Changes In Soil Biological Properties Research Articles

Functional diversity and behavioral changes of microbial communities under salt affected soils

Salt-affected soils (SASs) are globally distributed especially in the arid and semi-arid regions of the world which highly affect the crop growth and productivity. The soil physico-chemical and biological properties largely vary with different types of SASs which trigger the crop yield, nutrient imbalance and soil quality. Therefore, to understand the changes in soil microbiology in relation to soil characteristics, a micro plot study was conducted to evaluate the impact of soil salinity/sodicity on physical, chemical properties at surface (0–15 cm) and subsurface (15–30 cm) soils in relation to soil microbial population, activities and functional diversity with focusing on community-level physiological profiling (CLPP) study. Five types of soils based on pH, electric conductivity (EC) and salt concentration maintained for last 25 years - highly saline, moderately saline, highly sodic, moderately sodic and normal were evaluated in micro plots to understand the changes in soil biological properties in relation to salt concentration. The results revealed that the highest value of pHs, ECe (EC of soil saturated paste extract), cation exchange capacity (CEC), exchangeable sodium percentage (ESP), sodium adsorption ratio (SAR), anions and cations concentrations, bulk density (BD), infiltration rate (IR), penetration resistance (PR) were observed in highly saline and highly sodic soils at surface and subsurface soil layer. In surface and subsurface layers, organic carbon (0.67 and 0.52 %) and available N (110 and 195 kg ha−1) were found higher under normal soils than SASs (% OC: 0.20–0.34 and 0.17–0.38; available N: 75–80 and 47–77 kg ha−1), respectively. In relation to changes in soil physicochemical properties, average well color development (AWCD) was found highest with normal soils followed by moderately saline and moderately sodic soils and lowest was found in highly sodic soils at surface soils which indicates interference of salts in metabolic activities of microbes. The utilization of amino acids, amines, carboxylic acids, phenolic compounds and polymers was highest for normal soils followed by moderately saline and lowest was recorded for highly sodic soils. But AWCD for carbohydrates was highest in highly saline soils, followed by highly sodic soils in contrast to normal soil and lowest was found under moderately sodic soils. Shannon diversity index (H) and substrate richness (SR) were found higher (3.19 and 24.07) in normal soils than SASs. Similarly, effect of salt load was also reflected on less soil enzymatic activities such as dehydrogenase, aryl sulfatase, invertase, etc. under varying types of SASs. Thus, with the increasing salt load, chemical and physical properties of soils were found to deteriorate and directly affected the microbial population, activities and their diversity in soil. This study indicated that soil physico-chemical properties, functional diversity, population and community of microbes were highly influenced by nature of salts and their concentration that may affect the soil quality and crop yield.

Changes in Soil Biological Properties after Sewage Sludge and Pesticide Application in Wheat Cultivation

One of the solutions implemented in order to improve the quality of soils exposed to pesticides is the application of sewage sludge, which is a by-product of wastewater treatment. As an organic substrate, it provides soil with important nutrients, such as nitrogen and phosphorus, and enriches it with organic matter, thanks to which it can be a valuable fertilizer. The aim of the presented research was to evaluate the influence of granulated sewage sludge (GSS) on the biological properties of soil treated with herbicides (MCPA and dicamba) and fungicides (thiophanate-methyl and azoxystrobin). The following aspects were investigated: the activity of selected soil enzymes, the genetic biodiversity of bacteria and fungi, and the abundance of the bacterial gene responsible for ammonia oxidation. A field experiment was conducted, in which granulated sewage sludge (GSS) was applied to soil at a single dose of 3 t/ha. Wheat (Triticum aestivum L.) was sown on the prepared plots. The herbicides (H) and fungicides (F) as well as their mixture (F + H) were applied to the plants in the appropriate growth phases in the doses recommended by the producer. The control was soil without sewage sludge (C). The samples taken were tested for: dehydrogenases, catalases and urease activities, genetic biodiversity structure of bacteria and fungi by TRFLP assay, and the abundance of the bacterial amoA gene by qPCR. On the basis of the obtained results, it was found that the application of pesticides to soil fertilized with sewage sludge influenced the enzymatic activity of soil, and their activity differed depending on the tested enzyme. The activity of URE and DHA on the plots with GSS was higher by approx. 20% and 30%, respectively, as compared to the plots without GSS application. Moreover, both the genetic biodiversity of microorganisms and the abundance of amoA gene differed depending on the variant of the experiment. The GSS treatment of soil significantly influenced the growth of the studied gene as compared to C, and its abundance was 9.15 log10 gene copies/g DW of soil. Due to the content of nutrients in sewage sludge, it can be a valuable fertilizer in agricultural crops treated with pesticides.

