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.
Cites background from "Leaf litter decomposition of Piper ..."
...Litt er fall and accumulation, which includes both leaf and twig material, is an important source of soil organic matt er and nutrients in forest soils (Buol et al., 1997; Hartemink and O’Sullivan, 2001; Schaetzl and Anderson, 2005; Finkl and Restrepo-Coupe, 2007) such as those in and around the borrow pit....
"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....
"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)....
...…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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