Mapping soil aggregate stability using digital soil mapping: A case study of Ruiru reservoir catchment, Kenya

Kamamia, Ann W.; Vogel, Cordula; Mwangi, Hosea M.; Feger, Karl‐Heinz; Sang, Joseph; Jülich, Stefan

doi:10.1016/j.geodrs.2020.e00355

Cited by 18 publications

(16 citation statements)

References 61 publications

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“…In addition, for soils from the catchment of the Ruiru river, also located in the central highlands of Kenya, it was shown that macroaggregates (2-4.2 mm) displayed a large stability (Kamamia et al, 2021). The reported MWDs after application of the fast-wetting stability test were 2.5 mm for cropland and 3.2 mm for indigenous forest sites (Kamamia et al, 2021). These values are close to those observed in our study soils for 2-4 mm aggregates.…”

Section: Discussionsupporting

confidence: 88%

“…For example, soils with strongly contrasting clay content (220 and 650 g kg −1 ) but similar clay mineralogy (kaolinite) in the central highlands of Kenya displayed macroaggregate contents of 245 and 636 g kg −1 soil, respectively (Gentile et al, 2010). In addition, for soils from the catchment of the Ruiru river, also located in the central highlands of Kenya, it was shown that macroaggregates (2-4.2 mm) displayed a large stability (Kamamia et al, 2021). The reported MWDs after application of the fast-wetting stability test were 2.5 mm for cropland and 3.2 mm for indigenous forest sites (Kamamia et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

“…Accordingly, a higher Fe d to aluminous clay ratios seems to be disadvantageous for the formation and stability of such structures, especially in > 4 mm aggregates. The different pH-dependent charge characteristics of kaolinite and pedogenic Fe oxides (Kaiser and Guggenberger, 2003) and their relative share can lead to altered charge properties of soils (Anda et al, 2008). We hypothesize that an increasing amount of Fe oxides adds more positive charge, thus possibly reducing structural integrity and aggregate stability if not sufficiently compensated by OM or clay minerals.…”

Section: Land Use Impact On Aggregation Within Mineral Combinations -Implications For Aggregate Stabilitymentioning

confidence: 96%

“…Furthermore, the high clay-low Fe and high clay-high Fe combinations under forest also nicely demonstrate how nearly equal amounts of aluminous clay plus pedogenic Fe oxides (i.e., similar clay contents) cause different amounts of > 4 mm aggregates. Consequently, the connection between textural properties and aggregation can remain hidden (Barthès et al, 2008) without considering the mineralogical composition of the whole clay fraction (Fernández-Ugalde et al, 2013;King et al, 2019;West et al, 2004).…”

Section: Mineralogical Control On the Formation Of Large Macroaggregatesmentioning

confidence: 99%

“…Pedogenic iron (Fe d ) (oxyhydr)oxides (abbreviated as "Fe oxides") have been reported to facilitate macroaggregation (Peng et al, 2015) and aggregate stability (Duiker et al, 2003). Under the acidic conditions of weathered tropical soils, Fe oxides provide positively charged surfaces capable of reacting with negatively charged inorganic constituents, like clay minerals or OM (Kaiser and Guggenberger, 2003;Kleber et al, 2015;Six et al, 2004;Totsche et al, 2018). Aggregation might be ascribed to inorganic or organic cementing agents with no consensus about the relevance of each individual agent.…”

Section: Introductionmentioning

confidence: 99%

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Aluminous clay and pedogenic Fe oxides modulate aggregation and related carbon contents in soils of the humid tropics

