Basal Soil Research Articles

Zinc fortification and legume incorporation in forage based cropping systems: Implications for yield and nutrient dynamics

Aim: To evaluate the synergistic effects of legume intercropping and zinc fortification on forage yield, and plant and soil nutrient dynamics. Methodology: The experiment was laid out in a Factorial Randomized Block Design. Treatment combinations included five cropping systems, i.e., sole maize, sole cowpea, sole soybean, maize + cowpea (2:1), maize + soybean (2:1) and three zinc levels; Zn0= control or no zinc application, Zn1 = 20 kg ZnSO4 ha-1 (basal soil application) and Zn2 = 20 kg ZnSO4 ha-1 (basal soil application) + 0.5% ZnSO4 sprayed twice (30 DAS and 50 DAS). Results: Sole maize recorded highest dry matter (11938 kg ha-1) yield. Soil + foliar zinc application (Zn2) recorded an increase of 37.93 % increase in dry matter yield over control (Zn0). Maize + legumes recorded higher nitrogen uptake. There was an overall increase (122.34%) in zinc uptake from Zn0 to Zn2. Soil + foliar applied Zn increased ZnUE by 27.60 % (619.14 kg) over soil applied Zn (485.19 kg). Zn application increased Zn values of soil to 0.50 ppm with soil application and 0.56 ppm with soil + foliar application from the initial value of 0.36 ppm. Interpretation: Intercropping of legumes and application of 20 kg ZnSO4 as basal soil application plus two foliar applications of 0.5% ZnSO4 at 30 and 50 days after sowing significantly increased forage yield, nutrient uptake and enhanced soil zinc levels. Key words: Cropping systems, Intercropping, Legumes, Nutrient dynamics, Yield, Zn fortification

Enhancing Soil Health and Crop Productivity in Andisol Through Wheat- Fabaceae Intercropping

ABSTRACT Andisols are the least extensive soil order, accounting for less than 1% of Earth´s surface. Chile occupies 50% of the country´s land area for cereal production and is of great importance to agriculture. However, few studies have investigated the performance of cereal production under intercropping in P-deficient Andisols. The objective of this study was to evaluate the effects of two different Fabaceae species and wheat in an intercropping system on root morphology and soil properties. A 2-year field experiment was conducted using a completely randomized block experimental design with a factorial arrangement with two different phosphorus levels and cropping systems (wheat monoculture, wheat/lupine, and wheat/chickpea intercropping). Bulk soil samples were collected from a field that had been cultivated with wheat. Chemical properties, basal soil respiration, and enzymatic activity were measured. The morphological characteristics of wheat roots and crop yield were also determined. According to the multiple linear regression model (p < .001), this relative yield was related to an increase in phosphatase activity and root biomass. Furthermore, the Land Equivalent Ratio (LER) of the wheat/lupine intercrop surpassed 1 in both seasons, indicating improved soil and nutrient utilization. In contrast, the wheat/chickpea intercrops had LER values lower than one during the second season. This confirmed that wheat/lupine intercropping is a recommended practice for enhancing ecosystem services and agricultural production in Andisols.

Relationship between extreme species richness and Holocene persistence of forest-steppe grasslands in Transylvania, Romania

