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1.
PurposeThe aim of this research was to quantify the effect of plantain (Plantago lanceolata L.) on soil nitrification rate, functional gene abundance of soil ammonia oxidisers, and the concomitant effect on nitrous oxide emissions from urine patches in a shallow, free-draining soil in Canterbury during late autumn/winter season. Materials and methodsUrine was collected from dairy cows grazing either ryegrass/white clover (RGWC), 30% plantain (P30) mixed in with RGWC or 100% plantain (P100) pasture, and applied at two rates (700 or 450 kg N ha?1) to intact soil blocks growing either RGWC, P30 or P100 pasture. Results and discussionResults showed that increased plantain content reduced N-concentration in urine from 7.2 in RGWC urine to 4.5 and 3.7 g N L?1 in P30 and P100 urine, respectively. Total N2O emissions and emission factors (EF3) from urine-treated pastures were low, <?2 kg N ha?1 and <?0.22%, respectively. Urine application at the lower urine N-loading rate of 450 kg N ha?1 (i.e. representative of that in a P30 urine patch) resulted in 30% lower N2O emissions (P?<?0.01) and 35% lower soil nitrate concentrations (P?<?0.001) compared to those at the higher urine loading rate of 700 kg N ha?1 (i.e. representative of that in a RGWC urine patch). Increasing plantain content in the pasture sward from 0 to 30% and 100% with urine N applied at the same loading rate did not reduce N2O emissions or nitrification compared to the standard ryegrass-white clover pasture. Cow urine derived from the different pasture diets had no effect on N2O emissions, N transformation or ammonia-oxidiser abundance in soil compared to the RGWC urine applied at the same rate. ConclusionsThe main effect of plantain in this study appears to be related to the reduction in urine N-loading rate, rather than factors related to urine properties or plantain-soil interactions. 相似文献
2.
PurposeThe majority of biochar studies use soils with only a narrow range of properties making generalizations about the effects of biochar on soils difficult. In this study, we aimed to identify soil properties that determine the performance of biochar produced at high temperature (700 °C) on soil pH, cation exchange capacity (CEC), and exchangeable base cation (Ca2+, K+, and Mg2+) content across a wide range of soil physicochemical properties. Materials and methodsTen distinct soils with varying physicochemical properties were incubated for 12 weeks with four rates of biochar application (0.5, 2, 4, and 8% w/w). Soil pH, CEC, and exchangeable base cations (Ca2+, K+, and Mg2+) were determined on the 7th and 84th day of incubation. Results and discussionOur results indicate that the highest biochar application rate (8%) was more effective at altering soil properties than lower biochar rates. Application of 8% biochar increased pH significantly in all incubated soils, with the increment ranging up to 1.17 pH unit. Biochar induced both an increment and a decline in soil CEC ranging up to 35.4 and 7.9%, respectively, at a biochar application rate of 8%. Similarly, biochar induced increments in exchangeable Ca2+ up to 38.6% and declines up to 11.4%, at an 8% biochar application rate. The increment in CEC and exchangeable Ca2+ content was found in soils with lower starting exchangeable Ca2+ contents than the biochar added, while decreases were observed in soils with higher exchangeable Ca2+ contents than the biochar. The original pH, CEC, exchangeable Ca2+, and texture of the soils represented the most crucial factors for determining the amount of change in soil pH, CEC, and exchangeable Ca2+ content. ConclusionsOur findings clearly demonstrate that application of a uniform biochar to a range of soils under equivalent environmental conditions induced two contradicting effects on soil properties including soil CEC and exchangeable Ca2+ content. Therefore, knowledge of both biochar and soil properties will substantially improve prediction of biochar application efficiency to improve soil properties. Among important soil properties, soil exchangeable Ca2+ content is the primary factor controlling the direction of biochar-induced change in soil CEC and exchangeable Ca2+ content. Generally, biochar can induce changes in soil pH, CEC, and exchangeable Ca2+, K+, and Mg2+ with the effectiveness and magnitude of change closely related to the soil’s original properties. 相似文献
3.
