Soil Solution Nitrogen Research Articles

Vertical Distribution Patterns of Nitrogen and Phosphorus in Soil Solution: Insights from a Wetland Trial Site in the Li River Basin

Vertical Distribution Patterns of Nitrogen and Phosphorus in Soil Solution: Insights from a Wetland Trial Site in the Li River Basin

Defoliation severity is positively related to soil solution nitrogen availability and negatively related to soil nitrogen concentrations following a multi-year invasive insect irruption.

Understanding connections between ecosystem nitrogen (N) cycling and invasive insect defoliation could facilitate the prediction of disturbance impacts across a range of spatial scales. In this study we investigated relationships between ecosystem N cycling and tree defoliation during a recent 2015–18 irruption of invasive gypsy moth caterpillars (Lymantria dispar), which can cause tree stress and sometimes mortality following multiple years of defoliation. Nitrogen is a critical nutrient that limits the growth of caterpillars and plants in temperate forests. In this study, we assessed the associations among N concentrations, soil solution N availability and defoliation intensity by L. dispar at the scale of individual trees and forest plots. We measured leaf and soil N concentrations and soil solution inorganic N availability among individual red oak trees (Quercus rubra) in Amherst, MA and across a network of forest plots in Central Massachusetts. We combined these field data with estimated defoliation severity derived from Landsat imagery to assess relationships between plot-scale defoliation and ecosystem N cycling. We found that trees in soil with lower N concentrations experienced more herbivory than trees in soil with higher N concentrations. Additionally, forest plots with lower N soil were correlated with more severe L. dispar defoliation, which matched the tree-level relationship. The amount of inorganic N in soil solution was strongly positively correlated with defoliation intensity and the number of sequential years of defoliation. These results suggested that higher ecosystem N pools might promote the resistance of oak trees to L. dispar defoliation and that defoliation severity across multiple years is associated with a linear increase in soil solution inorganic N.

Chinese privet (Ligustrum sinense Lour.) alters the timing of litterfall and nutrient quality of leaf litter inputs in invaded riparian forests

The invasive non-native shrub Chinese privet occupies riparian forests throughout the southeastern US however little is known regarding its ability to impact ecosystem processes. This study aimed to characterize phenological patterns of privet litterfall, litter chemistry, and changes in availability of mobile soil nutrients within riparian zones invaded by privet. Comparisons of native and invaded sites showed that privet invasion alters the timing but not quantity of litter deposition. In contrast to native species, total privet litterfall displayed little seasonal variation however invaded sites had similar total litter mass compared to native sites. Within invaded sites privet litter was 26% of total litterfall in spring. Privet leaf litter was seasonally enriched in nitrogen during winter as compared to fall and spring. Compared to native sites, invaded sites had significantly increased soil nitrate availability and decreased soil carbon:nitrogen ratios. In contrast, dissolved organic matter and dissolved nitrogen in soil solution was lower in invaded compared to native sites. Results suggest that privet enhances litter and inorganic nitrogen availability in ways that have potential to impact decomposer and detritovore communities in the riparian zone and adjacent aquatic systems.

Effects of Detritivores on Nutrient Dynamics and Corn Biomass in Mesocosms.

(1) Background: Strategies aimed at managing freshwater eutrophication should be based on practices that consider cropland invertebrates, climatic change, and soil nutrient cycling. Specifically, detritivores play a crucial role in the biogeochemical processes of soil through their consumptive and burrowing activities. Here, we evaluated the effectiveness of increasing detritivore abundance as a strategy for nutrient management under varied rainfall. (2) Methods: We manipulated soil macroinvertebrate abundance and rainfall amount in an agricultural mesocosms. We then measured the phosphorus, nitrogen, and carbon levels within the soil, corn, invertebrates, and soil solution. (3) Results: Increasing detritivore abundance in our soil significantly increased corn biomass by 2.49 g (p < 0.001), reduced weed growth by 18.2% (p < 0.001), and decreased soil solution nitrogen and total organic carbon (p < 0.05) and volume by 31.03 mL (p < 0.001). Detritivore abundance also displayed a significant interaction effect with rainfall treatment to influence soil total P (p = 0.0019), total N (p < 0.001), and total C (p = 0.0146). (4) Conclusions: Soil detritivores play an important role in soil nutrient cycling and soil health. Incorporating soil macroinvertebrate abundance into management strategies for agricultural soil may increase soil health of agroecosystems, preserve freshwater ecosystems, and protect the valuable services they both provide for humans.

