Assessing the biological activity of oil-contaminated soddy-podzolic soils with different textures

The respiratory activity features in oil-contaminated soddy-podzolic soils of different textures have been studied. Unidirectional processes occur in contaminated loamy and loamy sandy soddy-podzolic soils; their intensities depend on the soil parameters. The mineralization rates of the oil products and the activity of the microflora in loamy soils exceed the corresponding parameters for loamy sandy soils. The long-term impact of oil and its transformation products results in more important disturbances of the microbial community in light soils. It has been shown that light soils containing 9% oil require longer time periods or more intensive remediation measures for the restoration of soil microbial cenoses disturbed by the pollutant.     

Mechanisms of potassium uptake efficiency and dynamics in the rhizosphere of safflower and sunflower in different soils

Potassium uptake efficiency of safflower and sunflower was studied under semi-controlled conditions in loamy and sandy soils. Both species performed better in loamy soil. Safflower had higher agronomic efficiency and higher relative root length under suboptimal K supply. Safflower had higher specific root density and less root radius at all K levels. Safflower had higher relative root-shoot ratio under suboptimal K in loamy soil. Both species had similar K-influx at low and optimal K in loamy soil, while sunflower had higher influx under suboptimal and optimal supplies in sandy soil. Safflower had higher shoot demand in both soils under suboptimal and optimal K. Both species depleted similar amounts of soil solution-K under suboptimal K in sandy soil, while sunflower was more efficient under suboptimal levels in loamy soils. Sunflower depleted more extractable-K under both suboptimal and optimal K. Safflower could be considered K-uptake efficient crop.     

Paleosols buried under kurgans of the Pit-grave culture in the steppe zone of the Cis-Ural region

The analysis of soil chronosequences developed from loamy and loamy sandy substrates and buried under kurgans dating back to the Pit-grave archaeological culture in the steppe zone of the Cis-Ural region demonstrated that it is possible to trace the dynamics of the soil properties and to perform paleoclimatic reconstructions for different intervals within the studied period. The properties of sandy soils changed more rapidly than the properties of loamy soils. For sandy soils, notable changes in their properties were revealed in the soil chronosequences dating back to the particular stages of the Pit-grave culture; for loamy soils, such changes could only be traced for the soils buried under the kurgans dating back to different stages of the Pit-grave culture.     

Dynamics of ecological and biological characteristics of soddy-podzolic soils under long-term oil pollution

The dynamics of respiratory and enzyme activities and toxicological properties of loamy-sandy and loamy soddy-podzolic soils (Retisols) under the long-term influence of oil pollution were studied. The concentrations of the pollutant, at which the activity (the ability of self-purification) of the indigenous soil microflora is preserved, were determined. The dynamics of the decrease of oil product content and the time of elimination of the toxic effects on higher plants at the initial pollutant contents were revealed. The parameters of the respiratory and enzyme activities in the course of the 365-day experiment showed that the microbial community of the loamy-sandy soil was more sensitive to oil pollution. The phytotoxic characteristics of the oil-containing loamy-sandy and loamy soils did not correlate with their respiratory and enzyme activities. This fact testifies to some differences in the mechanisms of their influence on living organisms with different organizational levels and to the necessity of taking into account a complex of parameters when assessing the state of the soils under the long-term effects of oil and its products.     

DMPP硝化抑制效果受其浓度、施用方式及土壤基质势的影响

The efficacy of nitrification inhibitors depends on soil properties and environmental conditions. The nitrification inhibitor 3.4-dimethylpyrazole phosphate （DMPP） was investigated in a sandy loam and a loamy soil to study its effectiveness as influenced by inhibitor concentration, application form, and soil matric potential. DMPP was applied with concentrations up to 34.6 mg DMPP kg^-1 soil as solution or as ammonium-sulfate/ammonium-nitrate granules formulated with DMPP. DMPP inhibited the oxidation of ammonium in both soils, but this effect was more pronounced in the sandy loam than in the loamy soil. When applied as solution, increasing DMPP concentrations up to 7 mg DMPP kg^-1 soil had no influence on the inhibition. The effectiveness of DMPP formulated as fertilizer granules was superior to the liquid application of DMPP and NH4^＋, particularly in the loamy soil. Without DMPP, a decline in soil matric potential down to -600 kPa decreased nitrification in both soils, but this effect was more pronounced in the sandy loam than in the loamy soil. DMPP was most effective in the sandy loam particularly under conditions of higher soil moisture, i.e., under conditions favorable for nitrate leaching.     