The most species-rich grasslands worldwide are known from the Carpathian Mts and their periphery in East-Central Europe. They occur in forest-steppe regions, transitional between temperate forest and arid steppe biomes. Their climate, largely suitable for forests, raises questions about the origin of these grasslands. Have they been forested in the past, or locally maintained through a disturbance regime? We addressed these questions to contribute to the broader understanding of Holocene dynamics of open habitats in temperate Europe. We employed soil charcoal analysis and soil morphology to reconstruct past representation of woody species with fine spatial resolution. Our study area was Romanian Transylvania, a region renowned for a well-developed forest-steppe. Six soil profiles along a climatic gradient were assessed: four in forest-steppe grasslands, two in grasslands in adjacent forest region (forest grasslands). The results revealed profound differences between forest-steppe and forest grasslands. Forest-steppe profiles showed Phaeozems with low specific anthracomass of woody species and continuous dominance by Juniperus, suggesting a long-term presence of grasslands. Forest grasslands showed Luvisols with higher anthracomass and abundant charcoal of broad-leaved trees, indicating establishment after deforestation. The high radiocarbon ages of charcoals in basal soil horizons point to a glacial origin of soils and the link of forest-steppe grasslands to glacial forests. Siberian hemiboreal forests and related grasslands may be modern analogues of the reconstructed ecosystems, sharing many species with present day forest-steppe. We suggest that disturbances such as fire, herbivore grazing, and human activities have played an important role in shaping the forest-steppe over time, contributing to the formation of today’s richest grasslands.

Soil biological fertility evolution in a chronosequence under long‐term rice cultivation after land reclamation in China

AbstractLand use significantly affects soil biological fertility through impacts on carbon (C) and nitrogen (N) cycling. The present study investigated the effects of long‐term rice cultivation after tidal flat reclamation on soil C and N metabolism, microbial biomass and biological fertility. Eighteen composite topsoil (0–20 cm) samples were identified in a chronosequence of coastal reclamation areas (0–700 years old) in subtropical monsoon climate zone, namely tidal flat (T0), salt marsh soil (S10) and paddy soil (P50, P100, P300 and P700). Using ANOVA analysis, mono‐exponential regression model, and multiple linear regressions, soil organic matter (SOM), total nitrogen (TN), cumulative C mineralization content (Ct) and N mineralization content (Nt), basal soil respiration (BSR) and microbial biomass C and N (MBC and MBN) in the P50‐P700 samples were significantly higher than those in the T0 and S10 samples, whereas C metabolic quotients (qCO2) in the P50‐P700 were significantly lower than those in the T0 and S10 samples. The time to steady state for SOM and TN are 357 years and 80 years, respectively; 133 and 221 years for Ct and Nt, respectively; and 318 and 183 years for MBC and MBN, respectively. Also, a soil biological fertility index (SBFI) was calculated on the basis of SOM, BSR, Ct, MBC, qCO2 and qCM. P100‐P300 samples had the highest SBFI score (28.7) and ranked in the class V (very high) of biological fertility, achieving steady‐state conditions after 146 years. SBFI was significantly positively correlated with SOM, TN, MBC, MBN, BSR, Ct and Nt, whereas it was significantly negatively correlated with pH, qCO2 and C mineralization quotient (qCM). MBC and qCM were two independent variables with considerable positive effects on SBFI. Long‐term rice cultivation could facilitate C and N accumulation and enhance biological fertility in soils via microbial activity, especially within 300 years. Our findings demonstrate that rice cultivation has the potential to enhance soil C and N accumulation. Carbon‐related SBFI is suitable for assessing soils under long‐term rice cultivation, mainly because the rice paddy field is an intensive and conservative system.

Environmental Impact of Choline Dihydrogenphosphate ([Chol][DHP]) on Seed Germination and Soil Microbial Activity

The applicability of ionic liquids has grown exponentially over the last few decades. This growth is due to the easy modification of these compounds formed by ions, through the proper choice of both moieties, and the possibility of introducing functional groups into their cations and anions. However, studies of their toxicity and effects on the environment remain scarce. This study analyses firstly the response to adding different concentrations of choline dihydrogen phosphate to the germination of seeds of eight plant species. It also examines the microbial population and the respiration of two soils with contrasting organic matter contents. Seeds were incubated in a Petri dish in a Phytotron with a photoperiod of 16 h under light at 24 °C and 8 h in darkness at 16 °C. The activity of microbial populations of untreated and treated soils was analysed by isothermal microcalorimetry at 25 °C. Basal soil respiration kinetics were measured at optimal moisture (80% of field water retention capacity) and temperature (25 °C) over 10 days. The results indicate that this compound has diverse effects on the different endpoints. Nevertheless, this compound can be classified as non-toxic considering its effects on seeds and on soil, at least in the medium- to long-term.