Use of microdialysis to assess short-term soil soluble N dynamics with biochar additions

To date there has been little effort to assess fine-scale soil solution nitrogen (N) dynamics over time and space in response to biochar application within days. Herein we applied microdialysis to investigate the spatial and temporal dynamics of free amino acids (AA), ammonium (NH4+), and nitrate (NO3−) following biochar application to a column containing sandy loam forest soil. Wood biochar (diameter ≤ 5 mm) was applied either at surface or mixed through the entire soil column. Biochar stimulated localized soluble N diffusive fluxes, and the vertical distribution of AA and NH4+ hotspots gradually matched the distribution of biochar particles in the soil matrix over time. Increases in soil AA and NH4+ concentrations were more homogeneous along soil profile when biochar was mixed through the soil core and were more concentrated at the surface when biochar was surface applied. Increases in NO3− concentrations were only observed at surface soil layers following biochar addition regardless of the application strategy and generally exhibited a high degree of variation over the course of the experiment. Microdialysis sampling allowed for quantification of ‘hotspots’ of soil soluble N in association with the “charosphere” across time and space.

Growing season warming and winter freeze–thaw cycles reduce root nitrogen uptake capacity and increase soil solution nitrogen in a northern forest ecosystem

Northern forest ecosystems are projected to experience warmer growing seasons and increased soil freeze–thaw cycles in winter over the next century. Past studies show that warmer soils in the growing season enhance nitrogen uptake by plants, while soil freezing in winter reduces plant uptake and ecosystem retention of nitrogen, yet the combined effects of these changes on plant root capacity to take up nitrogen are unknown. We conducted a 2-year (2014–2015) experiment at Hubbard Brook Experimental Forest in New Hampshire, USA to characterize the response of root damage, nitrogen uptake capacity, and soil solution nitrogen to growing season warming combined with soil freeze–thaw cycles in winter. Winter freeze–thaw cycles damaged roots, reduced nitrogen uptake capacity by 42%, and increased soil solution ammonium in the early growing season (May–June). During the peak growing season (July), root nitrogen uptake capacity was reduced 40% by warming alone and 49% by warming combined with freeze–thaw cycles. These results indicate the projected combination of colder soils in winter and warmer soils in the snow-free season will alter root function by reducing root nitrogen uptake capacity and lead to transient increases of nitrogen in soil solution during the early growing season, with the potential to alter root competition for soil nitrogen and seasonal patterns of soil nitrogen availability. We conclude that considering interactive effects of changes in climate during winter and the snow-free season is essential for accurate determination of the response of nitrogen cycling in the northern hardwood forest to climate change.

Fertilizer legacies meet saltwater incursion: challenges and constraints for coastal plain wetland restoration

Coastal wetland restoration is an important tool for climate change adaptation and excess nutrient runoff mitigation. However, the capacity of restored coastal wetlands to provide multiple ecosystem services is limited by stressors, such as excess nutrients from upstream agricultural fields, high nutrient legacies on-site, and rising salinities downstream. The effects of these stressors are exacerbated by an accelerating hydrologic cycle, expected to cause longer droughts punctuated by more severe storms. We used seven years of surface water and six years of soil solution water chemistry from a large (440 ha) restored wetland to examine how fertilizer legacy, changes in hydrology, and drought-induced salinization affect dissolved nutrient and carbon concentrations. To better understand the recovery trajectory of the restored wetland, we also sampled an active agricultural field and two mature forested wetlands. Our results show that nitrogen (N) and phosphorus (P) concentrations in soil solution were 2–10 times higher in the restored wetland compared to two mature forested wetlands, presumably due to legacy fertilizer mobilized by reflooding. Despite elevated nutrient concentrations relative to reference wetlands, the restored wetland consistently attenuated N and P pulses delivered from an upstream farm. Even with continued loading, N and P concentrations in surface water throughout the restored wetland have decreased since the initial flooding. Our results suggest that high nutrient concentrations and export from wetlands restored on agricultural lands may be a severe but temporary problem. If field to wetland conversion is to become a more widespread method for ameliorating nutrient runoff and adapting coastal plain ecosystems to climate change, we should adopt new methods for minimizing the initial export phase of wetland restoration efforts.