Kirsten¹,

Mikutta

Kimaro

et al. 2021

SOIL

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Abstract. Aggregation affects a wide range of physical and biogeochemical soil properties with positive effects on soil carbon storage. For weathered tropical soils, aluminous clays (kaolinite and gibbsite) and pedogenic Fe (oxyhydr)oxides (goethite and hematite; termed “Fe oxides”) have been suggested as important building units for aggregates. However, as aluminosilicates, aluminum hydroxides, and Fe oxides are part of the clay-sized fraction it is hard to separate how certain mineral phases modulate aggregation. In addition, it is not known what consequences this will have for organic carbon (OC) persistence after land-use change. We selected topsoils with unique mineralogical compositions in the East Usambara Mountains of Tanzania under forest and cropland land uses, varying in contents of aluminous clay and Fe oxides. Across the mineralogical combinations, we determined the aggregate size distribution, aggregate stability, OC contents of aggregate size fractions, and changes in aggregation and OC contents under forest and cropland land use. Patterns in soil aggregation were rather similar across the different mineralogical combinations (high level of macroaggregation and high aggregate stability). Nevertheless, we found some statistically significant effects of aluminous clay and pedogenic Fe oxides on aggregation and OC storage. An aluminous clay content > 250 g kg−1 in combination with pedogenic Fe contents < 60 g kg−1 significantly promoted the formation of large macroaggregates > 4 mm. In contrast, a pedogenic Fe content > 60 g kg−1 in combination with aluminous clay content of < 250 g kg−1 promoted OC storage and persistence even under agricultural use. The combination with low aluminous clay and high pedogenic Fe contents displayed the highest OC persistence, despite conversion of forest to cropland causing substantial disaggregation. This indicates that aggregation in these tropical soils is modulated by the mineralogical regime, causing moderate but significant differences in aggregate size distribution. Nevertheless, aggregation was little decisive for overall OC persistence in these highly weathered soils, where OC storage is more regulated by direct mineral–organic interactions.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Section: Land Use Impact On Aggregation Within Mineral Combinations -Implications For Aggregate Stabilitymentioning

confidence: 96%

Section: Mineralogical Control On the Formation Of Large Macroaggregatesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Aluminous clay and pedogenic Fe oxides modulate aggregation and related carbon contents in soils of the humid tropics

Kirsten¹,

Mikutta

Kimaro

et al. 2021

SOIL

Self Cite

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Digital mapping of soil physical and mechanical properties using machine learning at the watershed scale

Ghavami,

Ayoubi,

Mosaddeghi

et al. 2023

J. Mt. Sci.

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Using soil erosion as an indicator for integrated water resources management: a case study of Ruiru drinking water reservoir, Kenya

Kamamia

Vogel²,

Mwangi³

et al. 2022

Environ Earth Sci

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Functions and services provided by soils play an important role for numerous sustainable development goals involving mainly food supply and environmental health. In many regions of the Earth, water erosion is a major threat to soil functions and is mostly related to land-use change or poor agricultural management. Selecting proper soil management practices requires site-specific indicators such as water erosion, which follow a spatio-temporal variation. The aim of this study was to develop monthly soil erosion risk maps for the data-scarce catchment of Ruiru drinking water reservoir located in Kenya. Therefore, the Revised Universal Soil Loss Equation complemented with the cubist–kriging interpolation method was applied. The erodibility map created with digital soil mapping methods (R2 = 0.63) revealed that 46% of the soils in the catchment have medium to high erodibility. The monthly erosion rates showed two distinct potential peaks of soil loss over the course of the year, which are consistent with the bimodal rainy season experienced in central Kenya. A higher soil loss of 2.24 t/ha was estimated for long rains (March–May) as compared to 1.68 t/ha for short rains (October–December). Bare land and cropland are the major contributors to soil loss. Furthermore, spatial maps reveal that areas around the indigenous forest on the western and southern parts of the catchment have the highest erosion risk. These detected erosion risks give the potential to develop efficient and timely soil management strategies, thus allowing continued multi-functional use of land within the soil–food–water nexus.

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Mapping soil aggregate stability using digital soil mapping: A case study of Ruiru reservoir catchment, Kenya

Cited by 18 publications

References 61 publications

Aluminous clay and pedogenic Fe oxides modulate aggregation and related carbon contents in soils of the humid tropics

Aluminous clay and pedogenic Fe oxides modulate aggregation and related carbon contents in soils of the humid tropics

Digital mapping of soil physical and mechanical properties using machine learning at the watershed scale

Using soil erosion as an indicator for integrated water resources management: a case study of Ruiru drinking water reservoir, Kenya

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