Influence of Organic Manure on Organic Phosphorus Fraction in Soils

The transformation of organic P(Po) from organic manures in two types of soils (ultisol and entisol) and the influences of external addition of organic substance or inorganic P(Pi) on Po under the condition of the 60% maximum water capacity were investigated.The results obtained from Po fractionation experiments indicated that all the Po fractions except for the highly resistant Po fraction decreased during incubation.Application of pig feces and cow feces could largely increase each fraction of Po in the soils.Immediately after application of organic manure into the soils a large part of labile and moderately labile Po from organic manure was transferred into moderately resistant Po,which might be due to the fact that Ca-or Mg-inositol P was precipitated into Fe-inositol P.However,the availability of Po from organic manure in the soils would increase again after incubation because of the transformation of moderately labile and resistant Po fractions into labile Po fractions.Addition of cellulose or Pi into the soils showed a good effect on increasing all the Po fractions except for the highly resistant Po,and this effect was much more pronounced when cellulose was applied in combination with Pi.Therefore,in view of the effect of organic manure on improving P nutrition to plant,attention should be paid to both the Po and the organic substances from organic manure,It is suggested that application of Pi fertilizer combined with organic manure may be referred to as an effective means of protecting Pi from chemical fixation in soil.     

Remediation of Metal Contaminated Soil by Organic Metabolites from Fungi I—Production of Organic Acids

Investigations were made on living strains of fungi in a bioremediation process of three metal (lead) contaminated soils. Three saprotrophic fungi (Aspergillus niger, Penicillium bilaiae, and a Penicillium sp.) were exposed to poor and rich nutrient conditions (no carbon availability or 0.11 M d-glucose, respectively) and metal stress (25 µM lead or contaminated soils) for 5 days. Exudation of low molecular weight organic acids was investigated as a response to the metal and nutrient conditions. Main organic acids identified were oxalic acid (A. niger) and citric acid (P. bilaiae). Exudation rates of oxalate decreased in response to lead exposure, while exudation rates of citrate were less affected. Total production under poor nutrient conditions was low, except for A. niger, for which no significant difference was found between the poor and rich control. Maximum exudation rates were 20 µmol oxalic acid g^?1 biomass h^?1 (A. niger) and 20 µmol citric acid g^?1 biomass h^?1 (P. bilaiae), in the presence of the contaminated soil, but only 5 µmol organic acids g^?1 biomass h^?1, in total, for the Penicillium sp. There was a significant mobilization of metals from the soils in the carbon rich treatments and maximum release of Pb was 12% from the soils after 5 days. This was not sufficient to bring down the remaining concentration to the target level 300 mg kg^?1 from initial levels of 3,800, 1,600, and 370 mg kg^?1in the three soils. Target levels for Ni, Zn, and Cu, were 120, 500, and 200 mg kg^?1, respectively, and were prior to the bioremediation already below these concentrations (except for Cu Soil 1). However, maximum release of Ni, Zn, and Cu was 28%, 35%, and 90%, respectively. The release of metals was related to the production of chelating acids, but also to the pH-decrease. This illustrates the potential to use fungi exudates in bioremediation of contaminated soil. Nonetheless, the extent of the generation of organic acids is depending on several processes and mechanisms that need to be further investigated.     

Effect of Olive‐Derived Organic Amendments on Lead,Zinc, and Biochemical Parameters of an Artificially Contaminated Soil

Abstract

An incubation experiment was conducted to ascertain the effects of three olive‐derived organic amendments (fresh, compost, and vermicompost olive cake) on the soluble and diethylenetriamine pentaacetic acid (DTPA)–extractable lead (Pb) and zinc (Zn) and on different enzymatic activities in an artificially contaminated calcareous soil. Application of the compost and vermicompost, which increased amounts of humic acids in soil, initially stimulated dehydrogenase, ß‐glucosidase, and urease activities, which tended to decline afterward. In contrast, dehydrogenase and ß‐glucosidase activities were lower after application of the fresh olive cake. Amounts of soluble Pb and Zn increased when fresh olive cake was added to the soil, due to the high content of water‐soluble carbon in this amendment. On the contrary, application of the compost and vermicompost decreased the concentration of soluble Zn and did not change the soluble Pb levels in the soil. The DTPA‐Pb and DTPA‐Zn were scarcely affected by the application of the three olive‐derived amendments.     