PurposeNitrification and denitrification in the N cycle are affected by various ammonia oxidizers and denitrifying microbes in intensive vegetable cultivation soils, but our current understanding of the effect these microbes have on N2O emissions is limited. The nitrification inhibitor, 3,4-dimethylpyrazole phosphate (DMPP), acts by slowing nitrification and is used to improve fertilizer use efficiency and reduce N losses from agricultural systems; however, its effects on nitrifier and denitrifier activities in intensive vegetable cultivation soils are unknown. Materials and methodsIn this study, we measured the impacts of DMPP on N2O emissions, ammonia oxidizers, and denitrifying microbes in two intensive vegetable cultivation soils: one that had been cultivated for a short term (1 year) and one that had been cultivated over a longer term (29 years). The quantitative PCR technique was used in this study. Three treatments, including control (no fertilizer), urea alone, and urea with DMPP, were included for each soil. The application rates of urea and DMPP were 1800 kg ha?1 and 0.5% of the urea-N application rate. Results and discussionThe application of N significantly increased N2O emissions in both soils. The abundance of ammonia-oxidizing bacteria (AOB) increased significantly with high rate of N fertilizer application in both soils. Conversely, there was no change in the growth rate of ammonia-oxidizing archaea (AOA) in response to the applied urea despite the presence of larger numbers of AOA in these soils. This suggests AOB may play a greater role than AOA in the nitrification process, and N2O emission in intensive vegetable cultivation soils. The application of DMPP significantly reduced soil NO3?-N content and N2O emission, and delayed ammonia oxidation. It greatly reduced AOB abundance, but not AOA abundance. Moreover, the presence of DMPP was correlated with a significant decrease in the abundance of nitrite reductase (nirS and nirK) genes. ConclusionsLong-term intensive vegetable cultivation with heavy N fertilization altered AOB and nirS abundance. In vegetable cultivation soils with high N levels, DMPP can be effective in mitigating N2O emissions by directly inhibiting both ammonia oxidizing and denitrifying microbes. 相似文献
4.
Abstract Two experiments were conducted to evaluate the inhibitory effects of 2-chloro-6 (trichloromethyl) pyridine (nitrapyrin) and dicyandiamide on nitrous oxide (N 2O), a greenhouse gas, emission from soils amended with ammonium sulfate. In the two experiments, samples of an Andosol and a Gray Lowland soil were kept in glass vessels sealed with a butyl rubber cap and incubated at 25°C. In the first experiment, nitrapyrin (1 µg g ?1 dry soil) and dicyandiamide (10 µg g ?1 dry soil) were applied to samples of a water-saturated Andosol and a Gray Lowland soil to which ammonium sulfate had been applied at a rate of 0.1 mg N g ?1 dry soil. Nitrapyrin decreased N 2O emissions from the Andosol and the Gray Lowland soil by 71% and 24%, respectively. Dicyandiamide decreased N 2O emissions from the Andosol and Gray Lowland soil by 31% and 18%, respectively. In the second experiment, nitrapyrin (1 µg g ?1 dry soil) was applied to samples of an Andosol at 51% water-filled pore space to which ammonium sulfate had been applied at rates of 0.01, 0.1 and 0.5 mg N g ?1 dry soil. Nitrapyrin decreased N 2O emissions by 62%, 83% and 74%, respectively. Changes in the NH + 4 and NO ? 2 + NO ? 3 concentrations in soil showed that nitrapyrin and dicyandiamide slowed down the nitrification process, but did not completely stop the process at any time. The results reveal the potential of nitrification inhibitors to decrease N 2O emission from fertilized soil in a wide range of moisture conditions and nitrogen levels. 相似文献
5.
