Vermicompost-amended Soils Research Articles

Effect of Arbuscular Mycorrhizal Fungi and Rock Phosphate on Growth, Physiology, and Biochemistry of Carob under Water Stress and after Rehydration in Vermicompost-Amended Soil.

In the Mediterranean region, reforestation programs record failures following successive drought periods. The use of different plant-growth-promoting amendments and the understanding of drought-induced physiological and biochemical responses of carob will contribute to the reforestation program's success. In this study, the effects of arbuscular-mycorrhizal-fungi (AMF), vermicompost (VC), and rock phosphate (RP) on carob seedlings under drought stress (DS) and recovery (REC) conditions were evaluated. A greenhouse experiment was conducted with carob seedlings grown in the presence of AMF, VC, and RP, applied alone or in combination under well-watered (WW), DS (by stopping irrigation for 12 days), and recovery (REC) conditions. The obtained results indicated that the triple combination (AMF + VC + RP) presented the highest improvement in water potential, photosynthetic pigment content, stomatal conductance, and chlorophyll fluorescence compared to the controls under DS and after REC. In addition, this combination resulted in improved tolerance of carob seedlings to DS and a high potential for rapid recovery after rehydration due to a high accumulation of sugars, proteins, and antioxidant enzymes. In summary, the results underline the importance of inoculating carob with AMF in combination with (in)-organic amendments in improving its tolerance to DS and its recovery performances.

Soil food web structure coordinated by soil omnivores sustains soil multifunctionality in moderate vermicompost amended fields

Biodiversity can enhance soil multifunctionality through strengthening biotic interactions in soil food webs, but largely unknown in agroecosystems. We therefore predicted that vermicompost, serving as an organic amendment and soil health conditioner, could enhance trophic interactions among bacteria, fungi and nematodes and mediate synergies and trade-offs among soil functions, especially when substituting synthetic fertilizer was applied to soils. Soil multifunctionality was assessed from plant growth and product quality, carbon and nutrient cycling, water and climate regulation in an intensive cropping system. Pepper, tomato and spinach were cultivated in rotation annually, with substituting vermicompost as a nutrient replacement for synthetic fertilizer for 5 years. Results showed that substituting a moderate dose of vermicompost for synthetic fertilizer offered the highest soil multifunctionality by enhancing synergies among multiple functions. The vermicompost-stimulated multifunctionality was primarily attributed to the cascading effects of the complex food web structure induced by omnivorous nematode. These effects were regulated by the physicochemical environment of the vermicompost-amended soil. Notably, the multifunctional benefits degraded when higher rates of vermicompost were applied, suggesting that over-use of vermicompost combined with an inadequate amount of synthetic fertilizer could simplify soil food web structure and decrease soil functions, mainly due to the nutrient limitation and increasing harmful substances as indicated by C:N stoichiometry, heavy metals and antibiotic resistance genes. In intensive agricultural systems, finding an optimal balance of organic amendments and synthetic fertilizer that supports complex soil food web interactions is therefore crucial for promoting multiple soil functions and particularly sustaining the production of high-quality food crops.

Influence of Biochar and Animal Manures Application on Ammonia and Nitrate Concentrations in the Root and Shoot of Three Varieties of Turnips