Lantana camara——an Ecological Bioindicator Plant for Decontamination of Pb-Impaired Soil Under Organic Waste-Supplemented Scenarios

Heavy metal extraction and processing from ores releases elements into the environment. Soil, being an "unfortunate" sink, has its bionomics impaired and affected by metal pollution. Metals sneak into the food chain and pose risk to humans and other edaphicdependent organisms. For decontamination, the use of an ecosystem-friendly approach involving plants is known as phytoremediation.In this study, different lead(Pb) concentrations(80, 40, 20, and 10 mg kg~(-1)) were used to contaminate a well-characterized soil,(un)supplemented with organic waste empty fruit bunch(EFB) or spent mushroom compost(SMC), with non-edible plant—Lantana camara. Lead removal by L. camara ranged from 45.51% to 88.03% for supplemented soil, and from 23.7% to 57.8% for unsupplemented soil(P 0.05). The EFB-supplemented and L. camara-remediated soil showed the highest counts of heavy metal-resistant bacteria(HMRB)(79.67 × 10~6–56.0 × 10~6 colony forming units(CFU) g~(-1) soil), followed by SMC-supplemented and L. camara-remediated soil(63.33 × 10~6–39.0 × 10~6 CFU g~(-1) soil). Aerial metal uptake ranged from 32.08 ± 0.8 to 5.03 ± 0.08 mg kg~(-1) dry weight, and the bioaccumulation factor ranged from 0.401 to 0.643(P 0.05). Half-lives(t_(1/2)) of Pb were 7.24–2.26 d in supplemented soil,18.39–11.83 d in unsupplemented soil, and 123.75–38.72 d in the soil without plants and organic waste. Freundlich isotherms showed that the intensity of metal absorption(n) ranged from 2.44 to 2.51 for supplemented soil, with regression coefficients of determination(R~2) between 0.901 2 and 0.984 0. The computed free-energy change(?G) for Pb absorption ranged from -5.01 to 0.49 kJ mol~(-1) K~(-1) for EFB-supplemented soil and -3.93 to 0.49 k J mol~(-1) K~(-1) for SMC-supplemented soil.     

Release of Soil Nonexchangeable K by Organic Acids

The amounts of soil nonexchangeable K extracted with 0.01mL/L oxalic acid and citric acid solutions and that with boiling 1mL/L HNO3 for ten minutes were remarkably significantly correlated with each other,and the amount extracted with the oxalic acid solution was higher than that with the citric acid solution.The soil nonexchangeable K release was comprised of two first-order kinetic processes.The faster one was ascribed to the interlayer K in outer sphere,while the slower one to that in inner sphere.The rate constants of the soil nonexchageable K were significantly correlated with the amounts of nonexchangeable K ex tracted with boiling 1mL/L HNO3 for ten minutes.Study on the fitness of different kinetic equations indicated that the first-order,parabolic diffusion and zero-order equations could all describe the release of soil nonexchangeable K well,but Elovich equation was not suitable to describe it.     

Is the Period of 18 Years Sufficient for an Evaluation of Changes in Soil Organic Carbon under a Variety of Different Soil Management Practices?

The influence of differing soil management practices on changes seen in soil organic carbon (SOC) content of loamy Haplic Luvisol was evaluated. The field experiment included two types of soil tillage: 1. conventional tillage (CT) and 2. reduced tillage (RT) and two treatments of fertilization: 1. crop residues with nitrogen, phosphorus, and potassium (NPK) fertilizers (PR+NPK) and 2. NPK fertilizers (NPK). The results of SOC fluctuated from 9.8 to 14.5 g kg^?1 and the tillage systems employed and fertilization status did not have a statistically significant influence on SOC. The SOC content was higher in RT (12.4 ± 0.86 g kg^?1) than in CT (12.2 ± 0.90 g kg^?1). On average, there was a smaller higher value of SOC in PR+NPK (12.4 ± 1.02 g kg^?1) than in NPK (12.3 ± 0.88 g kg^?1). During a period of 18 years, reduced tillage and application of NPK fertilizers together with crop residues build up a SOC at an average speed of 7 and 16 mg kg^?1 year^?1, respectively, however conventional tillage and NPK fertilizer applications caused a SOC decline at an average speed of 104 and 40 mg kg^?1 year^?1, respectively.     

