Watanabe, A and Takada, H and Sarno, - and Afandi, . and Adachi, T and Oki, Y and Senge, M (2007) Assessment of degradation and generation of humus in a coffee soil affected by weed cover by means of a stable carbon isotopic ratio. European Journal of Soil Science, 58 (5). pp. 1042-1049. ISSN 1365-2389

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We evaluated the effect of soil conservation by weeds on the degradation and generation of humic acids, fulvic acids, and water-soluble non-humic substances (WS-NHS) in a red-acid soil (Vertic Dystrudept) (Indonesia) from the changes in humus composition and stable carbon isotopic ratio (C). Three plots, a weeded plot (T-1; the common practice), a plot covered with Paspalum conjugatum Berg., a C plant (T-2), and a plot in which native weeds were allowed to grow (T-3), were prepared. An incubation experiment determined the 13 C values of the humus fractions generated from Paspalum in soil. Based on the increase in 13 C value, the proportion of total C that originated from Paspalum C after 4 years under coffee was 16 _ 4% in the T-2 topsoil (0–10 cm). Humic and fulvic acids in the T-1 topsoil decreased to 46 and 84%, respectively, whilst both increased or remained constant in the T-2 and T-3 soils. The WS-NHS content varied little and was independent of land management. The preferential loss of the humic acids with a smaller degree of humification as assessed by their darkness in colour was shown in T-1. The decrease in the degree of humification suggested the accumulation of the weedderived humic acids in T-2 and T-3. In the T-2 topsoil, 36 _ 2%, 13 _ 3% and 15 _ 2% of C in the humic acids, fulvic acids and WS-NHS, respectively, were estimated to be Paspalum-derived after 4 years. The estimated initial C loss during the same period was 17 _ 3%, 14 _ 2% and 7 _ 2%, respectively, for those fractions, which suggests the fastest turnover rate for the humic acids and significant retardation of their degradation in soil colonized by weeds

Item Type: Article
Subjects: S Agriculture > S Agriculture (General)
Divisions: Fakultas Pertanian (FP) > Prodi Ilmu Tanah
Depositing User: SARNO
Date Deposited: 01 Nov 2016 04:13
Last Modified: 01 Nov 2016 04:13
URI: http://repository.lppm.unila.ac.id/id/eprint/1013

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