Mobility of heavy metals in polluted soils near zinc smelters

The distribution and the availability of Cd, Zn, Cu, and Pb along the entire profile of two highly polluted soils located near Zn smelters have been related to the chemical and mineralogical composition of the soil. Lead and Cu deposits always remain in the surface layers and their availability measured by neutral ammonium acetate extraction was very weak. The behavior of Cd and Zn appears different in sandy acidic podzolic soils and in neutral loamy soils. These metals are associated with the organic matter migration in podzolic soils, while they remain in the upper layers in loamy soils provided that the pH is higher than 6. When the pH drops below 6, the mobility of Cd increases while that of Zn increases only below pH 5. The availability of heavy metals is lower in neutral loamy soils than in sandy acidic soils due to precipitation of carbonates and phosphates. With increasing depth, Cd and Zn are more available if the soil is acid; but, if the soil is neutral and loamy the availability is kept low by adsorption on clays and free oxides. The results of the complex trace metals interactions with the soil components show a higher accumulation capacity for loamy soils than for sandy soils notwithstanding the fact that their CEC is similar.     

Effect of potassium fertilizer composition on the potassium status of soddy-podzolic soils under model experimental conditions

A model experiment was conducted with samples from arable horizons of loamy sandy and loamy soddy-podzolic soils under laboratory conditions. The samples were stored with KCl, K₂SO₄, and Potassium-E was added at rates of 240 and 960 kg/ha under alternating moistening and drying for 90 days. The contents of nonexchangeable, exchangeable, and easily exchangeable potassium and the K⁺ activity in 1: 2.5 water suspensions were measured in the original samples and after the end of the experiment. The contents of nonexchangeable, exchangeable, and easily exchangeable potassium were found to not be reliably affected by the composition of potassium fertilizers; the K⁺ activity was lower when potassium was added as K₂SO₄ than in the cases of KCl and Potassium-E.     

不同类型的污泥对土壤微生物性质的影响: 地中海退化土的田间试验研究

The recycling of suitable organic wastes can enhance soil fertility via effects on soil physical, chemical and biological properties. To compare the effects of digested (DS), thermally dried (TDS) and composted dewatered (CDS) sewage sludge on soil microbiological properties, an experiment was conducted at field sites for more than one year (401 d) when applied to two Mediterranean degraded soils (loam and loamy sand soils). All three types of sewage sludge had a significant effect on measured parameters. I...     

Lateral flow in loamy to sandy Kandiudults of the Upper Coastal Plain of Georgia (USA)

Interest in site-specific agronomic management in intensively cropped regions necessitates characterization of subsurface water movement for efficient water management (irrigation timing) and control of off-site agrichemical movement. Soils formed in fluvial sediments in portions of the Upper Coastal Plain of Georgia (USA) are extensively used for peanut, cotton, and corn production. Certain proximate soils in this region possess contrasting subsoil properties, and it was hypothesized that these differences would have major effects on water redistribution across the landscape. This could be important in irrigation management, where soils possessing increased impedance to vertical flow could require decreased irrigation as opposed to soils without vertical flow restrictions. At a site near Plains, GA. (USA), hydraulic properties of soils with differences in overlying sand thickness and contrasting argillic horizon textures (sandy vs. loamy) were evaluated. The soils were predominantly in loamy and sandy families of Typic, Arenic, and Grossarenic Kandiudults. Laboratory measurements, field monitoring of matric potentials under simulated and natural rainfall, and modeling (VS2DT) were utilized to evaluate soil hydraulic properties. Reduction in vertical K_s occurred in horizons containing higher clay (argillic horizon). Changes in tension and build ups in hydraulic gradients associated with infiltration and redistribution events existed above and within horizons with low K_s. Evidence suggested there was less groundwater recharge occurring in the loamy than in the sandy pedons, suggesting more pronounced lateral flow occurred in the loamier soils. Model simulations of water movement across a slightly sloping (1%) simulated landscape indicated lateral gradients of flow existed within the solum of these soils. Analyses of tracer (Br) movement suggested a very slight lateral redistribution occurred within a relatively short monitoring period within the sandy pedon's Bt1 horizon, and the Bt2 and Bt3 horizons of the loamy pedon. Evidence suggested both loamy and sandy argillic horizons slightly, but not overwhelmingly, induced lateral flow on these landscapes.     

