Kuvaus

Background: Over the last decades sub-Saharan Africa has experienced severe land degradation and food security challenges linked to loss of soil fertility and soil organic matter (SOM), recurrent drought and increasing population. Although primary production in drylands is strictly limited by water availability, nutrient deficiencies, particularly of nitrogen (N) and phosphorus (P), are also considered limiting factors for plant growth. It is known that SOM (often measured as soil organic carbon (SOC)) is a key indicator of soil fertility, therefore, management practices that increase SOM contents, such as increasing tree cover, can be expected to improve soil fertility. The objectives of this study were to investigate the effect of Acacia senegal (Senegalia senegal) trees on soil nitrogen, phosphorus and potassium (K) in relation to SOC, the potential of A. senegal for N-2 fixation, and to identify possible N and P ecosystem limitations. Methods: Soil nutrient (total N, P, K and available P and exchangeable K) concentrations and stocks were determined for the 0-10,10-20,20-30 and 30-50 cm layers of A. senegal plantations of varying age (ranging from 7 to 24-years-old) and adjacent grasslands (reference) at two sites in semi-arid areas of Sudan. At both sites, three plots were established in each grassland and plantation. The potential of A. senegal for N-2 fixation in relation to plantations age was assessed using delta N-15 isotopic abundances and nutrient limitations assessed using C:N:P stoichiometry. Results: Soil concentrations of all studied nutrients were relatively low but were significantly and directly correlated to SOC concentrations. SOC and nutrient concentrations were the highest in the topsoil (0-10 cm) and increased with plantations age. Acacia foliage delta N-15 values were >6%o and varied little with plantations age. Soil C:N and C:P ratios did not differ between grassland and plantations and only 0-10 cm layer N:P ratios showed significant differences between grassland and plantations. Discussion: The results indicated that soil fertility in the Sahel region is strongly related to SOM contents and therefore highlighting the importance of trees in the landscape. The higher mineral nutrient concentrations in the topsoil of the plantations may be an indication of 'nutrient uplift' by the deeper roots. The high foliar delta N-15 values indicated that N(2 )fixation was not an important contributor to soil N contents in the plantations. The accretion of soil N cannot be explained by deposition but may be related to inputs of excreted N brought into the area annually by grazing and browsing animals. The soil C:N:P stoichiometry indicated that the plantations may be limited by P and the grasslands limited by N.
Alkuperäiskielienglanti
Artikkeli e5232
LehtiPeerJ
Vuosikerta6
Sivumäärä22
ISSN2167-8359
DOI - pysyväislinkit
TilaJulkaistu - 10 heinäkuuta 2018
OKM-julkaisutyyppiA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä, vertaisarvioitu

