Cm Layer Of Soil Research Articles

Effects of Natural Succession and Forest Landscape Restoration on Soil C and Aggregate-Associated C in the Central Loess Plateau, China

Vegetation restoration is an effective measure for increasing the soil organic carbon (SOC) stock and mitigating the impacts of global warming. Grouping soil C according to aggregate particle size can help with more thoroughly understanding the dynamics of soil C during vegetation restoration. However, the dynamics of soil-aggregate-associated C after the restoration of different vegetation types remain unclear. As such, in this study, soil samples from the 0- to 10- and 10- to 20-cm soil layers in natural grasslands and plantations, which are the two most commonly used vegetation restoration types, were used to explore the dynamics of soil-aggregate-associated C for these different vegetation types. These grasslands and forestlands were converted from cropland since 1999. The results showed that soil and aggregate-associated C content were significantly affected by vegetation restoration types and soil depth. Vegetation restoration significantly increased the proportion of macroaggregates (> 0.25 mm) and soil C stocks; however, the improvements in soil aggregates and soil C stocks were similar for the two vegetation types. Vegetation restoration significantly increased the C content of aggregates of different particle sizes but only significantly increased the C stocks of soil macroaggregates, which had the highest C content among all the considered particle sizes. In addition, the contribution of macroaggregate C in the 0- to 10- and 10- to 20-cm soil layers to the soil C in the bulk soil also increased after vegetation restoration, reaching 57−64%. The results of random forest regression showed that the macroaggregate C content was the primary factor affecting the soil C stocks. This study demonstrated that natural succession and plantations have similar abilities to improve soil aggregates and soil C content in the central Loess Plateau and that the dynamics of macroaggregate C content dominate the dynamics of soil C stocks.

Gypsum and carbon amendments influence carbon fractions in two soils in Ohio, USA.

Carbon sequestration as influenced by management practices such as soil amendments is not yet fully understood. Gypsum and crop residues can improve soil properties, but few studies have focused on their combined effect on soil C fractions. The objective of this greenhouse study was to determine how treatments affected different forms of C, i.e., total C, permanganate oxidizable C (POXC), and inorganic C in 5 soil layers (0-2, 2-4, 4-10, 10-25, and 25-40 cm). Treatments were glucose (4.5 Mg ha-1), crop residues (13.4 Mg ha-1), gypsum (26.9 Mg ha-1) and an untreated control. Treatments were applied to two contrasting soil types in Ohio (USA)-Wooster silt loam and Hoytville clay loam. The C measurements were made one year after the treatment applications. Total C and POXC contents were significantly higher in Hoytville soil as compared to Wooster soil (P < 0.05). Across both Wooster and Hoytville soils, the addition of glucose increased total C significantly by 7.2% and 5.9% only in the top 2 cm and 4 cm layers of soil, respectively, compared to the control treatment, and residue additions increased total C from 6.3-9.0% in various soil layers to a depth of 25 cm. Gypsum addition did not affect total C concentrations significantly. Glucose addition resulted in a significant increase in calcium carbonate equivalent concentrations in the top 10 cm of Hoytville soil only, and gypsum addition significantly (P < 0.10) increased inorganic C, as calcium carbonate equivalent, in the lowest layer of the Hoytville soil by 32% compared to the control. The combination of glucose and gypsum increased inorganic C levels in Hoytville soils by creating sufficient amounts of CO2 that then reacted with Ca within the soil profile. This increase in inorganic C represents an additional way C can be sequestered in soil.

Effects of warming and isolation from precipitation on the soil carbon, nitrogen, and phosphorus, and their stoichiometries in an alpine meadow in the Qinghai–Tibet Plateau: A greenhouse warming study

