@article{zhang_qiu_gilliam_gillespie_tu_reberg-horton_hu_2022, title={Arbuscular Mycorrhizae Shift Community Composition of N-Cycling Microbes and Suppress Soil N2O Emission}, volume={8}, ISSN={["1520-5851"]}, DOI={10.1021/acs.est.2c03816}, abstractNote={Mycorrhizae are ubiquitous symbiotic associations between arbuscular mycorrhizal fungi (AMF) and terrestrial plants, in which AMF receive photosynthates from and acquire soil nutrients for their host plants. Plant uptake of soil nitrogen (N) reduces N substrate for microbial processes that generate nitrous oxide (N2O), a potent greenhouse gas. However, the underlying microbial mechanisms remain poorly understood, particularly in agroecosystems with high reactive N inputs. We examined how plant roots and AMF affect N2O emissions, N2O-producing (nirK and nirS) and N2O-consuming (nosZ) microbes under normal and high N inputs in conventional (CONV) and organically managed (OM) soils. Here, we show that high N input increased soil N2O emissions and the ratio of nirK to nirS microbes. Roots and AMF did not affect the (nirK + nirS)/nosZ ratio but significantly reduced N2O emissions and the nirK/nirS ratio. They reduced the nirK/nirS ratio by reducing nirK-Rhodobacterales but increasing nirS-Rhodocyclales in the CONV soil while decreasing nirK-Burkholderiales but increasing nirS-Rhizobiales in the OM soil. Our results indicate that plant roots and AMF reduced N2O emission directly by reducing soil N and indirectly through shifting the community composition of N2O-producing microbes in N-enriched agroecosystems, suggesting that harnessing the rhizosphere microbiome through agricultural management might offer additional potential for N2O emission mitigation.}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Zhang, Xuelin and Qiu, Yunpeng and Gilliam, Frank S. and Gillespie, Christopher J. and Tu, Cong and Reberg-Horton, S. Chris and Hu, Shuijin}, year={2022}, month={Aug} }
 @article{zhang_qiu_cheng_wang_liu_tu_bowman_burkey_bian_zhang_et al._2018, title={Atmospheric CO2 Enrichment and Reactive Nitrogen Inputs Interactively Stimulate Soil Cation Losses and Acidification}, volume={52}, ISSN={["1520-5851"]}, DOI={10.1021/acs.est.8b00495}, abstractNote={Reactive N inputs (Nr) may alleviate N-limitation of plant growth and are assumed to help sustain plant responses to the rising atmospheric CO2 (eCO2). However, Nr and eCO2 may elicit a cascade reaction that alters soil chemistry and nutrient availability, shifting the limiting factors of plant growth, particularly in acidic tropical and subtropical croplands with low organic matter and low nutrient cations. Yet, few have so far examined the interactive effects of Nr and eCO2 on the dynamics of soil cation nutrients and soil acidity. We investigated the cation dynamics in the plant-soil system with exposure to eCO2 and different N sources in a subtropical, acidic agricultural soil. eCO2 and Nr, alone and interactively, increased Ca2+ and Mg2+ in soil solutions or leachates in aerobic agroecosystems. eCO2 significantly reduced soil pH, and NH4+-N inputs amplified this effect, suggesting that eCO2-induced plant preference of NH4+-N and plant growth may facilitate soil acidification. This is, to our knowledge, the first direct demonstration of eCO2 enhancement of soil acidity, although other studies have previously shown that eCO2 can increase cation release into soil solutions. Together, these findings provide new insights into the dynamics of cation nutrients and soil acidity under future climatic scenarios, highlighting the urgency for more studies on plant-soil responses to climate change in acidic tropical and subtropical ecosystems.}, number={12}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Zhang, Li and Qiu, Yunpeng and Cheng, Lei and Wang, Yi and Liu, Lingli and Tu, Cong and Bowman, Dan C. and Burkey, Kent O. and Bian, Xinmin and Zhang, Weijian and et al.}, year={2018}, month={Jun}, pages={6895–6902} }
 @article{zhang_wang_yuan_xu_tu_fisk_zhang_chen_ritchie_hu_2018, title={Irrigation and weed control alter soil microbiology and nutrient availability in North Carolina Sandhill peach orchards}, volume={615}, ISSN={["1879-1026"]}, DOI={10.1016/j.scitotenv.2017.09.265}, abstractNote={Orchard management practices such as weed control and irrigation are primarily aimed at maximizing fruit yields and economic profits. However, the impact of these practices on soil fertility and soil microbiology is often overlooked. We conducted a two-factor experimental manipulation of weed control by herbicide and trickle irrigation in a nutrient-poor peach (Prunus persica L. cv. Contender) orchard near Jackson Springs, North Carolina. After three and eight years of treatments, an array of soil fertility parameters were examined, including soil pH, soil N, P and cation nutrients, microbial biomass and respiration, N mineralization, and presence of arbuscular mycorrhizal fungi (AMF). Three general trends emerged: 1) irrigation significantly increased soil microbial biomass and activity, 2) infection rate of mycorrhizal fungi within roots were significantly higher under irrigation than non-irrigation treatments, but no significant difference in the AMF community composition was detected among treatments, 3) weed control through herbicides reduced soil organic matter, microbial biomass and activity, and mineral nutrients, but had no significant impacts on root mycorrhizal infection and AMF communities. Weed-control treatments directly decreased availability of soil nutrients in year 8, especially soil extractable inorganic N. Weed control also appears to have altered the soil nutrients via changes in soil microbes and altered net N mineralization via changes in soil microbial biomass and activity. These results indicate that long-term weed control using herbicides reduces soil fertility through reducing organic C inputs, nutrient retention and soil microbes. Together, these findings highlight the need for alternative practices such as winter legume cover cropping that maintain and/or enhance organic inputs to sustain the soil fertility.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, author={Zhang, Yi and Wang, Liangju and Yuan, Yongge and Xu, Jing and Tu, Cong and Fisk, Connie and Zhang, Weijian and Chen, Xin and Ritchie, David and Hu, Shuijin}, year={2018}, month={Feb}, pages={517–525} }