Crude oil associated heavy metals (HMs) contamination in agricultural land: Understanding risk factors and changes in soil biological properties

Ecological and human risks of crude oil associated heavy metals (HMs) in the contaminated agricultural lands were evaluated employing different indices. The indices that were employed includes enrichment factor (EF), contamination factor (Cf),pollution load index (PLI), geo-accumulation index (Igeo), ecological risk index (ERI), contamination degree (Cd), Nemerow's pollution index (PN), exposure factor (ExF), hazard quotient (HQ) and hazard index (HI). Besides, the adverse effects of crude oil associated HMs on the soil biological properties were also analyzed. The results of Cf and EF were found consistent with each other showing the HMs in the decreasing order of contamination as Mn > Zn > Cr > Ni > Cu. The Igeo and ERI fall in the grade (Igeo>5) and (ERI ≥40) respectively. The results of PLI, Cd, PN and ExF values clearly indicate a high environmental risk of crude oil-associated HMs. The results of the human health risks assessment revealed the maximum level of HMs enters the body via ingestion. There were significant(p < 0.05) decreases (5.7–15.5 folds) in the activities of cellulase (0.194 ± 0.02–0.998 ± 0.1), phosphatase (0.173 ± 0.3–0.612 ± 1.5), catalase (0.328 ± 0.3–2.036 ± 1.5), urease (0.44 ± 0.3–1.80 ± 1.2), dehydrogenase (0.321 ± 0.2–0.776 ± 0.7),polyphenol oxidase (0.21 ± 0.5–0.89 ± 2.5)and peroxidase (0.13 ± 0.4–0.53 ± 1.03)in crude oil-contaminated soil. The Pearson's correlation confirmed the significant negative impact of HMs on the soil's biological properties.

Earthworms as an Ecological Indicator of Soil Recovery after Mechanized Logging Operations in Mixed Beech Forests

Soil damage caused by logging operations conducted to obtain and maximize economic benefits has been established as having long-term effects on forest soil quality and productivity. However, a comprehensive study of the impact of logging operations on earthworms as a criterion for soil recovery has never been conducted in the Hyrcanian forests of Iran. The aim of this study was to determine the changes in soil biological properties (earthworm density and biomass) and its recovery process under the influence of traffic intensity, slope and soil depth in various intervals according to age after logging operations. Soil properties were compared among abandoned skid trails with different ages (i.e., 3, 10, 20, and 25 years) and an undisturbed area. The results showed that earthworm density and biomass in the high traffic intensity and slope class of 20–30% at the 10–20 cm depth of the soil had the lowest value compared to the other treatments. Twenty-five years after the logging operations, the earthworm density at soil depth of 0–10 and 10–20 cm was 28.4% (0.48 ind. m−2) and 38.6% (0.35 ind. m−2), which were less than those of the undisturbed area, respectively. Meanwhile, the earthworm biomass at a soil depth of 0–10 and 10–20 cm was 30.5% (2.05 mg m−2) and 40.5% (1.54 mg m−2) less than the values of the undisturbed area, respectively. The earthworm density and biomass were positively correlated with total porosity, organic carbon and nitrogen content, while negatively correlated with soil bulk density and C/N ratio. According to the results, 25 years after logging operations, the earthworm density and biomass on the skid trails were recovered, but they were significantly different with the undisturbed area. Therefore, full recovery of soil biological properties (i.e., earthworm density and biomass) takes more than 25 years. The conclusions of our study reveal that the effects of logging operations on soil properties are of great significance, and our understanding of the mechanism of soil change and recovery demand that harvesting operations be extensively and properly implemented.

