Soil Chemical Fertility Research Articles

Changes in Soil Chemical Attributes in an Agrosilvopastoral System Six Years After Thinning of Eucalyptus.

The changes in soil chemical attributes in agrosilvopastoral systems after the thinning of trees are unclear. To address this gap, this study evaluated the effects of the thinning of eucalyptus hybrid Urograndis H-13 (Eucalyptus urophylla S. T. Blake × E. grandis W. Hill ex Maiden) on soil chemical fertility in an agrosilvopastoral system in an Arenic Hapludalf in Brazil. The experimental design was a randomized block with a 3 × 4 factorial design comprising three treatments (thinning of 0%, 50%, or 100% of the eucalyptus trees) and four sampling positions relative to the eucalyptus line (0, 2.0, 4.0, and 6.0 m). Six years after eucalyptus thinning, soil acidification was observed in the 0% and 50% eucalyptus thinning treatments, especially at 0 and 2 m from the eucalyptus line. Decreases in soil pH were associated with increases in the total acidity pH 7.0 (H+ + Al3+) and Al3+ content and decreases in the K+, Ca2+, and Mg2+ contents and base saturation over the soil profile (0-1.0 m).

Evaluation of Variable Rates of Zinc Sulfate Fertilization on Soil Chemical Characteristics, Fertility Status, and Growth Components of Wheat (Triticum aestivum): A Case Study on the Hilly Region of Uthal, Balochistan

Evaluation of Variable Rates of Zinc Sulfate Fertilization on Soil Chemical Characteristics, Fertility Status, and Growth Components of Wheat (Triticum aestivum): A Case Study on the Hilly Region of Uthal, Balochistan

Impact of Intercropping Five Medicinal Plants on Soil Nutrients, Enzyme Activity, and Microbial Community Structure in Camellia oleifera Plantations.

Intercropping medicinal plants plays an important role in agroforestry that can improve the physical, chemical, and biological fertility of soil. However, the influence of intercropping medicinal plants on the Camellia oleifera soil properties and bacterial communities remains elusive. In this study, five intercropping treatment groups were set as follows: Curcuma zedoaria/C. oleifera (EZ), Curcuma longa/C. oleifera (JH), Clinacanthus nutans/C. oleifera (YDC), Fructus Galangae/C. oleifera (HDK), and Ficus simplicissima/C. oleifera (WZMT). The soil chemical properties, enzyme activities, and bacterial communities were measured and analyzed to evaluate the effects of different intercropping systems. The results indicated that, compared to the C. oleifera monoculture group, YDC and EZ showed noticeable impacts on the soil chemical properties with a significant increase in total nitrogen (TN), nitrate nitrogen (NN), available nitrogen (AN), available phosphorus (AP), and available potassium (AK). Among them, the content of TN and AK in the rhizosphere soil of Camellia oleifera in the YDC intercropping system was the highest, which was 7.82 g/kg and 21.94 mg/kg higher than CK. Similarly, in the EZ intercropping system, the content of NN and OM in the rhizosphere soil of Camellia oleifera was the highest, which was higher than that of CK at 722.33 mg/kg and 2.36 g/kg, respectively. Curcuma longa/C. oleifera (JH) and Clinacanthus nutans/C. oleifera (YDC) had the most effect on soil enzyme activities. Furthermore, YDC extensively increased the activities of hydrogen peroxide and acid phosphatase enzymes; the increase was 2.27 mg/g and 3.21 mg/g, respectively. While JH obviously increased the urease activity, the diversity of bacterial populations in the rhizosphere soil of the intercropping plants decreased, especially the Shannon index of YDC and HDK. Compared with the monoculture group, the bacterial community abundance and structure of JH and YDC were quite different. The relative abundance of Actinobacteriota and Firmicutes was increased in YDC, and that of Acidobacteriota and Myxococcota was increased in JH. According to the redundancy analysis (RDA), pH, total potassium, and soil catalase activity were identified as the main factors influencing the microbial community structure of the intercropping systems. In conclusion, intercropping with JH and YDC increased the relative abundance of the dominant bacterial communities, improved the microbial community structure, and enhanced the soil nutrients and enzyme activities. Therefore, in the future, these two medicinal plants can be used for intercropping with C. oleifera.