 @article{wu_chen_tu_qiu_burkey_reberg-horton_peng_hu_2017, title={CO2-induced alterations in plant nitrate utilization and root exudation stimulate N2O emissions}, volume={106}, ISSN={["0038-0717"]}, DOI={10.1016/j.soilbio.2016.11.018}, abstractNote={Atmospheric carbon dioxide enrichment (eCO2) often increases soil nitrous oxide (N2O) emissions, which has been largely attributed to increased denitrification induced by CO2-enhancement of soil labile C and moisture. However, the origin of the N remains unexplained. Emerging evidence suggests that eCO2 alters plant N preference in favor of ammonium (NH4+-N) over nitrate (NO3−-N). Yet, whether and how this attributes to the enhancement of N2O emissions has not been investigated. We conducted a microcosm experiment with wheat (Triticum aestivum L.) and tall fescue (Schedonorus arundinaceus (Schreb.) Dumort.) to examine the effects of eCO2 on soil N2O emissions in the presence of two N forms (NH4+-N or NO3−-N). Results obtained showed that N forms dominated eCO2 effects on plant and microbial N utilization, and thus soil N2O emissions. Elevated CO2 significantly increased the rate and the sum of N2O emissions by three to four folds when NO3−-N, but not NH4+-N, was supplied under both wheat and tall fescue. While enhanced N2O emission was more related to the reduced plant NO3−-N uptake under wheat, it concurred with increased labile C under tall fescue. In the presence of NO3−-N, significantly lower shoot biomass N and 15N, but higher plant biomass C:N ratio, microbial biomass C and N, and/or soil extractable C indicated that eCO2 constrained plant NO3−-N utilization and likely stimulated root exudation. We propose a new conceptual model in which eCO2-inhibition of plant NO3−-N uptake and/or CO2-enhancement of soil labile C enhances the N and/or C availability for denitrifiers and increases the intensity and/or the duration of N2O emissions. Together, these findings indicate that CO2-enhancement of soil N and labile C favors denitrification, suggesting that management of N fertilizers in intensive systems will likely become more challenging under future CO2 scenarios.}, journal={SOIL BIOLOGY & BIOCHEMISTRY}, author={Wu, Keke and Chen, Dima and Tu, Cong and Qiu, Yunpeng and Burkey, Kent O. and Reberg-Horton, S. Chris and Peng, Shaolin and Hu, Shuijin}, year={2017}, month={Mar}, pages={9–17} }
 @article{wang_li_tu_hoyt_deforest_hu_2017, title={Long-term no-tillage and organic input management enhanced the diversity and stability of soil microbial community}, volume={609}, ISSN={["1879-1026"]}, DOI={10.1016/j.scitotenv.2017.07.053}, abstractNote={Intensive tillage and high inputs of chemicals are frequently used in conventional agriculture management, which critically depresses soil properties and causes soil erosion and nonpoint source pollution. Conservation practices, such as no-tillage and organic farming, have potential to enhance soil health. However, the long-term impact of no-tillage and organic practices on soil microbial diversity and community structure has not been fully understood, particularly in humid, warm climate regions such as the southeast USA. We hypothesized that organic inputs will lead to greater microbial diversity and a more stable microbial community, and that the combination of no-tillage and organic inputs will maximize soil microbial diversity. We conducted a long-term experiment in the southern Appalachian mountains of North Carolina, USA to test these hypotheses. The results showed that soil microbial diversity and community structure diverged under different management regimes after long term continuous treatments. Organic input dominated the effect of management practices on soil microbial properties, although no-tillage practice also exerted significant impacts. Both no-tillage and organic inputs significantly promoted soil microbial diversity and community stability. The combination of no-tillage and organic management increased soil microbial diversity over the conventional tillage and led to a microbial community structure more similar to the one in an adjacent grassland. These results indicate that effective management through reducing tillage and increasing organic C inputs can enhance soil microbial diversity and community stability.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, author={Wang, Yi and Li, Chunyue and Tu, Cong and Hoyt, Greg D. and DeForest, Jared L. and Hu, Shuijin}, year={2017}, month={Dec}, pages={341–347} }
 @article{yue_cheng_cong_zu-liang_jian-fei_2017, title={Quantitative Determination of Ferulic Acid Content in Chrysanthemum Morifolium cv. (Chuju) Continuous Cropping Soil Using Near Infrared Spectroscopy}, volume={45}, ISSN={["1872-2040"]}, DOI={10.1016/s1872-2040(17)61001-6}, abstractNote={A near infrared spectroscopy (NIRS) method was used for rapid quality evaluation of ferulic acid content in chrysanthemum morifolium cv. (Chuju) continuous cropping soil. Standard leverage, studentized residual and Mahalanobis distance were calculated to eliminate abnormal samples. After the initial near infrared spectrum was treated by two second derivative and Norris smoothing filter noise, 6000–4000 cm−1 wave number range and 7 factors were chosen for partial least squares (PLS) calibration model. The results showed that good correlations were presented between the calibration set/validation set and the HPLC values, and the calibration correlation coefficient (Rc) and validation correlation coefficient (Rcv) were 0.9914 and 0.9935. Root mean square error of calibration (RMSEC), root mean square error of prediction (RMSEP) and root mean square error of cross prediction (RMSECV) were 0.484, 0.539 and 0.615, respectively. This method was accurate, simple, rapid, nondestructive, and suitable for analysis of ferulic acid in continuous cropping soil.}, number={3}, journal={CHINESE JOURNAL OF ANALYTICAL CHEMISTRY}, author={Yue, Xie and Cheng, Zhou and Cong, Tu and Zu-Liang, Zhang and Jian-Fei, Wang}, year={2017}, month={Mar}, pages={363–367} }
 @article{xing_wang_zhou_bloszies_tu_hu_2015, title={EFFECTS OF NH4+- N/NO3--N RATIOS ON PHOTOSYNTHETIC CHARACTERISTICS, DRY MATTER YIELD AND NITRATE CONCENTRATION OF SPINACH}, volume={51}, ISSN={["1469-4441"]}, DOI={10.1017/s0014479714000192}, abstractNote={SUMMARY Most plants prefer nitrate (NO 3 − –N) to ammonium (NH 4 + –N). However, high NO 3 − –N in soil and water systems is a cause of concern for human health and the environment. Replacing NO 3 − –N in plant nutrition regimes with an appropriate amount of NH 4 + –N may alleviate these concerns. The purpose of this study was to evaluate the effects of different NH 4 + –N/NO 3 − –N ratios on chlorophyll content, stomatal conductance, Rubisco activity, net photosynthetic rate, dry matter yield and NO 3 − –N accumulation in spinach grown hydroponically. The NH 4 + –N/NO 3 − –N percentage ratios were 0:100 (control), 25:75, 50:50, 75:25 and 100:0. Chlorophyll a and b, total chlorophyll, stomatal conductance, initial activity and activation state of Rubisco and net photosynthetic rate in spinach leaves were all reduced by increased NH 4 + –N/NO 3 − –N ratios. Significant correlation existed between these measurements. However, no statistical differences in dry matter yield were revealed between the 0:100 and 25:75 treatments. Leaf nitrate concentrations were reduced by 38% at the 25:75 treatment relative to the 0:100 treatment. These findings suggest that lowering the relative proportion of NO 3 − –N in fertilizer could effectively reduce NO 3 − –N contents in leafy vegetables without decreasing their yields.}, number={1}, journal={EXPERIMENTAL AGRICULTURE}, author={Xing, Suzhi and Wang, Jianfei and Zhou, Yi and Bloszies, Sean A. and Tu, Cong and Hu, Shuijin}, year={2015}, month={Jan}, pages={151–160} }
