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| Titel |
Kinetics of potassium release in sweet potato cropped soils: a case study in the highlands of Papua New Guinea |
| VerfasserIn |
B. K. Rajashekhar Rao |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 6, no. 1 ; Nr. 6, no. 1 (2015-02-17), S.217-225 |
| Datensatznummer |
250115398
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| Publikation (Nr.) |
 copernicus.org/se-6-217-2015.pdf |
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| Zusammenfassung |
| The present study attempts to employ potassium (K) release parameters to
identify soil-quality degradation due to changed land use patterns in
sweet potato (Ipomoea batatas (L.) Lam) farms of the highlands of Papua
New Guinea. Rapid population increase in the region increased pressure on the
land to intensify subsistence production mainly by reducing fallow periods.
Such continuous cropping practice coupled with lack of K fertilization
practices could lead to a rapid loss of soil fertility and soil-resource
degradation. The study aims to evaluate the effects of crop intensification
on the K-release pattern and identify soil groups vulnerable to K depletion.
Soils with widely differing exchangeable and non-exchangeable K contents were
sequentially extracted for periods between 1 and 569 h in 0.01 M
CaCl2,
and K-release data were fitted to four mathematical models: first order,
power, parabolic diffusion and Elovich equations. Results showed two distinct
parts in the K-release curves, and 58–80% of total K was released to
solution phase within 76 h (first five extractions) with 20–42% K
released in the later parts (after 76 h). Soils from older farms that were
subjected to intensive and prolonged land use showed significantly
(P < 0.05) lower cumulative K-release potential than the farms recently brought to cultivation (new farms).
Among the four equations, first-order and power equations best described the K-release pattern; the
constant b, an index of K-release rates, ranged from
0.005 to 0.008 mg kg−1 h−1 in the first-order model and was between
0.14 and 0.83 mg kg−1 h−1 in the power model for the soils. In the
non-volcanic soils, model constant b values were significantly
(P < 0.05) higher than the volcanic soils, thus indicating the vulnerability of volcanic soils to K deficiency. The volcanic soils cropped
for several crop cycles need immediate management interventions either
through improved fallow management or through mineral fertilizers plus animal
manures to sustain productivity. |
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