Site-and watershed-level assessment of nutrient dynamics under shifting cultivation in eastern Madagascar
Identifieur interne : 001007 ( Istex/Corpus ); précédent : 001006; suivant : 001008Site-and watershed-level assessment of nutrient dynamics under shifting cultivation in eastern Madagascar
Auteurs : J. Brand ; J. L PfundSource :
- Agriculture, Ecosystems and Environment [ 0167-8809 ] ; 1998.
Abstract
Nutrient depletion is an important limiting factor for agricultural sustainability in shifting cultivation systems. This paper presents a case study examining nutrient dynamics for a hillrice-fallow system located on the eastern escarpment of Madagascar. A nutrient assessment was carried out, measuring total C, N, P, K, Ca and Mg concentrations in phytomass, ashes and harvests and total C and N, exchangeable K, Ca and Mg and available P concentrations in topsoils, soil loss material and river discharges. At representative slash-and-burn sites, the soil-pool of P and K increased from 100% beneath 5-year-old fallow vegetation to 166% and 126% at harvest, but Ca and Mg decreased. Comparisons between fallow and burnt fields showed that 95–98% of phytomass-fixed and 22–24% of soil-fixed C and N were lost by burning. Paddy at harvest only contained 1–7% of the nutrients in the burnt phytomass of the previous stand. Nutrients regenerated rapidly in the fallow vegetation, which after 1 year contained already 36–57% of the previous phytomass pool, whereas topsoil nutrient concentrations started to increase only after 3–5 years of fallow. The long-term nutrient depletion was studied by comparing nutrient stocks at sites and watersheds, which were characterised by increasing levels of degradation. The topsoil cation content increased during the early stages of shifting cultivation, but under long-term shifting cultivation, the soil nutrients fell to approximately 2/3 of the initial stock. The nutrient stocks of the most degraded vegetation unit (grassland) was merely 1.1–6.5% of the nutrient stocks in the rainforest. Finally, the nutrient stocks in a forested and a degraded watershed were calculated and compared. The established nutrient balances showed, that the dynamics and the depletion depend greatly on the spatio-temporal scale of observation, on the topography of the sites and on the type of nutrients.
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DOI: 10.1016/S0167-8809(98)00139-X
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<record><TEI wicri:istexFullTextTei="biblStruct"><teiHeader><fileDesc><titleStmt><title>Site-and watershed-level assessment of nutrient dynamics under shifting cultivation in eastern Madagascar</title><author><name sortKey="Brand, J" sort="Brand, J" uniqKey="Brand J" first="J" last="Brand">J. Brand</name><affiliation><mods:affiliation>Projet Terre-Tany/BEMA, BP 4052AntananarivoMadagascar</mods:affiliation></affiliation></author><author><name sortKey="Pfund, J L" sort="Pfund, J L" uniqKey="Pfund J" first="J. L" last="Pfund">J. L Pfund</name><affiliation><mods:affiliation>Projet Terre-Tany/BEMA, BP 4052AntananarivoMadagascar</mods:affiliation></affiliation></author></titleStmt><publicationStmt><idno type="wicri:source">ISTEX</idno><idno type="RBID">ISTEX:510740ED017D2F1D30BAB61A991E9E162ECD9890</idno><date when="1998" year="1998">1998</date><idno type="doi">10.1016/S0167-8809(98)00139-X</idno><idno type="url">https://api.istex.fr/document/510740ED017D2F1D30BAB61A991E9E162ECD9890/fulltext/pdf</idno><idno type="wicri:Area/Istex/Corpus">001007</idno><idno type="wicri:explorRef" wicri:stream="Istex" wicri:step="Corpus" wicri:corpus="ISTEX">001007</idno></publicationStmt><sourceDesc><biblStruct><analytic><title level="a">Site-and watershed-level assessment of nutrient dynamics under shifting cultivation in eastern Madagascar</title><author><name sortKey="Brand, J" sort="Brand, J" uniqKey="Brand J" first="J" last="Brand">J. Brand</name><affiliation><mods:affiliation>Projet Terre-Tany/BEMA, BP 4052AntananarivoMadagascar</mods:affiliation></affiliation></author><author><name sortKey="Pfund, J L" sort="Pfund, J L" uniqKey="Pfund