Leaf litter decomposition of Piper aduncum, Gliricidia sepium and Imperata cylindrica in the humid lowlands of Papua New Guinea
TL;DR: Piper leaf litter is a significant and easily decomposable source of K which is an important nutrient for sweet potato and the decomposition and nutrient release patterns had significant effects on the soil.
Abstract: No information is available on the decomposition and nutrient release pattern of Piper aduncum and Imperata cylindrica despite their importance in shifting cultivation systems of Papua New Guinea and other tropical regions. We conducted a litter bag study (24 weeks) on a Typic Eutropepts in the humid lowlands to assess the rate of decomposition of Piper aduncum, Imperata cylindrica and Gliricidia sepium leaves under sweet potato (Ipomoea batatas). Decomposition rates of piper leaf litter were fastest followed closely by gliricidia, and both lost 50% of the leaf biomass within 10 weeks. Imperata leaf litter decomposed much slower and half-life values exceeded the period of observation. The decomposition patterns were best explained by the lignin plus polyphenol over N ratio which was lowest for piper (4.3) and highest for imperata (24.7). Gliricidia leaf litter released 79 kg N ha(-1), whereas 18 kg N ha(-1) was immobilised in the imperata litter. The mineralization of P was similar for the three species, but piper litter released large amounts of K. The decomposition and nutrient release patterns had significant effects on the soil. The soil contained significantly more water in the previous imperata plots at 13 weeks due to the relative slow decomposition of the leaves. Soil N levels were significantly reduced in the previous imperata plots due to immobilisation of N. Levels of exchangeable K were significantly increased in the previous piper plots due to the large addition of K. It can be concluded that piper leaf litter is a significant and easily decomposable source of K which is an important nutrient for sweet potato. Gliricidia leaf litter contained much N, whereas imperata leaf litter releases relatively little nutrients and keeps the soil more moist. Gliricidia fallow is more attractive than an imperata fallow for it improves the soil fertility and produces fuelwood as additional saleable products.
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TL;DR: Serious attention must be paid to the availability of soil nutrients in order to sustain the cultivation of tropical shrubs potentially cultivated as sustainable energy crops with NPK fertilizer application.
Abstract: Background: Few species of tropical shrubs potentially produce biomass to replace fossil fuels for heat production and electricity. The aims of this study were to determine the growth and nutrient status of leaves of several types of energy crops from tropical shrub species with NPK fertilizer application. Methods: Randomized block design was used with ten replications of four levels of fertilizer treatment: T0 = 40 g, T1 = 80 g, T2 = 120 g and T4 = 160 g per plant. Results: The results indicated that fertilization increased plant growth and the quantity of nutrients in leaves. The plants accumulated a lot of potassium, followed by nitrogen and phosphorus. The species of tropical shrubs with the best growth were Vernonia amygdalina , Calliandra calothyrsus and Gliricidia sepium, which are all potentially cultivated as sustainable energy crops. Conclusions: Serious attention must be paid to the availability of soil nutrients in order to sustain the cultivation of these plants.
3 citations
Dissertation•
23 Apr 2015
3 citations
TL;DR: GMs+PRs is an appropriate combination for correcting nutrient deficiencies in tropical soils and significantly enhanced uptake of N, K, Ca, and Mg.
Abstract: Integrated nutrient management systems using plant residues and inorganic P fertilizers have high potential for increasing crop production and ensuring sustainability in the tropics, but their adoption requires in-depth understanding of nutrient dynamics in such systems. This was examined in a highly weathered tropical soil treated with green manures (GMs) and P fertilizers in two experiments conducted in the laboratory and glasshouse. The treatments were factorial combinations of the GMs (Calopogonium caeruleum, Gliricidia sepium, and Imperata cylindrica) and P fertilizers (phosphate rocks [PRs] from North Carolina, China, and Algeria, and triple superphosphate) replicated thrice. Olsen P, mineral N, pH, and exchangeable K, Ca, and Mg were monitored in a laboratory incubation study for 16 months. The change in soil P fractions and available P was also determined at the end of the study. Phosphorus available from the amendments was quantified at monthly intervals for 5 months by 33P-32P double isotopic labeling in the glasshouse using Setaria sphacelata as test crop. The GMs were labeled with 33P to determine their contribution to P taken up by Setaria, while that from the P fertilizers was indirectly measured by labeling the soil with 32P. The P fertilizers hardly changed Olsen P and exchangeable cations during 16 months of incubation. The legume GMs and legume GM
3 citations
Cites background from "Leaf litter decomposition of Piper ..."
...As these two fractions made the most important contributions to plant available P (Table 4), it suggests that that there was very little occlusion of the sorbed P in the presence of the legume GMs[42]....
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...This may have been achieved in this case by the action of organic acids and possibly the conservation of soil moisture because of the low rate of decomposition of Imperata[42]....
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TL;DR: Overall results suggest that DEA was fairly high in winter, but the influences of H. japonicus were minimal, and it is suggested that water availability may be a more dominant controlling variable than the presence of the invasive plant.
Abstract: One of the most serious problems involved in riparian restoration is the proliferation of invasive plants during or after a restoration project. Although many studies have assessed ecological influences of invasive plants, life history in particular, only a few have clarified the functional consequences of such changes. In this study, we aimed to determine the influences of an invasive plant, Humulus japonicus, and environmental conditions on riparian ecosystem functions, focusing on denitrification. Soil samples from five riparian ecosystems in Korea were collected on four occasions over a one-year period, and denitrification enzyme activity (DEA) was measured using an acetylene blocking method. DEA varied between 2.5 and>7000 ng N2O g−1 soil h−1. Overall results suggest that DEA was fairly high in winter, but the influences of H. japonicus were minimal. The results suggest that water availability may be a more dominant controlling variable than the presence of H. japonicus for DEA.