Analysis of Chemical Properties and Soil Fertility Status in Paddy Fields in Sakti Sub-district, Pidie Regency, Aceh

Analysis of Chemical Properties and Soil Fertility Status in Paddy Fields in Sakti Sub-district, Pidie Regency, Aceh

Divergent responses between lineages of arbuscular mycorrhizal fungi to soil phosphorus and nitrogen availability

Arbuscular mycorrhizal (AM) associations are multifunctional. Two important functions they perform are facilitating nutrient uptake in host plants and protecting plants from biotic stress, among other functions. AM fungal taxa vary in how capably they perform these functions and can also respond differently to environmental selection. Therefore, there is a need to better understand how particular environmental variables might alter the response of AM fungal communities. Here, we analysed data from a DNA-based survey of fungal communities in soils collected throughout Australia to observe relationships among soil nitrogen and phosphorus availability and the abundance of two AM fungal taxa that reportedly vary in function – the Gigasporaceae (putatively more important for nutrient uptake) and Glomeraceae (putatively more important for biotic stress). Relationships were assessed in three vegetation types – grasslands, forests and woodlands – to assess whether associations with soil nutrition varied depending on carbon availability for AM fungi. Fungi from the Gigasporaceae decreased in frequency as available phosphorus increased, while those from the Glomeraceae increased or were unresponsive as available phosphorus increased. Similar patterns were observed for nitrate availability, although only in woodlands. These patterns are consistent with expectations that AM fungi from the Gigasporaceae, in general, are better suited to alleviate nutrient limitation in hosts as soil chemical fertility decreases. This knowledge may aid in implementing optimal strategies involving AM fungal inoculum best suited to the local conditions of future land management and agricultural projects.

Municipal solid waste compost use can improve crop barley production and enhance soil chemical fertility

The study aims to point out the effect of municipal solid waste compost (MSWC) and traditional mineral fertilizers use, on rainfed forage barley herbage and grain production, nutritive value, and on soil chemical characteristics. During a three-year field trial, the MSWC treatments were COM1, 20 Mg ha−1 (DM) applied each year; COM2, 20 Mg ha−1 applied only the first year. The mineral fertilization was MIN50 (50 kg ha−1 of N + 46 kg ha−1 of P2O5), and MIN100 (100 kg ha−1 of N + 92 kg ha−1 of P2O5), applied each year. Fertilization treatments were compared with unfertilized control (COM0 and MIN0). Two years out of three COM1 showed a significant higher barley herbage dry matter (HDM) production and CP, when compared to COM0. COM1 in one year increased grain yield (YLD) whereas increased CP all years and decreased starch grain content two years out of three. MSWC strongly increased levels of sodium (Na) in herbage and grain. Mineral fertilizers levels significantly increased HDM production and YLD and their CP content compared to MIN0. Moreover, it lightly decreased herbage NDF, ADF, WSC and Total phenols content, raising in vitro dry matter digestibility (IVDMD). In soil, after three years of fertilization, COM1 increased SOC (Soil Organic Carbon), Total N, available P, exchangeable K and Mg content, but also exchangeable sodium percentage (ESP) and electrical conductivity (EC), showing higher values than COM2 and COM0. Mineral fertilization influenced only the available P soil level, increasing the content compared to MIN0. This paper pointed out that mineral fertilizers had clear short-term effects on the barley growth, yield, and nutritional value, but did not contribute to soil long-term fertility improvement. MSWC increased barley growth and yield reaching similar values obtained with mineral fertilizers. Above all, MSWC showed capability to improve soil fertility mainly in terms of organic matter and macronutrients and its use is consistent with the recent EU regulation on organic fertilizer productions (2018/84) that aims to “maintaining the long-term fertility of soils”.