J" first="J. L" last="Pfund">J. L Pfund</name><affiliation><mods:affiliation>Projet Terre-Tany/BEMA, BP 4052AntananarivoMadagascar</mods:affiliation></affiliation></author></analytic><monogr></monogr><series><title level="j">Agriculture, Ecosystems and Environment</title><title level="j" type="abbrev">AGEE</title><idno type="ISSN">0167-8809</idno><imprint><publisher>ELSEVIER</publisher><date type="published" when="1998">1998</date><biblScope unit="volume">71</biblScope><biblScope unit="issue">1–3</biblScope><biblScope unit="page" from="169">169</biblScope><biblScope unit="page" to="183">183</biblScope></imprint><idno type="ISSN">0167-8809</idno></series><idno type="istex">510740ED017D2F1D30BAB61A991E9E162ECD9890</idno><idno type="DOI">10.1016/S0167-8809(98)00139-X</idno><idno type="PII">S0167-8809(98)00139-X</idno></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0167-8809</idno></seriesStmt></fileDesc><profileDesc><textClass></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract" xml:lang="en">Nutrient depletion is an important limiting factor for agricultural sustainability in shifting cultivation systems. This paper presents a case study examining nutrient dynamics for a hillrice-fallow system located on the eastern escarpment of Madagascar. A nutrient assessment was carried out, measuring total C, N, P, K, Ca and Mg concentrations in phytomass, ashes and harvests and total C and N, exchangeable K, Ca and Mg and available P concentrations in topsoils, soil loss material and river discharges. At representative slash-and-burn sites, the soil-pool of P and K increased from 100% beneath 5-year-old fallow vegetation to 166% and 126% at harvest, but Ca and Mg decreased. Comparisons between fallow and burnt fields showed that 95–98% of phytomass-fixed and 22–24% of soil-fixed C and N were lost by burning. Paddy at harvest only contained 1–7% of the nutrients in the burnt phytomass of the previous stand. Nutrients regenerated rapidly in the fallow vegetation, which after 1 year contained already 36–57% of the previous phytomass pool, whereas topsoil nutrient concentrations started to increase only after 3–5 years of fallow. The long-term nutrient depletion was studied by comparing nutrient stocks at sites and watersheds, which were characterised by increasing levels of degradation. The topsoil cation content increased during the early stages of shifting cultivation, but under long-term shifting cultivation, the soil nutrients fell to approximately 2/3 of the initial stock. The nutrient stocks of the most degraded vegetation unit (grassland) was merely 1.1–6.5% of the nutrient stocks in the rainforest. Finally, the nutrient stocks in a forested and a degraded watershed were calculated and compared. The established nutrient balances showed, that the dynamics and the depletion depend greatly on the spatio-temporal scale of observation, on the topography of the sites and on the type of nutrients.</div></front></TEI><istex><corpusName>elsevier</corpusName><author><json:item><name>J Brand</name><affiliations><json:string>Projet Terre-Tany/BEMA, BP 4052AntananarivoMadagascar</json:string></affiliations></json:item><json:item><name>J.L Pfund</name><affiliations><json:string>Projet Terre-Tany/BEMA, BP 4052AntananarivoMadagascar</json:string></affiliations></json:item></author><subject><json:item><lang><json:string>eng</json:string></lang><value>Madagascar</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Nutrient balance</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Nutrient depletion</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Shifting cultivation</value></json:item></subject><language><json:string>eng</json:string></language><originalGenre><json:string>Full-length article</json:string></originalGenre><abstract>Nutrient depletion is an important limiting factor for agricultural sustainability in shifting cultivation systems. This paper presents a case study examining nutrient dynamics for a hillrice-fallow system located on the eastern escarpment of Madagascar. A nutrient assessment was carried out, measuring total C, N, P, K, Ca and Mg concentrations in