Burn Severity and Postfire Salvage Logging Effects on Vegetation and Soil System in a Short-Term Period in Mediterranean Pine Forests

Wildfires are a natural part of the dynamics of Mediterranean forest ecosystems. The fire patterns in the Mediterranean basin have been altered mainly due to changes in land use and climate change. In 2017, a wildfire in Yeste (Spain) burned 3200 hectares of two Mediterranean pine forests. We investigated the effects of burn severity and postfire salvage logging practices on vegetation and soil properties in four experimental areas distributed within the wildfire perimeter. These areas included unburned, low, high, and high burn severity with salvage logging, all located under Pinus halepensis Mill and Pinus pinaster Aiton stands. Salvage logging was applied 18 months after the fire. We established 72 circular plots (nine per treatment and pine species). We collected soil samples to analyze physicochemical and biological soil properties, including pH, electrical conductivity (EC), soil organic matter (SOM) content, carbon from microbial biomass (CBM), basal soil respiration (BSR), metabolic quotient (qCO2), and two enzymatic activities: β-glucosidase (GLU) and phosphatase (PHP). To understand how vegetation changed after fire, we implemented three linear transects per plot to calculate α-diversity indices (richness, Shannon, and Simpson), vegetation coverage (COBV), fraction of bare soil (BSOIL), the number of postfire seedlings (NSeed) and their average height (Hm), and we grouped vegetation into different postfire adaptive strategies: facultative seeder (R+S+), obligate resprouter (R+S−), obligate seeder (R−S+), and non-fire-adapted (R−S−). We ran ANOVA and Tukey’s HSD post hoc tests to evaluate the differences between burn severity and salvage logging practices on the variables examined for each pine stand. We used PCA and correlation analysis to identify plant-soil interactions. Our results suggest that Pinus halepensis stands were more affected by the wildfire than Pinus pinaster stands due to the distinct characteristics of each species (morphology of the leaves, bark thickness, cone structure, etc.) and the significant differences observed in terms of pH, SOM, CBM, qCO2, GLU, PHP, and Nseed. The proportion of obligate resprouter species was higher in Pinus halepensis stands, and the obligate seeder species were higher in Pinus pinaster stands. The study highlighted the importance of monitoring burn severity and postfire management practices to promote forest recovery and reduce wildfire risk. Limiting the negative impact of postfire salvage logging practices can enhance the resilience of vulnerable ecosystems.

The Short-Term Effects of Heavy Thinning on Selected Soil Carbon Pools and Microbial Activity in a Young Aleppo Pine Forest

Pinus halepensis Miller is a widespread tree species in the western Mediterranean basin, where very dense monospecific stands can be found, especially in natural regeneration after forest fires. Silvicultural thinning can reduce the competition of trees for natural resources and favour their development, although its effect depends on the habitat. The present study aims to know the effects on the soil at the physicochemical and microbiological levels after a heavy thinning in a young pine forest stand with a high stocking density. The stand is on a slope where the soil depth tends to decrease with altitude, and shows changes in its physicochemical properties between the upper and lower zones. Several soil carbon fractions (i.e., soil organic carbon (SOC), water-soluble organic carbon (WSOC), and microbial biomass carbon (MBC)), microbial activity (basal soil respiration (BSR)) and enzyme activities (acid phosphatase (AP) and urease (UA)) were analysed at specific dates over a period of about five years after a heavy thinning. The changes in organic matter content were abrupt in the slope, conditioning the observed differences. It is highlighted that the SOC and WSOC contents in the mineral soil were 2.5- and 3.5-fold significantly higher, respectively, in the upper shallow zone compared to the lower deeper zone. This was also reflected in significantly higher levels of gravimetric water content (GWC) and MBC (both about 1.4-fold higher), with higher levels of BSR and UA, and 2.5-fold significantly higher levels of AP. As a result, most of the properties studied showed no significant differences between the thinning treatment and the untreated control. Results varying between dates, with a strong dependence on climate (soil temperature and humidity) of WSOC and UA. It can be concluded that the heavy thinning applied in this short-term case study favoured the growth conditions of the pine without negatively affecting the soil properties studied.