Influence of Organic Matter Vis-à-Vis Humic Acid on the Transformation of Inorganic and Organic Forms of Nitrogen in a Typic Haplustept Soil

A laboratory experiment was conducted to study the changes in inorganic and organic forms of nitrogen (N) in a Typic Haplustept soil treated with mustard cake vis-à-vis humic acid in the presence and absence of inorganic N. Results revealed that irrespective of treatments, significantly higher amount of soluble nitrate (NO₃^-), hydrolysable ammonium (NH₄⁺), non-hydrolysable and total N were accumulated in the soil treated with mustard cake in the presence of inorganic N. However, on the other hand, a humic acid-treated system showed significantly higher content of exchangeable NH₄⁺ and hexosamine N. Application of humic acid alone leads to the accumulation of a significantly higher amount of total hydrolysable and unidentified N in the soil. Among the different treatments, NH₄⁺ fixation was more in mustard cake followed by humic acid-treated soil. Humic acid is more susceptible to mineralization than mustard cake, particularly with respect to total N accumulation in soils.     

Effect of Organic Manure Application on Physical Properties andHumus Characteristics of Paddy Soil

Long-term field experiment was established in 1978 on a coastal paddy soil to determine the effect of application of pig manure, rice straw and chemical N fertilizer on the physical property and humus characteristics of soil. Results showed that the porosity, the microstructural coefficient, the reactivities of organic C and N, the OlogK value, the degree of oxidation stability, the contents of o-alkyl C and alkyl C, and the ratio of aliphatic C to aromatic C of humic acid from soils received organic manure increased; whereas, the ratio of<10μm to >10μm of microaggregates, the humification degree of humus, the degree of organo-mineral complexation, the number-average molecular weight, the C/H ratio, the contents of carboxyl and aromatic C of HAs in them decreased. These results indicated that the application of organic manure not only improved the physical property of the paddy soil but also made the HA more aliphatic in structure and younger in origin.     

Study on Water-Soluble Organic Reducing Substances. I. Determination of Organic Reducing Substances by Differential Pulse Voltammetry

A new method was proposed for study of organic reducing substances in soils.According to the theoretical relationship between the voltammetric behaviors and reduction-oxidation reaction of reducing substances,the working conditions of differential pulse voltammetry (d.p.v.)for determining the organic reducing substances produced during the processes of the anaerobic decomposition of plant materials were established with a glass carbon electrode as working electrode,1M Ag-AgCl electrode with large area as reference electrode,0.2M NH4Ac as supporting from -0.5 to 1.2 voltage(vs.M Ag-AgCl).The peak current proportional to the concentration of reducing substances,and the characteristic peak potential of each organic reducing substance were regarded as the quantitative and qualitative base,respectively.These results obtained under the conditions mentioned above directly reflect both the reducing intensity and capacity of the organic reducing system in soils.     

Evaluating Methods of In‐Field Soil Organic Matter Analysis

Abstract

The actual content of the soil organic carbon (SOC) has to be periodically measured for soil classification and nutrient management purposes. Traditional SOC tests are relatively time consuming and costly. A rapid field test would be valuable to delineate soil map units with similar SOC to simplify the process of land evaluation while increasing precision. The objectives of this study were to develop and evaluate a new field measurement technique for the quick assessment of SOC. The new method measures the emitted CO₂ concentration 3 min after treatment of the soil sample with acidic potassium (K) permanganate solution. The inorganic carbonate content of the soil is measured separately with the addition of sulphuric acid only. Carbon dioxide concentration from both procedures is measured with a portable infrared gas analyzer. The difference between the concentrations measured after the two separate reactions provide an estimate of SOC. Samples from brown forest soils (ca Hapludalf) (0.19–5.53% SOC) were used for the method development. The correlation coefficient between the SOC determined by the new method and laboratory wet combustion method content was 0.76 for the full range of SOC and 0.81 for the soil samples with less than 20% carbonate.     