Many investigators have focused on the impact of fertilizers on crop yield and ignored fertilizers impact on the plants composition. The impact of seven types of soil treatments (sewage sludge, horse manure, chicken manure, vermicompost, elemental organic fertilizer, inorganic fertilizer, and native soil) and similar seven treatments amended with biochar on the concentrations of NH3 and NO3 in the roots and shoots of three commercial varieties of turnips, Brassica rapa was investigated. The three varieties (Purple Top White Globe PTWG, Scarlet Queen Red SQR, and Tokyo Cross TC) varied in concentrations of NH3 and NO3 levels. High levels of NO3 in edible plants is associated with harmful effects on human health, due to the risk of creation of carcinogenic N-nitroso compounds. NO3 in SQR roots and shoots (edible greens) was greater than varieties PTWG and TC. The concentration of NH3 averaged 20.2, 12.8, and 8.9 µg g−1 fresh turnip roots, whereas NO3 values averaged 107.6, 64.1, and 62.9 µg g−1 fresh turnip roots in varieties SQR, PTWG, and TC, respectively. Regardless of soil amendment type, the concentration of NH3 in the shoots (44.0 µg g−1) was greater than the roots (15 µg g−1). On the contrary, NO3 was higher in the roots (89.4 µg g−1) compared to the shoots (67.6 µg g−1 fresh tissue). Overall, biochar added to vermicompost amended soil increased NH3 by 73% compared to vermicompost not amended with biochar. Regarding acceptable daily intake (ADI) for NO3, none of the three varieties analyzed constitute any NO3 adverse effects on normal human intake. Similarly, consuming turnips grown in any of the animal manures tested do not represent any hazardous issues.

Garlic (Allium sativum L.) Cultivation Using Vermicompost-Amended Soil as an Aspect of Sustainable Plant Production

To achieve higher yields and maximum plant growth, excessive amounts of inorganic fertilisers are often applied to soils, affecting human and animal health and leading to the degradation of environmental resources. The use of organic fertilisers is proposed as an alternative to mineral fertilisation. One of the more frequently used organic fertilisers is vermicompost, which contains nutrients for plants in readily available forms and is characterised by the slow release of macronutrients and microelements into the soil environment. In a two-year field study, an attempt was made to use vermicompost produced from the waste mass of littoral plants as a soil amendment in the cultivation of garlic (Allium sativum). The experiment was conducted on raised beds with three treatments which were substitution of 10%, 25% and 50% vermicompost (V10, V25 and V50, respectively) to a heavy clay soil (SL), that with no addition acted as a control. Results showed that the 50% vermicompost addition had the most beneficial effect on selected (from a practical point of view) plant traits (e.g., diameter and mean bulb weight, mean number of cloves per bulb and mean clove weight, and mean yield), as well as on the content of macronutrients and microelements in garlic cloves. Lowest values of the analysed traits for A. sativum were found in the SL control group. No significant differences were found for the analysed parameters in the aboveground parts of plants in all the applied substrates.

Nutrient and colloid leaching from un-amended versus vermicompost-amended soil

This study aimed to investigate the effects of flow rate, initial soil moisture conditions and vermicompost (VC) application on total dissolved solids (TDS), nitrate (NO3), dissolved organic carbon (DOC) and colloid leaching from soil. Columns were filled with natural soil or VC-amended soil and were leached under unsaturated flow conditions using flow rates of 4.3–5.1, 2.5 and 0.4 mL/min. Two sets of experiments were conducted, one with the soils at initial air-dried conditions and the other with initial saturated conditions. Control experiments were conducted under saturated-flow conditions using flow rates of 2.7–3.8 mL/min for comparison. Results of the leaching experiments showed that EC, nitrate and DOC levels in the effluent were higher for the VC-amended soil versus the un-amended soil. Leaching under initial air-dried conditions and at the lowest flow rate (lowest water saturation) also produced higher EC, nitrate and DOC concentrations in the effluent. Conversely, effluent colloid concentrations were slightly higher for saturated-flow conditions, and elution behavior was similar between the un-amended and VC-amended soils. Statistical analysis revealed that the total leaching of TDS, nitrate, DOC and colloid under the initial air-dried conditions was not significantly different (p < 0.05) in comparison with the initial saturated conditions. Although, higher flow rates showed high amount of total leaching of TDS, nitrate, DOC and colloid, unsaturated flow rate of 2.5 mL/min leached more efficiently than flow rate of 2.7–4.3 mL/min in un-amended soil. Findings of this study would help decision makers to better manage soil salinity, drainage and groundwater pollution. Particularly, applying lower flow rates for irrigation applications to maintain unsaturated conditions can significantly decrease colloid migration and soil erosion.