Compost and Beneficial Pseudomonas Populations Promote Enzyme Activity, Amino Acids and Polymers Utilization Patterns in Heavy Metal Contaminated Soils

PGPR-assisted phytoremediation is a biotechnology offering opportunities to improve the state of contaminated soil ecosystems. The present study has investigated the potential of six beneficial isolates tolerant to Cd, Pb, and Zn and identified through 16S rDNA sequential analysis as Bacillus cereus, Pseudomonas putida, and Pseudomonas fluorescens to stimulate spinach growth and soil microbial community development in heavy metal-contaminated soil with or without the addition of compost. We found improved plant growth in all treatments with compost, but especially applying consortiums of isolates. Microbial enzyme activities and basal soil respiration were significantly higher in the rhizosphere and in amended treatments than in non-rhizosphere and control. The microbial community-level physiological profiles in the rhizosphere studied with the Ecoplates of BiologTM system showed increased metabolic potential in treatments with compost and beneficial bacteria. Principal component analysis revealed domination of amino acids and polymers utilizing communities in compost and bacterial consortium amended soils, carbohydrates and amino acids in compost and single strains application, and the lowest representation of amines and amides and phenolic compounds utilizers. Thus, may conclude that the use of quality organic amendments together with beneficial soil bacterial populations is a suitable and promising approach for the phytostabilization of soils contaminated with heavy metals.

Functional roles of biocrusts in enhancing soil quality in a semi-arid environment

Biocrusts play a wide range of ecological roles, especially in modifying surface soil properties and as a natural agent to combat soil degradation in fragile semi-arid and arid ecosystems globally. We examined the importance of biocrust on soil properties and quality in a semi-arid alluvial fan in northeastern Iran. The soil quality index (SQI) was used as the method for the quantitative evaluation of soil with or without biocrusts, using standard linear and nonlinear scoring methods. For this purpose, 17 biological, chemical, and physical soil properties were integrated into two indicator selection methods (total and minimum data set) and SQI has been calculated by the weighted additive method. The spatial patterns of SQI showed that overall the soil quality was (47%) increased in biocrust compared to non-biocrust soil. The increase of microbial biomass nitrogen, basal soil respiration, and microbial biomass carbon, and the decrease of available sodium and percentage sand were the most important indicators controlling the soil quality changes by biocrusts. In addition, biocrusts improved the soil structure by reducing bulk density and increasing the mean weight diameter of aggregates and available water capacity. Cyanobacteria communities of biocrusts were the initiators of soil quality improvement, while moss and cyanolichen communities played a major role from the moderate stages of biocrust occurrence. It is concluded that globally, in dry lands, biocrusts should be considered as signatures of enhanced soil quality.

Nickel sources affect soil biological properties but do not affect sorghum growth

Nickel (Ni) is an essential element, but it can be phytotoxic in high concentration, which may be caused by high availability in soil solution. The objective of this study was to evaluate the effect of sources and doses of Ni applied to a dystrophic Red Latosol cultivated with sorghum on i) the availability of the metal in the soil; ii) the impact on biological and biochemical properties of the soil; iii) the absorption and distribution in sorghum plants; and iv) crop productivity. The experiment was carried out within a completely randomized design with two nickel sources [nickel(II) nitrate, Ni(NO3)2 and nickel(III) oxide, Ni2O3], three doses (35, 70, and 140 mg Ni kg−1 soil), plus controls without Ni, with 3 replications. The concentrations of Ni in the soil, soil microbial biomass (SMB), basal soil respiration (BSR), metabolic quotient (qCO2), fluorescein diacetate (FDA) hydrolysis, and urease activity were determined. The concentrations of Ni in the leaf diagnostic and in the plant (shoot, root, and grains) were also measured. In the soil, the concentrations of available Ni remained between 0.21 and 54.01 mg Ni kg−1. Ni2O3 contributed very little to the increase in available Ni. SMB and the FDA hydrolysis were not affected by the Ni source or Ni dose, but BSR and qCO2 had significant increase with Ni application rates, suggesting the soil microorganisms faced stress. Soil urease activity was affected by Ni dose but not by Ni source. The dose of Ni as Ni(NO3)2 decreased the metal concentration in the plant, while that of Ni2O3 increased it. Nickel source did not affect dry mass production of the plants, but grain yield was affected in a dose-dependent manner when Ni2O3 was the source of Ni.

