The effects of reduced-impact logging practices on soil animal communities in the Deramakot Forest Reserve in Borneo

The effectiveness of reduced-impact logging practices on the maintenance of biodiversity in Borneo has been recognized for some organisms (e.g., mammals). We investigated the effects of reduced-impact logging and conventional selective logging practices on biodiversity by using soil fauna as indicators of disturbance. The study sites were the production forests of the Deramakot Forest Reserve and the Tangkulap Forest Reserve in Sabah, Malaysian Borneo (5°14–30′ N, 117°11–36′ E). We compared macro- and mesofauna in a pristine forest with no logging, a reduced-impact logged forest in Deramakot Forest Reserve, and a conventionally logged forest in Tangkulap Forest Reserve.The mean density of soil macrofauna (excluding ants) did not differ significantly among the three forest categories (nested ANOVA, p > 0.05). This tendency was also seen in the density and species richness of Oribatida and Collembola, which showed little difference among forest categories. Nonmetrical multidimensional scaling (NMS) ordination diagrams revealed a different community composition in conventionally logged forest sites compared with the other sites. The scores for the NMS first or second axis of soil fauna were correlated with one or more of the values for density, diversity, and species composition of trees. A RELATE test showed the congruence between trees and the Collembola and Oribatida community composition between sites. The results implied that the soil fauna community composition was related to tree communities. In conclusion, the impacts of logging on decomposers in the soil animal communities have been mitigated by the introduction of reduced-impact logging in Deramakot Forest Reserve through the protection of tree vegetation. It is important to consider monitoring the influence of selective logging on soil fauna with regard to the dynamics of the species (or group) composition because total density and species (or group) richness of soil fauna displayed only a marginal response to the different logging practices.     

Investigation of alternate herbicides for effective weed management in glyphosate-tolerant cotton

ABSTRACT

Glyphosate-resistant (GR) weeds are the biggest concern for all cotton stakeholders worldwide. Currently, 43 weeds species are resistant to glyphosate and the number is increasing at an alarming rate. Soil residual/pre-emergence (PRE) herbicides like Pendimethalin and S-metolachlor can be effectively used for the control of GR weeds; however, their use is very limited at farmer’s side due to the adoption of herbicide-tolerant technology with complete reliance on glyphosate. The present study was conducted to evaluate the performance of PRE and post-emergence (POST) herbicides in glyphosate-tolerant (GT) cotton. The herbicide treatments were pendimethalin and S-metolachlor as PRE-residual, and glyphosate was applied as POST at 20 days after sowing (DAS) either alone or in combination with other herbicides like S-metolachlor, pendimethalin, and haloxyfop. A second application of glyphosate was made at 35 DAS. Results revealed that pendimethalin and S-metolachlor treatments gave 100% suppression of all dominant weeds and increased lint yield by 310–350% as compared to weedy control. In contrast, glyphosate applied once and twice, gave weed biomass reduction of only 10–86%, and increased lint yield by 136–185% over weedy control. This research established that PRE application of pendimethalin and S-metolachlor can be included in the weed management program of GT cotton.     

Effects of Collembola on root properties of two competing ruderal plant species

Plant roots compete for nutrients mineralised by the decomposer community in soil. By affecting microbial biomass and activity Collembola influence the nutrient availability to plants. We investigated the effect of Collembola (Protaphorura fimata Gisin) on growth and competition between of two plant species, Cirsium arvense L (creeping thistle) and Epilobium adnatum Griseb. (square-stemmed willow herb), in a laboratory experiment. Two seedlings of each plant species were planted in rhizotrons either in combination or in monoculture (intra- and interspecific competition). Interspecific competition strongly reduced total biomass of C. arvense whereas E. adnatum suffered most from intraspecific competition. Collembola neither affected the competitive relationship of the two plant species nor shoot and root biomass. Although Collembola did not affect total root biomass they influenced root morphology of both plant species. Roots grew longer and thinner and had more root tips in presence of Collembola. Root elongation is generally ascribed to the exploitation of nutrient rich patches in soil. We hypothesise that changes in root morphology in presence of Collembola are due to Collembola-mediated changes in nutrient availability and distribution.     