IntroductionIn the Qinghai–Tibet Plateau (QTP), alpine meadows are among the most noticeable reflection of global climate change. However, effects of global warming on soils hosting alpine meadows in the QTP, such as reduced moisture because of low precipitation, remain unclear.MethodsHere, the soil moisture content (SMC), pH, dissolved organic carbon (DOC), ammonium nitrogen (NH4+–N), nitrate nitrogen (NO3−–N) and available phosphorus (AP) contents in the QTP were analyzed. The changes in and stoichiometries of total carbon, nitrogen, and phosphorus (TC, TN, and TP), microbial biomass carbon, nitrogen, and phosphorus (MBC, MBN, and MBP), β-1,4-glucosidase (BG), β-1,4-N-acetylglucoaminosidase (NAG), leucine aminopeptidase (LAP), and acid phosphatase (ACP) in the 0–30 cm layer of soils associated with warming in a greenhouse in the QTP from 2015 to 2020 were characterized.ResultsWe found that warming in the greenhouse significantly decreased the SMC, NO3−–N, MBC, MBN, MBP, BG, LAP, ACP, and enzymatic C:N ratio. The warming increased the DOC, NH4+–N, AP, MBC:MBN, and enzymatic N:P ratios noticeably. The pH, TC, TN, TP, C:N, C:P, N:P, MBC:MBP, MBN:MBP, and enzymatic C:P ratios were minimally affected.ConclusionThe results showed that warming and isolation from precipitation promoted mineralization of N and P in the soil but did not significantly alter the cycling of elements in soils in an alpine meadow.

Using jointly calibrated fine-scale drain models across Denmark to assess the influence of physical variables on spatial drain flow patterns

Study regionDenmark Study focusTile drainage, widespread across agricultural areas in Denmark, significantly impacts the hydrological cycle. Tile drain flow dynamics and their spatial patterns are crucial for water managers to address water quality and quantity issues. However, these processes are challenging to simulate accurately. In this study, we developed 10 m resolution drain models in MIKE SHE for 26 drain sites across Denmark to predict drain flow spatial and temporal dynamics. Joint calibration of all drain models was conducted by evaluating PBIAS and KGE of simulated and observed drain flow. Subsequently, we performed a correlation analysis between physical parameters and spatial patterns of simulated drain fraction (DF, ratio of drain flow to recharge per grid cell). New hydrological insightsThe jointly calibrated models achieved average PBIAS and KGE of − 6.7% and 0.53 respectively, for drain flow predictions across 26 drain sites. The correlation of DF with topographical variables was highest on a national scale and on most of the drain sites, including Gyldenholm1–4, Norsminde1–11, and other Jylland drain sites. Lillebæk drain sites showed a high correlation with average clay content in 0–30 cm layer of soil. Thus, in addition to developing scalable fine-resolution drain models for Denmark, this study also identifies the control parameters for spatial patterns of drain flows across Denmark.

Study of the Effects of Different Agronomic Practices on Inorganic Carbon in the Plough Layer of Dryland Field: A Meta-Analysis

Soil inorganic carbon (SIC) is an essential component of the soil carbon pool and plays a vital role in the global carbon cycle and climate change. However, few studies have examined the effects of different agronomic practices on the SIC content. This paper aims to study the effects of different agronomic practices on the SIC content in the 0- to 40-cm soil layer of dryland fields; the innovations are intended to explore the relative importance and synergistic effects of different agronomic practices on the SIC content of the plough layer of dryland fields. We screened out 136 peer-reviewed articles worldwide from 1990–2022, with a total of 2612 valid data pairs, using meta-analysis to assess the effects of different agronomic practices on the SIC content of the plough layer of dryland fields. Compared to conventional tillage (CT), both no-tillage (NT) and plastic film mulching (PM) were able to increase the SIC content in the 0- to 40-cm soil layer of dryland fields. NT increased the SIC content by 15.07 ± 3.48%, while PM gradually increased SIC accumulation as the soil layer deepened, with the greatest increase in SIC content in the 30- to 40-cm soil layer at 11.61 ± 5.89%. When organic manure application (M) and straw return mulching (SM) were applied, the SIC content in the 0- to 40-cm soil layer of dryland fields showed a non-significant reduction trend, with the largest changes in SIC content in the 0- to 10-cm soil layer, at 5.23 ± 2% and 4.69 ± 3.53% reductions, respectively. No-tillage straw return (NTS) significantly increased the SIC content in the 0- to 40-cm soil layer of dryland fields by 77.34 ± 5.6%, which was significantly higher than the independent effects of NT and SM, showing a more substantial synergistic effect. Different agronomic practices have different effects on the SIC content of dryland fields in the 0- to 40-cm soil layer, with NTS &gt; NT &gt; PM &gt; SM &gt; M. Among practices, NTS, NT and PM can increase the SIC content of the plough layer of dryland fields; in particular, NTS can increase the SIC content of 0- to 40-cm in dryland fields to the greatest extent through a synergistic effect. At the same time, SM and M showed an insignificant reduction effect.

