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Yakov Kuzyakov - One of the best experts on this subject based on the ideXlab platform.
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priming effects induced by glucose and decaying Plant Residues on som decomposition a three source 13c 14c partitioning study
Soil Biology & Biochemistry, 2018Co-Authors: Evgenia Blagodatskaya, Yakov Kuzyakov, Muhammad Shahbaz, Amit Kumar, Gunnar BorjessonAbstract:Abstract Decomposition of soil organic matter (SOM) may either increase or decrease after fresh organic inputs, the phenomena which are termed as "priming effect". Crop Residues and labile C additions can prime SOM decomposition, but it is not known how labile C inputs affect SOM in the presence of decaying Plant Residues varying in quality (e.g. from previous crops, a common situation in arable soils). We used a dual 13C/14C isotopic labelling to partition soil CO2 efflux and microbial biomass for three C sources: labile C (glucose), partly decomposed wheat Residues (leaves and roots) and SOM. 14C-labelled glucose was added to the soil after 30 days of pre-incubation with 13C-labelled Residues (separately leaves or roots). After glucose addition, the leaf residue decomposition rate declined by up to 65%, while roots remained unaffected. Despite the differences between residue decomposition rates, the quantity of primed SOM remained similar between leaf and root residue treatments after the addition of glucose. Glucose alone caused cumulative positive SOM priming of 193 μg C g−1 soil over 90 days, corresponding to 60% of SOM decomposition without addition. Addition of glucose to soil together with partly decomposed Plant Residues induced up to 45% higher SOM priming than single Residues priming effect (∼250 μg C g−1). Remarkably, this priming effect induced by glucose and Residues was only due to intensive SOM decomposition during the first 18 days. On the subsequent period (after 18 days of glucose), decline in SOM priming and increase in residue decomposition indicate a shift in microbial activity i.e. from active-to slow-growing microbes. Glucose addition strongly increased the proportion of microbial biomass from SOM but decreased the proportion from residue C, suggesting a preferential use of SOM over Plant Residues following glucose exhaustion. These results are consistent with the view that labile C inputs induce SOM priming and suggest for the first time, that labile C controls the intensity and decomposition rate of both SOM and decaying Plant Residues. Concluding, irrespective of the quality of partly decomposed Residues, input of labile C (e.g. through rhizodeposition) has overall an additive effect in increasing decomposition of SOM. Such studies of interactions between pools and identification of three C sources were only possible by the application of an innovative dual 13C/14C labelling approach.
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nitrogen fertilization decreases the decomposition of soil organic matter and Plant Residues in Planted soils
Soil Biology & Biochemistry, 2017Co-Authors: Bin Jia, Yakov KuzyakovAbstract:Abstract Nitrogen fertilization may affect the decomposition of soil organic matter (SOM) and Plant Residues in soil, but this effect is still very uncertain and depends on living Plants. We investigated the effects of mineral N (N min ) availability on SOM and Plant residue decomposition in wheat ( Triticum aestivum L.) growing soils in a pot experiment. Five treatments were assessed: (1) Control [no maize ( Zea Mays L.) Residues and no N fertilization]; (2) 15 N-urea addition; (3) 15 N maize leaves; (4) 15 N maize leaves + urea; and (5) 15 N-urea + maize straw. The decomposition of SOM and Plant Residues was traced by the changes of N and C in the light fraction (density -3 ) during the 127 days. Urea fertilization decreased the decomposition of SOM and maize Residues, as indicated by remaining N and C in the light fraction compared to soil without urea. The C decomposition was tightly coupled to that of N in the light fraction SOM. In soils with maize Residues, both maize- and SOM-derived light fractions decomposed slowly with N fertilization. Soil microbial biomass N content was increased by maize Residues but was unaffected by urea addition. Under low soil N min levels, microbes met their N demand by increasing an acquisition from accelerated decomposition of organic sources. To mine N in the N min limited soils, soil microbes might have directly taken up more N-containing organics and thus facilitated SOM decomposition. For such an acceleration of SOM decomposition, the presence of N uptake by living Plants was especially important, which decreased the N min in soil and so, increased N limitation for microorganisms. We concluded that N fertilization decreases SOM decomposition and increases the efficiency of C sequestration in soil through higher portion of un-decomposed crop Residues.