 @article{lee_tu_chen_hu_2014, title={Arbuscular mycorrhizal fungi enhance P uptake and alter plant morphology in the invasive plant Microstegium vimineum}, volume={16}, ISSN={["1573-1464"]}, DOI={10.1007/s10530-013-0562-4}, number={5}, journal={BIOLOGICAL INVASIONS}, author={Lee, Marissa R. and Tu, Cong and Chen, Xin and Hu, Shuijin}, year={2014}, month={May}, pages={1083–1093} }
 @article{cheng_booker_burkey_tu_shew_rufty_fiscus_deforest_hu_2014, title={SOIL MICROBIAL RESPONSES TO ELEVATED CO2 AND O-3 IN A NITROGEN-AGGRADING AGROECOSYSTEM}, volume={6}, ISBN={["978-1-77188-021-3"]}, DOI={10.1371/journal.pone.0021377}, abstractNote={Climate change factors such as elevated atmospheric carbon dioxide (CO2) and ozone (O3) can exert significant impacts on soil microbes and the ecosystem level processes they mediate. However, the underlying mechanisms by which soil microbes respond to these environmental changes remain poorly understood. The prevailing hypothesis, which states that CO2- or O3-induced changes in carbon (C) availability dominate microbial responses, is primarily based on results from nitrogen (N)-limiting forests and grasslands. It remains largely unexplored how soil microbes respond to elevated CO2 and O3 in N-rich or N-aggrading systems, which severely hinders our ability to predict the long-term soil C dynamics in agroecosystems. Using a long-term field study conducted in a no-till wheat-soybean rotation system with open-top chambers, we showed that elevated CO2 but not O3 had a potent influence on soil microbes. Elevated CO2 (1.5×ambient) significantly increased, while O3 (1.4×ambient) reduced, aboveground (and presumably belowground) plant residue C and N inputs to soil. However, only elevated CO2 significantly affected soil microbial biomass, activities (namely heterotrophic respiration) and community composition. The enhancement of microbial biomass and activities by elevated CO2 largely occurred in the third and fourth years of the experiment and coincided with increased soil N availability, likely due to CO2-stimulation of symbiotic N2 fixation in soybean. Fungal biomass and the fungi∶bacteria ratio decreased under both ambient and elevated CO2 by the third year and also coincided with increased soil N availability; but they were significantly higher under elevated than ambient CO2. These results suggest that more attention should be directed towards assessing the impact of N availability on microbial activities and decomposition in projections of soil organic C balance in N-rich systems under future CO2 scenarios.}, number={6}, journal={CARBON CAPTURE AND STORAGE: CO2 MANAGEMENT TECHNOLOGIES}, author={Cheng, Lei and Booker, Fitzgerald L. and Burkey, Kent O. and Tu, Cong and Shew, H. David and Rufty, Thomas W. and Fiscus, Edwin L. and Deforest, Jared L. and Hu, Shuijin}, year={2014}, pages={277–307} }
 @article{yi_wen-xia_tu_washburn_lei_hu_2014, title={Soil Carbon, Nitrogen and Microbial Dynamics of Pasturelands: Impacts of Grazing Intensity and Planting Systems}, volume={24}, ISSN={["2210-5107"]}, DOI={10.1016/s1002-0160(14)60027-8}, abstractNote={Management intensity critically influences the productivity and sustainability of pasture systems through modifying soil microbes, and soil carbon (C) and nutrient dynamics; however, such effects are not well understood yet in the southeastern USA. We examined the effects of grazing intensity and grass planting system on soil C and nitrogen (N) dynamics, and microbial biomass and respiration in a long-term field experiment in Goldsboro, North Carolina, USA. A split-plot experiment was initiated in 2003 on a highly sandy soil under treatments of two grass planting systems (ryegrass rotation with sorghum-sudangrass hybrid and ryegrass seeding into a perennial bermudagrass stand) at low and high grazing densities. After 4 years of continuous treatments, soil total C and N contents across the 0–30 cm soil profile were 24.7% and 17.5% higher at the high than at the low grazing intensity, likely through promoting plant productivity and C allocation belowground as well as fecal and urinary inputs. Grass planting system effects were significant only at the low grazing intensity, with soil C, N, and microbial biomass and respiration in the top 10 cm being higher under the ryegrass/bermudagrass than under the ryegrass/sorghum-sudangrass hybrid planting systems. These results suggest that effective management could mitigate potential adverse effects of high grazing intensities on soil properties and facilitate sustainability of pastureland.}, number={3}, journal={PEDOSPHERE}, author={Yi, Wang and Wen-Xia, Duan and Tu, C. and Washburn, S. and Lei, Cheng and Hu, S.}, year={2014}, month={Jun}, pages={408–416} }
 @article{cheng_booker_burkey_tu_shew_rufty_fiscus_deforest_hu_2014, title={Soil microbial responses to elevated CO2 and O-3 in a nitrogen-aggrading agroecosystem}, DOI={10.1201/b16845-14}, journal={Carbon Capture and Storage: CO2 Management Technologies}, author={Cheng, L. and Booker, F. L. and Burkey, K. O. and Tu, C. and Shew, H. D. and Rufty, T. W. and Fiscus, E. L. and Deforest, J. L. and Hu, Shuijin}, year={2014}, pages={277–307} }
 @article{yuan_wang_zhang_tang_tu_hu_yong_chen_2013, title={Enhanced allelopathy and competitive ability of invasive plant Solidago canadensis in its introduced range}, volume={6}, ISSN={["1752-993X"]}, DOI={10.1093/jpe/rts033}, abstractNote={Why invasive plants are more competitive in their introduced range than native range is still an unanswered question in plant invasion ecology. Here, we used the model invasive plant Solidago canadensis to test a hypothesis that enhanced production of allelopathic compounds results in greater competitive ability of invasive plants in the invaded range rather than in the native range. We also examined the degree to which the allelopathy contributes increased competitive ability of S. canadensis in the invaded range. We compared allelochemical production by S. canadensis growing in its native area (the USA) and invaded area (China) and also by populations that were collected from the two countries and grown together in a 'common garden' greenhouse experiment. We also tested the allelopathic effects of S. canadensis collected from either the USA or China on the germination of Kummerowia striata (a native plant in China). Finally, we conducted a common garden, greenhouse experiment in which K. striata was grown in monoculture or with