Multifarious allelochemicals exhibiting antifungal activity from Bacillus subtilis MBCU5.

A potential antagonist, designated strain Bacillus subtilis MBCU5 was previously isolated from vermicompost-amended soils of Gandhinagar, Gujarat, India. Crude allelochemicals from strain MBCU5 displayed strong antifungal activity against Macrophomina phaseolina as well as Rhizoctonia solani. These crude allelochemicals were tentatively identified as iturin, fengycin and surfactin through TLC and HPTLC analysis. Lipopeptides produced by MBCU5 were identified by MALDI-TOF-MS and LC-ESI-MS/MS analysis showed that iturin homologues (m/z 1020-1120), surfactin (m/z 1008.7 and m/z 1022.7), fengycin A and fengycin B (m/z 1400-1550) types of allelochemicals which are responsible for antifungal activity against pathogens. PCR analysis showed presence of genes (i.e. Iturin A synthetase KJ531680 and Surfactin synthetase KJ601726) involved in the biosynthesis of allelochemicals. Many reports showed lipopeptides from Bacillus species; this is the first report executed of multifarious allelochemicals from vermicompost-amended soil due to the presence of predominant Bacillus species.

Fate and effect of imidacloprid on vermicompost-amended soils under dissimilar conditions: Risk for soil functions, structure, and bacterial abundance.

The fate and impact of pesticide on soil depend partly on the agricultural practices, such as prior treatment with pesticide and/or organic amendments. As a means of determining how the previous soil conditions can affect the fate of imidacloprid (IMI) and its effect on soil functions, experiments were made with soil samples, double-amended or not with either vine-shoot (W) or olive cake (O) vermicompost or contaminated or not with IMI. These soil samples, incubated for 3months, were placed in two microcosms (M1 with the pre-amended soils and M2 with the pre-exposed soils), treated with IMI and amended with vermicomposts and then incubated for 3months. The IMI distribution on soil fractions, sorption processes, dissipation kinetics, and biochemical as well as genetic structure and bacterial abundance were determined to assess the fate and impact of IMI on the soil. The addition of W vermicompost to the soil reduced the IMI availability. The dissipation kinetic in soils from M1 and M2 followed, respectively, a single first-order and a double first-order in parallel models. The lowest IMI persistence corresponded to the soil from M2 amended with O-vermicompost with DT50 and DT90 values of 67d and 265d, while in the other soils 90% dissipation required >512d. The vermicomposts-amended contaminated soils increased the dehydrogenase activity by 2- and 4-fold respect the control soils. However, the urease activity decreased due to the IMI influence. The changes in the bacterial community in the contaminated soil amended with O-vermicompost during incubation were correlated with the dissipation rate constant of IMI, suggesting a better tolerance of microorganisms to IMI. Thus, in the soil contaminated with IMI, the amendment with the vermicompost from olive cake can mitigate the impact of this insecticide on soil functions and promote its depuration capability while minimizing environmental risks.

Evaluation of soil amendments as a remediation alternative for cadmium-contaminated soils under cacao plantations.