Reviews and syntheses: measuring ecosystem nitrogen status – a comparison of proxies

Abstract. There are many proxies used to measure nitrogen (N) availability in watersheds, but the degree to which they do (or do not) correlate within a watershed has not been systematically addressed. We surveyed the literature for intact forest or grassland watersheds globally, in which several metrics of nitrogen availability have been measured. Our metrics included the following: foliar δ15N, soil δ15N, net nitrification, net N mineralization, and the ratio of dissolved inorganic to organic nitrogen (DIN : DON) in soil solution and streams. We were particularly interested in whether terrestrial and stream based proxies for N availability were correlated where they were measured in the same place. Not surprisingly, the strongest correlation (Kendall's τ) was between net nitrification and N mineralization (τ = 0.71, p &lt; 0.0001). Net nitrification and N mineralization were each correlated with foliar and soil δ15N (p &lt; 0.05). Foliar and soil δ15N were more tightly correlated in tropical sites (τ = 0.68, p &lt; 0.0001), than in temperate sites (τ = 0.23, p = 0.02). The only significant correlations between terrestrial- and water-based metrics were those of net nitrification (τ = 0.48, p = 0.01) and N mineralization (τ = 0.69, p = 0.0001) with stream DIN : DON. The relationship between stream DIN : DON with both net nitrification and N mineralization was significant only in temperate, but not tropical regions. To our surprise, we did not find a significant correlation between soil δ15N and stream DIN : DON, despite the fact that both have been used to infer spatially or temporally integrated N status. Given that both soil δ15N and stream DIN : DON are used to infer long-term N status, their lack of correlation in watersheds merits further investigation.

Effects of freezing intensity on soil solution nitrogen and microbial biomass nitrogen in an alpine grassland ecosystem on the Tibetan Plateau, China

The change of freeze-thaw pattern of the Tibetan Plateau under climate warming is bound to have a profound impact on the soil process of alpine grassland ecosystem; however, the research on the impact of the freeze-thaw action on nitrogen processes of the alpine grassland ecosystem on the Tibetan Plateau has not yet attracted much attention. In this study, the impact of the freezing strength on the soil nitrogen components of alpine grassland on the Tibetan Plateau was studied through laboratory freeze-thaw simulation experiments. The 0–10 cm topsoil was collected from the alpine marsh meadow and alpine meadow in the permafrost region of Beilu River. In the experiment, the soil samples were cultivated at–10°C,–7°C,–5°C,–3°C and–1°C, respectively for three days and then thawed at 2°C for one day. The results showed that after the freeze-thaw process, the soil microbial biomass nitrogen significantly decreased while the dissolved organic nitrogen and inorganic nitrogen significantly increased. When the freezing temperature was below–7°C, there was no significant difference between the content of nitrogen components, which implied a change of each nitrogen component might have a response threshold toward the freezing temperature. As the freeze-thaw process can lead to the risk of nitrogen loss in the alpine grassland ecosystem, more attention should be paid to the response of the soil nitrogen cycle of alpine grasslands on the Tibetan Plateau to the freeze-thaw process.