Abstract Nitrogen (N) loss in the form of volatilized ammonia (NH 3) is a considerable problem when ammonium (NH 4 +) forming fertilizers are applied to calcareous or alkaline soils. The volatilization of NH 3 from urea phosphate (UP) and urea (U) was studied on three selected soils (Hayhook SL, Laveen L, and Latene L) with the use of a laboratory aeration system. Urea phosphate and U were each applied at rates of 0, 50, 100, and 200 mg N kg ‐1 soil, either to the surface dry or in solution or mixed with the soil. The volatilized NH 3 was trapped in sulfuric acid, sampled periodically, and analyzed for N with the semi microkjeldahl distillation apparatus. The highest N loss in the form of NH 3 occurred when U was applied to Hayhook soil (neutral to acidic, coarse textured, and low CaCO 3 content). However, UP applied to Hayhook soil resulted in the lowest NH 3‐N loss. Less NH 3‐N loss was found from U application to Laveen and Latene soils (fine textured with higher CaCO 3 content) than with Hayhook soil. The general trend was higher N loss when a surface application was made, either dry or in solution, than when the fertilizer was mixed with the soil. This trend showed an increase in the amount of volatilized NH 3 with increasing N application rates. Generally, UP is a potential fertilizer for supplying N and phosphorus (P) as plant nutrients with a low potential for losses due to NH 3 volatilization. 相似文献
6.
Abstract City sewage sludge was applied to the surface layer (0–10 cm) of two sandy soils, slightly calcareous with 8.9% CaCO 3 and moderately calcareous with 26.7% CaCO 3, at the rates of 0, 25, 50, 75, and 100 Mg ha ‐1. The effects of sewage sludge and its rates on total soluble salts, pH of soils and concentration and movement of some heavy metals within soils were investigated. Soil samples were packed at bulk density of 1.5 g cm ‐3 in PVC columns and incubated for 19 weeks. The results indicated that total soluble salts (EC) of the treated layer increased with increasing sewage sludge rates. Soluble salts also increased with an increase in soil depth for both soils. The pH values of treated layers in two soils decreased with increasing sewage sludge rates. With increasing sewage sludge rates, concentrations of heavy metals [cobalt (Co), nickel (Ni), cadmium (Cd), and leaf (Pb)] increased in the treated layers compared to the untreated layers and their mobility was restricted mostly to the upper 30‐cm depth. Movement of Co and Pb in both the soils was predominately limited up to a depth of 40 cm for Co and 5 cm for Pb below the treated soil layer. Nickel and Cd movement was mostly limited to a depth of 10 cm in slightly calcareous soil and 5 cm in moderately calcareous soil. Metal movement in the respective soils is ranked as Co>Ni=Cd>Pb and Co>Ni=Cd>Pb. The low concentrations of heavy metals and the restricted mobility with soil depth, suggest that this material may be used for agricultural crop production without any toxic effect on plants. 相似文献
7.
ABSTRACTWe studied (i) the pH buffer capacity (pHBC) of calcareous soils varied widely in calcite and texture, (ii) the contribution of soil properties to pHBC and (iii) the significance of using a model based on calcite dissolution to estimate the pHBC of calcareous soils. The pHBC of soils was measured by adding several rates of HCl to soils (100–6500 mM H + kg –1), in a 0.01 M CaCl 2 background and an equilibration time of 24 h. The pHBC (mM H + kg –1 pH ?1) varied from 55 to 3383, with the mean of 1073. The pHBC of the soils was strongly correlated with soil CaCO 3 equivalent (calcite) ( r = 0.94), sand ( r = ?0.72), silt ( r = 0.60), EC (r = 0.63), pH ( r = 0.55), and weakly ( r = 0.37) but significantly with clay content. The attained pHBC values indicated that calcite was probably the main buffer system in these soils. The chemical equilibrium model successfully predicted pH titration curves based on calcite dissolution, indicating buffering of acid inputs in the calcareous soils is dominated by calcite dissolution. The model can be used to simulate acidification of calcareous soils and to provide information for making environmental management decisions. 相似文献
8.
