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Xiao Z.,Nanjing Agricultural University | Xiao Z.,Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization | Liu M.,Nanjing Agricultural University | Liu M.,Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization | And 10 more authors.
Applied Soil Ecology | Year: 2016

Sustainable agriculture aims to manage soil and plant health while relying less on chemical inputs. The individual effect of organic amendments or resistant crop cultivars on the suppression of root pests through modulating soil and plant performance is being well documented. However, the interactions between organic amendments and crop cultivars are less well studied. A pot experiment was conducted across two tomato cultivars of distinct resistance to root-knot nematodes (RKNs, Meloidogyne incognita) with three amendments including inorganic fertilizer (IF), conventional compost (CC) and vermicompost (VC). All treatments were inoculated with second-stage juveniles of M. incognita to simulate the root-knot nematode disease in field condition and to focus on the comparison among different soil amendment effects. Plant growth (shoot height, shoot biomass, root biomass and root C:N ratio), root defense metabolites (phenolics) and their related genes expression, and soil properties including pH, electrical conductivity, available nutrients, 3-indoleacetic acid (IAA), microbial biomass and activity were analyzed at 14 and 30 days post inoculation (dpi). Compared with inorganic fertilizer, vermicompost significantly decreased the numbers of nematode-induced galls on susceptible (Sus) and resistant (Res) cultivar roots by 77% and 42% respectively at 14 dpi, and by 59% and 46% respectively at 30 dpi. Vermicompost also significantly increased root defense metabolite concentrations, defense related gene expression, and improved soil properties (p < 0.05) except for mineral nitrogen. Multivariate analyses further indicated that soil properties particularly pH, root primary and secondary defense metabolites were negatively associated with root gall. Moreover, soil microbial activity, pH and IAA concentration were the main soil properties positively associated with plant defense metabolites production and biomass for both susceptible and resistant cultivars. Overall, vermicompost could significantly suppress root pests via modulating soil properties as well as plant defenses, particularly for the susceptible plant. © 2016 Elsevier B.V.

Wu D.,Nanjing Agricultural University | Wu D.,Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization | Liu M.,Nanjing Agricultural University | Liu M.,Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization | And 10 more authors.
Soil Biology and Biochemistry | Year: 2015

Earthworms can enhance plant productivity by promoting nitrogen (N) mineralization in N-limited agroecosystems and may also enhance the risk of N2O emissions and NO3 --N leaching in N-enriched agroecosystems. However, direct evidence demonstrating the enhancement by earthworms of N2O emissions and NO3 --N leaching in the field is scarce, particularly in intensively managed systems. In addition, the interaction of earthworm feeding strategies and organic amendment may profoundly modulate N cycling. We examined these impacts using two earthworm species with distinct ecological strategies (epigeic Eisenia foetida and endogeic Metaphire guillemi) in combination with two manure application methods (surface mulch and incorporation into the soil) in a field experiment. Our results demonstrated that earthworm addition significantly increased the crop yield by 18%-47% and cumulative N2O emissions by 19%-25% largely regardless of earthworm species and manure application methods, respectively. However, earthworms did not significantly increase the leachate NO3 --N concentration. Earthworm-induced N2O emissions were primarily attributed to increased soil N availability (NO3 --N and microbial biomass N) and carbon (C) availability (dissolved organic C). In contrast, a stepwise regression revealed that an earthworm-promoted soil macroaggregation exerted negative effects on N2O emissions. Irrespective of earthworm species and manure application methods, earthworms had no stimulatory effects on the yield-scaled N2O-N because the promotion of crop productivity counteracted the extent of N2O increase. In conclusion, understanding the trade-off between earthworm services and dis-services will contribute to the development of environmentally justified soil management by allowing the full utilization of biological resources. © 2014 Elsevier Ltd.

Yang W.,Nanjing Agricultural University | Yang W.,Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization | Wang D.-S.,Nanjing Institute of Vegetable Science | Liu M.-Q.,Nanjing Agricultural University | And 11 more authors.
Chinese Journal of Applied Ecology | Year: 2015

In this experiment, different proportions of the cattle manure, tea-leaf, herb and mushroom residues, were used as food for earthworm (Eisenia fetida) to study the growth of the earth-worm. Then the characteristics and transformation of nutrient content and three-dimensional excitation emission matrix fluorescence (3DEEM) of dissolved organic matter (DOM) during vermistabilization were investigated by means of chemical and spectroscopic methods. The result showed that the mixture of different ratios of cattle manure with herb residue, and cattle manure with tea-leaf were conducive to the growth of earthworm, while the materials compounded with mushroom residue inhibited the growth of earthworm. With the increasing time of verimcomposting, the pH in vermicompost tended to be circumneutral and weakly acidic, and there were increases in electrical conductivity, and the contents of total nitrogen, total phosphorus, available nitrogen, and available phosphorus, while the total potassium and available potassium increased first and then decreased, and the organic matter content decreased. 3DEEM and fluorescence regional integration results indicated that, the fluorescence of protein-like fluorescence peaks declined significantly, while the intensity of humiclike fluorescence peak increased significantly in DOM. Vermicomposting process might change the compositions of DOM with elevated concentrations of humic acid and fulvic acid in the organics. In all, this study suggested the suitability of 3DEEM for monitoring the organics transformation and assessing the maturity in the vermicomposting. ©, 2015, Editorial Board of Chinese Journal of Applied Ecology. All right reserved.

Song X.,Nanjing Agricultural University | Song X.,Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization | Liu M.,Nanjing Agricultural University | Liu M.,Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization | And 13 more authors.
Waste Management | Year: 2014

A pilot-scale trial of four months was conducted to investigate the responses of heavy metal and nutrient to composting animal manure spiked with mushroom residues with and without earthworms. Results showed that earthworm activities accelerated organic matter mineralization (e.g. reduction in C/N ratio, increase in total concentrations of N, P, K) and humification (e.g. increase in humic acid concentration, humification ratio and humification index). Despite composting increased total heavy metal (i.e. As, Pb, Cu, Zn) concentrations irrespective of earthworm, the availability of heavy metals extracted by DTPA significantly (P< 0.05) decreased particularly in treatments with earthworms introduced. The shift from available to unavailable fractions of heavy metals was either due to earthworm bioaccumulation, as indicated by total heavy metal concentrations being higher in earthworm tissues, or due to the formation of stable metal-humus complexes as indicated by the promotion of humification. Our results suggest that vermicomposting process could magnify the nutrient quality but relieve the heavy metals risk of agricultural organic wastes. © 2014 Elsevier Ltd.

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