Nitrogen isotope tracer acquisition in low and tall birch tundra plant communities: a 2 year test of the snow–shrub hypothesis

Deciduous shrub density and landcover are increasing across many areas of the Arctic. Shrub growth may be promoted by a snow-shrub feedback whereby relatively tall shrubs accumulate deeper snow, raising winter soil temperature minima, increas- ing microbial activity, and enhancing soil solution nitrogen (N). Although there is good evidence for the above components of the hypothesis, it has not yet been determined if shrubs can access the elevated N pool generated by deepened snow. We added isotopic N tracer ( 15 N) in late summer to control and snowfenced low birch hummock tundra to test the influence of deepened snow on N cycling. Further- more, tracer was added to tall birch tundra to compare N cycling in low and tall shrub ecosystems that have the same species composition. Experimentally deep- ened snow in low birch tundra did not significantly affect 15 N uptake by shrubs or any other species 2 years after the tracer addition. However, there were strong differences between the low and tall birch ecosystems, with the deciduous shrubs and graminoids accumulating more 15 N than the evergreen shrubs in the relatively productive tall shrub site, and vice versa in the relatively infertile low birch site. The greater 15 N acquisition by birch in the more fertile site, together with the absence of a deepened snow effect on 15 N acquisition by any species in the low birch hummock ecosystem, suggest that climate-change induced increases in birch shrub growth and expansion across the landscape will tend to occur most rapidly in and around existing tall birch shrub patches.

Evaluating Status Change of Soil Potassium from Path Model

The purpose of this study is to determine critical environmental parameters of soil K availability and to quantify those contributors by using a proposed path model. In this study, plot experiments were designed into different treatments, and soil samples were collected and further analyzed in laboratory to investigate soil properties influence on soil potassium forms (water soluble K, exchangeable K, non-exchangeable K). Furthermore, path analysis based on proposed path model was carried out to evaluate the relationship between potassium forms and soil properties. Research findings were achieved as followings. Firstly, key direct factors were soil S, ratio of sodium-potassium (Na/K), the chemical index of alteration (CIA), Soil Organic Matter in soil solution (SOM), Na and total nitrogen in soil solution (TN), and key indirect factors were Carbonate (CO3), Mg, pH, Na, S, and SOM. Secondly, path model can effectively determine direction and quantities of potassium status changes between Exchangeable potassium (eK), Non-exchangeable potassium (neK) and water-soluble potassium (wsK) under influences of specific environmental parameters. In reversible equilibrium state of , K balance state was inclined to be moved into β and χ directions in treatments of potassium shortage. However in reversible equilibrium of , K balance state was inclined to be moved into θ and λ directions in treatments of water shortage. Results showed that the proposed path model was able to quantitatively disclose moving direction of K status and quantify its equilibrium threshold. It provided a theoretical and practical basis for scientific and effective fertilization in agricultural plants growth.

Controls on soil solution nitrogen along an altitudinal gradient in the Scottish uplands

Nitrogen (N) deposition continues to threaten upland ecosystems, contributing to acidification, eutrophication and biodiversity loss. We present results from a monitoring study aimed at investigating the fate of this deposited N within a pristine catchment in the Cairngorm Mountains (Scotland). Six sites were established along an elevation gradient (486–908m) spanning the key habitats of temperate maritime uplands. Bulk deposition chemistry, soil carbon content, soil solution chemistry, soil temperature and soil moisture content were monitored over a 5year period. Results were used to assess spatial variability in soil solution N and to investigate the factors and processes driving this variability. Highest soil solution inorganic N concentrations were found in the alpine soils at the top of the hillslope. Soil carbon stock, soil solution dissolved organic carbon (DOC) and factors representing site hydrology were the best predictors of NO3− concentration, with highest concentrations at low productivity sites with low DOC and freely-draining soils. These factors act as proxies for changing net biological uptake and soil/water contact time, and therefore support the hypothesis that spatial variations in soil solution NO3− are controlled by habitat N retention capacity. Soil percent carbon was a better predictor of soil solution inorganic N concentration than mass of soil carbon. NH4+ was less affected by soil hydrology than NO3− and showed the effects of net mineralization inputs, particularly at Racomitrium heath and peaty sites. Soil solution dissolved organic N concentration was strongly related to both DOC and temperature, with a stronger temperature effect at more productive sites. Due to the spatial heterogeneity in N leaching potential, a fine-scale approach to assessing surface water vulnerability to N leaching is recommended over the broad scale, critical loads approach currently in use, particularly for sensitive areas.

