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  • 1
    Electronic Resource
    Electronic Resource
    Soil phosphorus fractions and adsorption as affected by organic and inorganic sources (1998)
    Springer
    Plant and soil 198 (1998), S. 159-168 
    Details
    ISSN: 1573-5036
    Keywords: maize stover ; microbial biomass ; phosphorus adsorption ; resin P ; triple superphosphate ; Tithonia diversifolia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of organic and inorganic sources of phosphorus (P) on soil P fractions and P adsorption was studied in a field without plant growth on a Kandiudalf in western Kenya. A high-quality organic source, Tithonia diversifolia (Hemsley) A. Gray leaves, and a low-quality source, maize (Zea mays L.) stover, were applied alone or in combination with triple superphosphate (TSP). The P rate was kept constant at 15 kg P ha-1. Soil extractable P (resin, bicarbonate and sodium hydroxide), microbial biomass P and C and P adsorption isotherms were determined during 16 weeks after application of treatments. Application of tithonia either alone or with TSP increased resin P, bicarbonate P, microbial P, and sodium hydroxide inorganic P. Tithonia alone reduced P adsorption at 2–16 weeks. Maize stover had no effect on any of the P fractions or P adsorption. At 8 weeks, the application of tithonia reduced microbial C-to-P ratio (20) as compared to maize stover, TSP and the control (31–34). The reduction in P adsorption by tithonia was accompanied by increases in all measured P fractions, the sum of P in those fractions (resin, bicarbonate and sodium hydroxide) being larger than the P added. The reduction in P adsorption apparently resulted from competition for adsorption sites, probably by organic anions produced during decomposition of the high quality tithonia. Integration of inorganic P (TSP) with organic materials had little added benefit compared to sole application of TSP, except that combination of tithonia with TSP increased microbial biomass. The results indicate that a high quality organic input can be comparable to or more effective than inorganic P in increasing P availability in the soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004389704235
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    Paper (German National Licenses)
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  • 2
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    Market access and resource endowment define the soil fertility status of smallholder farming systems of South‐Kivu, DR Congo (2021)
    Details
    Publication Date: 2021-06-27
    Description: This study verified the inter‐related effect of ‘market distance’, defined as walking time, ‘farm typology’, defined as resource endowment, and ‘site’, defined as geographic location with contrasting agro‐ecologies, as well as farmers’ indigenous knowledge on soil fertility variability in smallholder farming systems in two distinct regions (Bushumba, Mushinga) of South‐Kivu, DR Congo. A total of 384 soil samples were selected from representative farmers’ fields and analysed for soil pH, soil organic carbon (SOC) content and quality, as well as nutrient contents, using midDRIFTS (mid‐infrared diffuse reflectance Fourier transform spectroscopy) and wet chemistry analyses. MidDRIFTS was also used to calculate SOC stability indexes as SOC quality proxies. ‘Market distance’ and ‘farm typology’ were key determinants of soil fertility variability, both with contrasting trends in Bushumba and Mushinga. Decreasing soil fertility with increasing market distance was noted across all farm typologies. ‘Farm typology’ was related to exchangeable calcium and magnesium, while ‘site’ resulted in a difference of plant available phosphorus. SOC quality indexes were related to ‘site’, interacting with ‘market distance’. A ‘market distance’ effect became obvious in the medium wealthy and poor farms of Mushinga, where a lower SOC quality in remote fields plots was noted with increasing market distance. In agreement with farmers’ indigenous knowledge, soil fertility levels were higher in deep than shallow soils, which were reflected in higher nutrient stocks in deep soils receiving organic amendments. Our results inferred that soil fertility variability across smallholder farms must consider various inter‐related determinants as basis for site‐specific fertility management interventions.
    Description: German Federal Ministry for Economic Cooperation and Development (BMZ)
    Keywords: farm typology ; farmers’ indigenous knowledge ; market distance ; midDRIFTS ; soil fertility variability
    Type: article
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  • 3
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    Agro‐ecology, resource endowment and indigenous knowledge interactions modulate soil fertility in mixed farming systems in Central and Western Ethiopia (2021)
    Details
    Publication Date: 2021-07-21
    Description: Site‐specific soil fertility management requires a fundamental understanding of factors that modulate soil fertility variability in the local context. To verify this assumption, this study hypothesized that soil fertility variability across two regions in Central and Western Ethiopia is determined by inter‐related effects of agro‐ecological zones and farmers’ resource endowment (‘wealthy’ versus ‘poor’ farmers). Mid‐infrared spectroscopy coupled to partial least squares regression (midDRIFTS‐PLSR) and wet‐laboratory analyses were used to assess the soil fertility (soil pH, total soil carbon [TC] and nitrogen [TN], plant‐available phosphorous [Pav] and potassium [Kav]) across four agro‐ecological zones: ‘High‐Dega’ (HD), ‘Dega’ (D), ‘Weina‐Dega’ (WD) and ‘Kola’ (K). MidDRIFTS peak area analysis of spectral frequencies (2,930 [aliphatic C‐H], 1,620 [aromatic C = C], 1,159 [C‐O poly‐alcoholic and ether groups] cm‐1) was applied to characterize soil organic carbon (SOC) quality and to calculate the SOC stability index (1,620:2,930). Higher TC in HD, as well as higher TN and Kav contents in K were found in fields of wealthy compared with poor farmers. Resource endowment dependent soil fertility management options revealed SOC of higher quality in wealthy compared with poor farms in D. Agro‐ecological zones distinctions contributed to these soil fertility differences. Farmers distinguished visually fertile and less fertile fields based on soil colour. Higher pH in K and WD as well as Pav in K and HD were found in fertile (brown/black) than less fertile (red) soils. To conclude, tailor‐made soil fertility management in the local context must consider agro‐ecological zones and resource endowment interactions along with farmers’ indigenous knowledge.
    Description: German Federal Ministry for Economic Cooperation and Development (BMZ) through the International Institute for Tropical Agricultural (IITA) with its LegumeCHOICE project
    Keywords: 631.4 ; agro‐ecological zones ; farmers’ indigenous knowledge ; midDRIFTS ; resource endowment ; SOC stability index ; soil fertility variability
    Type: article
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