Investigation of Soil Concentrations of Persistent Organic Pollutants, Trace Elements, and Anions Due to Iron–Steel Plant Emissions in an Industrial Region in Turkey

The spatial distribution of several air pollutants emitted from iron–steel industries in Hatay-Iskenderun industrial region in Turkey was investigated by measuring their concentrations in soil. Collected soil samples (n?=?20) were analyzed for persistent organic pollutants (POPs; i.e., polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polybrominated diphenyl ethers, and polychlorinated naphthalenes), anions, and trace elements. Generally, all measured POP concentrations and marker trace elements for iron–steel industry (Zn, Pb, and Cu) were high relative to those reported previously for rural and urban areas around the world, and they were comparable to those measured recently in a similar industrial region (Aliaga, Izmir, Turkey). For all investigated POPs, elements, and anions, the highest concentrations were measured at points located north of the iron–steel industries where their emissions are transported by the prevailing southerly winds. The spatial distribution and levels of POPs, elemental, and anionic concentrations indicated that the iron–steel plants in Hatay-Iskenderun region are important sources for these pollutants. Statistically significant relationships between several organic and inorganic pollutants further confirmed that they are emitted by common sources (iron–steel plants).     

Characterization of Organic Acids Recovered from Rhizosphere of Corn Grown on Biosolids‐Treated Medium

Abstract

Organic acid production by plants and microorganisms was quantified in sand media amended with biosolids in the presence and absence of corn (Zea mays L.) in a sand‐culture hydroponic medium. Total quantities of organic acids were greatest in treatments containing both plants and biosolids, with lesser amounts in treatments with plants alone, biosolids‐treated media alone, and a nutrient solution–irrigated blank medium. Biosolids enhanced organic acid production in the rhizosphere and influenced the composition of organic acid mixtures. Only lactic, acetic, butyric, and oxalic acids were detected in media without plants. When the medium was planted, additional organic acids were recovered including tartaric, maleic, succinic, valeric, glutaric, pyruvic, and propionic. Lactic, acetic, and butyric acids were predominant in solutions recovered from the planted media and collectively accounted for 0.65 to 0.75 of the COO^? mole fraction. Oxalic, maleic, and tartaric acids were the second most abundant and varied from 0.05 to 0.1 of the mole fraction, followed by succinic, valeric, glutaric, propionic, and pyruvic acids, comprising ≤0.05 of the mole fraction. Plant growth stage had no effect on relative proportions of organic acids but did influence the total quantities of organic acids recovered. Biosolids sources did not have a significant effect on either the quantity or composition of organic acids in any media. The predominance of organic acids that are microbial fermentation products suggests that the carbon contained in root exudates and biosolid amendments was transformed into a mixture of various fermentation products that accumulated in the rhizosphere solution and sand medium as a result of microbial growth and activity.     

Repeated Bray‐2 extractions of an Inceptisol and an Andisol

Abstract

Bray‐2 extractable phosphorus (Bray2‐P) is commonly used to measure plant‐available P in soil. The pool size of extractable P in the residual soil should be reduced after extraction. Phosphorus, once released with the Bray‐2 solution, is resorbed by the soil during the extraction‐filtration period. If P resorption is large, the Bray2‐P concentration is underestimated. The P absorption coefficient and composition of inorganic P [calcium (Ca)‐P, aluminum (Al)‐P, and iron (Fe)‐P] probably affect the Bray2‐P concentration. We investigated the effect of repeated Bray‐2 extractions on the Bray2‐P concentrations in relation to the P absorption coefficient and Ca‐P, Al‐P, and Fe‐P concentrations in two soils (an Inceptisol and an Andisol), which markedly differ in the P absorption coefficient. Test soil samples were the initial soil (S0) and soils after the 1st to 4th extractions (S1‐S4) for the Inceptisol, and S0, S1‐S4, and S7 for the Andisol. The Bray2‐P, Ca‐P, Al‐P, and Fe‐P concentrations in the S0 were 260, 75, 338, and 536 mg kg^‐1 in the Inceptisol, and 217, 31, 972, and 354 mg kg^‐1 in the Andisol, respectively. All of the extractable P concentrations in the Inceptisol decreased with increasing numbers of extractions, and the Bray2‐P, Ca‐P, Al‐P, and Fe‐P concentrations in the S4 were 5.3, 21, 5.7, and 30% of those in the S0, respectively. On the other hand in the Andisol, the Bray2‐P, Ca‐P, and Fe‐P concentrations did not decrease in the S1 and S2 compared with those in the S0, although the Al‐P concentration decreased with increasing numbers of extractions. The Bray2‐P, Ca‐P, Al‐P, and Fe‐P concentrations in the S7 were 23, 71, 16, and 79% of those in the S0, respectively. The P absorption coefficient in the S0 was higher in the Andisol (7,703 mg kg^‐1) than in the Inceptisol (1,582 mg kg^‐1), and it decreased with increasing numbers of extractions in both soils. The P absorption coefficient in the S7 Andisol was 51% of that in the S0, while the P absorption coefficient in the S4 Inceptisol was 24% of that in the S0. The results suggest that Presorption affects the efficiency of extraction with the Bray‐2 solution, and the composition of Ca‐P, Al‐P, and Fe‐P fractions. The Bray2‐P concentration in soil with high P absorption coefficient is underestimated due to P resorption.     