Tieteenalat

  • 4112 Metsätiede

Lainaa tätä

@article{5b9bf4273b3c43c4b9005c0d6a07518b,
title = "Linkages between soil carbon, soil fertility and nitrogen fixation in Acacia senegal plantations of varying age in Sudan",
abstract = "Background: Over the last decades sub-Saharan Africa has experienced severe land degradation and food security challenges linked to loss of soil fertility and soil organic matter (SOM), recurrent drought and increasing population. Although primary production in drylands is strictly limited by water availability, nutrient deficiencies, particularly of nitrogen (N) and phosphorus (P), are also considered limiting factors for plant growth. It is known that SOM (often measured as soil organic carbon (SOC)) is a key indicator of soil fertility, therefore, management practices that increase SOM contents, such as increasing tree cover, can be expected to improve soil fertility. The objectives of this study were to investigate the effect of Acacia senegal (Senegalia senegal) trees on soil nitrogen, phosphorus and potassium (K) in relation to SOC, the potential of A. senegal for N-2 fixation, and to identify possible N and P ecosystem limitations. Methods: Soil nutrient (total N, P, K and available P and exchangeable K) concentrations and stocks were determined for the 0-10,10-20,20-30 and 30-50 cm layers of A. senegal plantations of varying age (ranging from 7 to 24-years-old) and adjacent grasslands (reference) at two sites in semi-arid areas of Sudan. At both sites, three plots were established in each grassland and plantation. The potential of A. senegal for N-2 fixation in relation to plantations age was assessed using delta N-15 isotopic abundances and nutrient limitations assessed using C:N:P stoichiometry. Results: Soil concentrations of all studied nutrients were relatively low but were significantly and directly correlated to SOC concentrations. SOC and nutrient concentrations were the highest in the topsoil (0-10 cm) and increased with plantations age. Acacia foliage delta N-15 values were >6{\%}o and varied little with plantations age. Soil C:N and C:P ratios did not differ between grassland and plantations and only 0-10 cm layer N:P ratios showed significant differences between grassland and plantations. Discussion: The results indicated that soil fertility in the Sahel region is strongly related to SOM contents and therefore highlighting the importance of trees in the landscape. The higher mineral nutrient concentrations in the topsoil of the plantations may be an indication of 'nutrient uplift' by the deeper roots. The high foliar delta N-15 values indicated that N(2 )fixation was not an important contributor to soil N contents in the plantations. The accretion of soil N cannot be explained by deposition but may be related to inputs of excreted N brought into the area annually by grazing and browsing animals. The soil C:N:P stoichiometry indicated that the plantations may be limited by P and the grasslands limited by N.",
keywords = "4112 Forestry, Drylands, Soil nutrients, Woodland savanna, Nitrogen isotopes, Sahel, Senegalia senegal, N-15 NATURAL-ABUNDANCE, AFRICAN SAVANNA, PRECIPITATION GRADIENT, LAND DEGRADATION, IMPROVED FALLOWS, FARMING SYSTEMS, ORGANIC-MATTER, STABLE-ISOTOPE, C-4 VEGETATION, CLIMATE-CHANGE, Drylands, Soil nutrients, Woodland savanna, Nitrogen isotopes, Sahel, Senegalia senegal, N-15 NATURAL-ABUNDANCE, AFRICAN SAVANNA, PRECIPITATION GRADIENT, LAND DEGRADATION, IMPROVED FALLOWS, FARMING SYSTEMS, ORGANIC-MATTER, STABLE-ISOTOPE, C-4 VEGETATION, CLIMATE-CHANGE",
author = "Wafa Abaker and Frank Berninger and Gustavo Saiz and Jukka Pumpanen and Starr, {Michael Robert}",
year = "2018",
month = "7",
day = "10",
doi = "10.7717/peerj.5232",
language = "English",
volume = "6",
journal = "PeerJ",
issn = "2167-8359",
publisher = "PeerJ Inc.",

}

Linkages between soil carbon, soil fertility and nitrogen fixation in Acacia senegal plantations of varying age in Sudan. / Abaker, Wafa; Berninger, Frank ; Saiz, Gustavo; Pumpanen, Jukka ; Starr, Michael Robert.

julkaisussa: PeerJ, Vuosikerta 6, e5232, 10.07.2018.

Tutkimustuotos: ArtikkelijulkaisuArtikkeliTieteellinenvertaisarvioitu

TY - JOUR

T1 - Linkages between soil carbon, soil fertility and nitrogen fixation in Acacia senegal plantations of varying age in Sudan

AU - Abaker, Wafa

AU - Berninger, Frank

AU - Saiz, Gustavo

AU - Pumpanen, Jukka

AU - Starr, Michael Robert

PY - 2018/7/10

Y1 - 2018/7/10

N2 - Background: Over the last decades sub-Saharan Africa has experienced severe land degradation and food security challenges linked to loss of soil fertility and soil organic matter (SOM), recurrent drought and increasing population. Although primary production in drylands is strictly limited by water availability, nutrient deficiencies, particularly of nitrogen (N) and phosphorus (P), are also considered limiting factors for plant growth. It is known that SOM (often measured as soil organic carbon (SOC)) is a key indicator of soil fertility, therefore, management practices that increase SOM contents, such as increasing tree cover, can be expected to improve soil fertility. The objectives of this study were to investigate the effect of Acacia senegal (Senegalia senegal) trees on soil nitrogen, phosphorus and potassium (K) in relation to SOC, the potential of A. senegal for N-2 fixation, and to identify possible N and P ecosystem limitations. Methods: Soil nutrient (total N, P, K and available P and exchangeable K) concentrations and stocks were determined for the 0-10,10-20,20-30 and 30-50 cm layers of A. senegal plantations of varying age (ranging from 7 to 24-years-old) and adjacent grasslands (reference) at two sites in semi-arid areas of Sudan. At both sites, three plots were established in each grassland and plantation. The potential of A. senegal for N-2 fixation in relation to plantations age was assessed using delta N-15 isotopic abundances and nutrient limitations assessed using C:N:P stoichiometry. Results: Soil concentrations of all studied nutrients were relatively low but were significantly and directly correlated to SOC concentrations. SOC and nutrient concentrations were the highest in the topsoil (0-10 cm) and increased with plantations age. Acacia foliage delta N-15 values were >6%o and varied little with plantations age. Soil C:N and C:P ratios did not differ between grassland and plantations and only 0-10 cm layer N:P ratios showed significant differences between grassland and plantations. Discussion: The results indicated that soil fertility in the Sahel region is strongly related to SOM contents and therefore highlighting the importance of trees in the landscape. The higher mineral nutrient concentrations in the topsoil of the plantations may be an indication of 'nutrient uplift' by the deeper roots. The high foliar delta N-15 values indicated that N(2 )fixation was not an important contributor to soil N contents in the plantations. The accretion of soil N cannot be explained by deposition but may be related to inputs of excreted N brought into the area annually by grazing and browsing animals. The soil C:N:P stoichiometry indicated that the plantations may be limited by P and the grasslands limited by N.

