 cm-1, 3310.47 cm-1, 2412.22 cm-1, 3912.33 cm-1 3614.52 cm-1, 3852.11 cm-1 and 2112.11 cm-1, respectively. The silver nanoparticles synthesized could have the potential application in agricultural, pharmaceutical and food industries as well as petrochemical industries for the clean - up of crude oil contaminated soils. J. Bio-Sci. 32(2): 31-44, 2024

Soil pH-dependent efficacy of DMPP in mitigating nitrous oxide under different land uses

The emission pathways and intensities of nitrous oxide (N2O) vary across land uses, and the efficacy of mitigation measures may also differ. To investigate the key factors influencing the effectiveness of the nitrification inhibitor 3,4-Dimethylpyrazole phosphate (DMPP) in mitigating N2O under various land use conditions, we collected ten pairs of soils from tea plantations and adjacent cultivated land for laboratory incubation. As a complementary study, we conducted a meta-analysis based on 261 pairs of observations from 40 incubation studies to investigate the determinants of soil N2O mitigation by DMPP and to validate our experimental results. Results of the incubation experiment showed that DMPP was significantly less effective in mitigating N2O in tea plantation soils (73%) than in cropland soils (82%). Soil pH is a key factor influencing DMPP efficiency under different land use conditions. The lower pH of acidic tea plantation soils resulted in lower abundance and activity of ammonia-oxidizing bacteria (AOB). Under these low pH conditions, heterotrophic nitrification became an important source of N2O emissions in acidic tea plantation soils. As DMPP primarily inhibits AOB, it was less effective against heterotrophic nitrification, which likely contributed to its reduced efficacy in tea plantation soils compared to cropland soils. Our meta-analysis further confirmed the critical role of soil pH in determining DMPP effectiveness. The effect of soil pH on DMPP efficacy was mainly attributed to its regulation of heterotrophic and AOB-derived nitrification. These findings suggest that the field efficacy of DMPP in N2O abatement in tea plantations requires further investigation. Given the significant contribution of heterotrophic nitrification to N2O emissions in strongly acidic tea plantation soils, alternative N2O mitigation strategies should be explored.

Assessment of nutrient status, macro faunal diversity and microbial isolates in date palm plantation in Damaturu Yobe State, Nigeria

This research assessed nutrient status, macro-faunal diversity and microbial isolates in the soil of date palm plantation in Mai Sandari Damaturu, Yobe State. Parameters evaluated include; data on nutrient status of soils, assemblage and diversity of soil macro invertebrates and assemblage of microbial isolates based on growth performances of the date palm. The plantation was divided according to growth variabilities. Eighteen (18) auger points were taken, six (6) in each performance site based on the corresponding variability as observed. Soil samples were collected within same points for physicochemical analysis, microbial isolates and for soil macro-invertebrates ‘identification and enumeration. One-way Analysis of Variance (ANOVA) was used to compare results of nutrient status of soils and to test for significant differences in nutrient concentration of the soils samples, mean separation was done using Least Significant Difference (LSD). Soil macro-invertebrate assemblage was analyzed for diversity indices of species using relevant formulae. Nutrient agar medium at 105 dilutions inoculated in a petri-dishes and incubated at 30±10°C for 2-5 days for bacteria colonies, while for fungi and actinomycetes, sabaurond dextrose agar was used at 25°C for 5-7 days and afterward microorganisms per colony forming units (Cfu) were counted. Analysis of variance for the soil parameters tested at p≤ 0.05 level of significance showed no significant differences in all the parameters of soil physical properties based on growth performance sites. However, organic carbon, organic matter and TN vary significantly after the post-hoc tests across growth performance sites in chemical properties (p ≤ 0.05). Results showed a total of 2646 macro fauna scattered within the study area. Eleven (11) families of macro fauna were also identified in the study. Results from the study area showed that the area is highly rich in microorganisms. A total of 5096 colonies were scattered within 10 families in the study area. The finding of this study revealed that there was no significant difference among the physical properties across the study site leading to the conclusion that soil physical properties may not have been responsible for the observed differences in the growth of the Date Palm Plantation. A different pattern was however observed in the values of the chemical properties of the plantation where significant differences exist in organic carbon, organic matter and total nitrogen across these sites. Based on the findings of the study it is recommended that all application of agrochemicals except fertilizers in the plantation should be suspended until evidence of their efficiency on the palm trees is shown.