Productivity and grain quality of winter wheat under different tillage and fertilisation of typical chernozem soil

Аіm. To show the comparative productivity and quality parameters of winter wheat grain under No-till system in the first year of application with systematic surface tillage and minimum ploughing in grain 5-field crop rotation in the central part of the Forest-Steppe. Methods. Field, laboratory, comparative and calculation. Results. In the autumn period, under minimum tillage by systematic ploughing, the density was in the range of 1.08–1.13 g/cm3 with a total porosity of 57–59% and a ratio of categories of moisture to air pores of 0.6–0.7 to 1 with K = 1.33–1.44. Under the No-till system for ploughing, the density of the structure was at the optimum level (1.08–1.18 g/cm3) with a porosity of 55–59% and a ratio of 0.4–0.6 to 1 with = 1.22–1.44. Under systematic surface tillage, the structure density was in the range of 1.02–1.14 g/cm3 with differentiation of 0–30 cm of soil layer: loose (1.02 g/cm3) – compacted (1.14 g/cm3) – loosened (1.12 g/cm3), which is closer to the optimal value than under ploughing and No-till tillage system. The total consumption of productive moisture reserves in parts of a metre thick layer was higher from the 50–100 cm layer: under ploughing – 61%, No-till tillage – 62%, surface tillage – 56%, No-till tillage – 61%, which can be explained by the developed root system of winter wheat in autumn. Under ploughing and surface tillage, the yield of wheat grain was the same, while under No-till, the yield of winter wheat grain was significantly lower by 1.08–1.27 t/ha and 1.62-2.06 t/ha, or by 19.0-21.3% and 24-31%. Under ploughing and surface tillage – protein 13.2–13.5%, crude gluten – 25.2–25.6%, and under No-till 12.5–12.7% and 24.2–25.4%, respectively. Conclusions. The analysis of crop yields under different methods of cultivation and fertilisation showed that in the first year of application of No-till systems, compared to ploughing and surface tillage, their low efficiency was revealed.

The nutritive regime for leached black soil in an apple orchard depending on fertilizers

This article presents the results of studying the dynamics of the nutritive regime for leached black soil during the vegetation period of apple trees depending on the dosage and application times of compound fertilizers, as well as combinations of organic and mineral fertilizers. We detected a positive influence of fertilizers on the accumulation of liable forms of nitrogen, phosphorus, and potassium in the soil of the fruit orchard. The highest average content of ammonia absorbed during vegetation was observed in section N180P180K180 – 40.6 mg/kg, which was 10.4 mg/kg higher than in the unfertilized ref-erence section. The content of nitrates in the reference section was 8.9 mg/kg of the soil. The application of N60P60K60 increased their content by 2.3 mg/kg (25.8%), N90P90K90 - by 3.1 mg/kg (34.8%), N120P120K120 - by 4.8 mg/kg (53.9%). The application of mineral fertilizers at various rates had a significant impact on the content of liable phosphorus in the 0-40 cm layer of soil: its average content per vegetation period was 101.8 mg/kg of the soil for section N60P60K60 and 129,1 mg/kg for section N150P150K150. The content dynamics for exchangeable potassium in the fruit orchard soil was at the maximum at the beginning of the vegetation period and the minimum during fruit formation. Later on, the content increased during the harvesting stage but it was lower than the original level. The highest average content of exchange-able potassium per vegetation period was observed in section N150P150K150 – 184 mg/kg, which was 44 mg/kg higher than in the reference section. Out of the two sections treated with manure, the Manure 20 t/ha+N30P70 (with NPK reaching up to 120 kg/ha) section was deemed more efficient. The content of exchangeable potassium in it exceeded the reference section by 41 mg/kg.