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effects of polyacrylamide biopolymer and biochar on decomposition of soil organic matter and Plant Residues as determined by 14c and enzyme activities
European Journal of Soil Biology, 2012Co-Authors: Yasser M Awad, Evgenia Blagodatskaya, Yakov KuzyakovAbstract:Application of polymers for the improvement of aggregate structure and reduction of soil erosion may alter the availability and decomposition of Plant Residues. In this study, we assessed the effects of anionic polyacrylamide (PAM), synthesized biopolymer (BP), and biochar (BC) on the decomposition of 14 C-labeled maize residue in sandy and sandy loam soils. Specifically, PAM and BP with or without 14 C-labeled Plant residue were applied at 400 kg ha � 1 , whereas BC was applied at 5000 kg ha � 1 , after
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Effect of fertilization on decomposition of 14C labelled Plant Residues and their incorporation into soil aggregates.
Soil and Tillage Research, 2010Co-Authors: Bidisha Majumder, Yakov KuzyakovAbstract:14 C-labelled Plant residue ABSTRACT Returning crop Residues to soil helps to maintain soil C stocks. Organic C stocks and microbial biomass are important factors controlling the decomposition or retention of crop Residues in soil and the formation of aggregates. Little is known about the specific contribution of crop Residues to soil aggregate size fractions in the framework of long-term fertilization. This study investigated the effects of long-term fertilization on the decomposition of 14 C-labelled Plant Residues and their incorporation into soil organic matter (SOM) of different aggregate size fractions. Soils were collected from 0-10 cm in the Ap horizon of
Lionel Ranjard - One of the best experts on this subject based on the ideXlab platform.
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Role of Plant Residues in determining temporal patterns of the activity, size, and structure of nitrate reducer communities in soil.
Applied and environmental microbiology, 2010Co-Authors: D. Chèneby, Lionel Ranjard, David Bru, Noémie Pascault, Pierre-alain Maron, Laurent PhilippotAbstract:The incorporation of Plant Residues into soil not only represents an opportunity to limit soil organic matter depletion resulting from cultivation but also provides a valuable source of nutrients such as nitrogen. However, the consequences of Plant residue addition on soil microbial communities involved in biochemical cycles other than the carbon cycle are poorly understood. In this study, we investigated the responses of one N-cycling microbial community, the nitrate reducers, to wheat, rape, and alfalfa Residues for 11 months after incorporation into soil in a field experiment. A 20- to 27-fold increase in potential nitrate reduction activity was observed for residue-amended plots compared to the nonamended plots during the first week. This stimulating effect of Residues on the activity of the nitrate-reducing community rapidly decreased but remained significant over 11 months. During this period, our results suggest that the potential nitrate reduction activity was regulated by both carbon availability and temperature. The presence of Residues also had a significant effect on the abundance of nitrate reducers estimated by quantitative PCR of the narG and napA genes, encoding the membrane-bound and periplasmic nitrate reductases, respectively. In contrast, the incorporation of the Plant Residues into soil had little impact on the structure of the narG and napA nitrate-reducing community determined by PCR-restriction fragment length polymorphism (RFLP) fingerprinting. Overall, our results revealed that the addition of Plant Residues can lead to important long-term changes in the activity and size of a microbial community involved in N cycling but with limited effects of the type of Plant residue itself.
