Session 2 2 Development of the Best Intercropping Practices Decision Support Tool

Development of the
Best Intercropping Practices (IC)
Decision Support Tool (DST) – Version2
www.iita.org | www.cgiar.org | www.acai-project.org

Overview
Best Intercropping Practices DST:
1. Introduction (Veronica Uzokwe):
• The IC use case
• Learnings from the baseline
• Summary of year 2 achievements
2. Field activities (Mark Tokula and Haji Saleh):
• Field activities: Intercropping trials
• Field trial results
3. Advances with the DST development (Christine Kreye):
• Modelling framework
• Year1 – Year2 validation results
• The Decision Support Tool
4. Validation exercises (Chris Okoli and Wiston Mwombeki):
• First impressions from ongoing validation exercises
• Next steps and additional data needs

Introduction
Best Intercropping Practices DSTs:
• Specific purpose: recommend optimal time of planting, crop density and fertilizer application for
a maize (NG) / sweet potato (Zanzibar) intercrop to increase overall productivity
• Requested by: FCI (TZ) and 2SCALE (NG)
• Other partners: SG2000 (NG)
• Intended users: Extension Agents (EAs) supporting cassava growers
• Expected benefit: Intercrop yield increased by 2 tonnes/ha and cassava yield not affected or increased
by 0.5 tonnes/ha realized by 35,100 HHs, with the support of 124 extension agents,
on a total area of 17,550 ha, generating a total value of US$3,948,750
• Current version: V2: uses expert knowledge to estimate current crop performance and revenue based
on default or user-defined prices of roots and intercrop produce to recommend best
planting time, planting density and fertilizer regime for a preferred set of varieties,
maximizing overall net revenue or intercrop yield without affecting cassava yield
• Approach: Decision tree model based on analysis of field trial data
• Input required: Cropping objective (maximize total revenue or maximize cassava yield), prices of
intercrop produce (maize cobs (NG) / sweet potato (Zanzibar)) and cassava roots,
willingness to invest in fertilizer and knowledge of field history
• Interface: Paper-based decision tree, including guidelines for simple calculations to estimate
profitability

Principles of the Best Intercropping Practices Tool
1. Obtain details on current practice
2. Identify alternative options within given constraints
3. Evaluate to what extent the performance of alternative options is location-dependent, based on
analysis of multilocational field trial data
4. If so, identify GIS (or other) predictor variables to estimate location-specific effects of
interventions on intercrop yield and cassava root yield
5. Convert yield effects to changes in gross revenue based on prices of intercrop produce and
cassava roots (default values or user input)
6. Calculate net revenue (subtract cost of fertilizer)
7. Recommend optimal intercrop density, relative time of planting (Zanzibar only) and fertilizer regime
(if willing to invest in fertilizer) that maximizes cassava yield or overall net revenue using a
decision tree model
The IC-DST is developed based on following steps and principles:

What is current practice? – learnings from the RC survey
Tanzania (Zanzibar)
38% of cassava is intercropped, of which 45% by
sweet potato (45%), planted at the same time (67%)
or ± 2 weeks (29%). 0% of farmers apply fertilizer to
the sweet potato intercrop, and 62% commercialize
at least half of sweet potato produce. Main objective
is maximizing land use efficiency.
Nigeria
68% of cassava is intercropped, of which 75% by
maize, planted 2 weeks earlier (33%) or at the same
time (30%). 43% of farmers apply fertilizer to the
maize intercrop, and 94% commercialize at least half
of the maize produce. Main objective is faster access
to food and income.
Need picture here!

What are the alternative options?
2. Optimize the relative time of planting of the intercrop
• Reduce competition for light for the cassava crop
• Optimal time of planting will depend on the cropping objectives
3. Apply fertilizer
• Increased availability of nutrients (reduced belowground competition)
• Intercrop as an entry point for fertilizer application to cassava (benefits from residual effects)
• Modify the composition of the fertilizer regime to the specific cropping objectives
1. Modify (increase) the crop density:
• Optimize land use efficiency
• Choose best variety with minimal above- and belowground competition effect

Modelling framework
Are the effects of density and fertilizer application
dependent on field conditions?
Evaluate through multilocational field
testing covering target environments
Develop decision
tree models
Can we predict these effects
based on expert knowledge?