S. canadensis from the USA or China to test the effects of allelopathy on plant–plant competition with suitable controls such as adding activated carbon to the soil to absorb the allelochemicals and thereby eliminating any corresponding allopathic effects. Allelochemical contents (total phenolics, total flavones and total saponins) and allelopathic effects were greater in S. canadensis sampled from China than those from the USA as demonstrated in a field survey and a common garden experiment. Inhibition of K. striata germination using S. canadensis extracts or previously grown in soil was greater using samples from China than from the USA. The competitive ability of S. canadensis against K. striata was also greater for plants originating from China than those from the USA. Allelopathy could explain about 46% of the difference. These findings demonstrated that S. canadensis has evolved to be more allelopathic and competitive in the introduced range and that allelopathy significantly contributes to increased competitiveness for this invasive species.}, number={3}, journal={JOURNAL OF PLANT ECOLOGY}, author={Yuan, Yongge and Wang, Bing and Zhang, Shanshan and Tang, Jianjun and Tu, Cong and Hu, Shuijin and Yong, Jean W. H. and Chen, Xin}, year={2013}, month={Jun}, pages={253–263} }
 @article{xie_xu_liu_liu_zhu_tu_amonette_cadisch_yong_hu_2013, title={Impact of biochar application on nitrogen nutrition of rice, greenhouse-gas emissions and soil organic carbon dynamics in two paddy soils of China}, volume={370}, ISSN={["1573-5036"]}, DOI={10.1007/s11104-013-1636-x}, number={1-2}, journal={PLANT AND SOIL}, author={Xie, Zubin and Xu, Yanping and Liu, Gang and Liu, Qi and Zhu, Jianguo and Tu, Cong and Amonette, James E. and Cadisch, Georg and Yong, Jean W. H. and Hu, Shuijin}, year={2013}, month={Sep}, pages={527–540} }
 @article{cheng_booker_tu_burkey_zhou_shew_rufty_hu_2012, title={Arbuscular Mycorrhizal Fungi Increase Organic Carbon Decomposition Under Elevated CO2}, volume={337}, ISSN={["1095-9203"]}, DOI={10.1126/science.1224304}, abstractNote={The extent to which terrestrial ecosystems can sequester carbon to mitigate climate change is a matter of debate. The stimulation of arbuscular mycorrhizal fungi (AMF) by elevated atmospheric carbon dioxide (CO(2)) has been assumed to be a major mechanism facilitating soil carbon sequestration by increasing carbon inputs to soil and by protecting organic carbon from decomposition via aggregation. We present evidence from four independent microcosm and field experiments demonstrating that CO(2) enhancement of AMF results in considerable soil carbon losses. Our findings challenge the assumption that AMF protect against degradation of organic carbon in soil and raise questions about the current prediction of terrestrial ecosystem carbon balance under future climate-change scenarios.}, number={6098}, journal={SCIENCE}, author={Cheng, Lei and Booker, Fitzgerald L. and Tu, Cong and Burkey, Kent O. and Zhou, Lishi and Shew, H. David and Rufty, Thomas W. and Hu, Shuijin}, year={2012}, month={Aug}, pages={1084–1087} }
 @article{tu_wang_duan_hertl_tradway_brandenburg_lee_snell_hu_2011, title={Effects of fungicides and insecticides on feeding behavior and community dynamics of earthworms: Implications for casting control in turfgrass systems}, volume={47}, ISSN={0929-1393}, url={http://dx.doi.org/10.1016/j.apsoil.2010.11.002}, DOI={10.1016/j.apsoil.2010.11.002}, abstractNote={Earthworms play important roles in sustaining turfgrass systems through enhancing soil aeration, water filtration, and thatch mixing and decomposition. However, high surface activities of earthworms can lead to uneven playing surfaces, soil erosion and new niches favorable to weed invasion in the playing area of a golf course. Shifts from highly toxic and persistent to less toxic and easily degradable pesticides have been suggested to be largely responsible for high earthworm activities observed in turf systems worldwide. In this study, we examined the impact of fungicides and insecticides on earthworm behavior in controlled environments and on the dynamics of earthworm community in the field. Single application of insecticides Sevin (carbaryl) and Merit (imidacloprid) at the manufactures’ suggested doses significantly inhibited earthworm feeding activity for at least three weeks without leading to any earthworm death. Fungicides did not show significant toxicity to earthworms when applied only once, but their toxicities increased as application frequency increased. Consecutive weekly applications of Sevin, Merit and T-methyl for four times led to earthworm mortality of 35, 45 and 80%, respectively. In the field, six consecutive weekly applications of T-methyl and Sevin significantly reduced the abundance and biomass of earthworms with suppressive effects lasting for at least 6 weeks after the chemical application was terminated. Taken together, these findings suggest that the surface activities of earthworms in turfgrass systems may be managed through moderate application of pesticides at peak periods of earthworm activities.}, number={1}, journal={Applied Soil Ecology}, publisher={Elsevier BV}, author={Tu, Cong and Wang, Yi and Duan, Wenxia and Hertl, Peter and Tradway, Lane and Brandenburg, Rick and Lee, David and Snell, Mark and Hu, Shuijin}, year={2011}, month={Jan}, pages={31–36} }
 @article{wang_tu_cheng_li_gentry_hoyt_zhang_hu_2011, title={Long-term impact of farming practices on soil organic carbon and nitrogen pools and microbial biomass and activity}, volume={117}, ISSN={["0167-1987"]}, DOI={10.1016/j.still.2011.08.002}, abstractNote={Conventional agriculture with intensive tillage and high inputs of synthetic chemicals has critically depleted the soil C pools. Alternative practices such as no-tillage and organic inputs have been shown to increase soil C content. However, the long-term impact of these practices on soil C pools was not fully understood under humid and warm climate conditions such as the southeast USA. We hypothesized that a combination of sustainable production practices will result in greater microbial biomass and activity and soil organic C than any individual practice. To test this hypothesis, we conducted a long-term experiment examining how different farming practices affect soil C and N pools and microbial biomass and activities in a fine-sandy loam (FAO: Acrisol) in the southern Appalachian mountains of North Carolina, USA. The experiment was a randomized complete design with four replications. Six management treatments, i.e., tillage with no chemical or organic inputs (Control, TN), tillage with chemical inputs (TC), tillage with organic inputs (TO), no-tillage with chemical inputs (NC), no-tillage with organic inputs (NO), and fescue grasses (FG), were designed. Organic C and N pools and microbial properties in 0–15 cm soils were markedly