phytomass, ashes and harvests and total C and N, exchangeable K, Ca and Mg and available P concentrations in topsoils, soil loss material and river discharges. At representative slash-and-burn sites, the soil-pool of P and K increased from 100% beneath 5-year-old fallow vegetation to 166% and 126% at harvest, but Ca and Mg decreased. Comparisons between fallow and burnt fields showed that 95–98% of phytomass-fixed and 22–24% of soil-fixed C and N were lost by burning. Paddy at harvest only contained 1–7% of the nutrients in the burnt phytomass of the previous stand. Nutrients regenerated rapidly in the fallow vegetation, which after 1 year contained already 36–57% of the previous phytomass pool, whereas topsoil nutrient concentrations started to increase only after 3–5 years of fallow. The long-term nutrient depletion was studied by comparing nutrient stocks at sites and watersheds, which were characterised by increasing levels of degradation. The topsoil cation content increased during the early stages of shifting cultivation, but under long-term shifting cultivation, the soil nutrients fell to approximately 2/3 of the initial stock. The nutrient stocks of the most degraded vegetation unit (grassland) was merely 1.1–6.5% of the nutrient stocks in the rainforest. Finally, the nutrient stocks in a forested and a degraded watershed were calculated and compared. The established nutrient balances showed, that the dynamics and the depletion depend greatly on the spatio-temporal scale of observation, on the topography of the sites and on the type of nutrients.</abstract><qualityIndicators><score>8</score><pdfVersion>1.2</pdfVersion><pdfPageSize>522 x 745 pts</pdfPageSize><refBibsNative>true</refBibsNative><keywordCount>4</keywordCount><abstractCharCount>1930</abstractCharCount><pdfWordCount>7551</pdfWordCount><pdfCharCount>49641</pdfCharCount><pdfPageCount>15</pdfPageCount><abstractWordCount>292</abstractWordCount></qualityIndicators><title>Site-and watershed-level assessment of nutrient dynamics under shifting cultivation in eastern Madagascar</title><pii><json:string>S0167-8809(98)00139-X</json:string></pii><genre><json:string>research-article</json:string></genre><host><volume>71</volume><pii><json:string>S0167-8809(00)X0045-X</json:string></pii><pages><last>183</last><first>169</first></pages><issn><json:string>0167-8809</json:string></issn><issue>1–3</issue><genre><json:string>journal</json:string></genre><language><json:string>unknown</json:string></language><title>Agriculture, Ecosystems and Environment</title><publicationDate>1998</publicationDate></host><categories><wos><json:string>science</json:string><json:string>environmental sciences</json:string><json:string>ecology</json:string><json:string>agriculture, multidisciplinary</json:string></wos><scienceMetrix><json:string>applied sciences</json:string><json:string>agriculture, fisheries & forestry</json:string><json:string>agronomy & agriculture</json:string></scienceMetrix></categories><publicationDate>1998</publicationDate><copyrightDate>1998</copyrightDate><doi><json:string>10.1016/S0167-8809(98)00139-X</json:string></doi><id>510740ED017D2F1D30BAB61A991E9E162ECD9890</id><score>0.04010345</score><fulltext><json:item><extension>pdf</extension><original>true</original><mimetype>application/pdf</mimetype><uri>https://api.istex.fr/document/510740ED017D2F1D30BAB61A991E9E162ECD9890/fulltext/pdf</uri></json:item><json:item><extension>zip</extension><original>false</original><mimetype>application/zip</mimetype><uri>https://api.istex.fr/document/510740ED017D2F1D30BAB61A991E9E162ECD9890/fulltext/zip</uri></json:item><istex:fulltextTEI uri="https://api.istex.fr/document/510740ED017D2F1D30BAB61A991E9E162ECD9890/fulltext/tei"><teiHeader><fileDesc><titleStmt><title level="a">Site-and watershed-level assessment of nutrient dynamics under shifting cultivation in eastern Madagascar</title></titleStmt><publicationStmt><authority>ISTEX</authority><publisher>ELSEVIER</publisher><availability><p>©1998 Elsevier Science B.V.