Abstract The recovery of applied zinc (Zn) by plants is relatively small. Coupled with lack of leaching, this leads to accumulation of Zn in topsoil which may result in unfavorable growth conditions for the subsequent plants. Different extractants may be used for assessing the Zn status of soils previously treated with Zn sources. The extractability of retained Zn is influenced by soil properties. This experiment was conducted to study the influence of selected properties of calcareous soils on extractability of Zn by three popular Zn soil tests. Twenty samples from surface horizons (0–20 cm) of highly calcareous soils of southern Iran (pH 7.9 to 8.5; calcium carbonate equivalent 16 to 58%) previously treated with three levels of Zn (0, 10, and 20 mg Zn kg ‐1 soil as ZnSO 4#lb7H 2O) in triplicate and under one crop of corn ( Zea mays L.) were extracted with DTPA, EDTA‐(NH 4) 2CO 3 and Na 2‐EDTA. Extractability (EXT) in a particular extractant was defined as the slope of the regression line, relating extractable Zn of each soil to the rate of applied Zn, multiplied by 100. The EXT values of soils ranged from 24.9 to 73.0% for DTPA, 47.2 to 84.4% for EDTA‐(NH 4) 2CO 3, and 28.2 to 56.7% for Na 2‐EDTA. Stepwise regression equations showed that cation exchange capacity (CEC) and calcium carbonate equivalent (CCE) followed by clay content were the most influential soil properties in EXT of retained Zn of highly calcareous soils. The EXT values decreased with increase in CEC, and CCE but increased with increase in clay. 相似文献
9.
AbstractBoth nitrogen (N) deposition and biochar can affect the emissions of nitrous oxide (N 2O), carbon dioxide (CO 2) and ammonia (NH 3) from different soils. Here, we have established a simulated wet N deposition experiment to investigate the effects of N deposition and biochar addition on N 2O and CO 2 emissions and NH 3 volatilization from agricultural and forest soils. Repacked soil columns were subjected to six N deposition events over a 1-year period. N was applied at rates of 0 (N0), 60 (N60), and 120 (N120) kg Nh a ?1 yr ?1 without or with biochar (0 and 30 t ha ?1 yr ?1). For agricultural soil, adding N increased cumulative N 2O emissions by 29.8% and 99.1% ( p < 0.05) from the N60 and N120 treatments, respectively as compared to without N treatments, and N120 emitted 53.4% more ( p < 0.05) N 2O than the N60 treatment; NH 3 volatilization increased by 33.6% and 91.9% ( p < 0.05) from the N60 and N120 treatments, respectively, as compared to without N treatments, and N120 emitted 43.6% more ( p < 0.05) NH 3 than N60; cumulative CO 2 emissions were not influenced by N addition. For forest soil, adding N significantly increased cumulative N 2O emissions by 141.2% ( p < 0.05) and 323.0% ( p < 0.05) from N60 and N120 treatments, respectively, as compared to without N treatments, and N120 emitted 75.4% more ( p < 0.05) N 2O than N60; NH 3 volatilization increased by 39.0% ( p < 0.05) and 56.1% ( p < 0.05) from the N60 and N120 treatments, respectively, as compared to without N treatments, and there was no obvious difference between N120 and N60 treatments; cumulative CO 2 emissions were not influenced by N addition. Biochar amendment significantly ( p < 0.05) decreased cumulative N 2O emissions by 20.2% and 25.5% from agricultural and forest soils, respectively, and increased CO 2 emissions slightly by 7.2% and NH 3 volatilization obviously by 21.0% in the agricultural soil, while significantly decreasing CO 2 emissions by 31.5% and NH 3 volatilization by 22.5% in the forest soil. These results suggest that N deposition would strengthen N 2O and NH 3 emissions and have no effect on CO 2 emissions in both soils, and treatments receiving the higher N rate at N120 emitted obviously more N 2O and NH 3 than the lower rate at N60. Under the simulated N deposition circumstances, biochar incorporation suppressed N 2O emissions in both soils, and produced contrasting effects on CO 2 and NH 3 emissions, being enhanced in the agricultural soil while suppressed in the forest soil. 相似文献
10.