Soil solution nitrogen concentrations in a Japanese lawngrass (Zoysia japonica Steud.) and a tall fescue (Festuca arundinacea Schreb.) pasture under cattle grazing

Soil solution nitrogen (N) concentrations in a non-fertilized Japanese lawngrass (Zoysia japonica Steud.; JL, native species) pasture were compared with those in a fertilized tall fescue (Festuca arundinacea Schreb.; TF, improved species) pasture from May to December (late spring to early winter). Both pastures were grazed rotationally by breeding beef cattle in May–October. The TF pasture received a summer topdressing with compound fertilizer (8 g m–2 N, P2O5 and K2O). Annual herbage N consumption by cattle was lower in the JL (9.9 g N m–2) than in the TF (19.8 g N m–2). Soil solution N concentrations at the 10 and 30 cm depths were lower in the JL pasture ( 0.1), whereas the soil solution N in the TF pasture showed an increasing tendency with increasing soil inorganic N for the same soil depth and layer (r = 0.87, P < 0.1). The non-significant response of soil solution N to soil inorganic N in the JL pasture suggests that the lower soil solution N concentrations in this native grass pasture may not be explained only by the lack of fertilizer application to the pasture.

Nitrate leaching under maize cropping systems in Po Valley (Italy)

Intensive crop production in Po Valley (Northern Italy) is associated to high risk of nitrate leaching. A multi-year monitoring of soil solution nitrogen was conducted at 6 sites under the ordinary farm management of maize crop ( Zea mays L.) in order to assess NO 3–N leaching. The amount of N fertilizer (organic + mineral) varied from 209 to 801 kg N ha −1 year −1. Maize biomass ranged from 15 to 32 t ha −1 and N removal from 150 to 400 kg ha −1. Soil water solution was sampled at five depths along the soil profile (from 0.3 to 1.5 m) at time intervals of 7–30 days using suction cups. Soil water content (SWC) was measured daily by TDR at the same depths of suction cups. Soil water NO 3–N concentrations varied from 0 to 110 mg L −1, with the highest concentrations measured after fertilizer application. Once validated on measured SWC data, SWAP model was applied to estimate the drainage flux. Annual leaching was calculated by multiplying drainage flux by soil water NO 3–N concentration. N Leaching ranged from 14 to 321 kg ha −1 year −1, according to fertilization, crop N removal, rainfall, irrigation management, and it was mainly affected by N surplus.

Resposta do meloeiro à fertigação controlada através de íons da solução do solo: desenvolvimento vegetativo

O manejo da fertigação é feito mediante o uso de curvas de absorção de nutrientes; entretanto, o monitoramento dos nutrientes na solução do solo surge como técnica promissora. Objetivou-se estudar a resposta do meloeiro submetido a concentrações controladas de nitrogênio e potássio na solução do solo. Adotaram-se 13 tratamentos dispostos em delineamento inteiramente aleatorizado com 4 repetições. Os tratamentos resultaram do manejo controlado das concentrações de nitrogênio e potássio na solução do solo. A cultura foi irrigada por gotejamento e a fertigação realizada somente quando foi necessário. Avaliaram-se: comprimento da haste principal, diâmetro do caule, número de folhas, área foliar, área foliar média e matéria seca e se realizou análise de variância e de regressão com o uso do SAS. Aos 30 dias, as melhores concentrações de nitrogênio e de potássio foram 336 e 84 mg L-1, respectivamente. No final do ciclo a melhor concentração de nitrogênio na solução do solo foi de 336 mg L-1 e a de potássio variou entre 35 e 44 mg L-1.