Elevated plant-available cadmium (Cd) in soils results in contamination to cacao (Theobroma cacao L) beans. Effectiveness of vermicompost and zeolite in reducing available Cd in three cacao-growing soils was studied under laboratory conditions. Sorption-desorption experiments were conducted in soils and amendments. Cadmium was added at 0 or 5mgkg(-1) (spiked), then, amendments were incorporated at 0, 0.5, or 2%. Amended soils were incubated at room temperature for 28days. Plant-available Cd was determined using 0.01M CaCl2 (WSE) and Mehlich 3 (M3) extraction procedures in subsamples taken from individual bags at six time intervals. Soils and amendments displayed different sorption characteristics and a better fit was attained with Freundlich model (R (2) > 0.82). Amendments were ineffective in reducing extractable Cd in non-spiked soils. In Cd-spiked soils, vermicompost at 2% significantly reduced WSE-Cd (P < 0.01) from 3.36, 0.54, and 0.38mgkg(-1) to values lower that instrument's detection in all the three soils and significantly diminished M3-extractable Cd (P < 0.05) from 4.62 to 4.11mgkg(-1) in only one soil. Vermicompost at 0.5% significantly decreased WSE-Cd (P < 0.01) from 3.04 and 0.31 to 1.69 and 0.20mgkg(-1), respectively, in two soils with low sorption capacity for Cd. In contrast, zeolite failed to reduce WSE- or M3-extractable Cd in all studied soils. A negative correlation occurred between soil pH and WSE-Cd (r > -0.89, P < 0.01). The decrease in WSE-Cd appears to be associated with the increase in pH of the vermicompost-amended soils.

Comparison of the Effect of Vermicompost and Inorganic Fertilizers on Vegetative Growth and Fruit Production of Tomato (&amp;lt;i&amp;gt;Solanum lycopersicum&amp;lt;/i&amp;gt; L.)

This study attempted to compare the effect of cow manure vermicompost and inorganic fertilizers on the vegetative growth and fruits of tomato plant (Solanum lycopersicum L.). An air dried sandy loam soil was mixed with five rates of vermicompost equivalent to 0 (control), 5, 10, 15 and 20 t ha-1 and three rates of NPK fertilizer equivalent to 50% (N-P-K = 69-16-35 kg ha-1), 100% (N-P-K = 137-32-70 kg ha-1) and 200% (N-P-K = 274-64-140 kg ha-1). The treatments were replicated three times. The data revealed that shoot length, number of leaves, dry matter weight of shoots and roots, fruit number and fruit weight were influenced significantly (P < 0.05) by the application of vermicompost and NPK fertilizer in the growth media. The highest dose of vermicompost of 20 t ha-1 increased dry weight of shoot of 52 folds and root of 115 folds, number of fruit(s)/plant of 6 folds and mean fruit weight of 29 folds while the highest rate of NPK fertilizer of 200% increased dry weight of shoot of 35 folds and root of 80 folds, number of fruit(s)/plant of 4 folds and mean fruit weight of 18 folds over the control treatment. The growth performance of tomato was better in the vermicompost amended soil pots than the plants grown in the inorganic fertilizer amended soil pots. This study suggested that the vermicompost served as a potential source of nutrients for plant growth.

Isolation and identification of allelochemicals produced by B. sonorensis for suppression of charcoal rot of Arachis hypogaea L.

Bacillus sonorensis MBCU2 isolated from vermicompost-amended soil from Gujarat, India showed most antagonistic activity against Macrophomina phaseolina by dual culture screening. The culture supernatant of MBCU2 completely suppressed the mycelia growth of pathogen, indicating that suppression was due to the presence of allelochemicals in the culture filtrate. Results of scanning electron microscopy revealed that MBCU2 caused morphological alteration in mycelia of M. phaseolina as evident by hyphal lysis and perforation. Lipopeptides (iturin A and surfactin) produced by MBCU2 were detected and identified by MALDI-TOF-MS as well as liquid chromatography coupled with ESI-MS/MS. Pot trial studies conducted by seed bacterization with MBCU2 resulted in statistically significant increase in Arachis hypogaea L. vegetative growth parameters such as root length (91%), shoot length (252%), fresh weight (71%), dry weight (57%), number of pod (128%), and number of seed (290%) in M. phaseolina infested soil over control as well as decreased M. phaseolina disease severity. We suggest that allelochemicals production can be linked to the mechanism of protection of A. hypogaea L. from M. phaseolina by B. sonorensis MBCU2.