Size spectra of the edaphic fauna of typical Argiudol soils of the Rolling Pampa Region, Argentina.

Soil-dwelling organisms populate the spaces-referred to as interstices-between the litter on the soil surface and the pores in the soil's organo-mineral matrix. These organisms have pivotal roles in soil ecosystem functions, such as the breakdown and decomposition of organic matter, the dispersal of bacterial and fungal spores and biological habitat transformation. These functions, in turn, contribute to broader ecosystem services like carbon and nutrient cycling, soil organic matter regulation and both chemical and physical soil fertility.This study provides morphological data pertaining to a range of soil organism sizes, specifically in Argiudol soils subjected to varying levels of agricultural activity in the Rolling Pampas Region, one of the world's most extensive and fertile plains.The primary focus is on soil microarthropods-namely, Acari (mites) and Collembola (springtails)-with a body width of less than 2 mm. These organisms constitute the majority of life in the intricate soil pore network. Additionally, the study documents species of earthworms (Oligochaeta, Crassiclitelata), recognised as ecosystem engineers for their ability to create physical channels in the soil matrix and to distribute organic matter. Moreover, the study includes measurements of morphological traits of soil-dwelling "macrofauna" (organisms with a body width greater than 2 mm), which are also implicated in various soil ecosystem functions. These include population regulation by apex predators, organic matter decomposition, biogenic structure formation, nutrient mobilisation and herbivory. In this paper, we report both the geographical locations and individual measurements of key morphological traits for over 7,000 specimens, covering a range of soil-dwelling organisms. These include springtails (Entognatha, Collembola), mites (Arachnida, Acari), earthworms (Oligochaeta, Crassiclitellata) and additional soil macrofauna. All specimens were collected from typical Argiudol soils located in three distinct agricultural systems characterised by varying levels of land-use intensity. To our knowledge, no other dataset exists providing this information for the Argentinian Pampas.

Soybean yield, seed protein and oil concentration, and soil fertility affected by off-season crops

The main cropping system in Brazil is soybean-maize off-season, particularly in tropical climate regions. However, there is a lack of information about the effects of alternative off-season crops on soybean performance and soil chemical fertility. The objective of this study was to evaluate, in a long-term experiment, the effects of off-season crops on soybean yield, seed protein and oil concentration, and soil chemical fertility under a no-tillage system. A seven-year experiment was conducted in Londrina, Paraná, Brazil. Treatments comprised six crop systems in the soybean off-season: (i) maize with nitrogen (N) fertilizer topdressing (80 kg N ha−1, (ii) maize without N fertilizer topdressing, (iii) wheat without N fertilizer topdressing, (iv) ruzigrass (Urochloa ruziziensis) without fertilizers, (v) showy rattlebox (Crotalaria spectabilis) without fertilizers, and (vi) unplanted fallow. Maize and wheat were used as cash crops and ruzigrass and showy rattlebox as cover crops. Ruzigrass had the highest straw production (average of 6.8 Mg ha−1 year−1) and improved soil fertility, especially organic carbon and potassium concentrations in the superficial soil layer. Ruzigrass and wheat off-season provided the highest soybean yields in succession (4311 and 4228 kg ha−1, respectively), whereas maize without N and fallow resulted in the lowest soybean yields (3841 and 3825 kg ha−1, respectively). Ruzigrass off-season provided the greatest yield stability of soybean and the fallow the lowest yield stability (coefficients of variation of 14.70 % and 23.78 %, respectively). The highest soybean seed protein concentration was observed with ruzigrass (368 g kg−1) and the lowest with fallow (353 g kg−1). The highest seed oil concentration was observed in maize with N and showy rattlebox (224 g kg−1 for both off-season crops) and the lowest with wheat (216 g kg−1). The ruzigrass provided the highest soybean seed protein and oil yields (1586 and 945 kg ha−1) and fallow the lowest (1352 and 845 kg ha−1). The ruzigrass used as soybean off-season cover crop improved the soil chemical fertility and soybean grain yield.