V1 version of the IC DST (end of 2017)

Intercropping Trials - Nigeria
Current overview of trials and status of trials
Nigeria CIM 2016 CIM 2017
Zone planted harvested
maize
harvested
cassava
planted harvested
maize
harvested
cassava
South East 85 73 73 110 99 99
South West 47 45 44 66 39 47
Total 132 118 117 176 138 146

Harvest and establishment of 2 sets of trials based on step-wise intensification
CIM-2 trials:
 Planted in 2016
 Harvested in 2017
CIM-3 and CIM-4 trials:
 Planted in 2017
 Harvested in 2018
Overview of year 2-3 trials

Impressions and learnings from the field – some pictures
• Farmers generally prefer intercropping maize with cassava in southwest Nigeria as they see it as a
means to getting some quick income while waiting for cassava, which is partially reinvested to
maintain the cassava plots.
• Farmers do not see any negative effect of planting maize with cassava but noticed that the planting
position of cassava relative to maize is crucial to attain high benefits in a cassava-maize intercrop.

Model: yield ~ 0 + MaizeLevel + Fertilizer + (0 + Fertilizer|fieldID)
Results 2017-2018 trials
Cassava root yield (2018)
= 40,000 maize plants/ha
Fertilizer
Maize Fertilizer = Fertilizer regime
targeting maize crop
Cassava Fertilizer = Fertilizer regime
targeting cassava crop
Yield penalty of ~ 1 t/ha when
intercropping with maize at high
density vs. low density.
No difference between the two
fertilizer regimes. Both increase
yield by ~3 t/ha.

Model: yield ~ 0 + MaizeLevel*Fertilizer + maizeVariety + (0 + Fertilizer|fieldID)
No reward in additional maize cobs
from increased planting density
without fertilizer application.
Higher cob yields when targeting
fertilizer to the maize crop.
Maize cob yield (2017)
Fertilizer
Maize Fertilizer = Fertilizer regime
targeting maize crop
Cassava Fertilizer = Fertilizer regime
targeting cassava crop

Relating variation in yield response to maize height…
Recursive partitioning for simple decision rule:
• Control maize is a good indicator to
distinguish response classes
• All fields were responsive;
only 1 field with maize height < 50cm,
only 10 fields with maize height > 150cm
• Highest response if control maize height =
100-150 cm

Factors 2016 - 2017 2017 - 2018
Cassava density High cassava density → higher
cassava yield
Only high density cassava throughout
Cassava density Cassava yield not affected by maize
density
Slight yield penalty of cassava (~ 1t /ha) at
high maize density
Maize density High maize density → always higher
cob yield
Low maize density → safer without fertilizer
Fertilizer F1 is suitable in both crops confirmed
Intensification
steps
High density maize and cassava
without fertilizer →
high density crops with fertilizer
Low density maize + high/low density
cassava without fertilizer →
high density crops with fertilizer
Indicator maize
height
Suitable to indicate fertilizer
application
Not confirmed (see validation exercises)
Maize variety Higher yields of white maize in Benue Same trend in validation exercises
Comparison of 2017-2018 and 2019-2019 results

Intercropping Trials - Zanzibar
Evaluate effects of planting density, planting time and fertilizer application
on sweet potato:

Current overview of trials and status of trials
Zanzibar CIS 2017 CIS 2018
planted harvested
sweetpotato
harvested
cassava
planted harvested
sweetpotato
harvested
cassava
Unguja 75 66 64 75 68 ongoing
Pemba 25 22 22 25 17 ongoing
Total 100 88 86 100 85

SWP monocrop – no fertilizer
SWP monocrop + fertilizer
SWP intercrop simultaneous planting
+ fertilizer
SWP intercrop planted @ 2 weeks delay
+ fertilizer
SWP intercrop planted @ 2 weeks
delay – no fertilizer
Cassava monocrop – no fertilizer

On-farm trials with 80 farmers across Unguja and Pemba
Sweet potato yield 2017
Conclusions from 2017 sweet potato harvest
Sweet potato suffers somewhat from
competition with cassava, with yield losses of
5 – 15% (higher in high-yielding fields).
Delayed planting of sweet potato causes yield
reductions of 0 – 45%.
Increasing density is not advantageous for a
sweet potato intercrop. A density of 10,000
vines/ha is recommended.
Effects of density and relative planting time
depend on time of planting and amount of
rainfall received.