生物质炭施用可能对土壤中氮素硝化过程和N2O排放产生影响。本研究通过室内培养试验，研究铵态氮肥与玉米秸秆生物质炭施用量（0、1%、2%、5%、10%w/w）对酸性（pH=5.10）和石灰性紫色土（pH=8.15）氮素硝化率、净硝化速率及N2O排放特征的影响。结果表明：（1）酸性和石灰性紫色土生物质炭处理平均净硝化速率相比对照分别降低了33.7%~93.7%和7.5%~40.9%，生物质炭添加抑制了酸性和石灰性紫色土硝化作用，在酸性紫色土中生物质炭对氮素硝化作用的抑制作用随施用量的增加而增强，在石灰性紫色土中无明显规律。（2）与对照相比，酸性紫色土N2O累计排放量在1%生物质炭（1%BC）和2%生物质炭（2%BC）处理下降幅分别为15.9%和27.7%，在5%生物质炭（5%BC）和10%生物质炭（10%BC）处理下增幅分别为60.1%和93.2%。石灰性紫色土生物质炭各处理N2O累积排放量均显著高于对照。（3）综合考虑酸性紫色土1%、2%生物质炭量施用下对硝化作用抑制和N2O减排综合效果最好，在石灰性紫色土中无明显抑制和减排效果。 相似文献
11.
Karanjin, a furanoflavonoid ( 3-methoxy furano –? 2 ′ , 3 ′ , 7, 8-flavone), is obtained from the seeds of karanja tree ( Pongamia glabra Vent.), which is reported to have nitrification inhibitory properties but has been tested in few soil types. Efficiency of karanjin as a nitrification inhibitor in seven different soils of India was tested in a laboratory incubation study. The soils (800?g) were adjusted to field capacity moisture content, fertilized with urea and urea combined with karanjin at a rate of 20% of applied urea-N (100?mg?kg ???1 soil) and incubated at 35°C for a period of 7 weeks, during which urea [CO(NH 2) 2], ammonium (NH 4 ?+?), nitrite (NO 2 ???) and nitrate (NO 3 ???) content in the soils was measured periodically and nitrification inhibition at different stages was calculated. Urea hydrolysis was almost complete within 72?h of application in all the soils and was not affected by karanjin. Karanjin had conserved ammonium in all the soils at all stages and nitrate formation was effectively minimized. Nitrite in soils was short-lived and low. Nitrification inhibition by karanjin remained high for a period of approximately 6 weeks, decreased with time and ranged from 9?–?76% for all the soils. The study shows that this plant product can be an effective nitrification inhibitor in several types of soil. 相似文献
12.
Abstract The introduction of plant materials into a soil can impact the nitrogen (N) status and the fertilizer requirement for agronomic crop production. Consequently, an accurate estimate of N mineralization from soil organic matter and incorporated plant material is necessary to adequately make a N fertilizer recommendation. The purpose of this study was to evaluate the effect of plant parameters including type, size, incorporation rate, and time after incorporation on N mineralization and to derive localized values for parameters in a widely used potential N mineralization model. Soil from the Ap horizon of a Latahco silt loam was amended with alfalfa ( Medicago saliva L.), spring pea ( Pisum sativum L.), and winter wheat ( Triticum aestivum L.) plant materials sized to either <1,1 to 2, or > 2 mm at rates of 0, 2, 4, and 6%. The soils were incubated at 35°C for 20 weeks. The inorganic N in soils was removed by leaching with 100 mL 0.001M CaCl 2 in 5‐ to 10‐mL intervals followed by 25 mL of a nutrient solution devoid of N (0.002M CaSO 4; 0.002M MgSC> 4; 0.005M Ca(H 2PO 4)2; and 0.0025M K 2SO 4) at 0, 2, 4, 6, 8, 12, 16, and 20 weeks. The main effects of plant material type (PM), size (S), incorporation rate (R), and incubation time (T) and many 2‐, 3‐, and 4‐factor interactions on N mineralization were statistically significant at P=0.05. Based on w 2, incubation time (T), and incorporation rate (R) were the two most important factors affecting N mineralization. The amount of N mineralized increased exponentially with increasing time and linearly with the incorporation rate. In addition, the incorporation of plant material not only increased potentially mineralizable N by as much as 5.1 times but also accelerated N mineralization in soil by increasing the N mineralization rate constant 75%. 相似文献
13.