Changes in soil biological properties in different management and tillage systems in petrocalcic argiudoll

We analyzed the effect of different tillage systems under different land-use histories, on biological properties of soil during one year. The experiment was carried out at a Petrocalcic Argiudoll of Tres Arroyos (Buenos Aires, Argentina). The specific aim was to describe and compare the soil organic carbon (SOC), the soil basal respiration (BR) and the activities of the enzyme dehydrogenase, urease and acid-phosphomonoesterase under zero and conventional tillage on soils under pasture and intensive agriculture. The SOC concentration was highest in summer (postharvest) independently of tillage system or land-use history. However, in autumn the plots under conventional tillage showed higher values of SOC than those with zero tillage, independently of land-use history. The BR had a significant benefit in favour of summer pasture soils. The effect of land-use history or the tillage system on the enzymes activity was dependent of sampling season. The soil enzymes were more sensible than SOC and BR. In temporal studies the effect of sampling season is strongest that others factors as tillage systems or land-use history.

Biological Soil Properties in Integrated Crop-Livestock-Forest Systems

Currently, agricultural productivity and sustainable development are the desired bases for the creation of production systems. Farming for greater production and the efficient use of soil resources are at the core of modern systems. However, the way in which agricultural management and practices can change soil quality has become increasingly important. The aim of this study was to detect changes in soil biological properties caused by implementation of the integrated crop-livestock-forest system (iCLF) and to identify the properties suitable for detecting changes in soil biological quality. Soil samples were collected from the 0.00-0.10 m layer in Nova Canaa do Norte, MT, Brazil, and Cachoeira Dourada, GO, Brazil, in areas of the iCLF with 1 (iCLF1) or 3 (iCLF3) eucalyptus rows and in areas of recovered and degraded pasture. In Cachoeira Dourada, in the iCLF1, samples were taken in the tree row and at 2.5, 5.0, and 10.0 m from this row. In Nova Canaa in the iCLF3, samples were taken in the center row and at 3.0, 6.0, 9.0, and 12.0 m from this row. In Cachoeira Dourada, samples were taken in the center row and at 1.5, 3.0, 4.5, 6.0, and 9.0 m from this row. All samples had five replicates. In Nova Canaa, the iCLF1 caused less disturbance in the microbial population than the degraded pasture, which was evidenced by the lower metabolic quotient and basal respiration. The sampling position in relation to the tree row had little effect on comparison of the iCLF with the degraded pasture in regard to soil biological properties. Carbon and N of the microbial biomass and the microbial quotient were the best properties for differentiating the iCLF from the degraded pasture. ICLFs have not yet led to improvements in soil biological quality in relation to the degraded pasture.

Influence of boron and organic matter on the changes in soil biological properties and yield of rape (Brassica campestris) in an aeric endoaquept

Field experiments were conducted during winter seasons of 2006 -07 and 2007-08 to study the influence of boron and organic matter application on the changes in soil biological properties in an aeric endoaquept (pH,7.5;organic carbon content, 0.61%; CaCl2–extractable boron 0.32 mg/kg) growing rape (Brassica campestris L.) as a test crop. The results reveal that non-symbiotic nitrogen fixing bacteria (NFB), non symbiotic nitrogen fixing capacity, phosphate solubilising micro-organisms (PSM), phosphate solubilising capacity (PSC) and microbial biomass carbon (MBC) have been found to be influenced with different treatments, being recorded highest (90.45, 69.29 × 105/g soil; 11.73, 9.63; 80.29, 63.28 mg of N2 fixed/g of soil/g of sucrose; 0.038, 0.032 mg/g dry soil and 159.48, 149.58 µg/g dry soil respectively) in the treatment T4 where lower level (0.5 kg/ha) of boron as calbor and organic matter at 5 tonnes/ha was applied along with recommended levels of N, P2O5 and K2O (80:40:40) in both rhizosphere (R) and non- rhizosphere (NR) soils. The yield of rape was also recorded highest (8.95 q/ha) in the treatment T4 ( lower level (0.5 kg/ha) of boron as calbor,organic matter at 5 tonnes/ha and recommended levels of N, P2O5 and K2O ( 80:40:40 ). From the stepwise technique of multiple regression it was revealed that the NFB at R and NR, PSC at R and NR, PSM at R and NR and MBC at NR are only important predictors which can explain 99 % of total variance.