Soil microbial community response to surfactants and herbicides in two soils

The environmental impacts of herbicides on desirable plants and the soil biota are of public concern. The surfactants that are often used with herbicides are also under scrutiny as potentially harmful to soil biological systems. To address these concerns, we used two soils, a silt loam and a silty, clay loam from south central Missouri, to investigate the impacts of herbicides and surfactants on soil microbial communities using phospholipid fatty acid (PLFA) analysis. The surfactants used in this study were alkylphenol ethoxylate plus alcohol ethoxylate (Activator 90), polyethoxylate (Agri-Dex), and a blend of ammonium sulfate, drift reduction/deposition polymers and anti-foam agent (Thrust). The herbicides were glyphosate, atrazine and bentazon. Surfactants and herbicides were applied to soils at label rate, either alone or combined, to 4000 g soil per pot. The two soils differed in history, texture, some chemical characteristics and several microbial community characteristics. A few of the chemicals altered some of the components of the microbial community after only one application of the chemical at field-rate. The Cole County, MO silt loam showed larger changes in the microbial community with application of treatments. For the Boone County, MO silty clay loam, Activator 90, Agri-Dex and bentazon treatments increased microbial biomass determined by PLFA; Thrust decreased PLFA markers, bacteria to fungi ratio; and Agri-Dex at both rates decreased monounsaturated fatty acids. Changes in the microbial community due to herbicides or surfactants were minimal in this study of a single application of these chemicals, but could be indicators of potential long-term effects. Long-term studies are needed to determine the changes in the microbial community after several years of annual applications of herbicides and surfactants on a wide array of soil types and management practices.     

Effects of preemergence and postemergence herbicides on urea hydrolysis and nitrification of urea nitrogen in soil

The influence of 5 and 50 mg active ingredient kg^-1 soil of nine preemergence and nine postemergence herbicides on transformations of urea N in soil was studied in samples of two coarse-textured and two fine-textured soils incubated aerobically at 20°C. The effects of each herbicide on soil urea transformations was measured by determining the amounts of urea hydrolyzed and the amounts of NO _inf3 ^sup- and NO _inf2 ^sup- produced at various times after treatment with urea. Applied at the rate of 5 mg active ingredient kg^-1 soil, none of the herbicides retarded urea hydrolysis in the four soils used, but four of the postemergence herbicides (acifluorfen, diclofop methyl, fenoxaprop ethyl) retarded urea hydrolysis in the two coarse-textured soils. All the herbicides tested except siduron retarded nitrification in the two coarse-textured soils when applied at 50 mg of urea N active ingredient kg^-1 soil, and fenoxaprop ethyl and tridiphane markedly retarded nitrification of urea N in all four of the soils when applied at this rate. One-way analysis of variance and correlation analyses indicated that the inhibitory effects of the 18 herbicides tested on nitrification of urea N in soil increased with a decrease in the organic-matter content and an increase in the sand content of the soil. Present address: Department of Soil and Environmental Sciences, University of California, Riverside, CA 92521, USA     

Herbicides have negligible effects on ants and springtails in an Australian wheat field

The effects of herbicides applied to a direct drilled and traditionally tilled wheat field on trap catches of the abundant Collembola and Formicidae were examined. Significantly higher abundances of Collembola and species richness of ants were found on the direct-drilled plots. A significant effect of the herbicides, bromoxynil (C₇H₃Br₂NO) and hoegrass (diclofop-methyl), on the activity of two of the fourteen species of surface-dwelling Collembola was detected but no effect was observed on surface-active Formicidae. Jeannenotia stachi numbers were significantly more reduced on the direct-drilled compared to the traditionally tilled plot after herbicide treatment possibly because of higher predator abundance on the latter. In the short term, herbicides have a minimal effect on most species of surface-active arthropods although Collembola were more adversely affected than Formicidae.     

Olive mill waste and glyphosate‐based herbicide addition to olive grove soils: effects on microbial activities and their responses to drying–rewetting cycles

The objective of this experimental study was to determine the effect of agronomic practices usually implemented in olive groves (addition of olive mill waste and herbicides) on soil microbial communities and to test whether drought enhanced such effects. For that purpose, mesocosms containing soil cores from olive groves were incubated for 5 months under either of the three treatments: (i) addition of olive mill waste (OMW), (ii) addition of glyphosate‐based herbicide (Gly treatment) and (iii) both treatments. Half of the mesocosms were subjected or not (controls) to drying–rewetting cycles (D/Rw) for 1 month (1 D/Rw) or 3 months (3 D/Rw). In the controls, 2 months after the Gly treatment, higher lipase activities were observed compared with no practice treatment as well as a significant change in catabolic profiles of cultivable microbial communities. Three months later, lipase activities significantly decreased under the Gly treatment. Addition of OMW together with Gly treatment counteracted the negative effect of the herbicide on lipase activities. After three D/Rw cycles, Gly treatment modified catabolic profiles and induced a decrease in functional diversity. Overall, the combination of glyphosate‐based herbicide with OMW was a conservative practice that maintained soil functioning and led to a better response to D/Rw cycles.     