3 citations
Cites background from "Leaf litter decomposition of Piper ..."
...Similarly, previous studies on the decomposition rates of invasive plant have observed faster turnover of organic matter and nutrients, in particular nitrogen [10,11,25,26,34,35]....
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...japonicus would exhibit higher denitrification rates because invasive plants have been reported to have a higher rate of nitrogen turnover [10,11,25,26]....
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01 Jan 1999
TL;DR: In this article, a collaborative research project, "Improving smallholder farming systems in Imperata areas of Southeast Asia: a bioeconomic modelling approach" sponsored by the Center for international Forestry Research and the Australian Centre for International Research, is described.
Abstract: This is a report of a collaborative research project, 'Improving smallholder farming systems in Imperata areas of Southeast Asia: a bioeconomic modelling approach' sponsored by the Center for international Forestry Research and the Australian Centre for International Research. The nature of the Imperata problem and the methodology is outlined. Imperata is essentially restricted to upland areas, since it does not coexist with lowland rice farming. There is a section on bioeconomic analysis of traditional smallholder 'shifting cultivation' farming systems where the fallow is Imperata and another contains a series of case study descriptions of successful tree growing by smallholders on Imperata grasslands. The core modelling work of the project is reported. Various tree-based interventions are modelled with and without an animal component. Some of these modelled farming systems are already in place in farmers' fields. In these cases, possible management or policy interventions analysed with the models can point the way to productive and economic improvements. In other cases, the farming systems modelled are 'experimental' in nature. Imperata grows on uplands of various slopes, but some special attention is given to Imperata on steeply sloping land where soil erosion is a particular problem. Finally, two key issues in relation to tree growing on Imperata grassland, fire control and carbon sequestration, are addressed. These are viewed both from the viewpoints of the individual smallholder and of the broader society. This is an overview and compilation of studies, many of which were previously reported in a series of project papers published by Centre for Resource and Environmental Studies, Australian National University between 1995 and 1998.
2 citations
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TL;DR: Two general analytical approaches to the examination of decomposition data are reviewed and single and double exponential models best describe the loss of mass over time with an element of biological realism.
Abstract: The study of plant litter decomposition in terrestrial ecosystems commonly employs litter bags to compare the loss of mass among species, among sites, and under various experimental manipulations, or to investigate the process itself. Analysis of the resulting data is quite variable among investigators, and at times inappropriate. Two general analytical approaches to the examination of decomposition data are reviewed. Analysis of variance is useful if the intent is to compare treatment means, but does not directly test hypotheses regarding decomposition rates. If the intent is to determine rate constants, than fitting mathematical models to data is the more appropriate analysis. Single and double exponential models best describe the loss of mass over time with an element of biological realism. See full-text article at JSTOR
937 citations
Book•
01 Nov 1996
TL;DR: Pathways and processes in decomposition foraging, feeding and feedback manipulation of plant litter quality synchrony and soil organic matter - theory into practice?
Abstract: Pathways and processes in decomposition foraging, feeding and feedback manipulation of plant litter quality synchrony and soil organic matter - theory into practice? building soil organic matter modelling - providing the framework.
933 citations
786 citations
"Leaf litter decomposition of Piper ..." refers methods in this paper
...Lignin was determined by the procedure of Van Soest and Wine (1968), and polyphenol by that of Dalzell and Kerven (1998), using purifiedLeucaena pallidacondensed tannin as standard....
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TL;DR: In this article, the chemical composition and N release patterns of legumes being used in tropical agroecosystems were determined in a laboratory experiment and three patterns of net N mineralization emerged during the 8-weeks.
Abstract: Leguminous plant materials used as mulches, green manures and cover crops are generally assumed to provide a readily-available source of N to crops. However, little is known about the chemical composition and N release patterns of the variety of legumes being used in tropical agroecosystems. N release patterns from the leaflets of 10 troplcal legumes and rice straw were determined in a laboratory experiment. Ground leaf material was allowed to decompose in an acid soil (pH 4.5) for 8 weeks and the soil was analyzed periodically for extractable NH4+-N and NO3∼, -N. N release in the soil plus plant material were compared to that of the soil without plant material added and related to the N, lignin and polyphenolic concentrations of the leaflets. Three patterns of net N mineralization emerged during the 8-weeks. One pattern exhibited by the control soil, rice straw and leaves of two of the leguminous plants was a low, positive net mineralization. Another pattern showed much higher rates of mineralization than the control soil and the third pattern showed initial net immobilization followed by low but positive net mineralization rates. The amount of N mineralized during the 8 weeks as compared to the control soil ranged from +46 to −20% of the N added in plant material. Net mineralization was not correlated to % N or % lignin in the leaf material but was found to be negatively correlated to the polyphenolic concentration, r = −0.63, or the polyphenolic-to-N ratio, r = −0.75. Mineralization in excess of the control soil was found only for materials with a polyphenolic-to-N ratio
724 citations
TL;DR: In this article, the decomposition and nutrient release patterns 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.
Abstract: 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.
577 citations
"Leaf litter decomposition of Piper ..." refers background in this paper
...The rapid initial loss of K, particularly from the piper leaf litter, is commonly found in litter bag studies (Budelman, 1988; Palm and Sanchez, 1990; Tian et al., 1992a)....
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...…number of studies have been conducted under laboratory conditions (Handayanto et al., 1997; Lupwayi and Haque, 1998; Palm and Sanchez, 1991; Tian et al., 1992b) or under field conditions with no crop after the fallow (Budelman, 1988; Handayanto et al., 1994; Mwiinga et al., 1994; Oglesby…...
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