Ground-based skidder traffic changes chemical soil properties in a mountainous Oriental beech (Fagus orientalis Lipsky) forest in Iran

Increased soil compaction following harvest traffic is an inroad for adverse changes in soil biological properties and processes, soil microbial activity, bacterial communities, and growth and development of plant roots. This study investigated the impacts of three levels of traffic intensity (3–6, 7–14, and 15+ passes) of a Timberjack 450C skidder on changes in several chemical soil properties at two levels of skid trail slope gradients (gentle =<20% and steep >20% inclination) in the Hyrcanian forest. Skidding increased soil bulk density between 19% and 39% and, averaged over both slope gradients, reduced amounts of soil organic carbon (33–67%), concentrations of nitrogen (51–80%), phosphorous (0–17%), potassium (11–36%), and hydrogen ions (78–98%) compared to undisturbed areas. Most soil damage occurred after a few skidder passes, particularly on steep slopes that generally experienced the highest level of soil deterioration. The primary mechanism that induced immediate chemical soil changes was an uplift and exposure of deeper soil layers in response to compression and displacement of the former soil surface. Skidding can jeopardize the sustainability of forest ecosystems by creating unfavorable changes in soil characteristics and nutrient status.

Evaluation of soil biological properties of 9- and 15-year-old stands in the oil palm plantation in Perak, Malaysia

Opening land for oil palm cultivation provokes many debates around the world regarding on the fate of biodiversity. A study was conducted to evaluate and compare soil biological properties of 9-year-old (P1) and 15-year-old (P2) stands of an oil palm plantation in Bikam, Perak, Malaysia. Composite samples were collected at depths of 0-15 cm (topsoil) and 15-30 cm (subsoil) located within six subplots (20 m × 20 m). The microbial population count was estimated using a spread-plate technique, and the Fluorescein diacetate (FDA) hydrolysis assay was used to measure microbial enzymatic activity. A rapid ethanol-free chloroform fumigation extraction technique was used for microbial biomass extraction, and the extracts were respectively analyzed by wet dichromate oxidation and Kjeldahl digestion for biomass carbon (C) and nitrogen (N). At the 0-15 cm depth, the microbial biomass C and N contents in the soils from both plots were significantly different (P<0.05). At the 15-30 cm depth, only microbial enzymatic activity was significantly different between plots. Although the addition of fertilizers to the soil is believed to be a predisposing factor, no significant differences in P1 and P2 plots for the biomass C and N in soils at the 15-30 cm depth were observed. Variations in the MBC/MBN ratio in soils of the P1 and P2 plots indicate that changes occurring in the soil microbial composition are due to the availability of soil organic substrates and N. Thus establishment of an oil palm plantation does contribute to changes in soil biological properties. Key words: Oil palm, different ages, microbial population, enzymatic activity, biomass C and N, rapid chloroform-fumigation extraction technique.

Responses of Soil Microbial Communities in the Rhizosphere of Cucumber (Cucumis sativus L.) to Exogenously Applied p-Hydroxybenzoic Acid

Changes in soil biological properties have been implicated as one of the causes of soil sickness, a phenomenon that occurs in continuous monocropping systems. However, the causes for these changes are not yet clear. The aim of this work was to elucidate the role of p-hydroxybenzoic acid (PHBA), an autotoxin of cucumber (Cucumis sativus L.), in changing soil microbial communities. p-Hydroxybenzoic acid was applied to soil every other day for 10 days in cucumber pot assays. Then, the structures and sizes of bacterial and fungal communities, dehydrogenase activity, and microbial carbon biomass (MCB) were assessed in the rhizosphere soil. Structures and sizes of rhizosphere bacterial and fungal communities were analyzed by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and real-time PCR, respectively. p-Hydroxybenzoic acid inhibited cucumber seedling growth and stimulated rhizosphere dehydrogenase activity, MBC content, and bacterial and fungal community sizes. Rhizosphere bacterial and fungal communities responded differently to exogenously applied PHBA. The PHBA decreased the Shannon-Wiener index for the rhizosphere bacterial community but increased that for the rhizosphere fungal community. In addition, the response of the rhizosphere fungal community structure to PHBA acid was concentration dependent, but was not for the rhizosphere bacterial community structure. Our results indicate that PHBA plays a significant role in the chemical interactions between cucumber and soil microorganisms and could account for the changes in soil microbial communities in the continuously monocropped cucumber system.