</p></availability><date>1998</date></publicationStmt><notesStmt><note type="content">Fig. 1: Evolution of total carbon, sum of exchangeable cations and exchangeable aluminimum concentration in topsoils (0–20cm) under increasing fallow duration.</note><note type="content">Fig. 2: Mean nutrient stocks (kg/ha) in phytomass and litter, ash, hillrice and topsoil (0–20cm) during a slash-and-burn cycle. The sizes of the boxes represent the mean proportion of the stock of the six analysed elements as compared with the first stage (Fallow 5 years: 100%).</note><note type="content">Fig. 3: Mean nutrient stocks (kg/ha) in phytomass and topsoil (0–20cm) at increasing degradation stages under long-term shifting cultivation. The sizes of the boxes represent the mean proportion of stock of the six analysed nutrients as compared with the first stage (rainforest: 100%).</note><note type="content">Table 1: Nutrient concentrations in phytomass, ashes, cultures, litter and topsoil (0–20cm) during one slash-and-burn cycle (mean ± SD)</note><note type="content">Table 2: Nutrient balance at site level during the cropping season of hillrice (6 month) after slashing and burning a 5-year-old fallow</note><note type="content">Table 3: Mean nutrient concentrations in vegetation and topsoils at increasing degradation stages</note><note type="content">Table 4: Annual nutrient losses during three successive phases of degradation under shifting cultivation</note><note type="content">Table 5: Nutrient balance at site level (middle-slope) for the long-term degradation from rainforest to degraded fallow under shifting cultivation (approximately 20 slash-and-burn cycles in 125 years)</note><note type="content">Table 6: Nutrient balance at watershed-level for the long-term degradation from a forested watershed to a degraded watershed under shifting cultivation (200 years)</note></notesStmt><sourceDesc><biblStruct type="inbook"><analytic><title level="a">Site-and watershed-level assessment of nutrient dynamics under shifting cultivation in eastern Madagascar</title><author xml:id="author-1"><persName><forename type="first">J</forename><surname>Brand</surname></persName><note type="correspondence"><p>Corresponding author. Tel.: +26-124-1463; fax: +261-23-4884; e-mail: brand@terretany.fofifa.mg</p></note><affiliation>Projet Terre-Tany/BEMA, BP 4052AntananarivoMadagascar</affiliation></author><author xml:id="author-2"><persName><forename type="first">J.L</forename><surname>Pfund</surname></persName><affiliation>Projet Terre-Tany/BEMA, BP 4052AntananarivoMadagascar</affiliation></author></analytic><monogr><title level="j">Agriculture, Ecosystems and Environment</title><title level="j" type="abbrev">AGEE</title><idno type="pISSN">0167-8809</idno><idno type="PII">S0167-8809(00)X0045-X</idno><imprint><publisher>ELSEVIER</publisher><date type="published" when="1998"></date><biblScope unit="volume">71</biblScope><biblScope unit="issue">1–3</biblScope><biblScope unit="page" from="169">169</biblScope><biblScope unit="page" to="183">183</biblScope></imprint></monogr><idno type="istex">510740ED017D2F1D30BAB61A991E9E162ECD9890</idno><idno type="DOI">10.1016/S0167-8809(98)00139-X</idno><idno type="PII">S0167-8809(98)00139-X</idno></biblStruct></sourceDesc></fileDesc><profileDesc><creation><date>1998</date></creation><langUsage><language ident="en">en</language></langUsage><abstract xml:lang="en"><p>Nutrient depletion is an important limiting factor for agricultural sustainability in shifting cultivation systems. This paper presents a case study examining nutrient dynamics for a hillrice-fallow system located on the eastern escarpment of Madagascar. A nutrient assessment was carried out, measuring total C, N, P, K, Ca and Mg concentrations in phytomass, ashes and harvests and total C and N, exchangeable K, Ca and Mg and available P concentrations in topsoils, soil loss material and river discharges. At representative slash-and-burn sites, the soil-pool of P and K increased from 100% beneath 5-year-old fallow vegetation to 166% and 126% at harvest, but Ca and Mg decreased. Comparisons between fallow and burnt fields showed that 95–98% of phytomass-fixed and 22–24% of soil-fixed C and N were lost by burning. Paddy at harvest only