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a microcosm experiment to evaluate the influence of location and quality of Plant Residues on residue decomposition and genetic structure of soil microbial communities
Soil Biology & Biochemistry, 2007Co-Authors: Bernard Nicolardot, Lamia Bouziri, Fabiola Bastian, Lionel RanjardAbstract:The effects of location (soil surface vs. incorporated in soil) and nature of Plant Residues on degradation processes and indigenous microbial communities were studied by means of soil microcosms incubation in which the different soil zones influenced by decomposition i.e. Residues, soil adjacent to Residues (detritusphere) and distant soil unaffected by decomposition (bulk soil) were considered. Plant material decomposition, organic carbon assimilation by the soil microbial biomass and soil inorganic N dynamics were studied with 13 C labelled wheat straw and young rye. The genetic structure of the community in each soil zone were compared between residue locations and type by applying B- and F-ARISA (for bacterial- and fungal-automated ribosomal intergenic spacer analysis) directly to DNA extracts from these different zones at 50% decomposition of each residue. Both location and biochemical quality affected residue decomposition in soil: 21% of incorporated 13 C wheat straw and 23% left at the soil surface remained undecomposed at the end of incubation, the corresponding values for 13 C rye being 1% and 8%. Residue decomposition induced a gradient of microbial activity with more labelled C incorporated into the microbial biomass of the detritusphere. The sphere of influence of the decomposing Residues on the dynamics of soluble organic C and inorganic N in the different soil zones showed particular patterns which were influenced by both residue location and quality. Residue degradation stimulated particular genetic structure of microbial community with a gradient from residue to bulk soil, and more pronounced spatial heterogeneity for fungal than for bacterial communities. The initial residue quality strongly affected the resulting spatial heterogeneity of bacteria, with a significance between-zone discrimination for rye but weak discrimination between the detritusphere and bulk soil, for wheat straw. Comparison of the different detrituspheres and residue zones (corresponding to different residue type and location), indicated that the genetic structure of the bacterial and fungal communities were specific to a residue type for detritusphere and to its location for residue, leading to conclude that the detritusphere and residue corresponded to distinct trophic and functional niches for microorganisms. r 2007 Elsevier Ltd. All rights reserved.
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A microcosm experiment to evaluate the influence of location and quality of Plant Residues on residue decomposition and genetic structure of soil microbial communities
Soil Biology and Biochemistry, 2007Co-Authors: Bernard Nicolardot, Lamia Bouziri, Fabiola Bastian, Lionel RanjardAbstract:The effects of location (soil surface vs. incorporated in soil) and nature of Plant Residues on degradation processes and indigenous microbial communities were studied by means of soil microcosms incubation in which the different soil zones influenced by decomposition i.e. Residues, soil adjacent to Residues (detritusphere) and distant soil unaffected by decomposition (bulk soil) were considered. Plant material decomposition, organic carbon assimilation by the soil microbial biomass and soil inorganic N dynamics were studied with 13C labelled wheat straw and young rye. The genetic structure of the community in each soil zone were compared between residue locations and type by applying B- and F-ARISA (for bacterial- and fungal-automated ribosomal intergenic spacer analysis) directly to DNA extracts from these different zones at 50% decomposition of each residue. Both location and biochemical quality affected residue decomposition in soil: 21% of incorporated 13C wheat straw and 23% left at the soil surface remained undecomposed at the end of incubation, the corresponding values for 13C rye being 1% and 8%. Residue decomposition induced a gradient of microbial activity with more labelled C incorporated into the microbial biomass of the detritusphere. The sphere of influence of the decomposing Residues on the dynamics of soluble organic C and inorganic N in the different soil zones showed particular patterns which were influenced by both residue location and quality. Residue degradation stimulated particular genetic structure of microbial community with a gradient from residue to bulk soil, and more pronounced spatial heterogeneity for fungal than for bacterial communities. The initial residue quality strongly affected the resulting spatial heterogeneity of bacteria, with a significance between-zone discrimination for rye but weak discrimination between the detritusphere and bulk soil, for wheat straw. Comparison of the different detrituspheres and residue zones (corresponding to different residue type and location), indicated that the genetic structure of the bacterial and fungal communities were specific to a residue type for detritusphere and to its location for residue, leading to conclude that the detritusphere and residue corresponded to distinct trophic and functional niches for microorganisms.