Long-term effects of biochar on soil chemistry, biochemistry, and microbiota: Results from a 10-year field vineyard experiment

Application of biochar to soil has been recommended as a carbon sequestration approach that can also improve soil physical and chemical properties. The addition of biochar to soil can change the physicochemical properties of the soil, leading to a subsequent modification of the microbial community. However, the long-term implications of these changes remain insufficiently elucidated. Here, we examined soil chemical and biochemical properties of the bulk soil and employed next-generation sequencing techniques to analyze the microbiological properties of both bulk and rhizosphere soils after 10 years of biochar application. Specifically, we compared these properties between soil treated with two doses of biochar, i.e., SB and DB, and untreated soil, i.e., CK. After 10 years, biochar application increased the soil organic carbon from 12.7 g.kg−1 in CK to 17.3 and 23.1 g.kg−1, in SB and DB, respectively. Moreover, biochar application led to a slight decrease in soil bulk density, and increased the soil pH value 6.33 in CK to 7.07 in DB. Moreover, our findings revealed a distinct taxonomic signature within bacteria; however, this signature was not observed in terms of diversity. Specifically, we observed an increase in the abundance of oligotrophic bacteria compared to copiotrophic bacteria. The double dose of biochar increased the fungal species richness in the rhizosphere, particularly of Basidiomycota yeasts, from a relative abundance of 9.4 % in the CK soil to 17.0 % in the SB soil and 24.8 % in the DB soil and reduced putative plant pathogens like Phaeoacremonium and Aspergillus. Biochar amendment can significantly improve soil physical, chemical, and biological fertility on the long-term even under intensive viticulture management, with no detectable detrimental effects on microbial diversity and soil functions, and potential of soil organic carbon storage.

Sustainable Restoration of Soil Functionality in PTE-Affected Environments: Biochar Impact on Soil Chemistry, Microbiology, Biochemistry, and Plant Growth

Biochar can be useful for the functional recovery of soils contaminated with potentially toxic elements (PTEs), even if its effectiveness is variable and sometimes limited, and conflicting results have been recently reported. To shed some light on this regard, softwood-derived biochar was added at 2.5 (2.5-Bio) and 5.0% w/w (5.0-Bio) rates to an acidic (pH 5.74) soil contaminated by Cd (28 mg kg−1), Pb (10,625 mg kg−1), and Zn (3407 mg kg−1). Biochar addition increased soil pH, available P and CEC, and reduced labile Cd, Pb, and Zn (e.g., by 27, 37, and 46% in 5.0-Bio vs. the unamended soil). The addition of biochar did not change the number of total heterotrophic bacteria, actinomycetes, and fungi, while it reduced the number of Pseudomonas spp. and soil microbial biomass. Dehydrogenase activity was reduced in amended soils (e.g., by ~60 and 75% in 2.5- and 5.0-Bio, respectively), while in the same soils, urease increased by 48 and 78%. Approximately 16S rRNA gene amplicon sequencing and the Biolog community-level physiological profile highlighted a significant biochar impact (especially at a 5% rate) on soil bacterial diversity. Tomato (but not triticale) yield increased in the amended soils, especially in 2.5-Bio. This biochar rate was also the most effective at reducing Cd and Pb concentrations in shoots. Overall, these results demonstrate that 2.5% (but not 5.0%) biochar can be useful to restore the soil chemical fertility of PTE-polluted soils with limited (or null) impact on soil microbial and biochemical parameters.

