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Organic matter transformations and soil fertility in a treed pasture in semiarid NE Brazil

Organic matter transformations and soil fertility in a treed pasture in semiarid NE Brazil Planted silvo-pastoral systems are formed by sparing selected native trees when land is cleared for pasture establishment, or by planting selected species – often known agroforestry species – into the establishing pasture. Isolated trees within pastures and savannas are often associated with `resource islands', characterized by higher fertility and organic matter levels under the tree canopies. We here examine the processes underlying the differences in fertility and organic matter in a buffel grass ( Cenchrus ciliaris L.) pasture that contained two tree species ( Ziziphus joazeiro Mart., Spondias tuberosa Arruda Cam.) preserved from the native thorn forest and a planted agroforestry species ( Prospois juliflora Swartz D.C). The objective is to distinguish effects of soil variability from those induced by the presence of trees or the planting of pasture. The δ 13 C signatures of the original (largely C3) vegetation, the preserved and planted trees, and the planted C4 grass were used to distinguish the provenance of organic matter in the top soil (0–15 cm). This allowed the conclusion that all trees maintained C3 derived C at the original thorn forest level, while lower levels under pasture were due to mineralisation of organic matter. The net rates of forest-derived C loss under pasture varied with soil type amounting to between 25 and 50% in 13 years after pasture establishment. Only on Alfisol, C inputs from the pasture compensated for the C3-C losses. Analysis of organic and inorganic P fractions indicated Z. joazeiro and P. juliflora enriched the soil under their canopy with P, whereas S. tuberosa had no positive effect on fertility. A combination of ANOVA and spatial analysis and mapping was used to show vegetation effects. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant and Soil Springer Journals

Organic matter transformations and soil fertility in a treed pasture in semiarid NE Brazil

Tiessen, H.; Menezes, R.S.C.; Salcedo, I.H.; Wick, B.
Plant and Soil , Volume 252 (2) – May 1, 2003
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References (52)

Publisher
Springer Journals
Copyright
Copyright © 2003 by Kluwer Academic Publishers
Subject
Environment; Ecology; Plant Sciences; Plant Physiology; Soil Science & Conservation
ISSN
0032-079X
eISSN
1573-5036
DOI
10.1023/A:1024762501920
Publisher site
See Article on Publisher Site

Abstract

Planted silvo-pastoral systems are formed by sparing selected native trees when land is cleared for pasture establishment, or by planting selected species – often known agroforestry species – into the establishing pasture. Isolated trees within pastures and savannas are often associated with `resource islands', characterized by higher fertility and organic matter levels under the tree canopies. We here examine the processes underlying the differences in fertility and organic matter in a buffel grass ( Cenchrus ciliaris L.) pasture that contained two tree species ( Ziziphus joazeiro Mart., Spondias tuberosa Arruda Cam.) preserved from the native thorn forest and a planted agroforestry species ( Prospois juliflora Swartz D.C). The objective is to distinguish effects of soil variability from those induced by the presence of trees or the planting of pasture. The δ 13 C signatures of the original (largely C3) vegetation, the preserved and planted trees, and the planted C4 grass were used to distinguish the provenance of organic matter in the top soil (0–15 cm). This allowed the conclusion that all trees maintained C3 derived C at the original thorn forest level, while lower levels under pasture were due to mineralisation of organic matter. The net rates of forest-derived C loss under pasture varied with soil type amounting to between 25 and 50% in 13 years after pasture establishment. Only on Alfisol, C inputs from the pasture compensated for the C3-C losses. Analysis of organic and inorganic P fractions indicated Z. joazeiro and P. juliflora enriched the soil under their canopy with P, whereas S. tuberosa had no positive effect on fertility. A combination of ANOVA and spatial analysis and mapping was used to show vegetation effects.

Journal

Plant and Soil – Springer Journals

Published: May 1, 2003

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