Effect of certain herbicides on soil microbial populations and their influence on saprophytic growth in soil and pathogenicity of take-all fungus

Summary The application of diquat + paraquat, glyphosate and trifluralin to unsterilized field soil increased take-all caused by the fungus, Gaeumannomyces graminis var. tritici Walker by 13.0% 16.6% and 10.8% respectively, while no effect on disease was recorded in sterilized soil treated with the same herbicides. The herbicides tested had no effect on the saprophytic growth of the pathogen with the exception of glyphosate, which increased its growth in unsterilized soil. The application of diquat + paraquat and glyphosate to unsterile soil had no effect on the numbers of actinomycetes. The diquat + paraquat treatment, however, increased populations of fungi while the glyphosate decreased the numbers of bacteria. The proportion of soil fungi antagonistic to the pathogen was reduced in glyphosate-treated soil. The frequency of occurrence of Eupenicillium euglaucum (v. Beyma) Stolk & Samson (strain B), and Penicillium verruculosum Peyr. (strain B), which were strong and low level antagonists of Ggt on agar, were reduced in their occurrence in soil by 7.7% and 2.5% respectively, following glyphosate treatment. Moreover, the numbers of Aspergillus viridinutans Ducker & Thrower, which showed moderate antagonism to the pathogen, was decreased by 1.9% and 4.1% in diquat + paraquat and glyphosate treatments respectively. The proportion of antagonists rather than total numbers of fungi appears to be related to the treatment effect observed on the soil growth and pathogenicity of G. graminis var. tritici in our investigation. The increase in disease of wheat in certain herbicide-treated soils may be due to the shift in soil microbial populations away from those which are antagonistic to the pathogen.     

Short term response of soil microinvertebrates to application of entomopathogenic nematode-infected insects in two tillage systems

Entomopathogenic nematodes (EPN) in the families Steinernematidae and Heterorhabditidae occur naturally in the soil and are produced commercially for the management of soil-dwelling pests. EPN infected cadavers also represent a potential resource for other soil organisms. We examined the short-term (24 h) response in abundance, diversity and community composition of localized soil microinvertebrates to the presence of EPN-infected insect cadavers in no-till and conventional-till maize. We hypothesized that the response of soil microinvertebrates to the EPN-infected cadavers would vary by soil management practices and EPN species. We expected to observe greater numbers and diversity of arthropods in no-till compared with conventional-till soil, and in the vicinity of steinernematid-infected insect cadavers compare to what would be found in the vicinity of heterorhabditid-infected cadavers. 45,606 invertebrates were collected and identified to 134 morphotaxa. Tillage regime accounted for the majority of the variation observed (84.6%), whereas nematode treatment accounted for 7.5%. Taxonomic richness of invertebrates was greater in treatments with Steinernema carpocapsae-infected cadavers than with Heterorhabditis bacteriophora-infected cadavers. Some invertebrates increased in abundance where EPN were applied whereas others decreased, regardless of tillage practice. Applications of Galleria cadavers infected with steinernematids elicited positive responses from two mite taxa, Galumnidae and Scheloribates spp., while negative responses were elicited from three mite (Histiostomatidae, Scheloribates spp., Eupodes spp.), taxa and Entomobryidae (Collembola) in response to applications of Heterorhabditis-infected cadavers.     

Collembola species composition and diversity effects on ecosystem functioning vary with plant functional group identity