Sweet potato yield 2017 Cassava yield 2018
Negative effects of sweet potato intercropping on cassava yield observed, and similar (-6.6 t/ha ~ -37%) in both systems.
Significant variation between sites in effects of intercropping on cassava yield, varying between -5% and -60% (LER = 1.4 – 1.9).

Sweet potato yield 2018
Competition effects of cassava on sweet potato are more severe than in 2017!
with yield reduction of ~30% if planted simultaneously, and ~50% if sweet potato planting
is delayed by 2 weeks (very consistent across locations).
Cassava harvest planned in February – March 2018. If cassava yield reductions remain
around 40%, then LER = 1.1 – 1.5.
Tested technologies (increased density and delayed introduction of sweet potato) do not
result in yield increases. Farmer’s most common practice (simultaneous planting of a
low density sweet potato crop) appears best-performing.
Cassava – sweet potato intercropping is only sensible if the farmer wishes to maximize
land use efficiency, and grow both crops with priority to the sweet potato. The farmer
must be willing to accept substantial losses in cassava yield.
Use of fertilizer to increase yield could be further tested.

How are these results fed into the DST?
Nigeria:
1. There is a small yield penalty for cassava roots of about 1 t/ha by intensification in maize
2. There appears to be higher uncertainty and fluctuation in cassava root than maize cob prices
=> also base V2 on responses of maize
3. Lessons from the first trials and validation exercises for maize
• Farmers value fresh maize cobs for the market
• Evaluate responses by cob size
• Not all LGAs have a market for fresh cobs => include dry cobs int V2
• Large cobs fetch highest prices; base decisions on this fraction
• Use trials of 2017 (CIM-3 and CIM-4) for V1 development
4. Response to higher planting density of large maize cobs is not site-specific and low (for the
selected maize variety) => low density will be the blanket recommendation for maize.
5. The height and appearance of maize (without fertilizer application) at tasselling can be used as
indicator for the response to fertilizer.
6. The maize fertilizer regime (F1) is preferred in all situations (over F2).
7. Maize cob prices and fertilizer availability and cost will drive the decision-making in the DST.

Packaging in a tool for field use
How to make this framework available for quick and easy use?
IC-DST packaged as a simple paper-based decision tree with inputs:
1. Variety recommendation:
• erect cassava
• early maturing maize (90-95 days)
2. High planting densities
• cassava: 12,500 plants ha-1
• maize: 40,000 plants ha-1 if fertilizer is applied / high fertility conditions,
20,000 plants ha-1 otherwise
3. Fertilizer regime:
• target the maize crop
• cassava benefits as well
4. Fertilizer recommendation:
• site-specific
• use farmers’ experience with their maize crop
(plant height at tasselling)
5. Profitability of fertilizer application:
• based on expected additional large maize cobs
• look-up table [cost of fertilizer x price of large cobs]
• formula for easy calculation

Can the maize height be used to predict fertilizer use?
Do measured maize height and farmers’ estimates match?
→ usually correct for tall maize
→ difficult to distinguish medium and low height
Numbers / category
Previous maize height Low Medium Tall Total % correct
low 0 3 9 12
% 0 3 8 11 0
medium 3 28 18 49
% 3 26 17 46 57
tall 0 6 40 46
% 0 6 37 43 87
Total 3 37 67 107
% 3 35 63 100
Measured maize height in LM

How to capture maize performance without input use?
1 2 3 4 5
Visualization of expected maize performance (if grown without fertilizer input)
Likely unresponsive
to sole fertilizer
(improve soil fertility:
apply manure)
Recommend fertilizer application
Standard recommendation
No economically
justified response

How are these results fed into the DST?
Zanzibar:
Sweet potato
1. Sweet potato suffers from cassava, yield losses of 5 – 30% (higher in high-yielding fields), less than
observed in other studies.
2. Delayed planting of sweet potato causes yield reductions of 0 – 50%.
→ Plant sweet potato and cassava at the same time
3. Increasing density is not advantageous for sweet potato (but has advantages for weed control).
→ Recommended density = 10,000 vines/ha in intercrop.
4. Effects of density and relative planting time are not site-specific.
→ Recommendations will mainly be driven by cropping objectives and sweet potato tuber prices
Cassava
1. Intercropping reduces cassava yield by 5 – 60%
→ Yield penalty is site-specific
2. LER remains positive
3. Intercropping can be recommended when the farmer wants to maximize land use efficiency.
→ sweet potato is the more important crop

