Assessing the effect of soil nutrients on cassava root yield using data from nutrient omission trials conducted in Nigeria and Tanzania.

1. Assessing the effect of soil nutrients on cassava root yield using data from nutrient
omission trials conducted in Nigeria and Tanzania.
Habai R. Masunga1 , Roel Merckx3, Pieter Pypers2, Meklit Chernet2, Guillame Ezui5, Geoffrey Mkamilo4, Peter Mlay1
1Tanzania Agricultural Research Institute (TARI), Ukiriguru Center, Mwanza, Tanzania; 2International Institute for tropical Agriculture (IITA), Central Africa Hub, IITA-ICIPE office, ICIPE, old
Kasarani road, P.O Box 30772 – 00100, Nairobi, Kenya; 3Katholieke Universiteit Leuven, Faculty of Bio-Science Engineering, Kasteelpark Arenberg 20 - box 2459, 3001 Leuven, Belgium.
4Tanzania Agricultural Research Institute (TARI), Headquorter, Dodoma, Tanzania. 5International plant research Institutet (IPPNI), Nairobi. Correspondence author: rafaelhabai@gmail.com
INTRODUCTION
 Cassava requires substantial amount of soil nutrients, particularly nitrogen, phosphorus and potassium
(Osundare, 2014), although it may grows and yield in infertile soils (Odedina et al., 2015).
 Yet the yield response to added nutrients in cassava is variable depending on soil and environmental diversity
(Senkoro et al., 2018).
 Nutrient omission trials is a useful technique to assess the effect of soil nutrients for increased roots production in
various agro-ecologies of cassava producing areas of Tanzania and Nigeria.
OBJECTIVE
 This research was undertaken to determine the effect of N, P and K nutrients for cassava using nutrient omission
trials in diverse environments across the major cassava producing areas of Tanzania and Nigeria
MATERIAL AND METHODS
Experimental design and set up:
 There were two trial set up: set up one had 8 treatments (white) and set u two had 12 treatments (red) (Figure
below). Trials were established in clusters of 10 farmers within vicinity of EA for 3 seasons. NPK was repeated
to extract more variations in fertilized yield.
 Three varieties were planted (Table below) based on accessibility and preferences to farmers in respective areas
of research. These multi-locational trials were laid down in a RCBD where each farmer was equal to a replicate.
Data collection and analysis:
 Crop harvesting was done manually at 12 MAP and yield assessment done in a fresh basis
 Linear mixed model (using R) was used to extract the best linear unbiased predictions (BLUPs); treatments,
season and country regarded as fixed and fields as random term.
Model: yield ~ treatment + season:country + (0 + treatment|fieldID)
RESULTS
Parameter Nigeria Tanzania
Location SW, SE LZ, SZ
Cultivar TME419 (SW, SE) Mkombozi (LZ), Kiroba (SZ)
Gross plot 7x6.4 (44.8m2) 8x7 (56 m2)
Net plot 5x4.4) 22 m2
6x5 (30 m2
Spacing 1 m x 0.8 m 1 m x 1 m
Planting density 12,500 10,000
o On average NPK increased root yield up to 30 t/ha in Nigeria for 2018 season and to 13 t/ha
in Tanzania
o Omission of N and K highly limited root yield in all season in Nigeria and P in Tanzania for
2017 season
Cassava yield response to N, P and K applied (t/ha)
o High yield response to N was 13 t/ha in Nigeria for 2018 season and 7 t/ha in Tanzania in
2018.
o Yield response to K was 6 t/ha in Nigeria for the 2017 and 4 t/ha in Tanzania for 2018, while
response to P was between 3 and 5 t/ha in both Tanzania and Nigeria in all seasons.
CONCLUSIONS
o Application of N, P and K nutrients increased cassava root yields with variations across
regions and growing seasons.
o On average N and K nutrients are highly demanded by cassava in most sites in Nigeria and
P in Tanzania
ACKNOWLEDGEMENT
Authors thank the IITA under ACAI project for funding the current research. We are grateful to our
collaborators and farmers who participated fully in the field work.
Cassava fresh root yield (t/ha)