ZYMOGRAPHIC IDENTIFICATION AND BIOCHEMICAL CHARACTERIZATION OF CHITINASE AGAINST PHYTOFUNGAL PATHOGENS

An endospore forming Gram positive bacterium (MBCU4) was isolated from a vermicompost amended soil, and confirmed as Bacillus subtilis through the 16S rRNA sequence analysis. An extracellular chitinase was detected from this strain of B. subtilis under specific environmental condition. An attempt was made to purify the enzyme by ammonium sulfate precipitation followed by DEAE sepharose CL-6B column chromatography. The purified enzyme was demonstrated as a single band, having the molecular weight 31kDa on SDS PAGE analysis and its activity in the gel was determined by clear zone on zymogram. Further characterization of the isolated enzymes has showed that this enzyme is most active at pH 6.0 and at the optimized temperature of 50 0C. The purified chitinase exhibited high degree of antifungal activity particularly by degrading their cell wall components of plant pathogens Macrophomina phaseolina (69.0%) and Rhizoctonia solani (52.0%). It infers that the chitinase produced by B. subtilis could play an important role for biopesticidal activity.

Effect of carbofuran on enzymatic activities and growth of tomato plants in natural, fertilized and vermicompost-amended soils

The effects of carbofuran, a widely used carbamate pesticide, on soil enzymatic activities such as fluorescein diacetate hydrolysis (FDAH), dehydrogenase, and acid and alkaline phosphatases were studied at different time intervals in unamended soil and soil amended with inorganic fertilizers and vermicompost, cropped with tomato plants. The results showed that all enzymatic activities varied with carbofuran application rates and increased significantly up to 1.0 kg active ingredient (a.i.) ha−1 dose of carbofuran. The most significant increase was observed at 0.20 kg a.i. ha−1 dose both in unamended and amended soils. This showed that carbofuran was not toxic to all enzymatic activities studied upto 1.0 kg a.i. ha−1 dose of carbofuran in both systems. A significant decrease in all enzymatic activites were observed at higher dose of carbofuran both in unamended and amended soils relative to their respective controls. Highest enzymatic activities were observed in vermicompost amended soil and minimum in fertilized soil compared to control. The results indicated that the growth of tomato plants was significantly higher at 0.20 kg a.i. ha−1 dose of carbofuran in all the cases and followed the order: fertilized soil > vermicompost amended soil > natural soil and was positively correlated with the enzyme activities.

Cultivation of beans ( Phaseolus vulgaris L.) in limed or unlimed wastewater sludge, vermicompost or inorganic amended soil

Wastewater sludge can be vermicomposted to increase its nutrient content and reduce pathogens. The effect of vermicompost wastewater sludge on soil characteristics and growth of bean plants ( Phaseolus vulgaris L.) was compared with that of inorganic fertilizer, untreated sludge or sludge treated with lime to pH 12. Plants cultivated in vermicompost amended soil developed best while those amended with inorganic fertilizer least. Bean plants grown in the unlimed amended soil had the highest total N content of 3.97 g kg −1, but only 6 active and 8 total nodules. Plants cultivated in unamended soil and added with inorganic fertilizer had >20 active and total nodules, but ≤2.12 g N kg −1 dry plant. It was found that limed and unlimed sludge stimulated development of bean plants to a larger extent than those cultivated in inorganic fertilized soil or unamended soil in the greenhouse, but less than those cultivated in vermicompost amended soil.

Arabidopsis thalianaresistance to insects, mediated by an earthworm‐produced organic soil amendment