Abstract The ammonium acetate (NH 4OAc)‐EDTA soil phosphorus (P) extraction method was compared to either the Bray‐1 soil P extraction method for non‐calcareous soils or the Olsen soil P extraction method for calcareous soils to predict com and wheat plant tissue P concentration and grain yield responses. The NH 4OAc‐EDTA method predicted yield and tissue P concentration responses to P fertilizer applications more accurately than the Olsen method at three of five sites. Both the Bray‐1 and NH 4OAc‐EDTA methods were successful in predicting corn and wheat yield responses to P fertilizer applications in non‐ calcareous soils in many locations. However, a direct comparison of extracted soil P levels showed that the NH 4OAc‐EDTA method extracted soil P at levels which were more closely related to the Bray‐1 method than the Olsen method. 相似文献
14.
Abstract An incubation experiment was conducted to examine the effects of the phosphorus (P) application on nitrous oxide (N 2O) and nitric oxide (NO) emissions from soils of an Acacia mangium plantation in Indonesia. The soils were incubated with and without the addition of P (Ca[H 2PO 4] 2; 2 mg P g soil) ?1) after adjusting the water-filled pore space (WFPS) to 75% or 100%. The P addition increased N 2O emissions under both WFPS conditions and NO emissions at 75% WFPS. Some possible mechanisms are considered. First, the P addition stimulated nitrogen (N) cycling, and N used for nitrification and/or denitrification also increased. Second, the P addition could have relieved the P shortage for nitrifying and/or denitrifying bacteria, producing N 2O and NO. Our results suggest that the application of P fertilizer has the potential to stimulate N 2O and NO emissions from Acacia mangium plantations, at least when soils are under relatively wet conditions. 相似文献
15.
PurposeThe iron redox cycle is closely tied to the fate of carbon in terrestrial ecosystems, especially paddy soils. Varies diurnally and seasonally, light—the crucial environmental factor—may be a fundamental factor elucidating temporal and spatial variabilities of carbon-containing gases emission. The role of sunlight in the iron-mediated carbon cycle, however, has not been fully elucidated. We conduct this study to test the role of light in the iron-mediated carbon cycling. Materials and methodsIn this study, we conducted anaerobic incubation experiments of a calcareous paddy soil in serum vials under alternating dark and light conditions. The dynamic evolution of the carbon and iron contents was evaluated by measuring the CO2, CH4, and O2 concentrations in the headspace of the vials, as well as the water-soluble inorganic carbon, microbial biomass carbon, and HCl-extractable ferrous iron contents in soil slurries. We also analyzed the soil microbial community structure by high-throughput 16S rRNA gene sequencing. Results and discussionThe results highlighted the positive correlation between carbon mineralization and ferric iron reduction under dark conditions. Under light conditions, however, ferrous iron was oxidized by the O2 generated via oxygenic photosynthesis of phototrophic bacteria such as Cyanobacteria, along with a decreased production of CO2, CH4, and water-soluble inorganic carbon. The abundance of Cyanobacteria positively correlated to O2 levels and MBC content significantly. Light-induced periodic variations in the redox conditions facilitated carbon fixation in microbial biomass and up to 31.79 μmol g?1 carbon was sequestrated during 30 days light incubation. ConclusionsThese results indicate that light inhibits the emission of carbon-containing greenhouse gases associated with the iron redox cycle in calcareous paddy soil. Assimilation of inorganic carbon by phototrophs may responsible for the inhibition of carbon mineralization. Our study suggests that procedures allowing more light to reach the soil surface, for instance, reducing the planting density, may mitigate greenhouse gas emissions and promote carbon sequestration in paddy soils. 相似文献
16.
