The document discusses the opti-fert program implemented at a flower farm in Thika to improve fertilizer use and reduce water waste through irrigation management. It comprises two phases: monitoring nutrient leaching and optimizing irrigation and fertilization based on data from soil water extractors and moisture probes. Results indicated a significant reduction in nutrient leaching, irrigation volumes, and fertilizer input, alongside improvements in soil health and crop quality.

1. OPTIFERT
Nutrient Leaching; Irrigation control;
Soil Water Extractors; Irrigation; Soil
Moisture Probes

2. Introduction
• Cropnuts has been testing OPTIFERT at a flower
farm in Thika farm from Feb 2014 till Sept 2014.
• OPTI-FERT is a two stage program with the
objective of improving fertilizer use and reducing
water waste through excessive irrigation:
1. PHASE I: Monitoring of nutrient leaching down the
profile derived from the current practices, and
2. PHASE II: Implementation of corrective
management, optimizing irrigation and fertilization
• The method involves the use of Soil Water
Extractors (SWE) and a Soil Moisture Probe.

3. Methodology
• Soil Water Extractors (SWE)
– Inert porous ceramic cup allows the soil solution to
freely permeate into & out of the instrument
– SWE installed next to a drip line; Soil solution extracted
twice a week
– 9 SWE were installed in 3 locations at 30, 60 & 90cm
– The samples were analysed in the lab for drain water to
quantify nutrients (in particular Ca & NO3)
• Aquacheck Soil Moisture Probes
– 8 sensors distributed every 10cm down to 80cm
– One reading per sensor every 30min;
– Data is stored & uploaded onto an online server every 2
hours and visualized using an online software

4. Results
• Phase I: irrigation of 40m3/ha/day in one event
– Evidence of strong nutrient leaching in all sites
(highest levels of NO3 and Ca at 60 and 90 cm)
• Phase II: irrigation volumes and events reduced
and regulated based on Aquacheck probe data
– Reduction of nutrient leaching by 60%
– Reduction of water consumption by 25%
– Reduction of fertilizer input by 15%

5. Results – Leaching
• Average effect of improved water management:
– 47% less nitrates in A60 and 52% less in A90
– 34% less calcium in A60 and 61% less in A90

6. Results – Soil Moisture
• Time span of graph: 10th June – 8th August
– Moisture content (%) at 6 of the 8 levels
Root activity within top 20cm
Excessively wet profile allowed to dry:
Increasing root activity in 30cm & 40cm

7. Results – Soil Moisture
• Root zone graph
– Moisture content (%) in the root zone
RAW
(60%
of
AWC)
Upper management zone line (apply water to here) URAW
Lower management zone line (apply water now)
LRAW
VERY WET START OF MANAGING
PROFILE ALLOWED TO DRY

8. Aquacheck Soil Moisture Monitoring
• Aquacheck allows managing irrigation precisely,
telling the management when & how much to
irrigate
• Irrigate up to the URAW line and dry to the
LRAW line before irrigating
• No more over-irrigation
– Reduction of water wastage & leaching of fertilizer;
– Increased soil aeration for healthier, deeper, roots

9. Conclusion
• The SWE allowed to quantify the leaching of nutrients down the
profile
• Over-irrigation due to uncontrolled irrigation management has been
the cause of leaching
• Reducing the irrigation (volumes & events) led to a reduction in
leaching
• Irrigation management (and soil aeration) can be improved using
Aquacheck
• It is believed that appropriate irrigation management will also lead to:
– Improved crop quality (bud size, stem shelf life)
– Improved general crop health
– Hardiness of crop (due to deeper roots)
– Reduced incidents of disease

10. OPTI-FERT
Thank You