Soil enzymes and biological activity at different levels of organic matter stability
01 Mar 2016-Journal of Soil Science and Plant Nutrition (Chilean Society of Soil Science)-Vol. 16, Iss: 1, pp 14-30
TL;DR: A greater stabilization capacity of MF in allophanic soils than in kaolinitic soils due to the amorphous minerals clay materials was confirmed, and an inverse and significant relationship between Al pyrophosphate (Al bound to SOM) and the C-CO2 in volcanic soil, whereas the same correlation did not occur in kaalinitic soil.
Abstract: Soil biological activity has important implications for soil carbon (C) sequestration. However, very little is known about the environmental factors, particularly the effect of soil mineralogy on availability of C for soil microorganisms. In this study, we have investigated the influences of soil type (clay mineralogy)on C mineralization and its effects on biological activity at different levels of soil organic matter stability. Two soils an allophanic, derived from recent volcanic ash and a kaolinitic, resulting from metamorphic parent materials were physically fractioned in to light(LF, coarse sand 250-2000 µm), intermediate (IF, fine sand53-250 µm) and mineral (MF,silt and clay < 53 µm) fractions. Several biological and biochemical analyses at Ah horizons of mineral soil and physical fractions were conducted: soil respiration, enzymatic activities, carbohydratesand microbial biomass, amongst others soil variables. The results indicated that the bulk soiland physical fractions had a significant impact on cumulative C mineralizedafter 30 days of incubation and soil enzyme activities. More than 76% of total C-CO2 variation was explained by stepwise multiple regression analysis including factors such as soil enzymes (s-glucosidase, dehydrogenase and phosphatase) and inorganic P. Soil ATP extractionwas agood indicator of microbial activity, because of a positive and significant correlation among ATP and i) C-CO2 and ii) metabolic quotient (soil respiration rate divided by microbial biomass). We also found an inverse and significant relationship between Al pyrophosphate (Al bound to SOM) and the C-CO2 in volcanic soil, whereas the same correlation did not occur in kaolinitic soil. Our results confirmed a greater stabilization capacityof MF in allophanicthan in kaolinitic soils due to the amorphous minerals clay materials.
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TL;DR: In this paper, the roles of soil enzymes such as β-glucosidase, phosphatase and urease are reviewed and the implications of their activities for soil quality.
Abstract: Soil is a fundamental resource and it is crucial to manage its quality in order to enhance agricultural productivity and environmental quality. Soil enzymes catalyze several biochemical reactions which result in the transformation of organic matter, and the release of inorganic nutrients for plant growth and nutrient cycling. Soil enzyme activities are useful biological soil quality indicators since they are operationally practical, very sensitive, integrative, easy to measure and more responsive to soil tillage and structure than other soil variables. There are several enzymes in soil, but those involved in hydrolases and the degradation of main litter components are used most often for evaluating soil quality. This paper reviews the roles of soil enzymes such as β-glucosidase, phosphatase and urease, as well as the implications of their activities for soil quality.
229 citations
Cites background from "Soil enzymes and biological activit..."
...These reactions produce glucose as the final product, an important C energy source for the growth and activity of soil microorganisms (Merino et al., 2016). β-glucosidase’s involvement in C cycling has remarkably facilitated its adoption for soil quality testing....
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...These reactions produce glucose as the final product, an important C energy source for the growth and activity of soil microorganisms (Merino et al., 2016)....
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TL;DR: In this article, the effects of organic and inorganic manures on maize and their residual impacts on soil physico-chemical characteristics were investigated and a significant and positive correlation (R2= 0.52, 0.91 and 0.55) was observed among maize grain yield and available N, P, K contents.
Abstract: Organic and inorganic nutrients are important for crop productivity and soil health. Present study investigated the effects of organic and inorganic manures on maize and their residual impacts on soil physico-chemical characteristics. Sheep manure (SM), poultry manure (PM) and farmyard manure (FYM) were applied as organic nutrient source while urea, diammonium phosphate (DAP) and sulphate of potash (SOP) were used at different concentrations as inorganic nutrients source viz., T1: Unfertilized control; T2: NPK at 250-150-125 kg ha -1; T3: SM at 15 t ha-1; T4: FYM at 16 t ha -1; T5: PM at 13 t ha -1; T6: NPK at 150-85-50 + 8 t ha -1 SM; T7: NPK at 15085-50 + 8.5 t ha-1 FYM and T8: NPK at 150-85-50 + 7 t ha -1 PM. Results showed that growth and yield of maize were substantially improved by fertilizer application alongside organic manures whereas soil total organic C and total N, P, K contents increased when inorganic fertilizers were applied alone or in combined with organic manures. However, soil pH and soil bulk density decreased due to application of organic fertilizer and showed a negative correlation with grain yield. Further, a significant and positive correlation (R2= 0.52, 0.91 and 0.55) was observed among maize grain yield and available N, P and K contents, respectively in the soil. Conclusively, integration of inorganic fertilizers with organic manures can be used with optimum rates to improve crop productivity on sustainable basis. This study will be helpful in crafting sustainable nutrient management programs in future to enhance crop productivity with high efficiency and minimum nutrient loss.