Substrate‐Induced Respiration of a Sandy Soil Treated with Different Types of Organic Waste

A sandy soil was amended with different types of sewage sludge (digested, dried, and composted) and pig slurry. The composted sludges displayed higher organic‐matter stability (39–45%) than only digested sludge (26–39%) or digested + dried sludge (23–32%). The microbial biomass of the dried sludge was undetectable. Digested and composted sludges and pig slurry displayed microbial biomasses (12492–13887 µg g^?1, 1221–2050 µg g^?1, and 5511 µg g^?1, respectively) greater than the soil (108 µg g^?1). The wastes were applied at seven doses, ranging from 10 to 900 g kg^?1. Soils were incubated for 28 days. Substrate‐induced respiration (SIR) was measured for 12 consecutive hours on day 1 and on day 28. The results showed that SIR increased with the dose of organic amendment. However, SIR decreased when moderate doses of pig slurry or high doses of digested + dried sludge were tested. The possibility of using this inhibition as an ecotoxicological indicator is discussed.     

Spatial Characteristics of Soil Organic Carbon Storage in China＇s Croplands

The soil organic carbon （SOC） pool is the largest component of terrestrial carbon pools. With the construction of a geographically referenced database taken from the second national general soil survey materials and based on 1546 typical cropland soil profiles, the paddy field and dryland SOC storage among six regions of China were systematically quantified to characterize the spatial pattern of cropland SOC storage in China and to examine the relationship between mean annual temperature, precipitation, soil texture features and SOC content. In all regions, paddy soils had higher SOC storage than dryland soils, and cropland SOC content was the highest in Southwest China. Climate controlled the spatial distribution of SOC in both paddy and dryland soils, with SOC storage increasing with increasing precipitation and decreasing with increasing temperature.     

Effects of Organic Amendments on Productivity and Profitability of Bell Pepper–French Bean–Garden Pea System and on Soil Properties during Transition to Organic Production

A transition period of at least 2 years is required for annual crops before the produce may be certified as organically grown. There is a need to better understand the various management options for a smooth transition from conventional to organic production. The purpose of this study was to evaluate the effects of different organic amendments and biofertilizers (BFs) on productivity and profitability of a bell pepper–french bean–garden pea system as well as soil fertility and enzymatic activities during conversion to organic production. For this, the following six treatments were established in fixed plots: composted farmyard manure (FYMC, T₁); vermicompost (VC, T₂); poultry manure (PM, T₃) along with biofertilizers (BF) [Rhizobium/Azotobacter + phosphorus solubilizing bacteria (Pseudomonas striata)]; mix of three amendments (FYMC + PM + VC + BF, T₄); integrated nutrient management (FYMC + NPK, T₅); and unamended control (T₆). The yields of bell pepper and french bean under organic nutrient management were markedly lower (25.2–45.9% and 29.5–46.2%, respectively) than with the integrated nutrient management (INM). Among the organic treatments, T₄ and T₁ produced greater yields of both bell pepper (27.96 Mg ha^?1) and french bean (3.87 Mg ha^?1) compared with other treatments. In garden pea, however, T₄ gave the greatest pod yield (7.27 Mg ha^?1) and was significantly superior to other treatments except T₅ and T₁. The latter treatment resulted in the lowest soil bulk density (1.19 Mg m^?3) compared with other treatments. Similarly, soil organic C was significantly greater in all the treatments (1.21–1.30%) except T₂ compared to T₆ (1.06%). Plots under INM, however, had greater levels of available nitrogen–phosphorus–potassium (NPK) than those under organic amendments. T₁ plots showed greater dehydrogenase and acid phosphatase activities compared with other treatments. However, T₄ and T₅ plots had greater activities of β-glucosidase and urease activities, respectively. The cost of cultivation was greater under organic nutrient management (except T₂) compared with INM. The latter treatment gave greater gross margin and benefit/cost (B/C) ratio for all vegetables, except that T₂ gave greater B/C ratio in garden pea compared with other treatments. We conclude that T₁ and T₄ were more suitable for enhancing the productivity of bell pepper–french bean–garden pea system, through improved soil properties, during transition to organic production.     

