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Improved crop management systems for
sustainable cassava production in sub-Saharan
Africa
African Cassava Agronomy Initiative (ACAI)
Second Annual Review Meeting
and Planning Workshop
11 – 15 Dec. 2017
Gold Crest Hotel, Mwanza, Tanzania
Joy Adiele

Improved crop management systems
for sustainable cassava production in
sub-Saharan Africa
Joy G. Adiele

Van Ittersum & Rabbinge,
Field Crops Res. (1997)
YIELD GAP
Production ecological principles

nutrient-limited production situation
© Wageningen University & ISRIC

Objectives
 Quantify effects of optimized NPK combination when tested on poor soils
and effects of micro-nutrient addition on nutrient use efficiency and yield
 determine how K nutrition influences light and nutrient use efficiency of
cassava, relative growth and death rate of the leaves, rate of development,
and partitioning fractions
 understand the dynamics of soil nutrient availability and uptake by cassava,
in order to provide the right dose of fertiliser at the right time and increase
the recovery rate
 test and improve current cassava crop growth models in order to;
 better accurately assess yield gaps,
 test approaches to identify nutrient deficiencies
 provide insight in fertilizer requirements that may lead to improved
fertilizer blends

Agro-ecological map of Nigeria

Morphological assessments
Intermediate
harvests
Final
harvests
Pre-
planting
soil
sampling
Post
harvest
soil
sampling
Materials & Methods
1 42.5 1280
Months after planting

Treatment acronyms
Trt/plot
number
Treatment Nitrogen
(kg N ha-1)
Phosphorus
(kg P ha-1)
Potassium
(kg K ha-1)
Micro-nutrient
S-Ca-Mg-Zn-B
1 N0PfKfMn 0 100 300 +
2 NfP0KfMn 300 0 300 +
3 NfPfK0Mn 300 100 0 +
4 NfPfKfMn 300 100 300 +
5 NfPfK1Mn 300 100 240 +
6 NfPfK2Mn 300 100 180 +
7 NfPfK3Mn 300 100 120 +
8 NfPfK4Mn 300 100 60 +
9 NfPfKfMn0 300 100 300 -
10 NOT full rate 150 40 180 -
11 NOT half rate 75 20 90 -
12 Control 0 0 0 -

Results
0
50
100
150
200
250
300
350
400
450
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
April
May
June
July
Aug
Sept
Oct
BenueRainfall(mm)
Aug 2016 - Oct 2017
Benue
Limiting
nutrients – N & P
4 MAP, NFPFKFMN0 - highest yield @ 10.33 fresh
yield t/ha
Final harvest- significant increase among all
treatments
NFPFKFMN0 - highest yield @ 70.05 t/ha. Control
had the lowest yield of 27.02 t/ha
 Second harvest - low yield increase

0
100
200
300
400
500
600
700
800
900
Sep
Oct
Nov
Dec
Jan
Feb
Mar
April
May
June
July
Aug
Rainfallamount(mm)
Sep 2016 - August 2017
Results
Cross River
Most limiting
nutrients – N
At ~4MAP, NFPFKFMN0 recorded the
highest yield @ 23.84 fresh yield t/ha
At final harvest, NFPFKFMN0 had the
greatest yield at 113.5 t/ha. Control
maintained the lowest yield of 26.25 t/ha

The NFPFKFMN0 maintained the
highest fresh root yield of 126.5 t/ha at
final harvest, with the control
recording 31.17 t/ha, the lowest . The
most limiting nutrient was K
ResultsEdo
Most limiting
nutrients – K

Amongst the 3 location,
Edo recorded the
highest yield among the
treatments, except in
the treatment where K
was limited.
Results

Results
Benue
Cross river
RootyieldtonsDM/ha
RootyieldtonsDM/ha
RootyieldtonsDM/ha
Edo

The second year data of the trials are being collected. PhD field project will be
concluded by June-July, 2018
Proposed PhD thesis defense comes up in June 2019
Way forward
It is expected that both yields and the efficiency
of nutrients applied will strongly improve and
that the financial risk for farmers will be
effectively reduced

Water Availability and Potassium
Uptake of Cassava, Nigeria
Rob van den Beuken

Water Availability and Potassium
Uptake of Cassava, Nigeria
Rob van den Beuken
MSc student, WUR

Introduction
 Water availability affects:
– Nutrient availability
– Crop nutrient demand
 The response of cassava to water limitation is well
researched:
– Maintains root growth
– Reduces leaf canopy
– Partially closes its stomata

But...
 The effect of water limitation on nutrient uptake of
cassava is not well known
 This research will focus on Potassium, because it is one
of the main macro nutrients for cassava and strongly
related to soil moisture
 Potassium (K), plays a major role in:
 translocating assimilates to the storage roots
 Stomatal regulation

Research Question & Hypotheses
Question:
How does potassium uptake affect cassava growth in relation to
soil moisture content in Nigeria?
Hypotheses:
 Soil moisture content strongly affects K uptake (demand and
availability)
 K uptake increases the maximum rooting depth (fibrous roots)
 Transpiration is reduced when K uptake is low, because of the
increasing stomatal resistance during daytime

Methodology
 Set up a water balance based on soil physical properties:
 Air dry, wilting point, field capacity, saturation soil
moisture content
 Rooting depth measurements
 Stomatal resistance and leaf temperature measurements
over time
 Implement K uptake and findings in the LINTUL-Cassava
model to see the overall effect on cassava growth

 Soil parameters:
 Soil water characteristics (field capacity, wilting point, saturation):
Pedotransfer functions
 Maximum rooting depth, etc
 LINTUL calibrated for cassava
Summary
LINTUL (Light Interception and Utilization):
 Crop parameters:
 Light use efficiency: 1.40 g biomass DM MJ−1 IPAR (Veltkamp,
1985), 1.5 g biomass DM MJ−1 IPAR (Ezui et al., 2017)
 Light extinction coefficient,
 Storage roots bulking initiation (40-45 days after planting for
TME 419)
 Root growth rate

Thank
you!
?