The relationship between decomposer diversity and ecosystem functioning is little understood although soils accommodate a significant proportion of worldwide biodiversity. Collembola are among the most abundant and diverse decomposers and are known to modify plant growth. We examined the effects of Collembola species diversity (one, two and three species belonging to different life history groups) and composition on litter decomposition and the performance of plant communities (above- and belowground productivity) of different functional groups (grasses, forbs and legumes). Collembola densities did not increase with diversity indicating niche overlap. Generally, Collembola species composition was a better predictor for ecosystem functioning than Collembola species number with the impacts of Collembola diversity and composition on ecosystem functioning strongly depending on plant functional group identity. Non-linear effects of Collembola diversity on litter decomposition and plant productivity suggest pronounced and context dependent species interactions and feeding habits. Net surface litter decomposition was decreased by Collembola, whereas root litter decomposition was at maximum in the highest Collembola diversity treatment. Forbs benefitted most from the presence of three Collembola species. Similarly, Collembola diversity influenced root depth distribution in a plant functional group specific way: while grass root biomass decreased with increasing Collembola diversity in the upper and lower soil layer, legume root biomass increased particularly in the lower soil layer. Idiosyncratic and context dependent effects of Collembola diversity and composition even in rather simple assemblages of one to three species suggest that changes in Collembola diversity may have unpredictable consequences for ecosystem functioning. The finding that changes in Collembola performance did not directly translate to alterations in ecosystem functioning indicates that response traits do not necessarily conform to effect traits. Distinct plant functional group specific impacts of Collembola diversity on root depth distribution are likely to modify plant competition in complex plant communities and add a novel mechanism how decomposers may affect plant community assembly.     

Preliminary investigations on the effects of no‐till corn production methods on specific soil mesofauna populations

Abstract

Moldboard plowing, chisel plowing and no‐till methods were used to produce field corn (Zea mays) in an old grass sod. Grain yields were similar ranging between 13,100 and 14,186 kg/ha. The greatest spread in soil temperatures was only 2.1 C with the plowed soil always being warmest. Mean soil organic matter levels of the surface soil ranged between 1.9 percent on the moldboard plowed plots and 3.3 on the no‐till plots. Ten species of soil Collembola were identified. Collembola and Acarina populations were concentrated in the surface 5 cm of soil and were present in greatest numbers in the No‐Till soil.     

Temperature tolerance in soil microarthropods: Simulation of forest-fire heating in the laboratory

Forest fires markedly reduce the abundance of surface-dwelling soil animals; animal densities also decline in soil layers underlying the char layer. The aim of the present study was to determine lethal temperatures for different species within the more abundant microarthropod groups in boreal forests, namely Collembola, Protura, Mesostigmata and Oribatida. In the laboratory, forest soil humus containing naturally occurring microarthropods was heated in plastic bags to avoid desiccation. Each sample was heated to one of 11 different temperatures between 20 and 60 °C for 1, 4, or 12 h. At the 1-h exposure, 36 °C was the highest temperature tolerated before significant decreases in numbers were detected. The corresponding temperatures after 4- and 12-h exposures were 34 °C for Oribatida and 30–32 °C for Collembola, Protura and Mesostigmata, respectively. Individual species responded differently, and the most heat-tolerant species within Oribatida was Tectocepheus velatus (40 °C at 4-h exposure) while Friesea mirabilis and Mesaphorura sp. (36 °C at 4-h exposure) were the most tolerant within Collembola. During a forest fire, temperatures higher than those tolerated by the investigated groups and species may well be reached.     

ABSTRACT of the Articles Printed in Journal of the Science of Soil and Manure,Japan

Changes in soil moisture determine the reproductive, respiratory, and metabolic activities of soil microorganisms and hence the rate of microbial nitrogen (N) mineralization. Soil moisture also affects the feeding activity and movement of soil invertebrates. Bacterial and fungal grazing by soil invertebrates such as Collembola and nematodes is known to increase N mineralization by increasing the reproductive, respiratory, and metabolic activities of microorganisms. Therefore, to assess the effect of soil moisture on N mineralization, faunal responses need to be considered. We used microcosms to investigate the effect of soil moisture on N mineralization mediated by a species of Collembola, Folsomia candida Willem. We used four moisture levels corresponding to matric potentials of ?42.5, ?11.8, ?0.8, and ?0.5 kPa and investigated the effects of these on Collembola with respect to feeding activity, growth, and contribution to N mineralization. The microbial biomass and ratio of bacterial to fungal biomass tended to increase with increasing soil moisture. Collembola feeding activity and growth increased with increasing soil moisture conditions. Collembola significantly enhanced N mineralization in soil at water potentials of ?11.8 and ?0.5?kPa. The greatest relative increase in N mineralization attributed to Collembola occurred in the ?11.8?kPa treatment. The change in contribution of the Collembola to N mineralization with soil moisture was most likely induced by changes in Collembola feeding activity and microbial community structure. The growth in body length of the Collembola was significantly greater at higher moisture conditions than at the lowest moisture condition, indicating that increases in both metabolic activity and biomass of the Collembola population contributed to the enhanced N mineralization.     