contained 1–7% of the nutrients in the burnt phytomass of the previous stand. Nutrients regenerated rapidly in the fallow vegetation, which after 1 year contained already 36–57% of the previous phytomass pool, whereas topsoil nutrient concentrations started to increase only after 3–5 years of fallow. The long-term nutrient depletion was studied by comparing nutrient stocks at sites and watersheds, which were characterised by increasing levels of degradation. The topsoil cation content increased during the early stages of shifting cultivation, but under long-term shifting cultivation, the soil nutrients fell to approximately 2/3 of the initial stock. The nutrient stocks of the most degraded vegetation unit (grassland) was merely 1.1–6.5% of the nutrient stocks in the rainforest. Finally, the nutrient stocks in a forested and a degraded watershed were calculated and compared. The established nutrient balances showed, that the dynamics and the depletion depend greatly on the spatio-temporal scale of observation, on the topography of the sites and on the type of nutrients.</p></abstract><textClass><keywords scheme="keyword"><list><head>Keywords</head><item><term>Madagascar</term></item><item><term>Nutrient balance</term></item><item><term>Nutrient depletion</term></item><item><term>Shifting cultivation</term></item></list></keywords></textClass></profileDesc><revisionDesc><change when="1998">Published</change></revisionDesc></teiHeader></istex:fulltextTEI><json:item><extension>txt</extension><original>false</original><mimetype>text/plain</mimetype><uri>https://api.istex.fr/document/510740ED017D2F1D30BAB61A991E9E162ECD9890/fulltext/txt</uri></json:item></fulltext><metadata><istex:metadataXml wicri:clean="Elsevier, elements deleted: ce:floats; body; tail"><istex:xmlDeclaration>version="1.0" encoding="utf-8"</istex:xmlDeclaration><istex:docType PUBLIC="-//ES//DTD journal article DTD version 4.5.2//EN//XML" URI="art452.dtd" name="istex:docType"><istex:entity SYSTEM="gr1" NDATA="IMAGE" name="gr1"></istex:entity><istex:entity SYSTEM="gr2" NDATA="IMAGE" name="gr2"></istex:entity><istex:entity SYSTEM="gr3" NDATA="IMAGE" name="gr3"></istex:entity></istex:docType><istex:document><converted-article version="4.5.2" docsubtype="fla"><item-info><jid>AGEE</jid><aid>1360</aid><ce:pii>S0167-8809(98)00139-X</ce:pii><ce:doi>10.1016/S0167-8809(98)00139-X</ce:doi><ce:copyright year="1998" type="full-transfer">Elsevier Science B.V.</ce:copyright></item-info><head><ce:title>Site-and watershed-level assessment of nutrient dynamics under shifting cultivation in eastern Madagascar</ce:title><ce:author-group><ce:author><ce:given-name>J</ce:given-name><ce:surname>Brand</ce:surname><ce:cross-ref refid="CORR1">*</ce:cross-ref></ce:author><ce:author><ce:given-name>J.L</ce:given-name><ce:surname>Pfund</ce:surname></ce:author><ce:affiliation><ce:textfn>Projet Terre-Tany/BEMA, BP 4052AntananarivoMadagascar</ce:textfn></ce:affiliation><ce:correspondence id="CORR1"><ce:label>*</ce:label><ce:text>Corresponding author. Tel.: +26-124-1463; fax: +261-23-4884; e-mail: brand@terretany.fofifa.mg</ce:text></ce:correspondence></ce:author-group><ce:abstract><ce:section-title>Abstract</ce:section-title><ce:abstract-sec><ce:simple-para>Nutrient depletion is an important limiting factor for agricultural sustainability in shifting cultivation systems. This paper presents a case study examining nutrient dynamics for a hillrice-fallow system located on the eastern escarpment of Madagascar. A nutrient assessment was carried out, measuring total C, N, P, K, Ca and Mg concentrations in phytomass, ashes and harvests and total C and N, exchangeable K, Ca and Mg and available P concentrations in topsoils, soil loss material and river discharges. At representative slash-and-burn sites, the soil-pool of P and K increased from 100% beneath 5-year-old fallow vegetation to 166% and 126% at harvest, but Ca and Mg decreased. Comparisons between fallow and burnt fields showed that 95–98% of phytomass-fixed and 22–24% of soil-fixed C and N were lost by burning. Paddy at harvest only contained 1–7% of the nutrients in the burnt phytomass