The effect of interaction of types and dosages of liquid organic fertilizer on eggplant (Solanum melongena L.) growth and outcome

The use of liquid organic fertilizer (POC) is expected to improve soil physical, chemical and biological fertility. Soil fertility increases, maximum plant growth will increase production both in quality and quantity. This study aims to determine the effect of the interaction between the type of treatment and the dose of POC on the growth and production of eggplant. This study was a factorial experiment consisting of two factors, namely POC types consisting of 2 levels: POC kitchen waste (P1); Banana weevil POC (P2) and POC doses consisting of 4 levels: without POC (D0); 10 ml/tan (D1); 20 ml/tan (D2); 30 ml/tan (D3) with randomization according to a completely randomized design (CRD). Observations were made when the eggplant plants were 10 HST with an interval of 10 days until the plants were 40 days old. The parameters observed were plant height, number of leaves, stem diameter, fruit length per plant, fruit diameter, number of fruit per plant, and fruit weight per plant. Observational data were analyzed using variance, if the results were significantly different it was continued with the smallest significant difference test (LSD) at the 5% level. The results showed that there was no significant interaction between the type of treatment and the dose of POC on all observed parameters. The various POC treatments significantly affected the parameters of plant height and number of leaves at all observed ages, stem diameters at 20 30, 40 DAP, and fruit weight per plant. POC dose treatment significantly affected the parameters of plant height and number of leaves at all ages of observation, stem diameter at 20, 30, and 40 DAP, number of fruit and fruit weight of the plants. Giving banana weevil POC resulted in better eggplant growth and production than kitchen waste POC. POC dose of 30 ml/plant resulted in the best eggplant growth and production. Because the results of the study showed that the effect of POC dose was still linear (the higher the POC dose, the higher the production).

Immediate changes in soil chemical and biological fertility and short-term changes in soil biological activity following bench terrace construction for eucalypt reforestation

Over the last decades, eucalypt plantations have increasingly involved intensive soil mobilization by heavy machinery. In north-central Portugal, bench terracing with bulldozers has become a common practice for eucalypt re-/afforestation. Its impacts on soil properties and functions, however, have received little research attention so far.The present study aimed to address the changes in topsoil fertility from immediately before to immediately after the construction of terraces. This was done for two contrasting micro-sites (tree-patch and inter-patch). Topsoil fertility was characterized in terms of both total and labile carbon and nitrogen as well as available phosphorous. In addition, this study aimed to assess the short-term impacts of terracing on soil respiration, as an indicator of soil biological activity. Soil respiration was monitored at monthly intervals during the first year following terracing at the terraced as well as at a nearby, non-terraced eucalypt plantation.The construction of bench terraces led to a significant immediate reduction in topsoil contents of total and labile carbon and nitrogen as well as available phosphorus. The reductions were inferred to result from the mixing of the A, B, C and R horizons, in combination with a priming effect due to soil aeration and resulting exposure of carbon and nitrogen compounds to soil micro-organisms. Bench terrace construction furthermore increased spatial heterogeneity in topsoil fertility, turning differences in carbon, nitrogen and phosphorus contents between tree and inter-patches significant immediately afterwards. Likewise, soil respiration tended to be significantly different between tree-patches and inter-patches at the terraced site but not between tree-patches and inter-patches at the neighbouring non-terraced site. These short-term impacts of bench terracing on the spatial patterns in soil respiration are likely to reflect its immediate impacts on the spatial patterns in soil fertility. The present findings plainly justified further research on the medium and long-terms« impacts of bench terracing on eucalypt soil properties and functions.