different after 15 years of continuous treatments. Both no tillage and organic inputs significantly promoted soil microbial biomass by 63–139% and 54–126%; also microbial activity increased by 88–158% and 52–117%, respectively. Corresponding increases of soil organic C by 83–104% and 19–32%, and soil organic N by 77–94% and 20–32% were measured. The combination of no tillage and organic management increased soil organic C by 140% over the conventional tillage control, leading to a soil C content comparable to an un-disturbed grassland control. No tillage reduced the proportion of organic C in the light fraction with d < 1.0 g cm−3 (from 1.53–3.39% to 0.80–1.09%), and increased the very heavy fraction with d > 1.6 g cm−3 (from 95% to 98%). Organic inputs, however, had little impact on C distribution among different density fractions of the soil except light fraction in tillage treatment. Over all, no-tillage practices exerted greater influence on microbial biomass levels and activity and soil organic C levels and fractionations than organic inputs. Our results support the hypothesis and indicate that management decisions including reducing tillage and increasing organic C inputs can enhance transformation of soil organic C from the labile into stable pools, promote soil C accumulation, improve soil fertility and while mitigate atmospheric CO2 rise.}, journal={SOIL & TILLAGE RESEARCH}, author={Wang, Yi and Tu, Cong and Cheng, Lei and Li, Chunyue and Gentry, Laura F. and Hoyt, Greg D. and Zhang, Xingchang and Hu, Shuijin}, year={2011}, month={Dec}, pages={8–16} }
 @article{sydorovych_raczkowski_wossink_mueller_creamer_hu_bell_tu_2009, title={A technique for assessing environmental impact risks of agricultural systems}, volume={24}, ISSN={["1742-1713"]}, DOI={10.1017/S174217050999010X}, abstractNote={Abstract Conventional agriculture often aims to achieve high returns without allowing for sustainable natural resource management. To prevent environmental degradation, agricultural systems must be assessed and environmental standards need to be developed. This study used a multi-factor approach to assess the potential environmental impact risk of six diverse systems: five production systems and a successional system or abandoned agronomic field. Assessment factors were soil quality status, amount of pesticide and fertilizer applied and tillage intensity. The assessment identified the best management practices (BMP)–conventional tillage system as a high-risk system mostly because of extensive tillage. The certified organic system was also extensively tilled and was characterized by P build-up in the soil, but performed well based on other assessment factors. Conversely, the BMP–no tillage and the crop–animal integrated system were characterized as low risk mainly because of reduced tillage. The paper discusses assessment strengths and weaknesses, ways to improve indicators used, and the need for additional indicators. We concluded that with further development the technique will become a resourceful tool to promote agricultural sustainability and environmental stewardship and assist policy-making processes.}, number={3}, journal={RENEWABLE AGRICULTURE AND FOOD SYSTEMS}, author={Sydorovych, Olha and Raczkowski, Charles W. and Wossink, Ada and Mueller, J. Paul and Creamer, Nancy G. and Hu, Shuijin and Bell, Melissa and Tu, Cong}, year={2009}, month={Sep}, pages={234–243} }
 @article{tu_booker_burkey_hu_2009, title={Elevated Atmospheric Carbon Dioxide and O-3 Differentially Alter Nitrogen Acquisition in Peanut}, volume={49}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2008.10.0603}, abstractNote={ABSTRACT Elevated atmospheric CO 2 and ozone (O 3 ) may affect productivity of legumes in part by altering symbiotic N 2 fixation. To investigate this possibility, measurements of plant biomass, N levels and natural 15 N abundance (δ 15 N) were used to examine the effects of elevated CO 2 and O 3 on N acquisition in field‐grown peanut ( Arachis hypogaea L.) using open‐top chambers. Seasonal 12‐h daily average CO 2 treatment concentrations were 376, 550, and 730 μmol mol −1 Carbon dioxide treatments were applied in reciprocal combinations with seasonal 12‐h daily average O 3 concentrations of 21, 49, and 79 nmol mol −1 At mid‐vegetative growth, elevated CO 2 significantly reduced leaf N concentrations by up to 44%, but not δ 15 N values. Elevated O 3 did not significantly affect N concentrations or δ 15 N values. At harvest, plant N concentrations were similar among treatments except for a 14% reduction in the highest‐level CO 2 –O 3 treatment. Plant N accumulation varied in proportion with treatment effects on biomass production, which was increased with elevated CO 2 when averaged over the O 3 treatments and suppressed by high‐level O 3 at ambient CO 2 Elevated CO 2 reduced plant δ 15 N values in low‐ and mid‐level O 3 treatments while mid‐ and high‐level O 3 increased them at ambient CO 2 The changes in δ 15 N values suggested that N 2 fixation activity was stimulated with elevated CO 2 and inhibited by elevated O 3 Elevated CO 2 ameliorated detrimental O 3 effects to varying extents depending on the concentrations of the two gases. These results indicated that interactions between CO 2 and O 3 on plant physiology can alter N acquisition processes, with impacts on peanut productivity likely dependent in part on these changes.}, number={5}, journal={CROP SCIENCE}, author={Tu, Cong and Booker, Fitzgerald L. and Burkey, Kent O. and Hu, Shuijin}, year={2009}, pages={1827–1836} }
 @article{liu_tu_hu_gumpertz_ristaino_2007, title={Effect of organnic, sustainable, and conventional management strategies in grower fields on soil physical, chemical, and biological factors and the incidence of Southern blight}, volume={37}, ISSN={["1873-0272"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34748831003&partnerID=MN8TOARS}, DOI={10.1016/j.apsoil.2007.06.007}, abstractNote={The objectives of our research were to evaluate the impact of organic, sustainable, and conventional management strategies in grower fields on soil physical, chemical, and biological factors including soil microbial species and functional diversity and their effect on the Basidiomycete plant pathogen Sclerotium rolfsii, causal agent of Southern blight. Soils from 10 field locations including conventional, organic and sustainable farms were sampled and assayed for disease suppressiveness in greenhouse assays, and soil quality indicators. Soils from organic and sustainable farms were more suppressive to Southern blight than soils from conventional farms. Soils from organic farms had improved soil chemical factors and higher levels of extractable C and N, higher microbial biomass carbon and nitrogen, and net mineralizable N. In addition, soil microbial respiration was higher in soils from organic than sustainable or conventional farms, indicating that microbial activity was greater in these soils. Populations of fungi and thermophiles were significantly higher in soils from organic and sustainable than conventional fields. The diversity of bacterial functional communities was also greater in soils from organic farms, while species diversity was similar. Soils from organic and sustainable farms had improved soil health as indicated by a number of soil physical, chemical and biological factors and reduced disease.}, number={3}, journal={APPLIED SOIL ECOLOGY}, author={Liu, Bo and Tu, Cong and Hu, Shuijin and Gumpertz, Marcia and Ristaino, Jean Beagle}, year={2007}, month={Nov}, pages={202–214} }