Microbiological attributes as indicators of soil quality in coffee growing systems in Southwest Bahia, Brazil.

Microorganisms are important indicators of soil quality due to their sensitivity to changes, reflecting the impacts caused by different land uses. The objective of this study was to evaluate the microbiological and physical-chemical attributes of the soil in areas cultivated with coffee under three different management systems (shaded coffee and full sun coffee with two spacings), as well as in adjacent areas under pasture and native forest, in Bahia, Brazil. The microbiological and physicochemical indicators evaluated were basal soil respiration (MBR), soil total organic carbon (TOC), microbial biomass carbon (MBC), metabolic quotient (qCO2), microbial quotient (qMic), enzyme activities (urease, acid phosphataseand fluorescein diacetate hydrolysis (FDA)). Physical and chemical indicators (particle size, texture, pH, P, K+, Ca2+, Mg2+, Al3+, and sum of bases) were also evaluated. Biological and chemical attributes were much more discriminative of study areas in the dry season. Microbial quotient (qMic) and metabolic quotient (qCO2) in the dry season showed that pasture is the most degraded land use. Conversely, nature forest and coffee with Grevillea were similar and were the best ones. In general, soil quality indicators were more sensitive to discriminate pasture and native forest from coffee systems, which, in turn, were not well discriminated among themselves.

Exploring soil-root interactions: A comparative study of wheat species and soil types

Soil-plant interactions of different wheat species (e.g., common, synthetic, durum and wild emmer ancestor) have not been studied yet. Therefore, our study was conducted to examine the interactive effect of 39 treatments including four wheat species (twelve varieties) and three soil types (loamy sand, sandy loam and sandy clay loam) on soil physical and biophysical quality indicators in a greenhouse pot experiment. The rhizosphere data were compared with the no plant (control) soil as well. The results revealed that the rhizosphere soils had a greater soil organic carbon (SOC) storage compared to the no plant soil, with the synthetic wheat species possessing the highest SOC content (order of SOC: synthetic > durum > emmer > common > control). The highest and the lowest SOC values (0.79 and 0.69 kg 100 kg−1) were observed in the rhizosphere of synthetic wheat S88 and common wheat CK varieties, respectively. The SOC showed a positive correlation with root morphological traits such as root volume and root dry weight. Basal soil respiration (BSR) showed significant variation among the four wheat species, and common and emmer ones had the highest BSR values. The maximum and minimum values of BSR (21.9 and 10.9 mg CO2 kg−1 soil day−1) were observed in the rhizosphere of the common species planted in sandy loam soil and in the loamy sand bulk soil (control), respectively. The presence of plant roots significantly increased BSR compared to the control (bulk soil); on average, the BSR in the rhizosphere was 21% greater than the control. Both the wheat species and soil type significantly affected the soil water repellency index (RI) and wettability parameters, but the interactive effects of treatments (i.e., wheat species and soil type) were not significant. The soils in all of the studied treatments were sub-critically or slightly water repellent (i.e., contact angle lower than 90°). The RI values were measured in the order emmer > durum > common > control ≥ synthetic; however, the difference between the synthetic species and bulk soil was not significant. Plant roots increased the soil hydrophobicity by increasing the SOC storage and significant variations in RI among the wheat species indicated that the emmer, durum and common species with greater RI might have better soil physical quality in the rhizosphere. The wheat plants substantially increased water-stable aggregates and decreased water-dispersible clay in the rhizosphere compared to the bulk soil. These findings showed that wheat roots were able to alter the structural stability of the rhizosphere soil. Correlation analysis indicated that soil structural stability was closely related to the SOC, microbial activity, water repellency and root morphological traits. Principal component analysis was used to enhance visualization, identify interrelationships between soil quality indicators and categorize wheat varieties.