Abstract Mungbean [ Vigna radiata (L). Wilczek] grown in rainfed calcareous soils suffers with phosphorus (P) deficiency. In view of high cost and low use efficiency of P fertilizer, greenhouse, incubation, and field experiments were carried out for determining P deficiency diagnostic criteria and efficient method of P fertilizer application in mungbean. In a pot culture experiment using a P‐deficient Typic Ustocherpt, maximum increase in grain yield with P was 686% over the control; and fertilizer requirement for near‐maximum (95%) grain yield was 30 mg P kg ‐1 soil where fertilizer was mixed with the whole soil volume (broadcast) and 14 mg P kg ‐1 where mixed with 1/4th soil volume (band placement). In a field experiment on a P‐deficient Typic Camborthid, however, maximum increase in grain yield was 262% over the control. Band placement resulted in 73% fertilizer saving as P requirement was 66 kg ha ‐1 by broadcast and only 18 kg ha ‐1 by band placement. Critical P concentration range appears to be 0.27–0.33% in young whole shoots (≤30 cm tall) and 0.25–0.30% in recently matured leaves. In an incubation study using the same Typic Ustochrept, P extracted by the sodium bicarbonate (NaHCO 3), the ammonium bicarbonate‐diethlylenetriaminepentaacetic acid (AB)‐DTPA), and the Mehlich 3 soil tests correlated closely with each other, P concentration of whole shoots, and total P uptake by mungbean plants. Critical soil test P levels for pot grown mungbean were NaHCO 3,9 mg kg ‐1; AB‐DTPA, 7 mg kg ‐1; and Mehlich 3, 23 mg dm ‐3 soil. The more efficient and economical ‘universal’ soil test, AB‐DTPA, is recommended for P fertility evaluation of calcareous soils. 相似文献
17.
PurposeNatural sepiolite (SP) has proven effective on the in-situ immobilization remediation of Cd-contaminated soils. But the practical remediation effect may largely influenced by water management and the application of organic manure. The effects of chicken manure (CM) on SP-amended soils were investigated under normal and saturated water conditions using a pot experiment with Brassica campestris L. Materials and methodsCd-contaminated paddy soils were amended with CM, SP, and CM?+?SP with no amendment as control. The amount of sepiolite was 0.5% (w/w, the same below) either in SP or CM?+?SP amended soils, while the amount of CM was 0.5, 1.0, and 2.0% in CM and CM?+?SP-amended soils. The plant metal contents, fresh weight, and soluble sugar content of plant edible parts were measured on harvest. Soil Cd was extracted by diethylenetriaminepentaacetic acid (DTPA) and HCl to estimate the mobility of heavy metal. Soil pH and dissolved organic matter (DOM) of rhizosphere soil were determined. The electronegative charges of soils were also measured using the zeta potential. Results and discussionThe application of CM and increasing soil moisture on SP-amended soil increased plant growth to a greater extent than the application of SP alone. The application of CM along with the increase of soil moisture decreased Cd uptake and translocation in plants grown on SP-amended soil compared to the application of SP alone. Cd content of edible plant parts reached a minimum of 0.24 mg kg?1 with the application of 2.0% CM on SP-amended soils under water-saturated conditions, which was approximately 50% lower than the Cd concentration found when applying SP alone. ConclusionsThe results of this study suggest that the application of sepiolite on Cd contaminated soil can effectively reduce Cd uptake by B. campestris L., and the addition of CM combined with effective water management also appears to further reduce Cd absorption and accumulation. 相似文献
18.
AbstractA short-term study was conducted to investigate the greenhouse gas emissions in five typical soils under two crop residue management practices: raw rice straw ( Oryza sativa L., cv) and its derived biochar application. Rice straw and its derived biochar (two biochars, produced at 350 and 500°C and referred to as BC350 and BC500, respectively) were incubated with the soils at a 5% (weight/weight) rate and under 70% water holding capacity for 28 d. Incorporation of BC500 into soils reduced carbon dioxide (CO 2) and nitrous oxide (N 2O) emission in all five soils by 4?40% and 62?98%, respectively, compared to the untreated soils, whereas methane (CH 4) emission was elevated by up to about 2 times. Contrary to the biochars, direct return of the straw to soil reduced CH 4 emission by 22?69%, whereas CO 2 increased by 4 to 34 times. For N 2O emission, return of rice straw to soil reduced it by over 80% in two soils, while it increased by up to 14 times in other three soils. When all three greenhouse gases were normalized on the CO 2 basis, the global warming potential in all treatments followed the order of straw > BC350 > control > BC500 in all five soils. The results indicated that turning rice straw into biochar followed by its incorporation into soil was an effective measure for reducing soil greenhouse gas emission, and the effectiveness increased with increasing biochar production temperature, whereas direct return of straw to soil enhanced soil greenhouse gas emissions. 相似文献
19.