不同形态磷酸盐及施用方式对石灰性土壤磷移动性和有效性的影响

  【目的】  磷的固定是石灰性土壤中磷肥效益低的重要原因,研究两种施肥方式下不同形态磷源在石灰性土壤中的迁移以及有效性,为实现磷肥减施增效提供理论基础。  【方法】  采用土柱模拟试验方法进行研究,供试土壤为粘质和壤质石灰性土壤。供试磷酸盐为磷酸脲、焦磷酸和聚磷酸,壤土施磷量为0.0581 g/柱,粘土为0.0594 g/柱。施用方式包括一次施用和分4次滴施,同时以不施用磷酸盐土柱为对照。于地下室内 (27 ± 1.0)℃培养28天后将土柱在?80℃条件下快速冷冻固形,从土表向下0—100 mm内每隔5 mm作为一个切割单元,100—300 mm间每隔20 mm作为一个切割单元,测定每层土壤的水溶性磷和Olsen-P含量。  【结果】  培养28天后,一次施用条件下,磷在壤土中的移动距离表现为聚磷酸 (90 mm) > 焦磷酸 (60 mm) > 磷酸脲 (50 mm),粘土中表现为聚磷酸 (80 mm) > 焦磷酸 (70 mm) > 磷酸脲 (60 mm)。分次滴施条件下,聚磷酸 (95 mm) 在壤土中的移动距离比磷酸脲 (65 mm) 和焦磷酸 (70 mm) 分别增加46.2%和35.7%,在粘土中聚磷酸 (90 mm) 的移动距离较磷酸脲 (70 mm) 和焦磷酸 (75 mm) 分别增加28.6%和20.0%。磷浓度下降到一半时所达到土柱深度 (半运移深度) 的结果表明,在壤土一次施用条件下,半运移深度表现为聚磷酸 (15.1 mm) > 焦磷酸 (11.4 mm) > 磷酸脲 (10.5 mm),分次滴施条件下半运移深度为聚磷酸 (20.0 mm) > 焦磷酸 (14.4 mm) > 磷酸脲 (14.3 mm)。在粘土一次施用条件下,半运移深度为聚磷酸 (17.7 mm) > 焦磷酸 (15.8 mm) > 磷酸脲 (14.8 mm),分次滴施条件下,聚磷酸、焦磷酸和磷酸脲的半运移深度依次为51.3、27.1和41.4 mm。相关性分析结果表明,不论一次施用还是分次滴施,聚磷酸和焦磷酸处理均随着水溶性磷含量的增加,有效磷含量在粘土上的增加量大于在壤土上的,分次滴施聚磷酸较一次施用在同样水溶性磷含量下,有效磷的含量在粘土和壤土中的差距减小,焦磷酸处理中水溶性磷与有效磷在两种土壤上较为接近。磷酸脲一次施用后,有效磷在粘土中随水溶性磷的变化量大于在壤土中,分次滴施结果则相反。  【结论】  在质地为壤土和粘土的石灰性土壤中,不论是一次性施用还是分次滴施,磷的移动性均表现为聚磷酸 > 焦磷酸 > 磷酸脲,且分次滴施3种磷源时磷的移动性和有效性均显著高于一次施用。同样水溶性磷含量条件下,粘土中磷的有效性高于壤土,分次滴施提高土壤磷素有效性的效果表现为粘土优于壤土。     

Microbial destruction of chitin in soils under different moisture conditions

The most favorable moisture conditions for the microbial destruction of chitin in soils are close to the total water capacity. The water content has the most pronounced effect on chitin destruction in soils in comparison with other studied substrates. It was found using gas-chromatographic and luminescent-microscopic methods that the maximum specific activity of the respiration of the chitinolytic community was at a rather low redox potential with the soil moisture close to the total water capacity. The range of moisture values under which the most intense microbial transformation of chitin occurred was wider in clayey and clay loamy soils as compared with sandy ones. The increase was observed due to the contribution of mycelial bacteria and actinomycetes in the chitinolytic complex as the soil moisture increased.     