Impacts of biostimulants on crop yield and biological activity under drought conditions

AbstractIntroductionBiostimulants are proposed to have a role in sustainable food production and are being increasingly used strategies to limit the negative effects of drought stress on crop yield and soil health. However, how different biostimulants used alone, or in combination with conventional management approaches affect soil health and crop yield under drought in different soils is not well understood. Here we conducted a glasshouse experiment to investigate this.Materials and MethodsTwo soil types from fields maintained under intensive (IM) and extensive (EM) management practices were used with two commercial biostimulants [Universal Natural Plant food (UNP) and Converte Seed Primer (CSP)] on soil microbial populations and crop yield (lettuce) under well‐watered and drought stressed conditions. We examined the activity and biomass of soil microorganisms as well as seed germination and root and shoot biomass to examine the effect of application of biostimulants on parameters of soil health and crop yield.ResultsBiostimulants generally increased crop yield, basal soil respiration and microbial biomass, with effects stronger in EM soils than in IM soils, but effects on soil enzyme activities were variable. The combined use of biostimulant and inorganic fertiliser negated the benefits of the biostimulant on soil biological properties in some cases. Nevertheless, effects of biostimulants had a positive impact on crop yield with the combined use of soil‐applied and seed applied biostimulants have the greatest impact on plant biomass and also conferring some resistance in both soil microbial communities and plant growth to drought.ConclusionsWhile biomass and activity of the microbial community and plant growth responses to biostimulant additions are both soil and biostimulant dependent, their combined use has potential to aid both plants and maintain promote microbial activity under of drought, compared to conventional fertiliser treatments in extensively managed soils.

Spatial relationship of landform surface features and biocrusts, and their effect on soil microbial biomass on an alluvial fan

AbstractThe spatial cover of biocrusts represents a suitable habitat for the activity of soil microorganisms in semi‐arid and arid regions. Microorganisms are one of the essential components of soil quality. Therefore, it is necessary to understand the processes of biocrust habitat formation in landforms and their mutual relationship with soil properties. We studied the spatial distribution of biocrusts and their effect on soil microbial biomass and carbon activity in a semi‐arid alluvial fan in NE Iran. A total of 72 soil samples (using plots 0.25 m2) from the topsoil layers (0–5 cm) were collected along the alluvial fan in September 2020. Soil surface properties and microbial biomass in two categories of biocrust and non‐biocrust were investigated in three classes of biocrusts coverage obtained by geostatistics. Our results revealed that biocrusts had a negative correlation with gravel coverage and elevation; in contrast, the suitable spaces for biocrusts growth were created by cobble clasts. The biocrusts have provided favourable conditions for soil microorganisms by altering the properties of the soil (such as increasing organic carbon, nitrogen and available phosphorus and decreasing pH), and thus they increased basal soil respiration and microbial biomass. Different microbial activities were led by the predominant type of biocrusts, as the chlorolichen crusts had the most significant effect on increasing the microbial biomass phosphorus while cyanolichen crusts increased the microbial biomass carbon. Moss and cyanolichen crusts increased microbial activity and respiration more than cyanobacteria crusts. Therefore, the soil quality has improved by biocrusts in semi‐arid ecosystems.