B.t. Kang - One of the best experts on this subject based on the ideXlab platform.
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An index for assessing the quality of Plant Residues under humid tropical conditions.
Applied Soil Ecology, 1995Co-Authors: Guanglong Tian, Lijbert Brussaard, B.t. KangAbstract:Abstract An equation was developed for calculating a Plant residue quality index (PRQI) in the (sub-)humid tropics using the C/N ratio and lignin and polyphenol concentration of Plant Residues. Among 18 Plant species tested, there was a large variation in PRQI. The PRQI was correlated with the decomposition rate of Plant Residues, soil microclimate, soil fauna density and maize crop performance in the field. Soil moisture and termite density increased with decreases in PRQI, whereas decomposition rate constants of Plant Residues, soil temperature and ant density increased with increase in PRQI. Improvement in crop performance, such as grain yield, by Plant residue mulching was lowest in the case of intermediate PRQI. It is concluded that PRQI can be used for selecting Plant Residues and projecting their agronomic value in the tropics.
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Breakdown of Plant Residues with contrasting chemical compositions under humid tropical conditions: effects of earthworms and millipedes
Soil Biology and Biochemistry, 1995Co-Authors: Guanglong Tian, Lijbert Brussaard, B.t. KangAbstract:Abstract The effects of tropical earthworms ( Eudrilus eugeniae ) and millipedes (Spirostreptidae) on the breakdown of Plant Residues [ Acioa (presently, Dactyladenia) barteri, Gliricidia sepium and Leucaena leucocephala prunings, maize ( Zea mays ) stover and rice ( Oryza sativa ) straw], with contrating chemical compositions, were studied in the field under humid tropical circumstances. Addition of earthworms significantly increased the breakdown of maize stover. Addition of millipedes significantly increased the breakdown of maize stover and rice straw. Combined addition of earthworms and millipedes generally resulted in greater Plant residue breakdown, compared to that of a single group of fauna. During 10 weeks of exposure, earthworms and millipedes, on average, accounted for the breakdown of all Plant Residues by 10.4 and 28.4%, respectively. Millipedes and earthworms contributed more to the breakdown of Plant Residues with low quality (high C-to-N ratio, lignin and polyphenol contents) than to the degradation of those with high quality. It is concluded that fauna-enhanced breakdown of Plant Residues will have different effects on soil nutrient supply, depending on residue quality.
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Mulching effect of Plant Residues with chemically contrasting compositions on maize growth and nutrients accumulation
Plant and Soil, 1993Co-Authors: G. Tian, B.t. Kang, L. BrussaardAbstract:Effects of application of prunings of three woody species ( Acioa barteri, Gliricidia sepium and Leucaena leucocephala ), maize ( Zea mays L.) stover and rice ( Oryza sativa L.) straw as mulch on maize were studied on an Alfisol in southern Nigeria in 1990 and 1991. Maize dry matter and grain yield were higher with applications of Plant Residues and N fertilizer in both years. Addition of Leucaena prunings gave the highest maize grain yield in both years. Compared to the 1990 results, Acioa showed the least grain yield decline among the mulch treatments in 1991. Nutrient uptake was enhanced by applications of Plant Residues. Leucaena prunings had the highest effect in both years and increased the mean N, P, and Mg uptake by 96%, 84%, and 50%, respectively, over the control. Addition of Acioa prunings increased K and Ca uptake by 59% and 92%, respectively, over the control. ‘High quality’ (low C/N ratio and lignin level) Plant Residues enhance crop performance through direct nutritional contributions, whereas ‘low quality’ (high C/N ratio and lignin level) Plant Residues do so through mulching effects on the microclimate. ‘Intermediate quality’ Plant Residues have no clear effects on crop performance.