of the previous stand. Nutrients regenerated rapidly in the fallow vegetation, which after 1 year contained already 36–57% of the previous phytomass pool, whereas topsoil nutrient concentrations started to increase only after 3–5 years of fallow. The long-term nutrient depletion was studied by comparing nutrient stocks at sites and watersheds, which were characterised by increasing levels of degradation. The topsoil cation content increased during the early stages of shifting cultivation, but under long-term shifting cultivation, the soil nutrients fell to approximately 2/3 of the initial stock. The nutrient stocks of the most degraded vegetation unit (grassland) was merely 1.1–6.5% of the nutrient stocks in the rainforest. Finally, the nutrient stocks in a forested and a degraded watershed were calculated and compared. The established nutrient balances showed, that the dynamics and the depletion depend greatly on the spatio-temporal scale of observation, on the topography of the sites and on the type of nutrients.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:keywords class="keyword"><ce:section-title>Keywords</ce:section-title><ce:keyword><ce:text>Madagascar</ce:text></ce:keyword><ce:keyword><ce:text>Nutrient balance</ce:text></ce:keyword><ce:keyword><ce:text>Nutrient depletion</ce:text></ce:keyword><ce:keyword><ce:text>Shifting cultivation</ce:text></ce:keyword></ce:keywords></head></converted-article></istex:document></istex:metadataXml><mods version="3.6"><titleInfo><title>Site-and watershed-level assessment of nutrient dynamics under shifting cultivation in eastern Madagascar</title></titleInfo><titleInfo type="alternative" contentType="CDATA"><title>Site-and watershed-level assessment of nutrient dynamics under shifting cultivation in eastern Madagascar</title></titleInfo><name type="personal"><namePart type="given">J</namePart><namePart type="family">Brand</namePart><affiliation>Projet Terre-Tany/BEMA, BP 4052AntananarivoMadagascar</affiliation><description>Corresponding author. Tel.: +26-124-1463; fax: +261-23-4884; e-mail: brand@terretany.fofifa.mg</description><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">J.L</namePart><namePart type="family">Pfund</namePart><affiliation>Projet Terre-Tany/BEMA, BP 4052AntananarivoMadagascar</affiliation><role><roleTerm type="text">author</roleTerm></role></name><typeOfResource>text</typeOfResource><genre type="research-article" displayLabel="Full-length article"></genre><originInfo><publisher>ELSEVIER</publisher><dateIssued encoding="w3cdtf">1998</dateIssued><copyrightDate encoding="w3cdtf">1998</copyrightDate></originInfo><language><languageTerm type="code" authority="iso639-2b">eng</languageTerm><languageTerm type="code" authority="rfc3066">en</languageTerm></language><physicalDescription><internetMediaType>text/html</internetMediaType></physicalDescription><abstract lang="en">Nutrient depletion is an important limiting factor for agricultural sustainability in shifting cultivation systems. This paper presents a case study examining nutrient dynamics for a hillrice-fallow system located on the eastern escarpment of Madagascar. A nutrient assessment was carried out, measuring total C, N, P, K, Ca and Mg concentrations in phytomass, ashes and harvests and total C and N, exchangeable K, Ca and Mg and available P concentrations in topsoils, soil loss material and river discharges. At representative slash-and-burn sites, the soil-pool of P and K increased from 100% beneath 5-year-old fallow vegetation to 166% and 126% at harvest, but Ca and Mg decreased. Comparisons between fallow and burnt fields showed that 95–98% of phytomass-fixed and 22–24% of soil-fixed C and N were lost by burning. Paddy at harvest only contained 1–7% of the nutrients in the burnt phytomass of the previous stand. Nutrients regenerated rapidly in the fallow vegetation, which after 1 year contained already 36–57% of the previous phytomass pool, whereas topsoil nutrient concentrations started to increase only after 3–5 years of fallow. The long-term nutrient depletion was studied by comparing nutrient stocks at sites and watersheds, which