Agronomic zinc biofortification of potato (Solanum tuberosum) through soil and foliar zinc sulphate application in Rajasthan

An experiment was conducted during winter (rabi) seasons of 2020–21 and 2021–22 at Agricultural Research Station, Kota, Rajasthan to assess agronomical biofortification of potato (Solanum tuberosum L.) through soil and foliar zinc sulphate application The experiment consisted of 7 treatment combination of soil and foliar applications in a randomized block design with 4 replications. The results revealed that the application of ZnSO4 @2.5 kg/ha at the time of planting and foliar application of zinc sulphate @0.2% at 25 and 50 DAP (T7) gave significantly higher total tuber yield, and number of tubers. A significantly higher tuber zinc content was observed under treatment T7, where soil application of ZnSO4 @12.5 kg/ha at planting + 0.2% foliar application of ZnSO4 at 25 and 50 days after planting (DAP) compared to control, indicating more Zn accumulation. The benefit-cost analysis of tuber production under different basal soil application levels and foliar application revealed highest benefit-cost ratio of 2.59 with treatment T7 followed by T6 (2.39) and T3 (2.35). The apparent recovery efficiency and partial factor productivity were also higher with combined application of ZnSO4 through soil as well as foliar application. The experiment highlights the importance of soil and foliar zinc sulphate application for improved tuber yield and zinc fortification in a sustainable and cost-effective manner.

Agroecological assessment of fallow soils in the north‐west of the Republic of Bashkortostan

Aim. To analyse samples of fallow soils in the north‐west of the Republic of Bashkortostan in order to identify the main characteristics and properties of the soil cover. Material and Methods. Field studies were carried out in November 2021 and August 2022. A key site was chosen, an abandoned agricultural land in the territory of the Nizhnekaryshevsky village council of the Baltachevsky district. During the work, 45 soil samples were taken from the PY horizon (depth 10–20 cm). A morphological description of the soil was also carried out for the key area studied. During laboratory studies, the following properties were investigated: actual acidity, potential acidity, organic matter content, basal soil respiration. Results. The results obtained showed the spatial heterogeneity of the distribution of soil cover properties (actual and potential acidity, basal respiration, carbon and humus content) in the study area. Such heterogeneity is formed under the influence of a complex of physical and geographical factors. Conclusion. In the future, our research will also be devoted to the study of fallow lands on grey forest soils. Emphasis should be placed on studying the relationship between soil cover properties and plant communities and geological and geomorphological conditions. The study of various physical and geographical factors affecting the soil cover will make it possible to describe in more detail the entire mechanism and evolution of soils of abandoned agricultural lands.

Reducing nitrogen leaching using wood vinegar treated in urea-fertilized soil.

Wood vinegar (WV) is known to retard the release of ammonium (NH4+) from urea by inhibiting urea hydrolysis. However, the effect of WV on nitrogen leaching in soil is not known, and there are few studies on the effect of WV on microbial activity although WV exhibits antibacterial properties against pathogens in agriculture. Therefore, the purpose of this study was to investigate the effect of WV on controlling nitrogen leaching and soil microbial activity. Soils were treated with urea and WV, and the available inorganic nitrogen concentrations in the soil were compared with those from soils treated with N-(n-butyl)thiophosphoric triamide (NBPT), a commonly used urease inhibitor. The nitrate concentration in the soil was significantly decreased in the WV treatment, although the ammonium concentration was not affected by the WV treatment. Basal soil respiration was significantly increased in the WV and NBPT treatments although the microbial biomass was increased in the urea only treatment. The ammonium nitrogen concentration in the leachate was not significantly different in the WV and urea-treated soil compared to the urea-only treatment. However, the nitrate leaching increased in the soil treated only with urea at 16days after the treatment although there was no statistically significant difference in the total leached nitrate. Therefore, WV can be used to reduce nitrogen leaching and enhance soil microbial activity.