Losses of 15N-nitrogen by plant–soil system after herbicide application on black oat

Recent studies have demonstrated that the use of glyphosate or glufosinate-ammonium herbicides for some cover crop desiccation in conservationist systems could favor nitrogen (N) losses from the soil–plant system. In this context, the objective of this study was to evaluate the losses of N by the plant–soil system after the desiccation of black oat (Avena strigosa Schreb.) with the application of herbicides glyphosate, glufosinate-ammonium, or paraquat. Two greenhouse experiments were implemented using black oat plants fertilized with labeled (¹⁵N) ammonium nitrogen, and the N loss of the plant–soil system was quantified. The desiccation of black oat with glyphosate caused a reduction in root dry mass by approximately 60% in both experiments. The glyphosate and glufosinate-ammonium reduced the amount of N present in the aboveground portion; however, the paraquat herbicide did not modify it. None of the herbicides applied affected N losses in the black oat plant–soil system. However, 5–15% of the N applied as fertilizer was lost up to harvest. The results suggest that black oat can be used as a cover crop in direct sowing in order to avoid nitrogen losses in the soil–plant system.     

Species diversity and seasonal abundance of Collembola in turfgrass ecosystems of North America

In North America, lawns are the most widely used plantings in urban areas. However, despite the ubiquity and ecological roles of turfgrass soil arthropods, many aspects of their composition and diversity have been neglected. We investigated assemblages of Collembola and their seasonal fluctuations in a newly established lawn and a 10-year old lawn located in Québec City, Canada. Collembola were sampled every month from May to October in 2003 and 2004 by extracting individuals from soil cores using a modified Berlese funnel. A total of 21 species representing 17 genera and nine families were identified. Four species are new records for the province of Quebec: Brachystomella parvula, Mesaphorura simplex, Isotomodes productus, and Sphaeridia pumilis. Turfgrass supports mainly three cosmopolitan species from the Isotomidae family, which represent 73.5% of all Collembola collected during the survey: Parisotoma notabilis, Isotoma viridis, and Cryptopygus thermophilus. Collembola were twice more abundant at the newly established site, but there were minor differences in species diversity between sites and years. No clear patterns of seasonal relative abundance were observed for the whole Collembola populations, as well as for the three dominant species. Turfgrass ecosystem provides a suitable habitat for epedaphic and hemiedaphic Collembola, such as the Isotomidae, most likely because turfgrass mowing and natural leaf, stem and root replacement produces large amounts of decaying organic matter.     

Glyphosate Dissipation in Different Soils Under No-Till and Conventional Tillage

Glyphosate is the most used herbicide in Argentina, accounting for 62% of the commercialized pesticides on the market. It is used as a weed controller in no-till systems, and it is also applied to various genetically modified crops (e.g., soybean, corn, and cotton). Although it has a high solubility in water, it tends to adsorb and accumulate in agricultural soils. The main objectives of this work were to compare the dissipation of glyphosate and the accumulation of its metabolite aminomethylphosphonic acid (AMPA) over time in three soils from agricultural areas of Argentina under long-term management with no-till (NT) and conventional tillage (CT) practices. There were no differences in dissipation between NT and CT, indicating that the glyphosate-degrading microflora was not modified by the different tillage managements. Moreover, tillage practices did not alter the general soil properties; therefore, glyphosate bioavailability was not affected by NT or CT practice. Forty percent of the applied glyphosate was degraded within the first three days in all soils, indicating a fast initial dissipation rate. However, the dissipation rate considerably decreased over time, and the degradation kinetics followed a bi-exponential (or two-compartment) kinetic model. No differences were found between tillage practices. Dissipation was not related to the microbial activity measured as soil respiration. The fast decrease in the concentration of glyphosate at the beginning of the dissipation study was not reflected in an increase in the concentration of AMPA. The estimated half-lives for glyphosate ranged between 9 and 38 d. However, glyphosate bioavailability decreases over time, as it is strongly adsorbed to the soil matrix. This increases its residence time, which may lead to its accumulation in agricultural soils.     