Validation exercises – pilot study
• Currently 243 farmers across Tanzania and Nigeria involved in
pilot validation exercise…
• Supervised by trained extension agents, and coordinated by
primary development partners (SG2000 and Psaltry/2Scale
in Nigeria, and FCI in Tanzania to start in 2019)
• NARS teams of agronomists assist in training and monitoring.
• DSTs and all data collection through a suite of ODK forms

Validation exercises – overview
153 submissions on “Best Intercropping Practices” recommendations
143 validation exercises established, spread across 5 states (Oyo, Ogun, Benue, Cross River, Anambra)

Current maize performance:
16%: < knee-height → Don’t apply fertilizer, apply manure and improve soil fertility
43%: knee to chest height → Apply fertilizer, if price ratio cobs/fertilizer is favourable
41%: > chest height → Apply fertilizer, if price ratio is favourable but lower response
Does this hold? Too conservative?
Overview input parameters
• Price of cassava most variable
• Price of maize: 5-25 USD/100 cobs
• Cost of urea: 20-30 USD/50 kg bag
• Cost of NPK: 15-25 USD/50 kg bag
Some outliers / unrealistic costs or prices!
Cost of input & price of produce:

So what is being recommended?
47%: medium maize and
favourable price ratio
Recommend applying fertilizer
26%: medium maize but
risky price ratio
Do not apply fertilizer
11%: medium maize but
unfavourable price ratio
16%: low or tall maize

Results: maize yield effects
• Increased density only does not increase
nr of large or medium cobs, it only results
in more small cobs and more cobs that
are unfit for sale.
• About 25% of farmers have decreased
numbers of large and medium cobs from
increasing density only.
• Fertilizer application to a high density
maize crop increases cob numbers for all
classes, and especially more large and
medium cobs. This increase is significant
for 75% of farmers, varying between
2,500 – 10,000 more large cobs per
hectare.
• No negative effects of fertilizer application
observed on cob numbers.

Results: net revenue
• Increased density only did not entail an
overall increas in net revenue.
• For about 25% of farmers, increased
density resulted in small decreases in net
revenue.
• Fertilizer application to a high density
maize crop increases net revenue by on
average 350 $/ha (~ project target).
• About 2/3 of participants realize a
significant net revenue increase. Only a
minority (~5%) observed a small negative
impact on net revenue.
Was this as predicted by the DST?

Results: Evaluation of recommendations
Low density High density
High density
+ fertilizer
High density 10% 14% 36%
High density
+ fertilizer 4% 5% 31%
Best performing
Recommended

High density
+ fertilizer
High density
Best performing
Recommended
Correct recommendation!

High density
+ fertilizer
High density
Best performing
Recommended
Incorrect recommendation but no loss in revenue and no added cost

High density
+ fertilizer
High density
Best performing
Recommended
Incorrect recommendation with loss in revenue and limited added cost

High density
+ fertilizer
High density
Best performing
Recommended
Incorrect recommendation with loss in revenue and limited added cost
Incorrect recommendation with loss in revenue and substantial added cost

4% 5% 31%
10% 14% 36%
Limited loss in net revenue:
DST performs acceptably.
Lost opportunity in revenue:
DST is too conservative.

What if we change the decision rules?
1. Allow fertilizer application to tall maize
2. Set minimal VCR to 1.2 instead of 2 $/$

8% 15% 52%
7% 4% 16%
Proportion of correct recommendations increases from 44% to 56%
Proportion of incorrect recommendations with high cost
increases from 9% to 23%, but loss in revenue is limited.

How do we best handle risk?
1. Conservatively by minimal VCR of 2 $/$
• Some farmers loose opportunities;
• others are better protected against real loss of money
2. Risk friendly by minimal VCR of 1.2 instead of 2 $/$
• More farmers can realize their opportunities
• More farmers are at risk of loosing real money
3. Let the farmer choose the minimal VCR
• Farmer can make the choice about the risk (s)he is taking
• How well can farmers assess whether they can take a higher risk?