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Biological effects of Plant Residues with contrasting chemical compositions under humid tropical conditions: Effects on soil fauna
Soil Biology and Biochemistry, 1993Co-Authors: Guanglong Tian, Lijbert Brussaard, B.t. KangAbstract:Abstract Effects of application of five types of Plant Residues [Acioa barteri, Gliricidia sepium and Leucaena leucocephala prunings, maize (Zea mays) stover and rice (Oryza sativa) straw] as mulch on soil fauna were examined under field conditions in the humid tropics in 1990 and 1991. Earthworm mean population over 2 years was higher under any type of Plant Residues by 41% compared to control. Leucaena prunings supported the highest earthworm population. Mulched plots also showed 177% higher mean termite population over 2 years than control. Highest termite population was observed in plots mulched with Acioa prunings followed by maize stover > rice straw >Leucaena prunings >Gliricidia prunings. The mean ant populations were 36% higher with Leucaena and Gliricidia prunings, and were not affected by Acioa prunings, maize stover and rice straw as compared to control. Millipede populations were not significantly affected by mulching. Earthworm populations were negatively correlated with the ratio of lignin : N of Plant Residues. Ant populations were significantly related to the N content of Plant Residues (R2 = 0.87 and 0.84 for 1990 and 1991 respectively). The results imply that chemical Plant composition, particularly N and lignin contents, play a critical role in faunal abundance in the soil through their effect on palatability and decomposibility. Indirect microclimatic and mulching effects may also be important.
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Biological effects of Plant Residues with contrasting chemical compositions under humid tropical conditions-decomposition and nutrient release
Soil Biology and Biochemistry, 1992Co-Authors: Guanglong Tian, B.t. Kang, Lijbert BrussaardAbstract:Decomposition and nutrient release patterns of prunings of three woody agroforestry Plant species (Acioa barteri, Gliricidia sepium and Leucaena leucocephala), maize (Zea mays) stover and rice (Oryza sativa) straw, were investigated under field conditions in the humid tropics, using litterbags of three mesh sizes (0.5, 2 and 7 mm) which allowed differential access of soil fauna. The decomposition rate constants ranged from 0.01 to 0.26 week−1, decreasing in the following order; Gliricidia prunings >Leucaena prunings > rice straw > maize stover >Acioa prunings. Negative correlations were observed between decomposition rate constants and C:N ratio (P < 0.004), percent lignin (P < 0.014) and polyphenol content (P < 0.053) of Plant Residues. A positive correlation was observed between decomposition rate constant and mesh-size of litterbag (P < 0.057). These results indicate that both the chemical composition of Plant Residues and nature of the decomposer played an important role in Plant residue decomposition. Nutrient release differed with quality of Plant Residues and litterbag mesh-size. Total N, P, Ca and Mg contents of Plant Residues decreased with time for Gliricidia and Leucaena prunings, maize stover, and rice straw, and increased with time for Acioa prunings. There was some indication of N immobilization in maize stover and rice straw; P immobilization in Leucaena prunings and rice straw; and Ca immobilization in maize stover, rice straw and Gliricidia and Leucaena prunings. Acioa prunings immobilized N, P, Ca and Mg. All Plant Residues released K rapidly. Nutrient release increased with increasing mesh-size of litterbags, suggesting that soil faunal activities enhanced nutrient mobilization.
Robert Mikutta - One of the best experts on this subject based on the ideXlab platform.