Contact angles at the water–air interface of hydrocarbon-contaminated soils and clay minerals

Contact angles at the water–air interface have been measured for triturated preparations of clays and soils in order to assess changes in their hydrophobic properties under the effect of oil hydrocarbons. Tasks have been to determine the dynamics of contact angle under soil wetting conditions and to reveal the effect of chemical removal of organic matter from soils on the hydrophilicity of preparations. The potentialities of static and dynamic drop tests for assessing the hydrophilic–hydrophobic properties of soils have been estimated. Clays (kaolinite, gumbrine, and argillite) have been investigated, as well as plow horizons of soils from the Republic of Tatarstan: heavy loamy leached chernozem, medium loamy dark gray forest soil, and light loamy soddy-calcareous soil. The soils have been contaminated with raw oil and kerosene at rates of 0.1–3 wt %. In the uncontaminated and contaminated chernozem, capillary water capacity has been maintained for 250 days. The contact angles have been found to depend on the degree of dispersion of powdered preparation, the main type of clay minerals in the soil, the presence and amount of oxidation-resistant soil organic matter, and the soil–water contact time. Characteristic parameters of mathematical models for drop behavior on triturated preparations have been calculated. Contamination with hydrocarbons has resulted in a reliable increase in the contact angles of soil preparations. The hydrophobization of soil surface in chernozem is more active than in soils poorer in organic matter. The complete restoration of the hydrophilic properties of soils after hydrocarbon contamination is due to the oxidation of easily oxidizable organic matter at the low content of humus, or to wetting during several months in the absence of the mazut fraction.     

生物质炭与有机物料配施的土壤培肥效果及对玉米生长的影响

生物质炭作为一种多功能的土壤培肥材料被广泛应用,但其与传统有机物料的对比及配施研究还比较少。通过盆栽试验,研究了生物质炭与秸秆、发酵鸡粪单施及配施对壤质潮土和砂土养分含量、酶活性及玉米生长的影响,并采用主成分分析方法对3种有机物料的培肥效果进行综合评价。试验设6个处理,分别为不添加有机物料(CK)、添加生物质炭(BC)、小麦秸秆(WS)、发酵鸡粪(CM)、秸秆和生物质炭(WS+BC)、鸡粪和生物质炭(CM+BC)。研究结果表明,各处理均增加了砂土玉米生物量和株高,3种有机物料的提升幅度排序为:鸡粪生物质炭秸秆,鸡粪还可增加壤质潮土玉米生物量和株高。添加生物质炭和有机物料还可提高土壤有机质含量,其中生物质炭的提升幅度最大。此外,3种有机物料对土壤养分和酶活性的影响各异,单施鸡粪分别增加壤质潮土和砂土的碱解氮22.08%和26.67%,速效磷91.92%和53.65%,脲酶活性40.54%和36.94%;单施生物质炭分别增加壤质潮土和砂土速效磷83.52%和89.91%,速效钾79.38%和127.02%,过氧化氢酶活性3.41%和11.22%,却降低了土壤碱解氮含量,且与鸡粪配施后会抑制鸡粪中氮的有效性;单施秸秆分别增加壤质潮土和砂土速效钾49.48%和63.02%,β-葡糖苷酶活性51.86%和59.09%;生物质炭与鸡粪或秸秆配施可以更均衡地提升土壤肥力。通过主成分分析和相关分析发现,玉米生物量和株高与土壤氮、磷供应正变化的第2主成分(PC2)得分呈极显著正相关关系。因此,3种有机物料中,鸡粪对土壤氮、磷含量及相关酶活性影响最大;秸秆对土壤钾以及纤维素分解相关酶影响较大,而生物质炭对土壤肥力的提升作用更均衡,且土壤肥力综合得分最高。秸秆或鸡粪配施生物质炭可以更全面地提高土壤肥力。     

Effect of the particle-size distribution on the adsorption of copper, lead, and zinc by Chernozemic soils of Rostov oblast

The parameters of adsorption of Cu²⁺, Pb²⁺, and Zn²⁺ cations by soils and their particle-size fractions were studied. The adsorption of metals by soils and the strength of their fixation on the surface of soil particles under both mono- and polyelement contamination decreased with the decreasing proportion of fine fractions in the soil. The adsorption capacity of the Lower Don chernozems for Cu²⁺, Pb²⁺, and Zn²⁺ depending on the particle-size distribution decreased in the following sequence: clay loamy ordinary chernozem ∼ clay loamy southern chernozem > loamy southern chernozem > loamy sandy southern chernozem. According to the parameters of the adsorption by the different particle-size fractions (C _max and k), the heavy metal cations form a sequence analogous to that obtained for the entire soils: Cu²⁺ ≥ Pb²⁺ > Zn²⁺. The parameters of the heavy metal adsorption by similar particle-size fractions separated from different soils decreased in the following order: clay loamy chernozem > loamy chernozem > loamy sandy chernozem. The analysis of the changes in the parameters of the Cu²⁺, Pb²⁺, and Zn²⁺ adsorption by soils and their particlesize fractions showed that the extensive adsorption characteristic, namely, the maximum adsorption (C _max), was a less sensitive parameter characterizing the soil than the intensive characteristic of the process—the adsorption equilibrium constant (k).     