AB - Background: Over the last decades sub-Saharan Africa has experienced severe land degradation and food security challenges linked to loss of soil fertility and soil organic matter (SOM), recurrent drought and increasing population. Although primary production in drylands is strictly limited by water availability, nutrient deficiencies, particularly of nitrogen (N) and phosphorus (P), are also considered limiting factors for plant growth. It is known that SOM (often measured as soil organic carbon (SOC)) is a key indicator of soil fertility, therefore, management practices that increase SOM contents, such as increasing tree cover, can be expected to improve soil fertility. The objectives of this study were to investigate the effect of Acacia senegal (Senegalia senegal) trees on soil nitrogen, phosphorus and potassium (K) in relation to SOC, the potential of A. senegal for N-2 fixation, and to identify possible N and P ecosystem limitations. Methods: Soil nutrient (total N, P, K and available P and exchangeable K) concentrations and stocks were determined for the 0-10,10-20,20-30 and 30-50 cm layers of A. senegal plantations of varying age (ranging from 7 to 24-years-old) and adjacent grasslands (reference) at two sites in semi-arid areas of Sudan. At both sites, three plots were established in each grassland and plantation. The potential of A. senegal for N-2 fixation in relation to plantations age was assessed using delta N-15 isotopic abundances and nutrient limitations assessed using C:N:P stoichiometry. Results: Soil concentrations of all studied nutrients were relatively low but were significantly and directly correlated to SOC concentrations. SOC and nutrient concentrations were the highest in the topsoil (0-10 cm) and increased with plantations age. Acacia foliage delta N-15 values were >6%o and varied little with plantations age. Soil C:N and C:P ratios did not differ between grassland and plantations and only 0-10 cm layer N:P ratios showed significant differences between grassland and plantations. Discussion: The results indicated that soil fertility in the Sahel region is strongly related to SOM contents and therefore highlighting the importance of trees in the landscape. The higher mineral nutrient concentrations in the topsoil of the plantations may be an indication of 'nutrient uplift' by the deeper roots. The high foliar delta N-15 values indicated that N(2 )fixation was not an important contributor to soil N contents in the plantations. The accretion of soil N cannot be explained by deposition but may be related to inputs of excreted N brought into the area annually by grazing and browsing animals. The soil C:N:P stoichiometry indicated that the plantations may be limited by P and the grasslands limited by N.

KW - 4112 Forestry

KW - Drylands

KW - Soil nutrients

KW - Woodland savanna

KW - Nitrogen isotopes

KW - Sahel

KW - Senegalia senegal

KW - N-15 NATURAL-ABUNDANCE

KW - AFRICAN SAVANNA

KW - PRECIPITATION GRADIENT

KW - LAND DEGRADATION

KW - IMPROVED FALLOWS

KW - FARMING SYSTEMS

KW - ORGANIC-MATTER

KW - STABLE-ISOTOPE

KW - C-4 VEGETATION

KW - CLIMATE-CHANGE

KW - Drylands

KW - Soil nutrients

KW - Woodland savanna

KW - Nitrogen isotopes

KW - Sahel

KW - Senegalia senegal

KW - N-15 NATURAL-ABUNDANCE

KW - AFRICAN SAVANNA

KW - PRECIPITATION GRADIENT

KW - LAND DEGRADATION

KW - IMPROVED FALLOWS

KW - FARMING SYSTEMS

KW - ORGANIC-MATTER

KW - STABLE-ISOTOPE

KW - C-4 VEGETATION

KW - CLIMATE-CHANGE

U2 - 10.7717/peerj.5232

DO - 10.7717/peerj.5232

M3 - Article

VL - 6

JO - PeerJ

JF - PeerJ

SN - 2167-8359

M1 - e5232

ER -