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Denitrification induced by Plant Residues is driven by water-soluble organic carbon
2020Co-Authors: Ronny Surey, Corinna M. Schimpf, Leopold Sauheitl, Carsten W. Mueller, Pauline Sophie Rummel, Klaus Dittert, Klaus Kaiser, Jürgen Böttcher, Robert MikuttaAbstract:<p>Denitrification usually takes place under anoxic conditions and over short periods of time and depends on readily available nitrate and carbon sources. Variations in CO<sub>2</sub> and N<sub>2</sub>O emissions from soils amended with Plant Residues have mainly been explained by differences in their decomposability. Another factor rarely considered so far is water-extractable organic matter (WEOM) released into soil during residue decomposition. Here, we examined the potential effect of Plant Residues on denitrification with special emphasis on WEOM. A range of fresh and leached Plant Residues was characterized by elemental analyses, <sup>13</sup>C-NMR spectroscopy, and extraction with ultrapure water. The obtained solutions were analyzed for the concentration of organic carbon (OC), organic nitrogen (ON), and by UV-VIS spectroscopy. To test the potential denitrification induced by Plant Residues or three different OM solutions, these carbon sources were added to soil suspensions and incubated for 24 hours at 20 &#176;C in the dark under anoxic conditions; KNO<sub>3</sub> was added to ensure unlimited nitrate supply. Evolving N<sub>2</sub>O and CO<sub>2</sub> were analyzed by gas chromatography and acetylene inhibition was used to determine denitrification and its product ratio. The production of all gases as well as the molar N<sub>2</sub>O+N<sub>2</sub>-N/CO<sub>2</sub>-C ratio was directly related to the water-extractable OC (WEOC) content of the Plant Residues and the WEOC increased with carboxylic/carbonyl C and decreasing OC/ON ratios of the Plant Residues. Incubation of OM solutions revealed that the molar N<sub>2</sub>O+N<sub>2</sub>-N/CO<sub>2</sub>-C ratio and share of N<sub>2</sub>O are influenced by the WEOM&#8217;s chemical composition. In conclusion, the effect of Plant Residues on potential denitrification is governed by their composition and the related production of WEOM.</p>
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Potential denitrification stimulated by water-soluble organic carbon from Plant Residues during initial decomposition
Soil Biology and Biochemistry, 2020Co-Authors: Ronny Surey, Corinna M. Schimpf, Leopold Sauheitl, Carsten W. Mueller, Pauline Sophie Rummel, Klaus Dittert, Klaus Kaiser, Jürgen Böttcher, Robert MikuttaAbstract:Abstract Denitrification usually takes place under anoxic conditions and over short periods of time, and depends on readily available nitrate and carbon sources. Variations in CO2 and N2O emissions associated with Plant Residues have mainly been explained by differences in their decomposability. A factor rarely considered so far is water-extractable organic matter (WEOM) released to the soil during residue decomposition. Here, we examined the potential effect of Plant Residues on denitrification with special emphasis on WEOM. A range of fresh and leached Plant Residues was characterized by elemental analyses, 13C-NMR spectroscopy, and extraction with ultrapure water. The obtained solutions were analyzed for the concentrations of organic carbon (OC) and organic nitrogen (ON), and by UV-VIS spectroscopy. To test the potential denitrification induced by Plant Residues or three different OM solutions, these carbon sources were added to soil suspensions and incubated for 24 h at 20 °C in the dark under anoxic conditions; KNO3 was added to ensure unlimited nitrate supply. Evolving N2O and CO2 were analyzed by gas chromatography, and acetylene inhibition was used to determine denitrification and its product ratio. The production of all gases, as well as the molar (N2O + N2)–N/CO2–C ratio, was directly related to the water-extractable OC (WEOC) content of the Plant Residues, and the WEOC increased with carboxylic/carbonyl C and decreasing OC/ON ratio of the Plant Residues. Incubation of OM solutions revealed that the molar (N2O + N2)–N/CO2–C ratio and share of N2O are influenced by the WEOM's chemical composition. In conclusion, our results emphasize the potential of WEOM in largely undecomposed Plant Residues to support short-term denitrification activity in a typical ˈhot spot–hot momentˈ situation.
Guanglong Tian - One of the best experts on this subject based on the ideXlab platform.