 @article{chen_tu_burton_watson_burkey_hu_2007, title={Plant nitrogen acquisition and interactions under elevated carbon dioxide: impact of endophytes and mycorrhizae}, volume={13}, ISSN={["1365-2486"]}, DOI={10.1111/j.1365-2486.2007.01347.x}, abstractNote={Abstract Both endophytic and mycorrhizal fungi interact with plants to form symbiosis in which the fungal partners rely on, and sometimes compete for, carbon (C) sources from their hosts. Changes in photosynthesis in host plants caused by atmospheric carbon dioxide (CO 2 ) enrichment may, therefore, influence those mutualistic interactions, potentially modifying plant nutrient acquisition and interactions with other coexisting plant species. However, few studies have so far examined the interactive controls of endophytes and mycorrhizae over plant responses to atmospheric CO 2 enrichment. Using Festuca arundinacea Schreb and Plantago lanceolata L. as model plants, we examined the effects of elevated CO 2 on mycorrhizae and endophyte ( Neotyphodium coenophialum) and plant nitrogen (N) acquisition in two microcosm experiments, and determined whether and how mycorrhizae and endophytes mediate interactions between their host plant species. Endophyte‐free and endophyte‐infected F. arundinacea varieties, P. lanceolata L., and their combination with or without mycorrhizal inocula were grown under ambient (400 μmol mol −1 ) and elevated CO 2 (ambient + 330 μmol mol −1 ). A 15 N isotope tracer was used to quantify the mycorrhiza‐mediated plant acquisition of N from soil. Elevated CO 2 stimulated the growth of P. lanceolata greater than F. arundinacea , increasing the shoot biomass ratio of P. lanceolata to F. arundinacea in all the mixtures. Elevated CO 2 also increased mycorrhizal root colonization of P. lanceolata , but had no impact on that of F. arundinacea . Mycorrhizae increased the shoot biomass ratio of P. lanceolata to F. arundinacea under elevated CO 2 . In the absence of endophytes, both elevated CO 2 and mycorrhizae enhanced 15 N and total N uptake of P. lanceolata but had either no or even negative effects on N acquisition of F. arundinacea , altering N distribution between these two species in the mixture. The presence of endophytes in F. arundinacea , however, reduced the CO 2 effect on N acquisition in P. lanceolata , although it did not affect growth responses of their host plants to elevated CO 2 . These results suggest that mycorrhizal fungi and endophytes might interactively affect the responses of their host plants and their coexisting species to elevated CO 2 .}, number={6}, journal={GLOBAL CHANGE BIOLOGY}, author={Chen, Xin and Tu, Cong and Burton, Michael G. and Watson, Dorothy M. and Burkey, Kent O. and Hu, Shuijin}, year={2007}, month={Jun}, pages={1238–1249} }
 @article{tu_booker_watson_chen_rufty_shi_hu_2006, title={Mycorrhizal mediation of plant N acquisition and residue decomposition: Impact of mineral N inputs}, volume={12}, ISSN={["1365-2486"]}, DOI={10.1111/j.1365-2486.2006.01149.x}, abstractNote={Abstract Mycorrhizas are ubiquitous plant–fungus mutualists in terrestrial ecosystems and play important roles in plant resource capture and nutrient cycling. Sporadic evidence suggests that anthropogenic nitrogen (N) input may impact the development and the functioning of arbuscular mycorrhizal (AM) fungi, potentially altering host plant growth and soil carbon (C) dynamics. In this study, we examined how mineral N inputs affected mycorrhizal mediation of plant N acquisition and residue decomposition in a microcosm system. Each microcosm unit was separated into HOST and TEST compartments by a replaceable mesh screen that either prevented or allowed AM fungal hyphae but not plant roots to grow into the TEST compartments. Wild oat ( Avena fatua L.) was planted in the HOST compartments that had been inoculated with either a single species of AM fungus, Glomus etunicatum , or a mixture of AM fungi including G. etunicatum . Mycorrhizal contributions to plant N acquisition and residue decomposition were directly assessed by introducing a mineral 15 N tracer and 13 C‐rich residues of a C 4 plant to the TEST compartments. Results from 15 N tracer measurements showed that AM fungal hyphae directly transported N from the TEST soil to the host plant. Compared with the control with no penetration of AM fungal hyphae, AM hyphal penetration led to a 125% increase in biomass 15 N of host plants and a 20% reduction in extractable inorganic N in the TEST soil. Mineral N inputs to the HOST compartments (equivalent to 5.0 g N m −2 yr −1 ) increased oat biomass and total root length colonized by mycorrhizal fungi by 189% and 285%, respectively, as compared with the no‐N control. Mineral N inputs to the HOST plants also reduced extractable inorganic N and particulate residue C proportion by 58% and 12%, respectively, in the corresponding TEST soils as compared to the no‐N control, by stimulating AM fungal growth and activities. The species mixture of mycorrhizal fungi was more effective in facilitating N transport and residue decomposition than the single AM species. These findings indicate that low‐level mineral N inputs may significantly enhance nutrient cycling and plant resource capture in terrestrial ecosystems via stimulation of root growth, mycorrhizal functioning, and residue decomposition. The long‐term effects of these observed alterations on soil C dynamics remain to be investigated.}, number={5}, journal={GLOBAL CHANGE BIOLOGY}, author={Tu, C and Booker, FL and Watson, DM and Chen, X and Rufty, TW and Shi, W and Hu, SJ}, year={2006}, month={May}, pages={793–803} }