Key Activities
Key activities held in preparation of validation exercises
Discussion with partners around on-farm trial
• Selection and training of farmers to participate in the
trials management
• Over 100 farmers from 10 clusters were engaged:
7 clusters in Unguja and 3 in Pemba
• Major work for period was on trials management and
data collection
• Validation exercise to start in year 2019.
Evaluation of sweet potato and cassava crop performance

Testimonies from farmers
Mr Jeshi, from Bumbwini, FCI
Intercropping sweet potato and cassava is done out of
tradition. However these scientific studies are helping us
to get meaning to what we have been doing:
• Time of introducing sweet potato- we expect to see
the difference between plating time
• Spacing between plants and lines
• Application of fertilizers
I am eager to learn more and apply lessons immediately.
“Group training and experience sharing enhance
quick learning.”

Akama, from Donge Vibweni, FCI
(not on photo)
• Akama is a lady participating in ACAI project
• She testifies that the knowledge from proper
intercropping is helping her:
• Better land utilization
• To manage yield of both crops
• Increased household income from sale of both crops
• Sweet potatoes are increasingly becoming
commercial crop hence requires proper handling
“Farmers are looking forward to development of
tools to support their farming activities for the
two crops which are vital for food and income.”

Deve Suleiman- From Machui, FCI
(in blue shirt)
• Deve participates in ACAI project as a trained
Extension Agent.
• He is an influential farmer in his area (Machui).
• He says that while intercropping is not new,
the current knowledge is new and beneficial.
• Previously they were doing randomly hence
affecting yield of the main crop as well as the
intercrop.
“The entire process is helping farmers to
appreciate new knowledge, for example on
the use of fertilizer.”

Validation exercises NG – impressions from the field

Key Activities
Key activities held in preparation of validation exercises
Indoor training-of-trainers
Field demarcation exercise
Role play of IC-DST validation exercise

Key Activities
Objective: To observe and emulate the optimum
cassava and maize intercropping practices (IC)
Decision Support Tool (DST) under validation.
Farmer field days held by SG2000
SC reacting to farmers questions at Anambra
Farmer field day at Agir Gwer, Benue state
Date and Location:
• Anambra state – 17th, 27th & 28th Aug 2018 at
Umunze, Ukwwulu & Omogho
• Benue state – 19th, Oct,2018 at Apir

Kehinde Akingbade – SG2000 OG
I have learnt:
• about planting of one maize seed per hole.
• about spacing of 0.8m x 1m.
• new method of fertilizer application –
application of fertilizer between maize and
cassava.
• not to burn vegetation debris during land
preparation.
I was surprised that the maize was due for
harvest in just two months. This will give
farmers opportunity to plant maize up to three
times in one raining season.

Testimonies from Extension Agents
• I have learnt application of fertilizer at
planting. I formerly knew of fertilizer
application at 4WAP.
• I have learnt about planting of one
maize seed per hole.
• I now know ho to use ampligo for
control of army worm.
Adedayo Popoola – SG2000 OG

• I have learnt about maize spacing of
25cm x 25cm as against the traditional
1m x 1m and 50cm x 50cm.
• I have learnt about cassava spacing of
0.8m by 1m against 1m by 1m.
• I now understand importance of
effective monitoring of cassava field.
• I have learnt how to use ODK for data
collection.
Margaret Asuo – SG2000 CR

Chris E.Okoli – SG2000 AN
• Rewarding the EA for every activity performed
encourages hard work.
• I have learnt to plan an exercise, train, supply
materials and inputs as at when due and
supervise. This leads to quality data generation
and high yields.
• I have learnt how correct NPK fertilizer to a
maize intercrop can substantially increase cobs.
The validation exercises have exposed SG2000 to the use of smartphones in
extension delivery. The EAs can now advice the farmers right there in the field with
the use of smartphones to access the DSTs. The EAs can now easily collect data in
the field with the use of ODK.
Suggestion: DSTs should be available in English and in local languages.

Validation exercises – Next steps
• Do EAs and farmers understand the principles of the DST?
• Do they make sense to them?
• Do they agree with the emphasis on maize (maize to pay for the fertilizer)
• Are there concerns about high maize density when fertilizer is applied?
• What do they consider the reduction in cassava yield?
• What is the risk of army worm infestation and impact of pest control cost?
• Will the use of the DST influence their decision making at farm level?
• Land allocation for intercropping
• Change in market / trader who would buy higher amounts
Use the field day to interact with EAs and farmers !
Get more answers…

Thank you very much !!!
Questions and discussion

Session 2 2 Development of the Best Intercropping Practices Decision Support Tool

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Session 2 2 Development of the Best Intercropping Practices Decision Support Tool