Abstract Iron oxide is the most important electron acceptor in paddy fields. We aimed to suppress the methane emission from paddy fields over the long term by single application of iron materials. A revolving furnace slag (RFS; 245 g Fe kg -1) and a spent disposable portable body warmer (PBW; 550 g Fe kg -1) were used as iron materials. Samples of a soil with a low iron level (18.5 g Fe kg -1), hearafter referred to as “a low-iron soil” and of a soil with a high iron level (28.5 g Fe kg -1), hearafter referred to as “an iron-rich soil,” were put into 3 L pots. At the beginning of the experiment, RFS was applied to the pots at the rate of 20 and 40 t ha -1, while PBW was applied at the rate of 10 t ha -1 only, and in the control both were not applied. Methane and nitrous oxide emissions from the potted soils with rice plants were measured by the closed chamber method in 2001 and 2002. When RFS was applied at the rates of 20 and 40 t ha -1 to the low-iron soil, the total methane emission during the cultivation period significantly decreased by 25–50% without a loss of grain yield. Applied iron materials clearly acted as electron acceptors, based on the increase in the amount of ferrous iron in soil. However, the suppressive effect was not evident in the iron-rich soil treated with RFS or PBW. On the other hand, nitrous oxide emission increased by 30–95%. As a whole, when the total methane and nitrous oxide emissions in the low-iron soil were converted to total greenhouse gas emissions expressed as CO 2- C equivalents in line with the global warming potential, the total greenhouse gas emissions decreased by about 50% due to the application of RFS. 相似文献
20.
ABSTRACT Lucerne or alfalfa ( Medicago sativa L.) is grown as a forage crop on many livestock farms. In calcareous soils in eastern Turkey, lucerne production requires phosphorus (P) additions as the soils are naturally P deficient. Phosphorus sorption isotherms were used to estimate P fertilizer needs for lucerne grown for two years in a 3-cut system on a calcareous P deficient Aridisol in eastern Anatolia, Erzurum province, Turkey. Annual P applications ranged from 0–1200 kg P ha ?1. The Langmuir two-surface adsorption equation was used to derive the maximum P sorption capacity of unamended soil and to determine soil solution P, maximum buffer capacity (MBC), equilibrium buffer capacity (EBC), and P saturation at the optimum economic P rate (OEPR) for dry matter (DM) production. Soils were tested for Olson P at the onset of the study and after two years of P applications. In both years, tissue was analyzed for P content at flowering prior to first cutting. The OEPR (2-year average) was 754 kg P ha ?1 yr ?1 corresponding with a soil solution P concentration of 0.30 mg L ?1, a DM yield of 8725 kg DM ha ?1, and $528 ha ?1 annual profit. The P content of leaves at flowering increased linearly with P application beyond 100 kg P ha ?1 and was 3.2 g kg ?1 P at the OEPR. The unfertilized soil had an EBC, MBC, P saturation, and X max of 3304 mL g ?1, 3401 mL g ?1, 6%, and 1086 mL g ?1, respectively, whereas two years of fertilization to the OEPR decreased EBC and MBC to 358 mL g ?1 and 540 mL g ?1, and increased P saturation and Olsen P to 56% and 32 mg kg ?1, respectively. These results suggest a P saturation >50% or Olsen P >30 mg kg ?1 are needed to maintain an optimum soil solution concentration of 0.30 mg L ?1 in this calcareous Aridisol. Similar studies with different soils and initial soil test P levels are needed to conclude if these critical soil test values can be applied across the region. 相似文献
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