Global Within-Site Variance in Soil Solution Nitrogen and Hydraulic Conductivity Are Correlated with Clay Content

Nutrient fluxes in terrestrial ecosystems are governed by complex biological and physical interactions. Ecologists’ mechanistic understanding of these interactions has focused on biological controls including plant uptake and microbial processing. However, ecologists and hydrologists have recently demonstrated that physical controls are also important. Here, we show that within-site spatial variation in soil solution N concentrations is a function of soil clay content across a globally diverse array of field sites. Clay content explained 35 and 53% of the coefficient of variation (CV) in soil solution nitrate (NO3−) and dissolved organic nitrogen (DON), respectively. The CV of soil hydraulic conductivity is a similar function of clay content, suggesting that soil hydrology may be a significant mechanism affecting variation in soil solution N. Although vegetation physiognomy and soil C/N ratios are known to affect soil solution N concentrations, neither was significantly related to within-site spatial variation in NO3− or DON. However, the spatial variation of NO3− and DON was greater in younger forests than in paired older forests. Our data show that the heterogeneity of an important resource, soil solution N, is a predictable function of clay content. Resource heterogeneity, such as that described here for soil solution N, can affect population, community, and ecosystem processes.

Effects of prescribed fire in mixed oak forests of the southern Appalachians: forest floor, soil, and soil solution nitrogen responses

Abstract We examined nutrient cycling responses to prescribed fire on three sub-mesic, mixed-oak sites located in the Blue Ridge Physiographic province of the southern Appalachian Mountains: Alarka Laurel Branch (AL), Robin Branch (RB), and Roach Mill Branch (RM). Each study site was located within a sub-watershed that drained a first order stream. Our objective was to quantify the effects of prescribed burning on forest floor mass, nitrogen and carbon pools; and soil and soil water available nitrogen. Each site included a burned and unburned control area; both burned and control areas were sampled before and after burning. Within each plot, we sampled forest floor mass, carbon and nitrogen, soil and soil solution nitrate (NO3-N) and ammonium (NH4-N) concentrations before and after the prescribed burns. All prescribed fires were conducted in the dormant season and were low to moderate intensity. All sites lost a significant amount of forest floor mass due to burning; 82 to 91% of the Oi layer and 26 to 46...

Effects of nitrogen addition on dissolved N 2O and CO 2, dissolved organic matter, and inorganic nitrogen in soil solution under a temperate old-growth forest

Soil solutions at 15 cm and 60 cm depths under a Korean pine and broadleaf mixed forest (> 200 years old) at Changbai mountain, northeast China, were sampled using porous ceramic suction cups from July 2006 to October 2007, to study the effects of nitrogen (N) addition on the concentrations of dissolved nitrous oxide (N 2O) and carbon dioxide (CO 2), dissolved organic matter and inorganic N. The actual concentrations of dissolved N 2O and CO 2 in soil solutions could be obtained using a combination of continual three phase equilibrations and gas chromatography. The dissolved CO 2 concentrations in soil solutions at 15 cm and 60 cm depths varied from 4.3 to 15.5 and from 3.5 to 18.3 μg CO 2–C ml − 1 , respectively, and dissolved N 2O concentrations at both depths varied from 1.8 to 34.9 and from 2.5 to 99.3 ng N 2O–N ml − 1 , respectively. The addition of N sources such as (NH 4) 2SO 4, NH 4Cl and KNO 3 at a rate of 4.5 g N/m 2 each year tended to decrease concentrations of dissolved organic carbon (DOC) in soil solutions at 60 cm depth in 2007, which was contrary to the increase in dissolved CO 2 concentrations under N-fertilized forest plots. However, the N addition did not give an obvious effect on the concentrations of dissolved CO 2 and DOC in soil solutions at 15 cm depth. There was an increase in concentrations of NH 4 +–N, NO 3 −–N and dissolved organic nitrogen (DON) of soil solutions under N-fertilized forest plots. Rainfall after thawing in spring could promote the accumulation of dissolved N 2O in soil solutions at 15 cm and 60 cm depths, particularly at 60 cm depth under the (NH 4) 2SO 4 added plots, due to mineralization of DON and nitrification. All the tested properties of soil solutions at 15 cm and 60 cm depths were well correlated. Among these properties, the dissolved N 2O concentrations of soil solutions at both depths were better correlated with the DON concentrations at 60 cm depth, and the dissolved CO 2 concentrations at 15 cm depth with the DOC concentrations at both depths. Hence, both DOC and DON can contribute to the formation of dissolved CO 2 and N 2O in the soil solutions at varying depths under N-fertilized forest plots, respectively. Our observations strongly indicate that N inputs to temperate forest floors can affect the status of N and carbon processes in underlying forest soils.