Fаunistic Analysis and Distribution of Phytonematodes of Some Fruit Trees of The Southern Regions of Uzbekistan

The article analyzes data on the faunal analysis and distribution of phytonematodes of some fruit trees in the southern regions of Uzbekistan. As a result of the study, 42 species of plant nematodes were identified, belonging to 2 subclasses, 5 orders, 17 families and 25 genera. The basal soil and root system of fruit trees are dominated by the species Cephalobus persegnis, Eucephalobus oxyuroides, Chiloplacus sclerovaginatus, Panagrolaimus rigidus, Rhabditis brevispina, Aphelenchus avenae, Aphelenchoides parietinus, A. bicaudatus, A. blastophthorus, A. composticola, A. limberi, Quinisulcius capitatus, Helicotylenchus erythrinae, Pratylenchus pratensis and Ditylenchus dipsaci.

Spatial variability of urban forest topsoil properties: towards representative and robust sampling design.

Background: Soil spatial variability is a major concern when deciding how to collect a representative topsoil sample for laboratory analysis. Sampling design to capture site-specific variability is documented in the agricultural literature, but poorly understood for urban forest soils where soils may be characterized by strong horizontal and vertical variability and large temporal anthropogenic disturbances. Methods: This paper evaluates the spatial variability of selected topsoil properties under urban trees to define a statistically robust sampling design that optimizes the number of samples to reliably characterize basal soil respiration (BSR), a property associated with soil health. To provide a reference on variability, two additional soil properties were measured, unrelated to BSR: electrical conductivity (EC) and bulk density (BD). Thirteen sampling sites comprising both park and street trees ( Acer rubrum) were selected in Cambridge, MA, USA. Results: Results indicate street tree topsoil had approximately twice as much variation, requiring more intensive sampling, as did park tree topsoil, even though street trees had smaller soil sampling zones, constricted by tree pits. The variability of BSR was nearly identical to that of EC, and BD results varied least. A large number of samples would be required for acceptable levels of statistical reliability (90% CI - 10% ER) of 44.4, 41.7, and 6.4 for BSR, EC, and BD, respectively, whereas by accepting a lower level of certainty (80% CI - 20% ER) the number of required soil samples was calculated as 6.8, 6.4, and 0.4 for BSR, EC, and BD, respectively. Conclusions: The use of EC testing as a baseline measure to determine spatial variation in the topsoil is proposed, to alleviate the financial implications of more expensive BSR testing. Factors of topsoil disturbance and soil access restrictions at sites with severe root-sidewalk conflicts and the overall generalizability of the results are also discussed.

Cover crops on soil quality and yield of cowpea under no-tillage in the Amazon savanna

Conservation practices such as no-tillage are necessary to maintain, and/or improve agricultural soil quality. However, straw formation and maintenance in tropical regions is a limiting factor to adopting this system. In this sense, this research aimed to study the effect of cover crops on straw formation, soil quality indicators, and cowpea yield under no-tillage in the Amazon savanna. Two experiments were carried out in consecutive years, on a Latossolo Amarelo. The treatments consisted of the straw of cover crops in a single (S) and intercrop (I) system, as follows: Urochloa brizantha (UBS), Pennisetum glaucum (PGS), Crotalaria juncea (CJS), Canavalia ensiformis (CES), Mucuna aterrima (MAS), U. brizantha and C. juncea (UBCJI), U. brizantha and C. ensiformis (UBCEI), P. glaucum and C. juncea (PGCJI), P. glaucum and C. ensiformis (PGCEI), and spontaneous vegetation (SV). Cowpea was cultivated after desiccation of the cover crops. Most of the straw favored soil particle aggregation, except for C. juncea and SV, which negatively influenced this variable. Basal soil respiration, organic carbon content, potassium, base saturation, geometric mean diameter, macroaggregates, and macroporosity at layer of 0-0.10 m were the most sensitive indicators for improving soil quality in a savanna environment. UBS, UBCJI, and UBCEI were superior to the other treatments in improving soil quality. Almost all treatments increased cowpea yield by up to 29%, except for CJS and SV.