Influence of Enchytraeidae (Enchytraeus albidus) and compaction on nutrient mobilization in an urban soil

Soil compaction is an often-recorded characteristic of degraded soils, and—along with soil sealing and contamination—frequently found in urban habitats. Knowledge about the impact of soil degradation on the ecosystem functioning in urban environments is limited, although urbanization is the major ongoing land use change worldwide. Since urban soils are a potential habitat for soil animals, and burrowing soil fauna exerts a profound impact on the structure and functioning of soils, we studied the impact of increased bulk densities on the ability of Enchytraeus albidus (Enchytraeidae: Oligochaeta) to penetrate compacted soils. Moreover, it was our aim to characterize the influence of the worms on the mobilization of nutrients in urban soils. E. albidus was able to enter compacted sandy loamy soil columns with a bulk density of up to approx. 1.4 g cm⁻³, but only up to approx. 1.0 g cm⁻³ in pure sandy soil columns. Soil compaction increased the amounts of water-extractable sodium (7.5%) and magnesium (13.4%) compared to the non-compacted soil. Presence of E. albidus in the non-compacted soil resulted in higher water-extractable concentrations of sodium (17.4%), potassium (16.8%), calcium (11.3%), magnesium (13.2%), dissolved organic carbon (DOC, 14.5%) and nitrate (20.4%) in soil extracts. In the compacted soil, however, the enhanced nutrient availability due to the activity of the enchytraeids was less pronounced than in the non-compacted soil. Although the concentrations of DOC (13.5%), nitrate (15.6%), calcium (5.8%) and magnesium (4.0%) were significantly higher in the presence of E. albidus than in the columns without animals, the performance of the animals was partly impaired. This was most likely due to the higher penetration resistance of the compacted soils. The degree of compaction investigated in this study was relatively low-chosen to allow for the colonization of the soils by E. albidus. We conclude that the observed negative effects of increased bulk densities on the activity of soil enchytraeids can occur in any more frequented city park, thereby decreasing turnover rates and the supply of soil nutrients in urban ecosystems.     

Sorption and migration of zinc in taiga zone soils in laboratory and field experiments

The parameters of the zinc sorption and migration were experimentally determined under laboratory and field conditions for soils of forest and meadow biogeocenoses of Tver?? oblast. Two methods gave relatively close values for the parameters of the metal??s sorption by an almost neutral loamy sandy soddy soil of a meadow biogeocenosis. The potential capacity of an acid sandy loamy soddy-podzolic soil for zinc sorption determined under laboratory conditions was not completely realized under the field conditions, which was related to the properties of the biogeocenosis (the forest plants, the organization of the soil pore space, and the soil reaction) and the experimental conditions.     

Landau–Deryagin law and hydration energy of soils of different genesis

Linear regression equations between the logarithm of the total soil moisture potential and soil moisture content in the hygroscopic moisture range (Landau–Deryagin law) were derived for typical soils from different natural zones of European Russia. From these equations, a compact algorithm was developed for calculating the hydration energy of soils, which increases from 1280 to 10600 J/kg in the following soil series: heavy loamy soddy podzolic soil–heavy loamy gray forest soil–medium loamy light chestnut soil–heavy loamy brown semidesert soil–light clayey solonchak–light clayey chernozem–medium clayey krasnozem. Relationships were revealed between the hydration energy of soils, the specific surface of soils, the content of physical clay in soils, and the concentration of hydrated exchangeably adsorbed ions.     