The Impact of traditional cocoa-based agroforestry systems on chemical soil fertility in southwest of Côte d'Ivoire

The sustainability of cocoa farming is a major concern for Côte d'Ivoire. Extensive and "full sun" cropping systems need to be reviewed. Against this backdrop, a study was carried out in the south-west of the country (Soubré and Méagui), a major production zone, with the aim of assessing the impact of traditional agroforestry systems on soil fertility. Twenty-seven cocoa farms in the three sectors were visited. To assess the impact of cocoa-based agroforestry systems on soil chemical parameters, four criteria guided the choice of plots. These were mid-slope plots, 25 to 35 years old, unfertilized and denser in associated trees. Soil samples were taken from the 0-20 cm horizon. Organic carbon, total nitrogen, assimilable phosphorus, exchangeable bases (Ca, Mg, K and Na), cation exchange capacity and saturation rate were measured. The results show that traditional cocoa-based agroforestry systems have not impoverished the soil. In fact, chemical fertility in these plots respects the needs of cocoa trees. However, the study did not show an increase in soil organic matter due to the fall of leaves from associated trees. These results will enable the use of traditional agroforestry systems without fear of soil impoverishment due to any competition between cocoa trees and associated trees.

Respon Pertumbuhan Pakcoy (Brassica chinensis L.) terhadap Pemberian POC Limbah Baglog Jamur dan Kulit Semangka

Pakcoy (Brassica chinensis L.) is a vegetable from the Brassicaceae family. Pakcoy is a short-lived plant. Pakcoy contains fat, protein, Fe, Ca, P, Vitamins A, B, C, E, and K, with that pakcoy is very good for health and has prospects for high economic value. The first factor affecting the decline in pakcoy production is soil fertility. The continuous use of land with chemical fertilizers results in a decrease in biological, chemical and physical soil fertility, one of the efforts to overcome this problem is to improve cultivation techniques through fertilization. This study aims to determine the growth response of the pakcoy plant by administering liquid organic fertilizer from mushroom baglog waste and watermelon rinds. This study used a factorial complete randomized design with 2 factors, namely the interval of watering of liquid organic fertilizer and the volume of organic fertilizer dilution concentration and used quantitative descriptive analysis with the Two Way ANOVA test. The purpose of this study was to determine the growth response of the pakcoy plant to the application of liquid organic fertilizer from mushroom baglog waste and watermelon rinds. The results of this study indicated that the TIV3 treatment (watering interval once every 3 days with a volume of 30% dilution concentration) gave a response to plant height with an average of 18.05 cm, number of leaves with an average of 6 leaves, and an average fresh weight of 11.50 g.

Evolution of Soil Chemical Fertility in an Area under Recovery for 30 Years with Anthropic Intervention

The investigation and application of recovery techniques associated with the use of qualitative and quantitative indicators enable the ecological restoration of these sites. In this context, the main difficulty consists of establishing the A horizon, capable of supporting the emergence of other horizons, choosing appropriate species, and adding organic matter to the soil in a balanced way. Thus, this study aimed to evaluate over time (1992 to 2022) the chemical properties of a stripped oxisol that has been in the recovery process for 30 years, using liming, gypsum, and plant species. All treatments were cultivated with Urochloa decumbens (Stapf.) in 1999 and tree species in 2010, and the contents of phosphorus, organic matter, pH, and base saturation. ANOVA and Scott–Knott test (5%), Pearson correlation, and response surface analysis were performed for each studied soil attribute. The results showed that the treatments with green manure + limestone + gypsum had the highest values of organic matter compared to the recovery treatments and that the treatments have been efficient in soil recovery. Therefore, the soil undergoing recovery showed an increase in P, OM, pH, and base saturation until 2011, and the response surface method was the most efficient in analyzing the results over time.