EFEITOS DA DEGRADAÇÃO NOS ATRIBUTOS DE SOLOS SOB CAATINGA NO SEMIÁRIDO BRASILEIRO

ABSTRACT Anthropic activities in their various aspects have promoted soil degradation in the Brazilian semi-arid region (SAB). As a result, significant losses in productivity and in the ability of soils to fulfill their ecological functions have been reported. The present study investigated the effects of degradation on soil attributes and properties under dense (CAD) and sparse (CAE) shrubby Caatinga in Campina Grande, PB, Brazil. Samples from the 0-20 cm layer of soil were investigated via physical (particle size distribution and soil density), chemical (acidity, electrical conductivity, macronutrients, soil organic matter) and microbiological attributes (microbial biomass carbon (C-BMS), basal respiration of the soil (RBS) and metabolic quotient (qCO2) Data were submitted to the Mann-Whitney Test and Principal Component Analysis (PCA). Anthropic actions on the CAE promoted the exposure of the saprolitic layer on the surface. This layer has imperfect drainage, low levels of nutrients and organic matter and high sodicity, which contributes to the slow regeneration of vegetation. Carbon stock and microbial activity are significantly lower in CAE compared to CAD. Degradation resulted in losses of supporting ecosystem services (nutrient cycling and primary production) and regulation (erosion control and climate regulation). The results can be used to understand the dynamics of landscapes of low complexity (high degradation) in the SAB and serve as a framework to find strategies to restore the productive capacity of extensive degraded and/or desertified areas in the SAB.

Research on acidification and changes in mineral element concentrations in ferralsols from long-term tea plantations in Guizhou Province, China

Aims This study aimed to investigate where acidification occurred in soil profiles of Guizhou tea gardens, and the influence of acidification on the availability of soil mineral elements in order to inform soil nutrient management and improvement practices in tea gardens. Methods The acidification characteristics were investigated in soils from plantations grown for various numbers of years and across different soil layer profiles. Moreover, the pH buffering capacities (pHBC) of soils were evaluated and changes of mineral elements’ contents due to soil acidification were explored. Key results With increased tea plantation age, the acidification rate of 0–20-cm soil layers reached 0.025 pH unit/year. Soil acidification extended from the surface layer downwards through profiles, while the pH of entire soil layers were &lt;4.5 after 40 years of tea plantation. The pHBC of soils were &lt;30 mmol/kg, remaining at a weak sensitive level. Fe, Mn, Cu, Zn, Mo, and B concentrations exhibited decreasing trends in soils, while As, Pb, Cr, and Cd exhibited enrichment at the surface. Tea plantation age and soil depth were significantly correlated with the available concentrations of soil mineral elements. Conclusions Soil acidification gradually increased downward from the surface and soil minerals were lost in acidic environments, while the acid buffering capacity was reduced. Implications These results suggest that organic fertilisers and trace elements should be supplemented as needed in the management of tea gardens to achieve long-term stability of quality and yields.

Complementary influence of green-roof and roof-slab thermal conductivity on winter indoor warming assessed by finite element analysis

A green roof can modify the roof outer surface temperature (Tr) to influence indoor air temperature (Ti). Green roof design and roof-slab thermal insulation jointly determine the coupled-roof system’s thermal performance. This study investigated their joint effects on subtropical winter warming, which were seldom investigated. Custom-built houses without (bare roof) and with a 20-cm soil layer at circa 20% moisture content (soil roof) provided experiment plots to collect field data. The measured data tested the corrected finite element analysis model and simulated the combined influence of soil cover (properties kept constant) and a gradation of roof-slab thermal insulation on Ti in the unsteady heat transfer mode. Such multiple-factor and complex spatiotemporal studies are difficult using only field experiments and measurements. Average Ti was raised by 0.44 °C on a typical winter day, bringing 4.55% energy saving to indoor-heating budget. With poor roof-slab insulation, the soil roof significantly retained indoor warmth. With improved roof-slab insulation, the soil roof’s influence on Ti waned. A tipping point at 0.95 W/(m K) thermal conductivity signified a maximum threshold above which the green roof would not retain additional indoor heat. An upper threshold of thermal insulation at 0.35–0.05 W/(m K) was found, above which further insulation increase would not keep additional indoor warmth. Subtropical winter indoor warming by green roof was verified via two heat preservation mechanisms: retaining indoor heat to bring passive warming and delivering heat indoors to bring active warming. They were triggered by slightly warmed and notably warmed green-roof soil, respectively. The results ascertained quantitatively the complementary thermal role of green roof and roof slab. The findings can optimize the subtropical green-roof design and achieve winter indoor warming and thermal comfort.