 @article{kertulis-tartar_ma_tu_chirenje_2006, title={Phytoremediation of an arsenic-contaminated site using Pteris vitrata L.: A two-year study}, volume={8}, ISSN={["1549-7879"]}, DOI={10.1080/15226510600992873}, abstractNote={Abstract A field study was conducted to determine the efficiency of Chinese brake fern (Pteris vittata L.), an arsenic hyperaccumulator, on removal of arsenic from soil at an arsenic- contaminated site. Chinese brake ferns were planted on a site previously used to treat wood with chromated copper arsenate (CCA). Arsenic concentrations in surface and profile soil samples were determined for 2000, 2001, and 2002. In both 2001 and 2002, senesced and senescing fronds only, as well as all fronds, were harvested. Frond arsenic concentrations were not significantly different between the three harvests. Compared to senesced fronds, live fronds resulted in the greatest amount of arsenic removal. There were no significant differences in soil arsenic concentrations between 2000, 2001, and 2002, primarily due to the extreme variability in soil arsenic concentrations. However, the mean surface soil arsenic was reduced from 190 to 140 mg kg−1. Approximately 19.3 g of arsenic were removed from the soil by Chinese brake fern. Therefore, this fern is capable of accumulating arsenic from the CCA-contaminated site and may be competitive, in terms of cost, to conventional remediation systems. However, better agronomic practices are needed to enhance plant growth and arsenic uptake to obtain maximum soil arsenic removal and to minimize remediation time. KEY WORDS: arsenicchromated copper arsenate Pteris vittata L.phytoextractionhyperaccumulation ACKNOWLEDGMENTS This research was partially supported by the National Science Foundation (Grants BES-0086768 and BES-0132114). The authors gratefully acknowledge Mr. Thomas Luongo for analytical and field support and Ms. Heather Williams for her invaluable assistance with field sampling. Notes ∗The 2002 data are normalized to estimate for the entire year's harvests. Values represent means ± std dev. ∗The 2002 data are normalized to estimate for the entire year's harvests. Values represent means ± std dev. ∗Values represent means ± std dev.}, number={4}, journal={INTERNATIONAL JOURNAL OF PHYTOREMEDIATION}, author={Kertulis-Tartar, G. M. and Ma, L. Q. and Tu, C. and Chirenje, T.}, year={2006}, pages={311–322} }
 @article{hu_tu_chen_gruver_2006, title={Progressive N limitation of plant response to elevated CO2: a microbiological perspective}, volume={289}, ISSN={["0032-079X"]}, DOI={10.1007/s11104-006-9093-4}, number={1-2}, journal={PLANT AND SOIL}, author={Hu, Shuijin and Tu, Cong and Chen, Xin and Gruver, Joel B.}, year={2006}, month={Nov}, pages={47–58} }
 @article{tu_louws_creamer_mueller_brownie_fager_bell_hu_2006, title={Responses of soil microbial biomass and N availability to transition strategies from conventional to organic farming systems}, volume={113}, ISSN={["1873-2305"]}, DOI={10.1016/j.agee.2005.09.013}, abstractNote={Abstract Organic farming can enhance soil biodiversity, alleviate environmental concerns and improve food safety through eliminating the applications of synthetic chemicals. However, yield reduction due to nutrient limitation and pest incidence in the early stages of transition from conventional to organic systems is a major concern for organic farmers, and is thus a barrier to implementing the practice of organic farming. Therefore, identifying transition strategies that minimize yield loss is critical for facilitating the implementation of organic practices. Soil microorganisms play a dominant role in nutrient cycling and pest control in organic farming systems, and their responses to changes in soil management practices may critically impact crop growth and yield. Here we examined soil microbial biomass and N supply in response to several strategies for transitioning from conventional to organic farming systems in a long-term field experiment in Goldsboro, NC, USA. The transitional strategies included one fully organic strategy (ORG) and four reduced-input strategies (withdrawal of each or gradual reduction of major conventional inputs—synthetic fertilizers, pesticides (insecticides/fungicides), and herbicides), with a conventional practice (CNV) serving as a control. Microbial biomass and respiration rate were more sensitive to changes in soil management practices than total C and N. In the first 2 years, the ORG was most effective in enhancing soil microbial biomass C and N among the transition strategies, but was accompanied with high yield losses. By the third year, soil microbial biomass C and N in the reduced-input transition strategies were statistically significantly greater than those in the CNV (averaging 32 and 35% higher, respectively), although they were slightly lower than those in the ORG (averaging 13 and 17% lower, respectively). Soil microbial respiration rate and net N mineralization in all transitional systems were statistically significantly higher than those in the CNV (averagely 83 and 66% greater, respectively), with no differences among the various transition strategies. These findings suggest that the transitional strategies that partially or gradually reduce conventional inputs can serve as alternatives that could potentially minimize economic hardships as well as benefit microbial growth during the early stages of transition to organic farming systems.}, number={1-4}, journal={AGRICULTURE ECOSYSTEMS & ENVIRONMENT}, author={Tu, C and Louws, FJ and Creamer, NG and Mueller, JP and Brownie, C and Fager, K and Bell, M and Hu, SJ}, year={2006}, month={Apr}, pages={206–215} }
 @article{tu_ristaino_hu_2006, title={Soil microbial biomass and activity in organic tomato farming systems: Effects of organic inputs and straw mulching}, volume={38}, ISSN={["1879-3428"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-29744443972&partnerID=MN8TOARS}, DOI={10.1016/j.soilbio.2005.05.002}, abstractNote={Organic farming is rapidly expanding worldwide. Plant growth in organic systems greatly depends on the functions performed by soil microbes, particularly in nutrient supply. However, the linkages between soil microbes and nutrient availability in organically managed soils are not well understood. We conducted a long-term field experiment to examine microbial biomass and activity, and nutrient availability under four management regimes with different organic inputs. The experiment was initiated in 1997 by employing different practices of organic farming in a coastal sandy soil in Clinton, NC, USA. Organic practices were designed by applying organic substrates with different C and N availability, either in the presence or absence of wheat–straw mulch. The organic substrates used included composted cotton gin trash (CGT), animal manure (AM) and rye/vetch green manure (RV). A commercial synthetic fertilizer (SF) was used as a conventional control. Results obtained in both 2001 and 2002 showed that microbial biomass and microbial activity were generally higher in organically than conventionally managed soils with CGT being most effective. The CGT additions increased soil microbial biomass C and activity by 103–151% and 88–170% over a period of two years, respectively, leading to a 182–285% increase in potentially mineralizable N, compared to the SF control. Straw mulching further enhanced microbial biomass, activity, and potential N availability by 42, 64, and 30%, respectively, relative to non-mulched soils, likely via improving C and water availability for soil microbes. The findings that microbial properties and N availability for plants differed under different organic input regimes suggest the need for effective residue managements in organic tomato farming systems.}, number={2}, journal={SOIL BIOLOGY & BIOCHEMISTRY}, author={Tu, C and Ristaino, JB and Hu, SJ}, year={2006}, month={Feb}, pages={247–255} }
