Open AccessSpatial trends in the nitrogen budget of the African agro-food system over the past five decades
Author(s) -
Ahmed S. Elrys,
Mohamed K. Abdel-Fattah,
Sajjad Raza,
Zhujun Chen,
Jianbin Zhou
Publication year - 2019
Publication title -
environmental research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.37
H-Index - 124
ISSN - 1748-9326
DOI - 10.1088/1748-9326/ab5d9e
Subject(s) - manure , cycling , agriculture , environmental science , crop , human fertilization , per capita , nitrogen , zoology , agronomy , geography , biology , ecology , chemistry , forestry , population , demography , organic chemistry , sociology
Low nitrogen (N) fertilization is a dominant cause of malnutrition in Africa, but the spatial and temporal variability of N cycling patterns in Africa remain unclear. This study is the first to perform a detailed analysis of the N cycling patterns of 52 African countries from 1961 to 2016. We calculated the N use efficiency (NUE) in crop production, country-specific N fertilization trends, and the impacts of N fertilization on human protein demand and the environment. Over the past five decades, total N input to African croplands increased from 20 to 35 kg N ha −1 yr −1 , while the application of synthetic N fertilizers (SNF) increased from 4.0 to 15 kg N ha −1 yr −1 . N contributions from animal manure and biological N fixation remained lower than 10 kg N ha −1 yr −1 and 20 kg N ha −1 yr −1 , respectively. The total N crop production increased from 15 to 22 kg N ha −1 yr −1 from 1961 to 2016. Total N surplus in Africa increased from 5 to 13 kg N ha −1 yr −1 , while estimated gaseous losses increased from 4.0 to 11 kg N ha −1 yr −1 . However, NUE declined from 74% to 63% during the past five decades, and protein consumption increased from 2.99 to 3.78 kg N capita −1 yr −1 . These results suggest that Africa suffers from extremely low N input and that N loss is increasing in agricultural land. We recommend the implementation of an effective N management strategy incorporating the use of locally available organic material along with the balanced application of SNF. Such measures will require effective policy development and cooperation between all stakeholders.