Optimizing the spatial distribution of roots by supplemental irrigation to improve grain yield and water use efficiency of wheat in the North China Plain

Soil moisture affects the yield and water use efficiency (WUE) of winter wheat (Triticum aestivum L.) by regulating the spatial distribution of roots. Therefore, appropriate supplemental irrigation (SI) schemes are essential to achieve high yield and high WUE of wheat by constructing a reasonable root structure. In this study, field experiments were conducted the North China Plain (NCP) from 2018 to 2020. Based on the soil moisture management at sowing on a consistent basis, four SI regimes were set up: no irrigation after seedling emergence (W0), SI at jointing (W1), SI at jointing and anthesis (W2), and SI at regreening, jointing, and anthesis (W3). The results showed that although the grain yield of wheat increased with the SI frequency, the WUE decreased with increasing SI amount. SI at jointing and anthesis significantly increased WUE without reducing or slightly reducing the grain yield. The grain yield and WUE in 2018–2019 were significantly higher than those of the corresponding treatments in 2019–2020, and the yield of Bainong 4199 was higher than that of Zhoumai 18. The grain yield and WUE in 2018–2019 were significantly higher than those of the corresponding treatments in 2019–2020. The root length density (RLD) in the 0–20-cm soil layer increased with increasing SI frequency, but the proportion of RLD in the 40–60-cm soil layer decreased. The average RLD in the 0–60-cm soil layer and grain yield of Bainong 4199 were significantly greater than that of Zhoumai 18. Correlation analysis showed that the grain yield and WUE was positively correlated with the RLD in the 0–20-cm soil layer, and reached a very significant level with RLD in the 0–20-cm soil layer between rows. W2 and W3 in terms of root vigor and the grain filling rate 30 days after anthesis were significantly higher than W1 and W0 and also increased the contribution of post-anthesis dry matter to grain, resulting in an increase in grain weight. These results demonstrated that SI at jointing and anthesis could optimize the spatial distribution of roots, maintain higher root activity and filling rate at the late stage, increase accumulation and translocation of post-anthesis dry matter, and finally improve the yield and WUE. Therefore, we propose that Bainong 4199 was the preferred cultivars for this experiment，under sufficient soil moisture conditions before sowing, SI at jointing and anthesis is the optimal irrigation scheme for wheat on the NCP.

Экологические особенности накопления радионуклидов компонентами наземных экосистем зоны отчуждения

The studies were carried out 30 years after the Chernobyl accident on the lands of the former land use subject to natural successional changes. The patterns of the lateral distribution of 137Cs, 90Sr, 241Am in the upper 20-cm soil layer of various biogeocenoses, including those depending on the height fluctuations of the relief, have been studied. The values of the coefficient of variation (V) of the content of radionuclides in the upper soil layer decrease with the time that has passed since the accident. The highest value of the coefficient of variation (75.2 %) was obtained for 90Sr in the soil in the pine forest. The influence of various soil conditions on the entry of radionuclides into birch sap, cap mushrooms, and meadow grasses was studied. Despite the significant excess of the density of soil contamination with 137Cs of all the studied communities (up to 9.1 times), its volumetric activity in the juice is significantly lower than 90Sr, which indicates a lower availability of 137Cs compared to 90Sr. Dynamic processes of accumulation of radionuclides during the entire period of the movement of sap are studied. With increase in extent of moistening of the soil, accumulation of radionuclides in mushrooms tends to decrease. At the same time differences between types is established that connected with feeding habits of mushroom and variability of microclimatic conditions. The effect of soil moisture content, the ratio of 137Cs mobility forms in the soil on the biological availability of the radionuclide by meadow grasses was studied. A decrease in the specific activity of radionuclides in the plant components of ecosystems was found as the phytocenoses moved away from the epicenter of the accident at an identical density of soil contamination. A relationship has been established between the accumulation of radionuclides and the agrochemical parameters of the soil: maintenance of humus, absorption capacity, cation exchange capacity, hydrolytic acidity, content of exchange phosphorus, concentration of mobile calcium, magnesium and potassium on post-agrogenic lands. The analysis of the soil-to-plant transfer factors (Cf) and aggregated transfer factors (Tag), the discrimination coefficient (DF) of 137Cs by a chemical analog element (potassium) was carried out. Species features of plants associated with the transport of K+ - Cs+ cations make significant adjustments to the mechanisms of 137Cs accumulation. Attention is drawn to the significant increase in the concentration of 90Sr in all components in recent years.