Resilience of soil microbial activity and of amino acid dynamics to the removal of plant carbon inputs during winter

Many temperate agricultural soils have prolonged periods in the winter when plant carbon inputs to the soil are low. Soil maintained at low temperature in the absence of plants was used to simulate the conditions in a vineyard soil during winter. In a four month simulated overwintering period we showed that the concentration of dissolved organic carbon and nitrogen in soil solution slowly declined alongside heterotrophic soil respiration. Measurements of free amino acid concentrations and turnover indicated that the amino acid pool in soil was rapidly depleted but readily replenished throughout the four-month period. This indicates that the soil contained intrinsic reserves of labile C that was capable of supporting the soil microbial community in times of reduced plant C inputs.

The effect of afforestation with Scots pine (Pinus silvestris L.) of sandy post-arable soils on their selected properties. II. Reaction, carbon, nitrogen and phosphorus

Despite the extensive literature on the effect on soil properties of afforestation of former arable land, we still lack full understanding of whether the changes proceed in the same direction and at the same rate, and of how long is required to achieve a state of soil equilibrium typical of a natural forest ecosystem. Therefore, as part of a study comparing post-arable sandy soils (Dystric Arenosols) afforested with Scots pine (Pinus silvestris L.) with arable soils and soils of continuous coniferous forests, the range and direction of changes in pH, organic carbon (Corg), total nitrogen (Ntot), ammonium (N-NH4) and nitrates (N-NO3) in soil solution, total (Ptot) and available (Pav) phosphorus were determined. The studies were carried out in south-east Poland (51°30′-51°37′N, 22°20′-22°35′E). Ten paired sites of afforested soils (five with 14- to 17-year-old stands and five with 32- to 36-year-old stands) with adjacent cultivated fields, and five sites of continuous forest with present stands of ca. 130–150 years old were selected. Soil samples were taken from the whole thickness of master horizons and, in the case of the A horizon of the afforested soils, from three layers: 0–5 (A0–5), 5–10 (A5–10) and 10–20 cm (A10–20). The cultivated soils in the Ap horizon showed higher pH (by ca. 1.0 unit), lower Corg and C:N, similar Ntot, lower N-NH4, higher N-NO3, higher Ptot and Pav contents compared with the Ah horizon of continuous forest soils. The results indicated decreased soil pH in the former plough layer of the afforested soils, with the greatest decrease observed in the 0–5 cm layer. In these soils, the Corg content was considerably higher in the A0–5 layer, but lower in the two deeper layers and in the whole A horizon (0–20 cm) compared with the Ap horizon of the arable soils. The results indicate that the Corg content, after an initial phase of decline, again achieved a level characteristic of arable soils. The Ntot content in all layers of the A horizon of the afforested soils was lower than in the Ap horizon of the arable soils, and showed a reduction with stand age, especially in deeper layers. The C:N ratios in the mineral topsoil increased with stand age. N-NH4 content increased and N-NO3 decreased after afforestation. The Ptot and Pav contents in all layers and in the whole A horizon of the afforested soils, on stands of both ages, was lower than in the Ap of the cultivated soils. From the results, it could be concluded that, after more than 30 years of tree growth, the soils of the A horizon were still more similar to arable than to continuous forest soils with respect to Corg, Ptot and Pav. With respect to pH, N-NH4 and N-NO3, especially in the 0–5 cm layer, they were more similar to continuous forest soils than to cultivated soils, but with respect to Ntot and C:N ratio they were somewhere in between.