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Effects of residue quality and climate on Plant residue decomposition and nutrient release along the transect from humid forest to Sahel of West Africa
Biogeochemistry, 2007Co-Authors: Guanglong Tian, M. A. Badejo, Anthony I. Okoh, F. Ishida, G. O. Kolawole, Y. Hayashi, F. K. SalakoAbstract:Field litterbag studies were conducted in the 2000 rainy season and the 2000/2001 dry season along the transect of West African major agroecological zones (agroeco-zones) to measure the decomposition of, and N and P release from 5 Plant Residues (leaves of woody species) with increasing quality: Dactyladenia barteri, Pterocarpus santalinoides, Alchornea cordifolia, Senna siamea and Gliricidia sepium. The decomposition rate constant (wk−1) ranged from 0.034 (Dactyladenia, subhumid zone) to 0.49 (Gliricidia, humid zone) in the rainy season, and from 0.01 (Dactyladenia, subhumid zone) to 0.235 (Pterocarpus, arid zone) in the dry season. The direct correlation between the decomposition rate of Plant Residues and their quality was only valid in agroeco-zones where there is not moisture stress. Similarly, the direct correlation between the decomposition rate of Plant Residues and moisture availability was only valid for Plant Residues with high quality. The decomposition rate of the low quality Plant residue could increase from humid to arid zone in West Africa. In the arid zone, the low quality Plant residue could also decompose faster than high quality Plant residue. The climate-residue quality interactive effects on Plant residue decomposition in West Africa were attributed to the feedback of low quality Plant residue’s mulching effect, soil fauna and appreciable photodegradation in dry regions. A decomposition equation that could be used to predict the decomposition rate of Plant Residues with various qualities across agroeco-zones in West Africa was obtained from this study. The equation was expressed as follow: k = 0.122 − 0.000747*PRQI2− 0.0233*PRQI*CI + 0.00337*CI* PRQI2, in which k is the decomposition rate constant (wk−1), PRQI the Plant residue quality index, and CI the climate index (ratio of rainfall to sunshine hours cumulative during the entire decomposition). The response of N and P release from Plant Residues to residue quality and climate was similar to that of residue decomposition. At the late stage of the dry season decomposition, the high C/N and C/P ratio Plant residue (Dactyladenia leaves) that immobilized N and P in wet zones showed a release of N and P in the dry zone.
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An index for assessing the quality of Plant Residues under humid tropical conditions.
Applied Soil Ecology, 1995Co-Authors: Guanglong Tian, Lijbert Brussaard, B.t. KangAbstract:Abstract An equation was developed for calculating a Plant residue quality index (PRQI) in the (sub-)humid tropics using the C/N ratio and lignin and polyphenol concentration of Plant Residues. Among 18 Plant species tested, there was a large variation in PRQI. The PRQI was correlated with the decomposition rate of Plant Residues, soil microclimate, soil fauna density and maize crop performance in the field. Soil moisture and termite density increased with decreases in PRQI, whereas decomposition rate constants of Plant Residues, soil temperature and ant density increased with increase in PRQI. Improvement in crop performance, such as grain yield, by Plant residue mulching was lowest in the case of intermediate PRQI. It is concluded that PRQI can be used for selecting Plant Residues and projecting their agronomic value in the tropics.
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Breakdown of Plant Residues with contrasting chemical compositions under humid tropical conditions: effects of earthworms and millipedes
Soil Biology and Biochemistry, 1995Co-Authors: Guanglong Tian, Lijbert Brussaard, B.t. KangAbstract:Abstract The effects of tropical earthworms ( Eudrilus eugeniae ) and millipedes (Spirostreptidae) on the breakdown of Plant Residues [ Acioa (presently, Dactyladenia) barteri, Gliricidia sepium and Leucaena leucocephala prunings, maize ( Zea mays ) stover and rice ( Oryza sativa ) straw], with contrating chemical compositions, were studied in the field under humid tropical circumstances. Addition of earthworms significantly increased the breakdown of maize stover. Addition of millipedes significantly increased the breakdown of maize stover and rice straw. Combined addition of earthworms and millipedes generally resulted in greater Plant residue breakdown, compared to that of a single group of fauna. During 10 weeks of exposure, earthworms and millipedes, on average, accounted for the breakdown of all Plant Residues by 10.4 and 28.4%, respectively. Millipedes and earthworms contributed more to the breakdown of Plant Residues with low quality (high C-to-N ratio, lignin and polyphenol contents) than to the degradation of those with high quality. It is concluded that fauna-enhanced breakdown of Plant Residues will have different effects on soil nutrient supply, depending on residue quality.