Studies on the ecology of Bulinus globosus snails: Evidence against burrowing into the soil during the dry season

Background:Bulinus globosus snail was the intermediate host of schistosome hematobium and hard to be found during the dry season. This study aimed to understand the vertical distribution of B. globosus in desiccated and re-hydrated soils and provide evidence on whether snails can drill into the soil for summer.Methods: Four laboratory/field experiments were designed to study the downward movement of the snails in desiccated soils or upward movement in re-watered soils. In Experiment 1, aquaria containing snails on the soil surface were placed in an outdoor environment to desiccate naturally. Then, snails were retrieved from different soil layers. In Experiment 2, snails on the soil surface were covered with an extra 5 cm layer of soil and 4 cm layer of water. The snail positions and survival rates were checked on the first, third, fifth, seventh, and ninth day. In Experiment 3, a seasonal ditch was selected in the field. After the soil in the ditch was naturally desiccated, 1cm, 1–3cm, 3–5cm, and 5–10 cm depth of soil layers were screened to retrieve snails. In Experiment 4, after the above ditch was naturally re-watered, snails were checked in the surface water once a week for 5 weeks.Results: At the end of Experiment 1, all the snails were only found at the soil surface. At the end of Experiment 2, snails were found neither within nor on top of the 4 cm layer of extra mud. At the end of Experiment 3, 96.92% of snails remained on the soil surface. Next, 2.77% of living snails were found in the mud crack within 1–5 cm depth. In Experiment 4, after the experimental field was naturally re-watered, no snails were found above the soil surface.Conclusion:B. globosus snails do not initially move downward into the soil during the dry season or upward to the soil surface after being re-watered.

Root distribution pattern studies to assess the foraging zone in Melia dubia Cav.

Melia dubia is one of the important tree species in agroforestry models across India owing to its multifarious utilities, compatibility with various agricultural, horticultural and forage crops. Inspite of its pan India prevalence, research data pertaining to the spatial distribution of its root system is scarce which is primarily responsible for determination of the capacity to absorb water and nutrients preferentially over other allied crops. Belowground competitions are the major constraints to successful intercropping in woody/agroforestry ecosystems and thus spatial distribution of tree roots assumes paramount importance. The root distribution pattern of selected trees in a twelve-year-old Malabar neem (Melia dubia Cav.) plantation grown at 4 m x 4 m spacing was studied using the logarithmic spiral trench technique to assess the level of competitive/complementary impacts of the root system. Root intensity decreased steadily as the root diameter classes increased with function to soil depth as well as lateral distance. It was observed that 65.07 % of the total roots observed on the profile wall of the trench were fine roots (size class 2.5 to5.0 mm). Major share of the fine roots occupied near to the base of tree and 60.14% of fine roots were found to be accumulated in upper 20 cm layer of soil. In terms of lateral distance, maximum number of fine roots were recorded near the tree at 0.26 m with root intensity 431.1 m-2, and 65.85% of fine roots were found to be concentrated within 80 cm lateral distance from the tree.

Effects of Grass Inter-Planting on Soil Nutrients, Enzyme Activity, and Bacterial Community Diversity in an Apple Orchard.