Impacts of Metals and Metalloids on Soil Microbial Diversity and Ecosystem Function

Metal and metalloid concentrations in soil exert an enormous influence on the diversity, composition, and activity of soil microorganisms that carry out essential ecosystem services. At low concentrations, microorganisms can compete for essential trace elements that are required to support their growth and in this manner affect plant nutrition and disease through the production of metal chelators. At high concentrations, the toxic effects of metals result in reduced microbial diversity and altered rates of key biological processes that underlie ecosystem function. The latter is now of great concern as large land areas across the globe have become contaminated with metals from land application of wastes and atmospheric deposition of heavy metals. An understanding of how plants, soils, organic matter, and microorganisms influence metal transformations in the rhizosphere is thus critical for managing soils to assure the long term protection of soil quality, food safety, and ecosystem function. One of the major difficulties in making practical management decisions with respect to metal pollution for different types of soils has been our inability to derive bioindicators of soil quality that can provide indices of soil quality across the landscape at different scales and over time. Ecosystems respond very differently to acute and chronic metal toxicities depending on their chemical properties and prior exposure histories. Toxicities are particularly influenced by physico-chemical conditions in soils that influence the bioavailability of metals and metalloids to plants and microorganisms. Nonetheless, the dynamic nature of microbial communities, which respond much faster to changes in management practices than do soil physical and chemical properties enables us to use bioindicators as a sensitive tools for predicting possible long term changes in soil properties. From a land management perspective, it is critical that soil microbiologists offer appropriate bioindicators for use in measuring the impacts of soil pollution on soil biological properties and extend knowledge as to how specific bioindicators may reflect long term changes in soil quality that can be used to guide land management practices and remediation of contaminated soils. Responses of Microbial Communities to Metal Contamination The microbial community concept is based on the interactions among in all of the various species of bacteria, fungi, protozoa, and microfauna that carry out the various broad level functions of the soil, ranging from nutrient cycling to organic matter formation, and plant disease protection. Differences in the species composition of various soils are linked to changes in soil biological properties that in turn affect the long term chemical and physical properties and ability to support plant growth. Among the most basic functions are respiration

Application of Two Organic Amendments on Soil Restoration: Effects on the Soil Biological Properties

One method for recovering degraded soils in semiarid regions is to add organic matter to improve soil characteristics, thereby enhancing biogeochemical nutrient cycling. In this paper, we studied the changes in soil biological properties as a result of adding a crushed cotton gin compost (CCGC) and a poultry manure (PM) for 4 yr to restore a Xerollic Calciorthid located near Seville (Guadalquivir Valley, Andalusia, Spain). Organic wastes were applied at rates of 5, 7.5, and 10 Mg organic matter ha(-1). One year after the assay began, spontaneous vegetation had appeared in the treated plots, particularly in that receiving a high PM and CCGC dose. After 4 yr, the plant cover in these treated plots was around 88 and 79%, respectively, compared with 5% for the control. The effects on soil microbial biomass and six soil enzymatic activities (dehydrogenase, urease, BBA-protease, beta-glucosidase, arylsulfatase, and alkaline phosphatase activities) were ascertained. Both added organic wastes had a positive effect on the biological properties of the soil, although at the end of the experimental period and at high dosage, soil microbial biomass and soil enzyme activities were generally higher in the PM-amended soils compared to the CCGC-amended soils. Enzyme activity from the PM-amended soil was 5, 15, 13, 19, 22, 30, and 6% greater than CCGC-amended soil for soil microbial biomass, urease, BBA-protease, beta-glucosidase, alkaline phosphatase, arylsulfatase, and dehydrogenase activities, respectively. After 4 yr, the percentage of plant cover was > 48% in all treated plots and 5% in the control.

Changes in soil biological properties with the addition of metsulfuron-methyl herbicide

An incubation study was conducted to investigate the effects of metsulfuron-methyl herbicide on the soil microbial biomass in loamy sand soil. The herbicide was applied to the soil at four concentrations: control, 0.01, 0.10, and 1.00 μg·g−1 soil. Determinations of microbial biomass-C and microbial biomass-N contents were carried out 1, 3, 5, 7, 10, 15, 25, and 45 days after herbicide application. In comparison to untreated soil, the microbial biomass-C and biomass-N decreased significantly in soils treated with herbicide at concentrations of 0.1 and 1.0 μg·g−1 soil within the first 7 days of incubation. The application of metsulfuron-methyl herbicide to the soil reduced the Cmic/Corg and Nmic/Ntotal percentages, which decreased with increasing application rate of metsulfuron-methyl herbicide. Compared to the untreated control, a marked increase in the microbial biomass C: N ratio was observed in the herbicide treated soil. This effect was transitory and was significant only at the higher rates of metsulfuron-methyl.