were characterised by increasing levels of degradation. The topsoil cation content increased during the early stages of shifting cultivation, but under long-term shifting cultivation, the soil nutrients fell to approximately 2/3 of the initial stock. The nutrient stocks of the most degraded vegetation unit (grassland) was merely 1.1–6.5% of the nutrient stocks in the rainforest. Finally, the nutrient stocks in a forested and a degraded watershed were calculated and compared. The established nutrient balances showed, that the dynamics and the depletion depend greatly on the spatio-temporal scale of observation, on the topography of the sites and on the type of nutrients.</abstract><note type="content">Fig. 1: Evolution of total carbon, sum of exchangeable cations and exchangeable aluminimum concentration in topsoils (0–20cm) under increasing fallow duration.</note><note type="content">Fig. 2: Mean nutrient stocks (kg/ha) in phytomass and litter, ash, hillrice and topsoil (0–20cm) during a slash-and-burn cycle. The sizes of the boxes represent the mean proportion of the stock of the six analysed elements as compared with the first stage (Fallow 5 years: 100%).</note><note type="content">Fig. 3: Mean nutrient stocks (kg/ha) in phytomass and topsoil (0–20cm) at increasing degradation stages under long-term shifting cultivation. The sizes of the boxes represent the mean proportion of stock of the six analysed nutrients as compared with the first stage (rainforest: 100%).</note><note type="content">Table 1: Nutrient concentrations in phytomass, ashes, cultures, litter and topsoil (0–20cm) during one slash-and-burn cycle (mean ± SD)</note><note type="content">Table 2: Nutrient balance at site level during the cropping season of hillrice (6 month) after slashing and burning a 5-year-old fallow</note><note type="content">Table 3: Mean nutrient concentrations in vegetation and topsoils at increasing degradation stages</note><note type="content">Table 4: Annual nutrient losses during three successive phases of degradation under shifting cultivation</note><note type="content">Table 5: Nutrient balance at site level (middle-slope) for the long-term degradation from rainforest to degraded fallow under shifting cultivation (approximately 20 slash-and-burn cycles in 125 years)</note><note type="content">Table 6: Nutrient balance at watershed-level for the long-term degradation from a forested watershed to a degraded watershed under shifting cultivation (200 years)</note><subject><genre>Keywords</genre><topic>Madagascar</topic><topic>Nutrient balance</topic><topic>Nutrient depletion</topic><topic>Shifting cultivation</topic></subject><relatedItem type="host"><titleInfo><title>Agriculture, Ecosystems and Environment</title></titleInfo><titleInfo type="abbreviated"><title>AGEE</title></titleInfo><genre type="journal">journal</genre><originInfo><dateIssued encoding="w3cdtf">19981201</dateIssued></originInfo><identifier type="ISSN">0167-8809</identifier><identifier type="PII">S0167-8809(00)X0045-X</identifier><part><date>19981201</date><detail type="volume"><number>71</number><caption>vol.</caption></detail><detail type="issue"><number>1–3</number><caption>no.</caption></detail><extent unit="issue pages"><start>1</start><end>346</end></extent><extent unit="pages"><start>169</start><end>183</end></extent></part></relatedItem><identifier type="istex">510740ED017D2F1D30BAB61A991E9E162ECD9890</identifier><identifier type="DOI">10.1016/S0167-8809(98)00139-X</identifier><identifier type="PII">S0167-8809(98)00139-X</identifier><accessCondition type="use and reproduction" contentType="copyright">©1998 Elsevier Science B.V.</accessCondition><recordInfo><recordContentSource>ELSEVIER</recordContentSource><recordOrigin>Elsevier Science B.V., ©1998</recordOrigin></recordInfo></mods></metadata><serie></serie></istex></record>Pour manipuler ce document sous Unix (Dilib)
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|texte= Site-and watershed-level assessment of nutrient dynamics under shifting cultivation in eastern Madagascar
}}
| This area was generated with Dilib version V0.6.28. |  |