A Novel Ameliorant Biochar of Areca Nuts Skin and Sago Bark Waste for Increasing Soil Chemical Fertility

The waste of areca nuts skin and sago bark are alternatives of ameliorant material that can be used to support soil quality improvement. This research aims to study the potential of areca nuts and sago bark to be produced as biochar and to identify the chemical components they contain. The study employed a Completely Randomized Designed involving six treatments repeated three times. The observation parameters of soil chemical analysis, including the measurement of pH H2O (pH meter); Total-N (Kjeldahl); Available-P (Bray I); Exchangeable Cations (NH4OAC pH 7.0); and exchangeable-Al (KCl 1N). Data obtained from observation were statistically analyzed through the ANOVA method, and if they had a significant effect, the analysis was continued with Duncan’s Multiple Range Test (DMRT) at the level of α=5%. Findings showed that the administration of biochar can improve soil quality. Based on the analysis, biochar from sago bark waste brings a significant effect on increases of pH (5.26), available-P (12.99 cmol+kg-), Exchangeable-K (2.16 cmol+kg-), Exchangeable-Na (0.21 cmol+kg-), Exchangeable-Ca (4.83 cmol+kg-), Exchangeable-Mg (3.80 cmol+kg-), and the reduction of soil Exchangeable-Al (6.65 cmol+kg-). In comparison, biochar from betel nut peel waste has a significant effect on Total-N (0.15%), C-organic (1.66%), and CEC (23.38 cmol+kg-). The results of this study will be the basis for further research in utilizing agricultural waste so that the right combination of fertilizers is obtained to increase soil fertility and will indirectly increase crop production, especially in West Papua.

Data fusion of XRF and vis-NIR using p-ComDim to predict some fertility attributes in tropical soils derived from basalt

X-ray fluorescence (XRF) and visible and near-infrared (vis-NIR) spectroscopies have been capable of predicting soil properties. Both techniques enable environmentally friendly soil analysis with minimal or no sample preparation, providing information about inorganic and organic-mineral soil components. Recent studies have demonstrated that XRF and vis-NIR data fusion may improve the quality of predictive models for soil attributes. Although promising results have been related to the vis-NIR and XRF data fusion for soil analysis, no approach has been consistently optimal. In some cases, the data fusion worsened the models' performance compared with individual models. Moreover, most of these studies are focused on model performance. Few studies assess the synergism among different techniques and how their complementarities/differences may improve the knowledge about the sample spectral responses. For this purpose, this study aimed to assess p-ComDim analysis as a mid-level data fusion approach for soil fertility prediction using vis-NIR and XRF data. Complementarily, p-ComDim results were compared with vis-NIR and XRF individual models and low- and high-level data fusion approaches. Soil organic carbon (SOC), exchangeable calcium (Ca2+) and magnesium (Mg2+), pH, the sum of base (SB), and cation exchange capacity (CEC) were considered representative variables of the soil chemical fertility. A relative improvement ranging from 5% to 33% was observed comparing p-ComDim with vis-NIR and XRF individual models. Moreover, p-ComDim results were better when compared with the two data fusion approaches most used in literature for soil fertility prediction (low- and high-level data fusion). In addition, the p-ComDim analysis allowed extracting the weights (saliences) of each technique as well as the synergism among their variables to predict each attribute, demonstrating that the most important common dimensions (CDs) to the predictive models in all analyzed attributes were those with higher silences in the XRF block. It shows the synergism among different spectral ranges and the potential of p-ComDim for vis-NIR and XRF data fusion in soil fertility prediction. Therefore, the results from the present study may contribute to a better understanding between soil sample constituents and spectral responses, assisting in the explainability of the multivariate regression models.

Remediating petroleum hydrocarbons in highly saline–alkali soils using three native plant species