The orchard inter-planting pattern is being widely used in many countries of the world, but it is relatively new in China. This study evaluated the interrow mono- and mixed-planting of Lolium perenne (Lp) and Medicago sativa (Ms) in orchards on soil nutrient, enzyme activity, and bacterial community diversity in 0–10, 10–20, and 20–40 cm soil layers. The clean tillage orchard was used as control (CK) treatment. Compared with CK, Lp and Lp + Ms. significantly increased the contents of soil organic matter (OM), total nitrogen (TN), and alkali-hydrolyzable nitrogen (AN) in 0–20-cm soil layer, and up-regulated the activities of urease (URE) and alkaline phosphatase (ALP). The Lp treatment significantly increased the relative abundance of Gemmatimonadetes and Planctomycetes in the 0-10-cm soil layer. Besides, cover crops significantly increased the abundance of Actinobacteria, Gemmatimonadetes, and Chloroflexi in the 10–20-cm soil layer and that of Gemmatimonadetes and Chloroflexi in the 20–40 cm soil layer. The redundancy analysis (RDA) showed significant positive correlations of Actinobacteria with ALP, OM and TN and that of Bacteroidetes with available potassium (AK), and Proteobacteria with available phosphorus (AP). Overall, the grass inter-planting improved the soil nutrients, enzymes activities, and bacterial community composition of the soil. Based on these results, inter-planting perennial ryegrass in the apple orchards is a suitable grass-orchard inter-planting strategy in Weibei, Shaanxi Province of China.

Inorganic Phosphorus Transformation and Phosphorus Adsorption–Desorption Properties of Soil in a Cotton Field Under Mulched Drip Irrigation in Xinjiang: A Four-Year Field Assessment

Phosphorus (P) fertilizer is generally applied to enhance the soil P pool and meet crop demand, but most of the added P is absorbed by soil. This study aimed to explore the importance of P fractions and adsorption–desorption characteristics on the demand for P fertilizer to determine the optimum P fertilizer amount for a cotton field under mulched drip irrigation in Xinjiang, China. A 4-year experiment (2016–2019) was conducted in a cotton field to evaluate the effects of five P fertilizer addition levels (0, 75, 150, 300, and 450 kg P2O5 ha−1 year−1) on inorganic P fractions and P adsorption–desorption properties at different soil depths and explore the effects of soil properties on P adsorption. The 4-year continuous P fertilization enhanced the inorganic P content and altered the proportions of various P forms. A large proportion of P accumulated in soil was transformed into Ca8-P, followed by Ca2-P, mainly in the surface layer. The accumulation and transformation of P in fertilized soil reduced P adsorption and enhanced P desorption. Soils with higher P application levels had higher inorganic P accumulation with lower adsorption and higher desorption. The total P and Olsen-P in a 0- to 5-cm soil layer; Ca8-P and calcium carbonate (CaCO3) in a 5- to 10-cm soil layer; Olsen-P, Ca10-P, clay, and cation exchange capacity in a 10- to 20-cm soil layer; and Olsen-P in a 20- to 40-cm soil layer significantly affected the P adsorption–desorption (p &amp;lt; 0.05). The application rate of 75–150 kg P2O5 ha−1 year−1 produced lower inorganic P accumulation, favorable adsorption–desorption properties, and high cotton yield, and thus could be considered the optimal P fertilizer application level.

Site index for Chinese fir plantations varies with climatic and soil factors in southern China

Chinese fir [Cunninghamia lanceolata (Lamb.) Hook.] has a large native distribution range in southern China. Here, we tested differences in productivity of Chinese fir plantations in different climatic regions and screened the main environmental factors affecting site productivity in each region. Relationships of a Chinese fir site index with climatic factors and the soil physiochemical properties of five soil layers were examined in a long-term positioning observation trial comprising a total of 45 permanent plots in Fujian (eastern region in the middle subtropics), Guangxi (south subtropics) and Sichuan (central region in the middle subtropics) in southern China. Linear mixed effects models were developed to predict the site index for Chinese fir, which was found to vary significantly among different climatic regions. Available P, total N, bulk density and total K were dominant predictors of site index in three climatic regions. The regional linear mixed models built using these predictors in the three climatic regions fit well (R2 = 0.86–0.97). For the whole study area, the available P in the 0–20-cm soil layer and total N in the 80–100-cm soil layer were the most indicative soil factors. MAP was the most important climatic variable influencing the site index. The model evaluation results showed that the fitting performance and prediction accuracy of the global site index model using the climatic region as the dummy variable and random parameters and the most important soil factors of the three climatic regions as predictors was higher than that of global site index model using the climatic variable and the most indicative soil variables of the whole study area. Our results will help with further evaluation of site quality of Chinese fir plantations and the selection of its appropriate sites in southern China as the climatic changes.