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Biological effects of Plant Residues with contrasting chemical compositions under humid tropical conditions: Effects on soil fauna
Soil Biology and Biochemistry, 1993Co-Authors: Guanglong Tian, Lijbert Brussaard, B.t. KangAbstract:Abstract Effects of application of five types of Plant Residues [Acioa barteri, Gliricidia sepium and Leucaena leucocephala prunings, maize (Zea mays) stover and rice (Oryza sativa) straw] as mulch on soil fauna were examined under field conditions in the humid tropics in 1990 and 1991. Earthworm mean population over 2 years was higher under any type of Plant Residues by 41% compared to control. Leucaena prunings supported the highest earthworm population. Mulched plots also showed 177% higher mean termite population over 2 years than control. Highest termite population was observed in plots mulched with Acioa prunings followed by maize stover > rice straw >Leucaena prunings >Gliricidia prunings. The mean ant populations were 36% higher with Leucaena and Gliricidia prunings, and were not affected by Acioa prunings, maize stover and rice straw as compared to control. Millipede populations were not significantly affected by mulching. Earthworm populations were negatively correlated with the ratio of lignin : N of Plant Residues. Ant populations were significantly related to the N content of Plant Residues (R2 = 0.87 and 0.84 for 1990 and 1991 respectively). The results imply that chemical Plant composition, particularly N and lignin contents, play a critical role in faunal abundance in the soil through their effect on palatability and decomposibility. Indirect microclimatic and mulching effects may also be important.
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Biological effects of Plant Residues with contrasting chemical compositions under humid tropical conditions-decomposition and nutrient release
Soil Biology and Biochemistry, 1992Co-Authors: Guanglong Tian, B.t. Kang, Lijbert BrussaardAbstract:Decomposition and nutrient release patterns of prunings of three woody agroforestry Plant species (Acioa barteri, Gliricidia sepium and Leucaena leucocephala), maize (Zea mays) stover and rice (Oryza sativa) straw, were investigated under field conditions in the humid tropics, using litterbags of three mesh sizes (0.5, 2 and 7 mm) which allowed differential access of soil fauna. The decomposition rate constants ranged from 0.01 to 0.26 week−1, decreasing in the following order; Gliricidia prunings >Leucaena prunings > rice straw > maize stover >Acioa prunings. Negative correlations were observed between decomposition rate constants and C:N ratio (P < 0.004), percent lignin (P < 0.014) and polyphenol content (P < 0.053) of Plant Residues. A positive correlation was observed between decomposition rate constant and mesh-size of litterbag (P < 0.057). These results indicate that both the chemical composition of Plant Residues and nature of the decomposer played an important role in Plant residue decomposition. Nutrient release differed with quality of Plant Residues and litterbag mesh-size. Total N, P, Ca and Mg contents of Plant Residues decreased with time for Gliricidia and Leucaena prunings, maize stover, and rice straw, and increased with time for Acioa prunings. There was some indication of N immobilization in maize stover and rice straw; P immobilization in Leucaena prunings and rice straw; and Ca immobilization in maize stover, rice straw and Gliricidia and Leucaena prunings. Acioa prunings immobilized N, P, Ca and Mg. All Plant Residues released K rapidly. Nutrient release increased with increasing mesh-size of litterbags, suggesting that soil faunal activities enhanced nutrient mobilization.