140 citations
TL;DR: The results of this study are helpful to understand the role of various SCFs in stabilising added C originating from external wheat residue addition but warrant further validation under field conditions.
26 citations
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TL;DR: In this article, the authors investigated the impact of organic manures on crop productivity, soil physiochemical properties and soil water availability in a maize-based cropping system, and found that the combination of OM with mineral fertilizers increased crop productivity and fertilizer use efficiency.
Abstract: Soil quality deterioration, especially in intensive cropping systems, has become a serious problem for crop productivity; consequently, strategies for sustainable crop production and soil health are urgently required. Experiments on fields were organized to investigate the impact of organic manures on crop productivity, soil physiochemical properties and soil water availability in a maize-based cropping system. The experiment consisted of five treatments, including organic manures (OM) and inorganic nitrogen, phosphorus and potassium (NPK) fertilizers applied separately and in combinations: NPK = 250-150-125 Kg/ha (recommended rate), farmyard manure (FYM) = 16 t/ha, poultry manure (PM) = 13 t/ha, NPK + FYM = 150-85-50 Kg/ha + 8.5 t/ha and NPK + PM = 150-85-50 Kg/ha + 7.0 t/ha. The results showed that the combination of OM with mineral fertilizers increased crop productivity, fertilizer use efficiency and yield sustainability indices over the treatments amended with sole application of mineral fertilizers and OM. The analysis of undisturbed soil samples during different crop growth stages revealed that the addition of OM decreased the bulk density and increased the pore volume of soil at the beds of 0–20 and 20–40 cm. The application of OM to the soil not only increased saturated hydraulic conductivity of the soil but also improved total available and readily available water contents to the plants, especially when FYM was included at 16 t ha−1. Soil-water retention properties recorded over the entire seven-day monitoring period following irrigation in the OM-amended treatments were consistently higher than the sole mineral NPK application treatments. When testing the soil nutrient status during different crop growth stages, it was noted that by adding OM into the soil not only the status of the organic carbon of soil, extractable N and K and available P contents is increased, but the duration of their availability to the plants are also enhanced. The results of the study show that organic manures addition is of major significance for maintaining soil quality and crop production sustainably, and should be advocated in the nutrient management strategies of intensive water- and nutrient-demanding cropping systems.
17 citations
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07 Oct 2018
10,515 citations
"Soil enzymes and biological activit..." refers methods in this paper
...Olsen-P was measured by extracting with 0.5 M NaHCO3 adjusted to pH 8.5....
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...The soils were transported immediately to the laboratory under cold conditions, homogenized, sieved to <2 mm and characterized by soil pH in water, soil organic C (SOC), total N, inorganic P (Olsen) and other macronutrients (Table 1) (Matus et al., 2011; Garrido and Matus, 2012)....
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...Inorganic phosphorus was determined by the method Olsen (Olsen et al., 1954)....
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TL;DR: In this paper, the effects of fumigation on organic C extractable by 0.5 m K2SO4 were examined in a contrasting range of soils and it was shown that both ATP and organic C rendered decomposable by CHCl3 came from the soil microbial biomass.
Abstract: The effects of fumigation on organic C extractable by 0.5 M K2SO4 were examined in a contrasting range of soils. EC (the difference between organic C extracted by 0.5 M K2SO4 from fumigated and non-fumigated soil) was about 70% of FC (the flush of CO2-C caused by fumigation during a 10 day incubation), meaned for ten soils. There was a close relationship between microbial biomass C, measured by fumigation-incubation (from the relationship Biomass C = FC/0.45) and EC given by the equation: Biomass C = (2.64 ± 0.060) EC that accounted for 99.2% of the variance in the data. This relationship held over a wide range of soil pH (3.9–8.0).
ATP and microbial biomass N concentrations were measured in four of the soils. The (ATP)(EC) ratios were very similar in the four soils, suggesting that both ATP and the organic C rendered decomposable by CHCl3 came from the soil microbial biomass. The C:N ratio of the biomass in a strongly acid (pH 4.2) soil was greater (9.4) than in the three less-acid soils (mean C:N ratio 5.1).