Quantification of Organic Matter in Agricultural Soils from the Central Region of Paraná State,Brazil

The organic matter (OM) quantity in soils is of fundamental importance for agriculture. The indirect determination of the OM through the Total Organic Carbon (TOC) quantity is performed by most soil laboratories in Brazil using the Walkley–Black (WB) method. This procedure involves oxidation with potassium dichromate which is a cancerous reagent. The objective of this study is to optimize the parameters for OM determination by the gravimetric method and to estimate the van Bemmelen factor for the studied soil. The studied region is the second and third plateau of Parana State, Brazil, from which 50 agricultural soil samples were analyzed. The temperature and exposition time in muffle were determined after a thermal analysis. The optimized parameters for the gravimetric method were 3 h at 420°C in the muffle furnace. The results for WB and gravimetric methods presented a good correlation and the van Bemmelen factor for the studied soil was 4.37.     

Remediation of Metal-Contaminated Soil by Organic Metabolites from Fungi II—Metal Redistribution

Exudation of low molecular weight organic acids by fungi was studied in a project focusing on bioremediation of metal-contaminated soils. The production of acids (mainly oxalic and citric acid) as a response to nutrient variations and presence of metals has recently been reported (Arwidsson et al. 2009). A significant release of metals was observed and was related not only to the production of organic acids but also to the resulting pH decrease in the systems. The processes governing the release and redistribution of metals in the soil–water fungus system were the focus of the present continuation of the project, based on observations of Aspergillus niger, Penicillium bilaiae, and a Penicillium sp. The release of lead was 12% from the soil with the second highest initial load (1,600 mg kg^?1), while the release of copper was 90% from the same soil (140 mg kg^?1). The dominating mechanism behind the release and subsequent redistribution was the change in pH, going from near neutral to values in the range 2.1–5.9, reflecting the production of organic acids. For some of the systems, the formation of soluble complexes is indicated (copper, at intermediate pH) which favors the metal release. Iron is assumed to play a key role since the amount of secondary iron in the soils is higher than the total load of secondary heavy metals. It can be assumed that most of the heavy metals are initially associated with iron-rich phases through adsorption or coprecipitation. These phases can be dissolved, or associated metals can be desorbed, by a decrease in pH. It would be feasible to further develop a process in technical scale for remediation of metal-contaminated soil, based on microbial metabolite production leading to formation of soluble metal complexes, notably with copper.     

Methods to Estimate Aggregate Protected Soil Organic Carbon, 2: Does the Grinding of the Plant Residues Affect the Estimations of the Aggregate Protected Soil Organic Carbon?

A method to estimate the amount of soil organic carbon (SOC) physically protected within macroaggregates (>200 μm) consists of crushing soil samples and measuring the following SOC mineralization increase. This study investigated the effect of grinding the plant residues during soil crushing on the calculated amount of the protected SOC on two tropical soils (Arenosol and Ferralsol). Incubations of crushed and uncrushed soil samples amended with ground or unground plant residues were conducted. Our results showed that soil crushing increased SOC mineralization and that the presence of plant residues enhanced soil respiration also. The plant residues of the two soils had different decomposition rates, but grinding plant residues did not increase the amounts of cumulative carbon (C) mineralized after the 28 days of the experiment. We propose that the extra C mineralized after soil crushing is due to the breakdown of the soil structure and not to the grinding of plant residues.