Nutrient flows and balances in urban and peri-urban agroecosystems of Kano, Nigeria

Type Journal Article - Nutrient Cycling in Agroecosystems
Title Nutrient flows and balances in urban and peri-urban agroecosystems of Kano, Nigeria
Volume 95
Issue 2
Publication (Day/Month/Year) 2013
Page numbers 231-254
Nutrient balances are useful indicators to
assess the sustainability of farming systems. This study
study investigates inflow and outflow of major nutrients
in urban and periurban production systems in Kano,
Nigeria. To this end, 16 households representing three
different urban and peri-urban (UPA) farming systems
were studied using the MONQI toolbox (formerly
known as NUTMON) to calculate nutrient flows and
economic performances. The farm nitrogen (N) balance
was positive at 56.6, 67.4 and 56.4 kg farm-1 year-1
for commercial garden and crop-livestock (cGCL),
commercial gardening and semi-commercial livestock
(cGscL) and commercial livestock subsistence field
cropping (cLsC) farm types, respectively. The same
trend was observed for phosphorus (P) and potassium
(K) in all farm types except an annual negative K
balance of 16 kg farm-1 in cGCL. Across the different
activities within the farms, land uses had positive N
(359, 387 and 563 kg N ha-1 year-1
) and P (74, 219
and 411 kg P ha-1 year-1
) balances for all farm types,
but again a negative K balance in cGCL with an average
loss of 533 kg K ha-1 year-1
. Partial nutrient balances
in livestock production indicated a positive
balance for all nutrients across the farms types but were
slightly negative for P in cLsC. Commercial livestock
keeping (cLsC) was economically more profitable than
the other farm types with an average annual gross
margin (GM) and net cash flow (NCF) of $9,033 and
$935. Cropping activities within cGCL and cGscL had
GMs of $1,059 and $194 and NCFs of $757 and $206,
respectively, but livestock activities in both farm types
incurred financial losses. Potassium inputs were limited
under vegetable and crop production of cGCL,
threatening long-term K nutrient availability in this
system. Overall, the results indicated large annual
surpluses of N and P in urban and peri-urban vegetable
and crop production systems which pose a potential
threat when lost to the environment. Appropriate
policies should aim at promoting sustainable production
through efficient nutrient management in the Kano
UPA sector.

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