We propose that the organic C rendered extractable to 0.5 m K2SO4 after a 24 h CHCl3-fumigation (EC) comes from the cells of the microbial biomass and can be used to estimate soil microbial biomass C in both neutral and acid soils.
9,975 citations
"Soil enzymes and biological activit..." refers methods in this paper
...Microbial biomass C quotient Microbial biomass C (MB-C) was determined by fumigation of the sample with ethanol-free CHCl3 and extraction with 0.5 M K2SO4, according to Vance et al. (1987)....
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TL;DR: In this paper, a simple method of assaying soil phosphatase activity is described, which involves colorimetric estimation of the p-nitrophenol released by the enzyme when the soil is incubated with buffered (pH 6·5) sodium pnphosphorus solution and toluene at 37°C for 1 hour.
Abstract: A simple method of assaying soil phosphatase activity is described. It involves colorimetric estimation of the p-nitrophenol released by phosphatase activity when soil is incubated with buffered (pH 6·5) sodium p-nitrophenyl phosphate solution and toluene at 37° C for 1 hr. The method is rapid and precise, and it has significant advantages over methods previously proposed for assay of soil phosphatase activity.
3,503 citations
TL;DR: In this paper, an improved method to assay activities of α- and β-glucosidases and α-and β-galactosidase in soils is described.
Abstract: An improved method to assay activities of α- and β-glucosidases and α- and β-galactosidases in soils is described. It involves extraction and colorimetric determination of the p-nitrophenol released when 1 g of soil is incubated with 5 ml of buffered p-nitrophenyl glycoside solution at 37°C for 1 h. The reagents [0.5 M CaCl2 and 0.1 M Tris (hydroxymethyl)aminomethan THAM, pH 12] used for extraction of the p-nitrophenol released give quantitative recovery of p-nitrophenol added to soils and do not cause chemical hydrolysis of the substrates. Results showed that these enzymes have their optimum activities at buffer pH 6.0. The initial rates of p-nitrophenol release obeyed zero-order kinetics. β-Glucosidase activity was the most predominant of the four enzymes. The temperature dependence of the rate constant conformed to the Arrhenius equation up to the point of enzyme inactivation (60°C for α- and β-galactosidases and α-glucosidase and 70°C for β-glucosidase). The average activation energy values of these enzymes in three soils were 43.1, 30.8, 57.0 and 32.6 kJmol−1 for α-glucosidase, β-glucosidase, α-galactosidase and β-galactosidase activities, respectively. By using the Lineweaver-Burk plot. the Km values were the lowest for β-glucosidase activity. The Vmax values varied among the four enzymes and soils studied.
1,156 citations
"Soil enzymes and biological activit..." refers methods in this paper
...The reference method for the determination of these enzyme activities is described by Tabatabai (1982) and Eivazi and Tabatabai (1988)....
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01 Apr 2012
TL;DR: In this paper, a re-evaluation of our 10-year old paper on priming effects is presented, and the most important needs for future research are identified and evaluated.
Abstract: In this re-evaluation of our 10-year old paper on priming effects, I have considered the latest studies and tried to identify the most important needs for future research. Recent publications have shown that the increase or decrease in soil organic matter mineralization (measured as changes of CO 2 efflux and N mineralization) actually results from interactions between living (microbial biomass) and dead organic matter. The priming effect (PE) is not an artifact of incubation studies, as sometimes supposed, but is a natural process sequence in the rhizosphere and detritusphere that is induced by pulses or continuous inputs of fresh organics. The intensity of turnover processes in such hotspots is at least one order of magnitude higher than in the bulk soil. Various prerequisites for high-quality, informative PE studies are outlined: calculating the budget of labeled and total C; investigating the dynamics of released CO 2 and its sources; linking C and N dynamics with microbial biomass changes and enzyme activities; evaluating apparent and real PEs; and assessing PE sources as related to soil organic matter stabilization mechanisms. Different approaches for identifying priming, based on the assessment of more than two C sources in CO 2 and microbial biomass, are proposed and methodological and statistical uncertainties in PE estimation and approaches to eliminating them are discussed. Future studies should evaluate directions and magnitude of PEs according to expected climate and land-use changes and the increased rhizodeposition under elevated CO 2 as well as clarifying the ecological significance of PEs in natural and agricultural ecosystems. The conclusion is that PEs – the interactions between living and dead organic matter – should be incorporated in models of C and N dynamics, and that microbial biomass should regarded not only as a C pool but also as an active driver of C and N turnover.
1,120 citations