Rıdvan Kızılkaya

Soil Enzymes as Indication of Soil Quality

Soil, water and air are natural resources as well as pollution reservoirs. Soil quality can be changed by pollution, ecological perturbations and agricultural practices. Soil quality can be defined as, “the capacity of a specific kind of soil to function, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation”(Karlen et al. 1997). Preserving soil quality should be needed for sustaining of life and human nutrition. Soil enzymes are used as soil quality indicators for quick response of changes for environmental stress, pollution and agricultural practices much more sooner (1–2 year) than other soil properties (organic matter); easy to measure (relatively simple procedure), having relations with plant productivity, soil quality parameters (organic matter, soil physical properties, microbial activity, and microbial biomass), and biogeochemical cycle; and being integrative. This chapter mainly covers three distinct effects for changes in soils: (1) pollution (heavy metals, pesticides, industrial amendments or contaminants, hydrocarbons, acid precipitations, industrial air pollutants, sewage sludge, and waste usage), (2) ecological perturbations(land use, devegetation and revegetation, changing climatic conditions, and forest fires), and (3) agricultural practices (irrigation, fertilizers, amendments, different management and farming systems, crop rotation, and tillage).

Effects of Heavy Metals on Soil Enzyme Activities

The pollution of the soil with heavy metals is one of the worst legacies of our intensive agricultural–industrial activities, and it negatively affects various characteristics of the soil, including soil enzyme activities. Soil enzymes are natural molecules that catalyze soil microbial reactions and mainly originate from microorganisms and plants. Since enzyme activities play fundamental roles in soil chemical and biological reactions, their inhibition by heavy metals has received considerable attention and has been well documented by many researchers over the last few decades. The activities of soil enzymes have often been proposed as sensitive indicators of important microbial reactions involved in nutrient cycles and they respond to changes in the soil caused by natural or anthropogenic factors. In this regard, soil enzyme activities are often used to evaluate the impact of human activity on soil life. The purpose of this chapter is thus to emphasis some facts, hypotheses, and probabilities, as well as the results of research into the relationships between soil enzymes and heavy metals.

Earthworm Interactions with Soil Enzymes

As one of the dominant members of soil fauna, earthworms fulfill significant tasks in the soil ecosystem by participating in the physico-chemical processes of the soil, such as organic matter cycles, nutrient transformations, and modifications in soil structure. These processes are also directed by the activities and amounts of the enzymes produced by soil microorganisms that inhabit a wide range of soil environments including intestine systems, excretions, casts, and burrow linings of the earthworms. Therefore, microbial activity and the enzymes produced are considered to be closely related with earthworm life in soil. The purpose of this chapter is to describe the interactions between soil enzymes and earthworms at different levels in soil.

Microbiological Properties in Earthworm Cast and Surrounding Soil Amended with Various Organic Wastes

Abstract Changes produced in the microbiological properties of earthworm Lumbricus terrestris casts and surrounding soil by the addition of various organic wastes such as wheat straw (WS), tea production waste (TEW), tobacco production waste (TOW), cow manure (CM), and hazelnut husk (HH) were evaluated in an incubation experiment. Twenty‐one days after organic waste treatment, analyses of microbial biomass (Cmic), basal soil respiration (BSR), metabolic quotient (qCO2), and enzyme activities (dehydrogenase, catalase, β‐glucosidase, urease, alkaline phosphatase, and arylsulphatase) were carried out on collected cast and soil samples. Addition of organic wastes to the soil increased values of Cmic, BSR, and enzyme activities in soil and earthworm casts, indicating activation by microorganisms. Except for catalase activity, these values of microbiological parameters in casts were higher than in surrounding soil at all waste treatments and control. The addition of organic wastes caused a rapid and significant increase in organic carbon, total nitrogen, and microbiological properties in both soils; this increase was especially noticeable in soils treated with TEW.

Effects of Azadirachtin on Beet Soilborne Pomovirus and Soil Biological Properties on Sugar Beet

Beet soilborne pomovirus (BSBV) is an important soilborne virus disease in growing areas of sugar beet. BSBV was transmitted by Polymyxa betae Keskin. Effects of azadirachtin on BSBV and soil biological properties were studied under a greenhouse. The presence of BSBV was tested in soil samples using bait plant test and triple antibody sandwich-enzyme-linked immunosorbent assay (TAS-ELISA). The concentration of BSBV in sugar beet roots was significantly reduced by the application of azadirachtin to the soils. TAS-ELISA absorption values in 1.52, 3.04, and 7.60 ppm were lower than that 0.38 and 0.76 ppm of azadirachtin. Furthermore, in this study, it was determined the 0.38, 0.76, and 1.52 ppm doses of azadirachtin in soils had high amounts of soil biological properties (Cmic, BSR, DHA), while the 3.04 and 7.60 ppm doses had no statistical significance compared to the control treatments.