Wastewater C:N ratio effects on soil hydraulic conductivity and potential mechanisms for recovery

To sustain the performance of a land treatment system, soil hydraulic conductivity must be maintained. Biological clogging of soil pores tends to decrease hydraulic conductivity. The changes in soil biological properties and hydraulic conductivity were examined in repacked soil cores receiving weekly additions of wastewater with three C:N ratios for 28 weeks. We tested whether addition of a nitrification inhibitor (dicyandiamide, DCD) and polysaccharidase enzyme preparation (PEP) with wastewater would maintain hydraulic conductivity. Increases in wastewater C:N ratio increased soil microbial biomass, carbohydrate, and nematode population and decreased nitrate leaching and hydraulic conductivity, by up to 80%. While neither DCD nor PEP treatments lowered soil carbohydrate, both had increased hydraulic conductivity (in the range of 280–290%) in cores irrigated with high C:N wastewater, relative to `nil' treatment wastewater.

Evaluation of soil biological properties as potential bioindicators of soil health

Two long-term field trials in South Australia were used to detect and characterise changes in soil biological properties that were a consequence of different agricultural management. The properties examined were total bacteria, fungi, and actinomycetes; total pseudomonads; cellulolytic bacteria and fungi; mycorrhizal fungi; plant root pathogens (Gaeumannomyces graminis var. tritici, Rhizoctonia solani, Pythium irregulare); bacterial-feeding protozoa; soil mesofauna (collembola and acari); earthworms; microbial biomass; C and N mineralisation; in situ CO2 respiration; cellulose decomposition; and soil enzyme activity (peptidase, phosphatase, sulfatase). The sensitivity of these biological properties was assessed to tillage (no-tillage v. conventional cultivation), stubble management (stubble retained v. stubble harvested), crop rotation (continuous wheat v. wheat-sown pasture), and N fertilisation (nil v. 80 kg N/ha applied during the crop phase). Tillage, stubble management, crop rotation, and N fertilisation significantly (P&lt;0.01) affected C mineralisation and microbial biomass. Tillage with stubble management significantly affected root pathogenic fungi, protozoa, collembola, earthworms, and cellulose decomposition. Crop rotation affected mycorrhizal fungi, protozoa, and soil peptidase activity, and N fertiliser had a significant effect on mycorrhizal fungi, protozoa, and cellulose decomposition. As these biological properties are responsive to agricultural management, they may have potential as bioindicators. Total bacteria, fungi, and actinomycetes, cellulosedecomposing bacteria and fungi, soil phosphatase and sulfatase activity, and N mineralisation were less affected by these treatments and may therefore have limited potential as bioindicators.

Microbial biomass as an index for tillage-induced changes in soil biological properties

Indirect measurements of soil microbial biomass carbon (C) and nitrogen (N), using the chloroform fumigation-incubation method (CFIM), were utilized as indices of the soil biological condition on a range of tillage systems under different climatic and agronomic conditions. Biological properties within the soil profile were influenced by the degree of soil mixing, incorporation of crop residues, soil moisture regime and root growth. A wheat-fallow system reduced microbial biomass C and N in the 0–15-cm soil depth by 60%, compared to a continuous wheat system. Reduction in soil tillage caused a redistribution of biological properties within the soil. For spring cereals under semi-arid—sub-humid moisture regimes, after 4 years, zero tillage increased microbial biomass C and N in the 0–5 cm soil depth by 10–23%, compared with shallow tillage; this increase was gradually offset over time by a decline in microbial biomass at lower soil depths. In a per-humid region, a similar redistribution of soil microbial biomass was evident after 2 years. After 3 years, direct drilling of Italian ryegrass increased microbial biomass C and N in the 0–5-cm soil depth by 26–28%, compared to a cultivated system. The level of microbial biomass under the direct-drilled system was similar to that found under an associated permanent pasture. The CFIM provided a sensitive measure of tillage-induced changes in soil biological properties. Both microbial biomass C and N responded rapidly to changes in tillage and soil management. In general, the CFIM detected changes in soil biological properties prior to any measurable change in soil organic C or N.