Vermicompost is an organic soil amendment produced by earthworm digestion of organic waste. Studies show that plants grown in soil amended with vermicompost grow faster, are more productive and are less susceptible to a number of arthropod pests. In light of these studies, the present study was designed to determine the type of insect resistance (antixenosis or antibiosis) present in plants grown in vermicompost-amended potting soil. Additionally, the potential role of microarthropods, entomopathogenic organisms and non-pathogenic microbial flora found in vermicompost on insect resistance induction was investigated. Findings show that vermicompost from two different sources (Raleigh, North Carolina, and Portland, Oregon) were both effective in causing Arabidopsis plants to be resistant to the generalist herbivore Helicoverpa zea (Boddie). However, while the Raleigh (Ral) vermicompost plant resistance was expressed as both non-preference (antixenosis) and milder (lower weight and slower development) toxic effect (antibiosis) resistance, Oregon (OSC) vermicompost plant resistance was expressed as acute antibiosis, resulting in lower weights and higher mortality rates. Vermicompost causes plants to have non-preference (antixenosis) and toxic (antibiosis) effects on insects. This resistance affects insect development and survival on plants grown in vermicompost-amended soil. Microarthropods and entomopathogens do not appear to have a role in the resistance, but it is likely that resistance is due to interactions between the microbial communities in vermicompost with plant roots, as is evident from vermicompost sterilization assays conducted in this study.

Enzyme activities and diuron persistence in soil amended with vermicompost derived from spent grape marc and treated with urea

Mineral fertilizers, organic amendments, and pesticides are inputs commonly used in conventional farming practices. The aim of this study was to evaluate the effects of single or combined applications of spent grape marc-vermicompost, urea, and/or diuron on soil-enzyme activities and the persistence of this herbicide in soils with low organic carbon content. The application of vermicompost enhanced dehydrogenase (DHase) enzyme activity over time but altered soil urease activity to a very limited extent. The reduction in diuron concentrations and the increase in DHase activity indicated that the soil microorganisms were capable of degrading the ureic herbicide. Treatment with vermicompost and diuron had a stimulatory effect on soil microbial activity. On the whole, the application of diuron and urea to the vermicompost-amended soil raised DHase and urease activity to maximum levels (>3 μg INTF g −1 h −1 and >47 μg NH 4 + g −1 h −1, respectively). The application of urea to the unamended and vermicompost-amended soil decreased diuron persistence from 18.8 and 33 d to 12.5 and 15 d, respectively. Our findings show that although vermicompost additions reduce diuron availability, this boosts diuron degradation when combined with urea. These additions, under different soil management conditions, minimize the bioavailability and persistence of diuron and consequently the risk of leaching and seepage into aquifers. Compared with untreated soils, these types of treated soils could also improve agricultural sustainability and the quality of the environment.

Emission of CO 2 and N 2O from soil cultivated with common bean ( Phaseolus vulgaris L.) fertilized with different N sources

Addition of different forms of nitrogen fertilizer to cultivated soil is known to affect carbon dioxide (CO 2) and nitrous oxide (N 2O) emissions. In this study, the effect of urea, wastewater sludge and vermicompost on emissions of CO 2 and N 2O in soil cultivated with bean was investigated. Beans were cultivated in the greenhouse in three consecutive experiments, fertilized with or without wastewater sludge at two application rates (33 and 55 Mg fresh wastewater sludge ha − 1 , i.e. 48 and 80 kg N ha − 1 considering a N mineralization rate of 40%), vermicompost derived from the wastewater sludge (212 Mg ha − 1 , i.e. 80 kg N ha − 1 ) or urea (170 kg ha − 1 , i.e. 80 kg N ha − 1 ), while pH, electrolytic conductivity (EC), inorganic nitrogen and CO 2 and N 2O emissions were monitored. Vermicompost added to soil increased EC at onset of the experiment, but thereafter values were similar to the other treatments. Most of the NO 3 − was taken up by the plants, although some was leached from the upper to the lower soil layer. CO 2 emission was 375 C kg ha − 1 y − 1 in the unamended soil, 340 kg C ha − 1 y − 1 in the urea-amended soil and 839 kg ha − 1 y − 1 in the vermicompost-amended soil. N 2O emission was 2.92 kg N ha − 1 y − 1 in soil amended with 55 Mg wastewater sludge ha − 1 , but only 0.03 kg N ha − 1 y − 1 in the unamended soil. The emission of CO 2 was affected by the phenological stage of the plant while organic fertilizer increased the CO 2 and N 2O emission, and the yield per plant. Environmental and economic implications must to be considered to decide how many, how often and what kind of organic fertilizer could be used to increase yields, while limiting soil deterioration and greenhouse gas emissions.