 @article{bondada_tu_ma_2006, title={Surface structure and anatomical aspects of Chinese brake fern (Pteris vittata; Pteridaceae)}, volume={58}, ISSN={["1938-436X"]}, DOI={10.1663/0007-196X(2006)58[217:SSAAAO]2.0.CO;2}, abstractNote={The objective of this study was to describe a wide spectrum of surface structural and anatomical details of the Chinese brake fern (Pteris vittata) using scanning electron microscopy (SEM). SEM revealed that the epidermal cells of the pinnae were elongated with raised periclinal and sinuous anticlinal walls. The pinnae were hypostomatous with randomly scattered anomocytic stomatal complexes positioned at the same level as the epidermis. Stomates were large and elliptical (27.4 μm × 10.2 μm). Cross sections from the central regions of the rachis and the stipe revealed V- and U-shaped vascular bundles, respectively. In each vascular bundle, the xylem strands were sea-horse shaped (hippocampus). In contrast, the pinnae possessed a triangular vascular bundle with uniform mesophyll organization comprising of homogenous lobed parenchyma cells. The indumentum consisted of trichomes and scales, which formed various types of vestiture. Trichomes were borne only on the pinnae and scales on the rachis and stipe. The roots developed a dense network of long root hairs averaging 244 μm long, and the xylem consisted of tracheids with scalariform pitting. Sori were submarginal; continuous along both margins of the pinna and were covered with a false indusium. The sporangia were oblong with a short thick stalk and the annulus was positioned vertically resulting in transverse dehiscence of the sporangium. The paraphyses were uniseriate, unbranched, septate and found to be intermixed with the sporangia. The exine of the globose spores was adorned with thick reticulum in which the areoles contained round tubercles. This study describes surface features in detail, which is essential to studies examining the issue of whether morphological characteristics are related to arsenic hyperaccumulation inP. vittata.}, number={3}, journal={BRITTONIA}, author={Bondada, Bhaskar and Tu, Cong and Ma, Lena}, year={2006}, pages={217–228} }
 @article{zhang_rui_tu_diab_louws_mueller_creamer_bell_wagger_hu_2005, title={Responses of soil microbial community structure and diversity to agricultural deintensification}, volume={15}, number={4}, journal={Pedosphere}, author={Zhang, W. J. and Rui, W. Y. and Tu, C. and Diab, H. G. and Louws, F. J. and Mueller, J. P. and Creamer, N. and Bell, M. and Wagger, M. G. and Hu, S.}, year={2005}, pages={440–447} }
 @article{cao_ma_tu_2004, title={Antioxidative responses to arsenic in the arsenic-hyperaccumulator Chinese brake fern (Pteris vittata L.)}, volume={128}, ISSN={["1873-6424"]}, DOI={10.1016/j.envpol.2003.09.018}, abstractNote={This study measured antioxidative responses of Chinese brake fern (Pteris vittata L.) upon exposure to arsenic (As) of different concentrations. Chinese brake fern was grown in an artificially-contaminated soil containing 0 to 200 mg As kg(-1) (Na2HAsO4) for 12 weeks in a greenhouse. Soil As concentrations at < or =20 mg kg(-1) enhanced plant growth, with 12-71% biomass increase compared to the control. Such beneficial effects were not observed at >20 mg As kg(-1). Plant As concentrations increased with soil As concentrations, with more As being accumulated in the fronds (aboveground biomass) than in the roots and with maximum frond As concentration being 4675 mg kg(-1). Arsenic uptake by Chinese brake enhanced uptake of nutrient elements K, P, Fe, Mn, and Zn except Ca and Mg, whose concentrations mostly decreased. The contents of non-enzymatic antioxidants (glutathione, acid-soluble thiol) followed similar trends as plant As concentrations, increasing with soil As concentrations, with greater contents in the fronds than in the roots especially when exposed to high As concentrations (>50 mg kg(-1)). The activities of enzymatic antioxidants (superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase) in Chinese brake followed the same trends as plant biomass, increasing with soil As up to 20 mg kg(-1) and then decreased. The results indicated though both enzymatic and non-enzymatic antioxidants played significant roles in As detoxification and hyperaccumulation in Chinese brake, the former is more important at low As exposure (< or =20 mg kg(-1)), whereas the latter is more critical at high As exposure (50-200 mg kg(-1)).}, number={3}, journal={ENVIRONMENTAL POLLUTION}, author={Cao, XD and Ma, LQ and Tu, C}, year={2004}, pages={317–325} }
 @article{tu_koenning_hu_2003, title={Root-parasitic nematodes enhance soil microbial activities and nitrogen mineralization}, volume={46}, ISSN={["1432-184X"]}, DOI={10.1007/s00248-002-1068-2}, abstractNote={Obligate root-parasitic nematodes can affect soil microbes positively by enhancing C and nutrient leakage from roots but negatively by restricting total root growth. However, it is unclear how the resulting changes in C availability affect soil microbial activities and N cycling. In a microplot experiment, effects of root-parasitic reniform nematodes ( Rotylenchulus reniformis) on soil microbial biomass and activities were examined in six different soils planted with cotton. Rotylenchulus reniformis was introduced at 900 nematodes kg(-1) soil in May 2000 prior to seeding cotton. In 2001, soil samples were collected in May before cotton was seeded and in November at the final harvest. Extractable C and N were consistently higher in the R. reniformis treatments than in the non-nematode controls across the six different soils. Nematode inoculation significantly reduced microbial biomass C, but increased microbial biomass N, leading to marked decreases in microbial biomass C:N ratios. Soil microbial respiration and net N mineralization rates were also consistently higher in the nematode treatments than in the controls. However, soil types did not have a significant impact on the effects of nematodes on these microbial parameters. These findings indicate that nematode infection of plant roots may enhance microbial activities and the turnover of soil microbial biomass, facilitating soil N cycling. The present study provides the first evidence about the direct role of root-feeding nematodes in enhancing soil N mineralization.}, number={1}, journal={MICROBIAL ECOLOGY}, author={Tu, C and Koenning, SR and Hu, S}, year={2003}, month={Jul}, pages={134–144} }