Phytoremediation of total petroleum hydrocarbons (TPHs) contamination is a process that uses the synergistic action of plants and rhizosphere microorganisms to degrade, absorb and stabilize pollutants in the soil, and has received increasing attention in recent years. However, this technology still has some challenges under certain conditions (e.g., highly alkaline and saline environments). The present study was selected three native plant species (alfalfa, tall fescue, and ryegrass) to remediate petroleum pollutants in greenhouse pot experiments. The results indicate that TPH contamination not only inhibited plant growth, soil chemical properties and soil fertility (i.e. lower plant biomass, chlorophyll, pH, and electrical conductivity), but also increased the malondialdehyde, glutathione, and antioxidant enzyme activities (catalase and polyphenol oxidase). Further, correlation analysis results illustrated that TPH removal was strongly positively correlated with chlorophyll, soil fertility, and total organic carbon, but was negatively correlated with dehydrogenase, polyphenol oxidase, pH, and electrical conductivity. The highest TPHs removal rate (74.13%) was exhibited by alfalfa, followed by tall fescue (61.79%) and ryegrass (57.28%). The degradation rates of short-chain alkanes and low rings polycyclic aromatic hydrocarbons (PAHs) were substantially higher than those of long-chain alkanes and high rings PAHs. The findings of this study provide valuable insights into petroleum decontamination strategies in the highly saline - alkali environments.

Structural equation model was used to evaluate the effects of soil chemical environment, fertility and enzyme activity on eucalyptus biomass.

This paper aims to reveal the effects of multi-generational succession of eucalyptus on soil fertility, organic structure and biological properties. Soil samples were collected from eucalyptus plantations of different stand ages (5, 11, 17 and 21 years old) in a typical area in south Asia, soil organic fraction structure and content characteristics were investigated using Fourier transform infrared (FTIR), and structural equation modelling (SEM) was used to explore influences of soil fertility, enzyme activity and organic fraction on stand biomass. FTIR analysis showed that 11 infrared absorption peaks existed in the soils of this study area, attributed to silicates, aromatics, carbonate ions, sugars, esters, polysaccharides, aliphatic hydrocarbons and phenolic alcohols. Combined with the results of peak area integration, the content of esters, aromatics and phenolic alcohols was significantly higher in 17- and 21-year-old stand soils than in control soils. The results of SEM showed that organic components were negatively related (p < 0.01) to enzyme activity and biomass, with standardized coefficients of 0.53 and 0.49, respectively. In summary, multi-generation succession of eucalyptus trees can change the structure of soil organic functional group composition and promote the enrichment of aromatic and phenolic alcohol functional groups. Such changes can directly inhibit the increase in eucalyptus biomass and indirectly negatively affect biomass by inhibiting enzyme activity.

Shifting Long-Term Tillage to Geotextile Mulching for Weed Control Improves Soil Quality and Yield of Orange Orchards

Weed control in urban and peri-urban orange orchards is challenging due to operational and legislative restrictions. Tillage, besides from negatively affecting soil fertility and microorganisms, is demanding for humans. On the other hand, herbicides are advised against due to the possibility to reach waterbodies from the soil surface. Therefore, in urban and peri-urban areas, instead of tillage and herbicides, mulching with black plastic geotextile fabric is often used. This study aimed at assessing the impact of long-term soil mulching with black plastic geotextile fabric on soil fertility, microbial community and yield of an orange orchard in comparison to conventional tillage. To this aim, four soil management systems were set up: rotary tillage for the last 15 years, mulching with black plastic geotextiles for the last 15 years, rotary tillage for 7 years followed by mulching for the last 8 years, mulching for 7 years followed by rotary tillage for the last 8 years. Soil samples were analyzed to determine the chemical and biochemical parameters related to soil fertility. In addition, the abundances of the main microbial groups were investigated. Mulching increased soil total organic C at least by 65%. The greater soil organic C in mulched soil in turn contributed to increase the cation exchange capacity (+62% on average) and microbial biomass C (+120% on average). Additionally, the microbial quotient exhibited higher values in mulched soils compared to tilled ones, suggesting a greater soil organic matter accessibility by soil microorganisms. Moreover, mulching favored fungi over bacteria, and Gram-positive bacteria over Gram-negative bacteria, thus contributing to the establishment of a microbial community more efficient in utilizing C sources. The latter result was confirmed by the lower values of the metabolic quotient in mulched soil compared to tilled one. Overall, the black plastic geotextile fabric improved chemical and biochemical soil fertility that, in turn, lead to a higher orange yield in mulched soil.