Effects of Cu, Ni and Zn on Lettuce Grown in Metal-Enriched Vermicompost Amended Soil

A greenhouse experiment was conducted to test the effectiveness of cattle manure vermicompost enriched with Cu, Ni or Zn to increase plant yield. An oxisol amended with the metal-enriched vermicompost at the doses 0, 25, 50, 65, and 80 t ha−1 was used to grow lettuce (Lactuca sativa L). After 39 days of growth, the plants were weighed for fresh and dry matter weight determinations. The soil amended with the vermicompost was analyzed for determination of DTPA (diethylenetriaminepentaacetic acid)-extractable Cu, Ni and Zn. The distribution of the metals in the plants was determined and the metal concentrations compared with the levels commonly found in plants, as well as with the range of the critical levels of toxicity to plants. Within each dose of 50, 65 and 80 t ha−1 of the metal-enriched vermicomposts applied there was a decrease in lettuce yield as compared to the correspondent 50, 65 and 80 t ha−1 doses of the natural vermicompost applied. The Cu concentrations in the lettuce leaves from the pots with vermicompost enriched with this element were in the range commonly found in plants (from 5.9 to 13.9 mg kg−1), although in the roots they were relatively high (from 76.25 to 244.56 mg kg−1). The Ni concentrations in the leaves from the pots with the vermicompost contaminated with this element were within the range of critical levels of toxicity to plants, i.e., from 10 to 50 mg kg−1. In the case of Zn, its concentrations in the leaves from the pots with vermicompost enriched with this element were, in general, above the range of critical levels of toxicity to plants, i.e., from 200 to 500 mg kg−1. The plants grown in soil amended with vermicomposts enriched with Cu and Ni showed high Cu and Ni concentrations in the roots, while the plants grown in soil amended with vermicompost enriched with Zn showed high Zn concentrations in the leaves. The correlation coefficients between the DTPA-extractable Cu, Ni and Zn and their concentrations in the plants varied from 0.835 to 0.950.

Estimating soil resilience to a toxic organic waste by measuring enzyme activities

The ability of a degraded soil to respond to successive additions of a toxic organic waste (olive-mill solid waste) and its vermicompost was studied in a controlled incubation experiment for 32 weeks. Hydrolytic enzyme activities (phosphatase, β-glucosidase), oxidoreductase activities (dehydrogenase, o-diphenol oxidase) and indole acetic acid production, were used as measures of soil perturbation. No microbial activity, indicated by the total lack of dehydrogenase activity, was detected when the olive-mill solid waste was added to the soil. However, after 16 weeks, the activity returned to the original soil levels (1.35 μg INTF g −1 h −1). The addition of vermicomposted olive-mill solid waste increased the original soil dehydrogenase activity by five-fold, indicating a loss of toxicity of the waste during the vermicomposting process; the activity remained high throughout the experiment. At week 21, a second addition of olive solid waste, was made to both olive waste and vermicompost-amended soils, when the soil originally amended with olive waste had reached the activity measured in soil amended with vermicompost. Dehydrogenase activity recovered immediately, reaching levels up to seven-fold higher than the background levels of the soil. The ability of soil to respond to a toxic waste clearly differed after a period of exposure to the waste. The faster response was probably related to the increased pool of stabilized organic matter present in soil, arising from the stabilization of added olive waste in the soil or through the amended vermicompost. The amplitude (period of recovery to the initial state after disturbance) and the elasticity (speed of recovery) of the soil could also be monitored by o-diphenol oxidase and β-glucosidase activities. However, indole-3-acetic acid production proved to be a useful measure of perturbation only following the second addition of the olive waste.