Effects of Earthworms on the Availability and Removal of Heavy Metals in Soil

Earthworms originally evolved in aquatic ecosystems and began to colonize terrestrial ecosystems 600 million years ago. Over the past few decades, research into earthworms has revealed that they stimulate the physical, chemical, and biological properties of soil and hence enhance soil fertility. Recent works have revealed that earthworms are able to direct the fates of heavy metals by passing and accumulating toxic metals through and in their body tissues, and that this distinctive phenomenon is influenced by various factors.

Role of Plant Growth Promoting Bacteria and Fungi in Heavy Metal Detoxification

Heavy metals are found in nature and are the main component of a variety of enzymes, transcription factors, and other proteins. Excessive level of heavy metal is considered as a pollutant agent. Soil-heavy metals cannot be degraded biologically; they can only be transformed to organic complexes. Remediation techniques have high costs and low efficiency, whereas an alternative technique, phytoremediation has low cost and is environmentally friendly. To stimulate phytoremediation, fast-growing plants with high metal uptake and rapid and high biomass are required. Alternatively, soil microorganisms such as fungi and bacteria are used in heavy metal detoxification. This chapter reviews some recent advances in effect and significance of fungi and rhizobacteria in heavy metal detoxification.

Spatial distribution of heavy metals in soils of the Bafra plain in Turkey

For analyzing the spatial distribution of the Cd, Co, Cu, Ni, Pb, Zn, and heavy metal (HM) sources on the Bafra deltaic plain (the central Black Sea district of Turkey), 108 soil samples were collected from the 0- to 20-cm layer in an area of about 100 thousand ha. The soil enrichment factor (the ratio between the metal concentration in the soil samples and its content in the earth’s crust (EF)) was calculated to reveal the origin of the heavy metal (HM) pollution (natural or anthropogenic). Kriging interpolation and maps of the soil’s enrichment factors were used for the characterization of the spatial HM distribution. The maximal EF was found for Cd (12.826), while smaller EF values characterized the Pb, Ni, Co, and Cu. In some districts of the studied region, the Cd, Cu, and Zn concentrations were somewhat greater, probably, due to the application of high rates of phosphorus fertilizers and intense soil cultivation. A content exceeding the critical value was recorded for Ni. Probably, this fact was related to the elevated content of this metal in the parent rocks. None of the investigated soils can be referred to the category of polluted ones.

Vermicomposting of Anaerobically Digested Sewage Sludge with Hazelnut Husk and Cow Manure by Earthworm Eisenia foetida

ABSTRACT Vermicomposting of organic waste has an important part to play in an integrated waste management strategy. The aim of the present study was to investigate the ability of an epigeic earthworm Eisenia foetida to transform anaerobically digested sewage sludge (SS) amended with hazelnut husk (HH) and cow manure (CM) in different proportions under laboratory conditions (in darkness at 25°C ± 0.5°C). Three approaches investigated in the study were: (1) to find the best medium for growth and reproduction of E. foetida in different feed mixtures, (2) to analyze the heavy metal concentrations in different feed mixtures of SS&sbnd;HH&sbnd;CM before and after vermicomposting, and (3) to explore heavy metals accumulation of earthworms in sewage sludge with different feed mixtures. Number and biomass of earthworms and heavy metal contents in feed mixtures and earthworms were periodically monitored. The results indicated that maximum earthworm biomass was attained in a feed mixture of 20% SS + 40% CM + 40% HH, while the earthworm number was highest in a feed mixture of 30% SS + 35% CM + 35% HH during the vermicomposting period. Heavy metals concentration (Zn, Cu, Cd, Pb, Ni, and Cr) in all feed mixtures decreased associated with the increasing vermicomposting time. The heavy metals’ content in the feed mixtures was lower than that of initial mixtures. Metal analysis of earthworms revealed considerable bioaccumulation of heavy metals in their bodies’ tissue. Heavy metal analysis of earthworm body showed that increasing proportion of SS in the feed mixtures promoted the heavy metal content of earthworm body.

Vermicompost effects on wheat yield and nutrient contents in soil and plant

Vermicomposting of organic waste can play an important role in integrated waste management strategies. Ability of the earthworm Eisenia foetida to transform anaerobically digested sewage sludge (SS) amended with hazelnut husk (HH) and cow manure (CM) in different proportions (0% SS + 50% HH + 50% CM; 10% SS + 45% HH + 45% CM; 20% SS + 40% HH + 40% CM; 30% SS + 35% HH + 35% CM; 40 SS% + 30% HH + 30% CM; 50% SS + 25% HH + 25% CM) was studied in a greenhouse experiment in terms of the effects of vermicompost on wheat (Triticum aestium) yield and nutrient content in soil and plant. All vermicomposted and non- vermicomposted mixtures exhibited positive effect on the yield and nutrient concentrations of wheat compared to the control pots. The vermicomposted organic waste mixtures showed comparatively better effect on plant production than the non- vermicomposted organic waste mixtures. Vermicomposted 50% SS + 25% HH + 25% CM mixtures showed the highest positive effect on yield compared to the other treatments.