Population density, soil nutrient depletion, and economic growth in sub-Saharan Africa

Drechsel, Pay; Gyiele, Lucy; Kunze, D.; Cofie, Olufunke O.

doi:10.1016/s0921-8009(01)00167-7

Cited by 204 publications

(121 citation statements)

References 9 publications

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“…land degradation while about three per cent of GDP from agriculture is lost every year because of loss of nutrients from the soil (Drechsel, Gyiele, Kunze, & Cofie, 2001a). Farming households have responded to the decline in land productivity by abandoning degraded agricultural fields and converting new lands for agricultural production (Barbier 2000;Diagana, 2003).…”

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confidence: 99%

Reversing Agro-Based Land Degradation through Conservation Agriculture: Emerging Experiences from Zambia’s Smallholder Farming Sector

Umar¹

2012

SAR

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This study reports on the land degradation minimizing effects of Conservation Agriculture (CA) as promoted among smallholder Zambian farmers. It found no evidence of CA associated improvements in soil fertility after five years of CA practice, most probably because crop residues were removed from the fields. The study reports high phosphorus (15.53 mg kg -1 ) and potassium (0.75 cmol kg -1 ) levels, low nitrogen (0.12 %) and organic carbon (1.19 %) levels, and no plough/hoe pans in soils from both CA and conventionally (CV) managed fields. This is in part contrary to the dominant land degradation narratives which have been the basis for promoting CA in the study areas. Faidherbia albida, a leguminous tree promoted as part of the CA package in Zambia, is associated with significantly higher levels of nitrogen, organic carbon and potassium under its canopy. Its planting by CA farmers is linked to the incentives provided by CA promoters. Average maize yields of 3.8 t ha -1 and 2.8 t ha -1 were reported under CA and CV systems respectively. Government subsidies for mineral fertilizer and hybrid seed promote maize mono-cropping and remain unsupportive of CA. It is concluded that the dominant land degradation narrative, which posits population induced land degradation, may not hold in this case. Instead, the removal of crop residues and low levels of mineral fertilizer and manure amendments may better explain the soil fertility status of the study areas. More nutrient replacement strategies are required if the benefits of CA on soil fertility are to be actualized in the immediate future.

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Reversing Agro-Based Land Degradation through Conservation Agriculture: Emerging Experiences from Zambia’s Smallholder Farming Sector

Umar¹

2012

SAR

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“…Intense directionless occupation of soils in agriculture leads to imbalanced ecology. One of the greatest negative environmental impacts produced by such occupation is the process of soil erosion (Cerdan et al 2002;Van Muysen and Govers, 2002;Usón and Ramos, 2001;Zhou and Zhu, 2001) and the consequent lixiviation of nutrients to the rivers (Drechsel et al, 2001;Sequi et al, 1991;Bittencourt, 1982), causing eutrophication of the water body (Withers and Lord, 2002;Jaworski et al, 1992;Rosensteel and Strom, 1991;Esteves, 1988). It may also cause contamination and pollution of the environment (Manahan, 1994;Rose et al, 1991;Rossi et al, 1991) and cause a potential health hazard (Withers and Lord, 2002).…”

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confidence: 99%

Loss of macronutrients (N, P, K) in the hydrographic basin of the River Ivaí, an affluent of the River Paraná

Guiraud

Lenzi

Luchese

et al. 2004

Braz. arch. biol. technol.

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Influence of some environmental variables in the loss of macronutrients N, P, K, from the hydrographic basin of the (16.0-30.8 and 24.6); pH (5.18-8.50 and 7.15). Statistical analysis of data showed that quantity of macronutrient (N, K, P) carried off from the hydrographic basin of the River Ivaí were directly correlated to fluviometric levels (caused by rainfall and floodings) at 5% level of significance. Carried off quantities, in t a -1 , were N = 25,136.0; K = 21,010.0 and P = 1,161.2.

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“…Nesse sentido, parâmetros físico-químicos, tais como o potencial hidrogeniônico (pH), temperatura (T), potencial de oxidação e redução (Eh) e oxigênio dissolvido (OD) são essenciais, uma vez que alterações destes parâmetros resultam na variação das diversas formas de nitrogênio, que podem atingir concentrações tóxicas para peixes, zooplânctons, algas e para o próprio homem, por sua ligação com alguns tipos de câncer, mutações, anomalias e algumas vezes, até a morte de fetos (metemoglobinemia) por hipoxia e cianose [3][4][5][6][7][8][9][10][11][12][13][14][15].…”

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Dinâmica da série nitrogenada nas águas da bacia hidrográfica Apodi/Mossoró - RN - Brasil

2009

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The Apodi/Mossoró basin is one of the most important water resources in the state of Rio Grande do Norte. Recent studies have shown that nitrogen compounds stand out among the river’s main contaminants. There is thus a need to relate their presence to other physicochemical properties that influence their formation. This paper aims to correlate the concentrations of NO3-, NO2- and NH3 with the values of pH, T, Eh and DO in the waters of this basin. The results indicate the predominance of a strongly oxidizing environment, highlighting NO3- as the main form of nitrogen present, even in places where significant reductions in Eh and OD were observed. This paper gives a contribution for the development of control and treatment of sources of pollution and better management of water resources.

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Population density, soil nutrient depletion, and economic growth in sub-Saharan Africa

Cited by 204 publications

References 9 publications

Reversing Agro-Based Land Degradation through Conservation Agriculture: Emerging Experiences from Zambia’s Smallholder Farming Sector

Reversing Agro-Based Land Degradation through Conservation Agriculture: Emerging Experiences from Zambia’s Smallholder Farming Sector

Loss of macronutrients (N, P, K) in the hydrographic basin of the River Ivaí, an affluent of the River Paraná

Dinâmica da série nitrogenada nas águas da bacia hidrográfica Apodi/Mossoró - RN - Brasil

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