Effects of the annual invasive plant Impatiens glandulifera on the Collembola and Acari communities in a deciduous forest

Invasive plants can disturb interactions between soil organisms and native plants and thereby alter ecosystem functions and/or reduce local biodiversity. Collembola and Acari are the most abundant microarthropods in the leaf litter and soil playing a key role in the decomposition of organic material and nutrient cycling. We designed a field experiment to examine the potential effects of the annual invasive plant Impatiens glandulifera on species diversity, abundance and community composition of Collembola and Acari in leaf litter and soil in a deciduous forest in Switzerland. Leaf litter and soil samples were obtained from plots invaded by I. glandulifera since 6 years, from plots in which the invasive plant had been removed for 4 years and from plots which were not yet colonized by the invasive plant. The 45 leaf litter and soil samples were equally distributed over three forest areas, which were differently affected by a wind throw 12 years prior to sampling representing a natural gradient of disturbance. Collembola species richness and abundance in the leaf litter and soil samples were not affected by the presence of the invasive plant. However, the species composition of Collembola was altered in plots with I. glandulifera. The abundance of leaf-litter dwelling Acari was increased in invaded plots compared to the two other plot types. Furthermore, the presence of the invasive plant shifted the composition of Acari individuals belonging to different groups. Our field experiment demonstrates that an annual invasive plant can affect microarthropods which are important for nutrient cycling in various ecosystems.     

百草清除草剂对农田生态系统土壤动物群落结构的影响

用百草清除草剂对农田生态系统土壤动物进行染毒模拟实验,共获得土壤动物967个,隶属3门,6纲,10目。其中弹尾目、甲螨亚目为优势类群,其余为常见类群和稀有类群。实验结果表明,百草清除草剂处理组的动物种类和数量与对照组相比较明显减少,动物种类的减少主要取决于常见种类和稀有种类,动物数量的变化则主要是优势类群的数量消长。并且随着百草清溶液处理浓度的增加,土壤动物的种类和数量显著减少,但上、下层动物随染毒历时递减规律有所不同。     

Low importance for a fungal based food web in arable soils under mineral and organic fertilization indicated by Collembola grazers

We investigated the Collembola community at an arable field where mineral and organic fertilizers have been applied at low and high rates for 27 years. As food resources for Collembola, the soil microbial community was analyzed using phospholipid fatty acids (PLFAs). A special focus was put on AM fungi, which were estimated by the marker 16:1ω5 in PLFA (viable hyphae) and neutral lipid fatty acid (NLFA – storage fat in spores) fractions. Additionally, whole cellular lipids in crop plant tissues and manure were assessed. Greater Collembola species richness occurred in plots where mineral fertilizer was added. In contrast, soil microbial biomass including AM fungal hyphae increased with addition of organic fertilizer, while the amount of AM fungal spores and biomass of saprotrophic fungi were not affected by fertilizer type. The lipid pattern in wheat roots was altered by fertilizer type, application rate and their interaction, indicating different rhizosphere communities. In sum, the availability and composition of food resources for Collembola changed considerably due to farm management practice. The major diet of three dominant Collembola species, Isotoma viridis, Willemia anophthalma and Polyacanthella schäffer was determined by lipid profiling. Multivariate analysis demonstrated species specific lipid patterns, suggesting greater importance of species than management practice on the diet choice. Nevertheless, feeding strategy was affected by fertilizer type and availability of resources, as trophic biomarker fatty acids indicated feeding on wheat roots (and to some extent saprotrophic fungi) with mineral and a shift to soil organic matter (litter, detritus) with organic fertilization. Although AM fungi dominated the soil fungal community, the AMF marker 16:1ω5 was not detected in Collembola lipids, indicating that these were not consumed. The very low amount of saprotrophic fungi in the soil and the fact that Collembola as major fungal grazers did not feed on AM fungi indicates that the fungal energy channel in the investigated arable field is of little importance to the faunal food web.     

除草剂对土壤温室气体排放的影响

试验设对照、尿素、尿素＋草甘膦和尿素＋丁草胺4个处理,尿素氮用量为200mg·kg-1干土,除草剂用量为10mg有效成分·kg-1干土。在实验室恒温培养条件下,研究除草剂对菜田土壤温室气体排放的影响。结果表明,菜田土壤中施用氮肥显著增加了温室气体N2O、CO2和CH4的排放。尿素氮肥中添加草甘膦显著抑制N2O、CO2的排放,分别比尿素处理降低48.4%和20.2%;添加丁草胺显著抑制N2O排放,比尿素处理降低23.2%,对CO2排放略有减少但不显著;草甘膦和丁草胺对CH4排放都无明显影响。这说明除草剂对土壤温室气体的排放具有显著影响,但不同除草剂品种的效应也存在明显差异。因此,在农田温室气体排放估算时应考虑除草剂的施用对温室气体减排所产生的效果。