Effect of differential addition of water on mobility of fluopyram in two different soils of Kerala

ABSTRACT Fluopyram, a pyridyl ethyl benzamide broad-spectrum fungicide and nematicide, used for the management of plant parasitic nematodes and soil-borne fungi, is recommended for use in crops like tomato, potato and tobacco. Fluopyram being a pesticide used for drenching soil, there is every possibility of it getting leached down with water, ultimately leading to contamination of waterbodies. An experiment was conducted to study the downward movement of fluopyram in laterite and red loam soils in Kerala, India. Fluopyram and fluopyram benzamide, each at150 µg, were loaded separately on top of the respective soil column and were eluted separately with 20, 40, 80 and 160 mL each of water equivalent to 50, 100, 200 and 400 mm rainfall. It was observed that 76.84% and 74.85% of fluopyram and 73.48% and 64.24% of fluopyram benzamide were confined to the top 0–10 cm soil with application of 20 mL water in laterite and red loam soil, respectively. More than 50% of fluopyram and fluopyram benzamide were detected in the top 0–10 cm layer of soil with the application of 40 and 80 mL water. With the application of 160 mL water, considerable reduction in the concentration of both compounds was observed and the residues moved beyond 30 cm. Leaching of residues was more in laterite soil than in red loam soil, and they are in direct relation to the volume of water applied and the residues moved beyond 30 cm depth with 160 mL water.

Comparison of the Effect of Fertilization with Ash from Wood Chips on Bacterial Community in Podzolic and Chernozem Soils for the Cultivation of Winter Oilseed Rape: A Preliminary Study

The aim of the research was to investigate whether different doses of ash from biomass combustion (Salix viminalis L. willow) have an impact on the number and community of soil bacteria. The experiment was carried out on podzolic and chernozem soils in a one-way field experiment (control, NPK, 100, 200, 300, 400, 500 kg K2Oha−1). The ash from the biomass was characterized by pH 12.83 ± 0.68 and high content of macronutrients. Samples were taken from the 0–5 cm layer of soil under the cultivation of winter oilseed rape (Brassica napus L. var. Napus) in April and September 2021. The plate count method with PCA solid medium was used to determine the number of microorganisms, and mass spectrometry (MALDI-TOF MS) was used to analyze the microbiological community. The research showed an increase in the number of microorganisms after the use of the biomass ash fertilizer in the variants with ash doses from 200 to 500 kg K2Oha−1. The highest amount of soil bacteria in both tested soils was determined in these variants. In total, 44 bacterial species of 5 genera were identified in all variants: Bacillus, Paenarthrobacter, Pseudarthrobacter, Pseudomonas, and Rhodococcus. An important factor in the growth of the number of bacteria, in addition to the dose of biomass ash, was soil moisture, which in September was significantly higher than in April 2021 in both soils.

Spatial variability of soil organic matter and total nitrogen and the influencing factors in Huzhu County of Qinghai Province, China

ABSTRACT The soil organic matter (SOM) and soil total nitrogen (STN) is a significant concern in Qinghai–Tibet Plateau, China. This study analysed the spatial distribution of SOM and STN and determined their influencing factors to support the conservation of cultivated soil and development of sustainable agricultural strategies in the Plateau. In total, 120 soil samples were collected from the 0–20-cm soil layer in Huzhu County, Qinghai Province. Traditional statistical and geostatistical methods were used to analyse the spatial distribution of SOM and STN; a geographical detector (GeoDetector)was used to explore the factors influencing the spatial variation. The SOM and STN concentrations were 6.92–44.57 and 0.52–2.54 g/kg, respectively. The Cokriging interpolation map showed a similar spatial distribution pattern for SOM and STN concentrations, which decreased from the northeast to southwest directions in the study area. GeoDetector results revealed that the three primary factors influencing the spatial variability of SOM and STN were soil type, annual accumulated precipitation and elevation, with their explanatory power ranging between 38.4% and 59.5%. Two-factor interactions enhanced the explanatory power of the spatial variability of SOM and STN. The research results provide a reference for conservation tillage and precision agriculture.