Effects of three biochar types on activity of β-glucosidase enzyme in two agricultural soils of different textures

ABSTRACT

Biochar has attracted significant attention due to the long-lasting nature, and prominent influence on soil characteristics. This study was conducted to evaluate changes in the activity of β-glucosidase enzyme (BG) in loamy and sandy loam texture soils following two winter wheat growing seasons. The experimental design was a randomized complete block with three replicates and four treatments. The treatments were two soils, three biochars (rice husk, corn cob and bean harvest residue), five biochar rates (BR) and five levels of mineral fertilizers (FR) or dairy effluent (DE). The fertilizers were applied at the beginning of each season, while biochars were applied only at the beginning of experiment. Soil samples were collected following the second season and analyzed for the BG activity. Addition of biochars reduced the BG activity and the decline was higher in sandy loam compared to loamy soils. Negative effect of biochar to BG activity was greater at the highest BR (3.0%) than the lower BR. Fertilizer additions along with DE biochar had significant effect on BG activity that increased with higher FR. Given the importance of BG activity in soil organic matter decomposition, biochar application can be considered a sustainable way of increase in carbon sequestration.     

Soil Fertility Characteristics and Organic Carbon Stock in Soils of Vegetable Gardens Compared with Surrounding Arable Land at the Center of the Urban and Industrial Area of Ruhr,Germany

Soil fertility is the basis for production of high green mass, which has numerous essential benefits in urban areas. This study aimed to investigate the soil fertility of urban land. This was done by comparing soils from a vegetable garden and its surrounding arable land. A local brickwork dump was included. The soils were Hortisols, slightly stagnogleyic Luvisols, and a Regosol from sandy loamy silt. The location of the study was in the center of one of the world’s largest urban, hard-coal mining and heavy industry areas, the Ruhr area in Germany. The investigations for identifying the characteristic features of the soil fertility involved determination of the profile horizons, texture, pH, bulk density, C/N ratio, content and stocks of organic carbon, total nitrogen, available phosphorus and potassium, and soil water by field capacity. As they are expected to become construction land, the sites were already in a derelict state. The results show that all three soil types had high fertility characteristics. However, the fertility of the garden soils was much greater than that of the local arable land. This was due to the strong and deep accumulation of organic carbon due to compost application. The available phosphorus and potassium contents and field capacity were also distinctly increased in the garden soils. The spatial distribution and distribution with depth of pH, bulk density, organic carbon, nitrogen, available phosphorus, and potassium were extremely heterogeneous among the individual garden soils. In contrast, in the arable land, they were uniform. The organic carbon accumulation in the dump was in the range of that of the garden soils, but the nutrient contents were lower. These results show that the diversity of properties of urban soils is much higher than that of arable soils. The dereliction of arable, garden, and dump soil and vegetation by bushes and trees also affect the soil properties. There should be greater awareness of the high fertility of urban soils, such as vegetable garden soils. Vegetable garden soils have a high potential for contributing to solving urban problems by producing high volumes of biomass and storing water. Therefore, it should be demanded that vegetable garden soils receive a high protection status, and they should not be used for the establishment of construction.     

Impact of ecological and conventional arable management systems on chemical and biological soil quality indices in Nicaragua

We measured the activity and soil microbial biomass in volcanic ash soils from 10 sites under ecological farming (no pesticides, shallow ploughing, mulching, organic fertilizers, crop rotation) and 15 sites under conventional farming (pesticides, mineral fertilizers, deep ploughing). Our aim was to determine the effects of management system on soil quality and soil fertility in tropical Nicaragua in relation to soil type. None of these sites were irrigated. Conventional management led to significantly increased amounts of total soil P and a significantly larger biomass C-to-P ratio compared to ecological management. Almost all of the other microbial properties, i.e. soil basal respiration, ergosterol and biomass C were significantly improved by ecological management. Also the biomass C-to-soil C ratio was significantly increased, but not the metabolic quotient qCO₂ or the ergosterol-to-biomass C ratios, indicating that the positive effects of ecological management were mainly due to increased C input rates. Biomass C, ergosterol, and basal respiration rate were significantly larger at the loamy sites than at the sandy sites. The same was true for the biomass C-to-soil C ratio, but the ergosterol-to-biomass C ratio and the metabolic quotient qCO₂ were larger at the sandy sites. Our results demonstrate that ecological management is an important tool for soil conservation and sustainable management of arable land in Nicaragua. However, the decline in total P and the low P availability to soil microorganisms need attention as a precaution against P deficiency. The improvement was greatest at the loamy sites, although the effects of management system were in most cases independent of the soil type. For this reason, ecological management should be preferably promoted on loamy soils.