1 Introduction
August marked the end of harvest for most maize farmers in Kenya. As they clear their fields and prepare for the next season, one question dominates their minds: will they be able to afford the fertilizer that makes or breaks a good harvest?
Diammonium Phosphate (DAP) is the go-to fertilizer at planting. Farmers trust it because it consistently delivers higher yields. But while households across the country are paying more for essentials like maize flour and cooking oil, the uncertainity is whether fertilizer prices are also climbing. If they are, farmers face a tough choice - stretch already thin budgets, scale back on fertilizer, or turn to alternatives like locally available manure from subsitence farming.
This case study explores county-level market price data from the Ministry of Agriculture & Livestock Development to answer two critical questions:
- Are DAP fertilizer prices rising?
- Can maize farmers realistically afford them this season?
The answer matter not just for farmers, but for every Kenyan who relies on maize as the staple food.
2 Methods
This case study draws on county-level market price data from the Ministry of Agriculture & Livestock Development, provided in Excel format. The data was first uploaded into a PostgreSQL database for structured storage, where SQL queries were used to clean and standardize it for further analysis in R.
In R, categorical variables such as fertilizer type, market, and county were converted into factors, duplicates were removed, and descriptive labels were applied. Outliers were detected and excluded using the Interquartile Range (IQR) method to ensure reliability.
Once cleaned, exploratory data analysis (EDA) was carried out to understand distributions and guide the analysis. At the national level, descriptive statistics were used to compare the average retail prices of all fertilizer types. At the county level, the focus narrowed to DAP, where averages, deviations, and price ranges were examined to capture both cost levels and local variability.
To assess price movements over time, a line plot was produced, and year-over-year changes were calculated to evaluate whether DAP retail prices were rising, falling, or stabilizing across different markets.
3 Results
3.1 Price
3.1.1 National-Level Variation
DAP currently stands out as the most expensive fertilizer, retailing at an average of Ksh120 per kilogram. This makes it Ksh20 higher than NPK (Ksh100), the closest and most commonly sought alternative. For farmers buying in bulk, that Ksh20 difference quickly adds up, making NPK the more affordable option for those looking to cut costs.
Other fertilizers, such as Urea (Ksh89), TSP (Ksh82), MOP (Ksh80), CAN (Ksh75), Sulphate of Ammonia (Ksh63), and Ammonia Anhydrous (Ksh61), are all significantly cheaper. However, their usage patterns differ — many are applied at different stages of crop growth or for specific soil conditions, meaning they are not direct substitutes for DAP during planting.
3.1.2 County-Level Variation
While the national average price of DAP stands at Ksh120 per kg, county-level retail prices show notable variation.
| Kisumu offers DAP at a cheaper retail price | ||||
| DAP goes for an average of Ksh110 per Kg - this makes it Ksh10 cheaper than the national average of Ksh120 per Kg. | ||||
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Retail Price
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|---|---|---|---|---|
| Fertilizer | County | Average | Deviation | Range |
| DAP | Kitui1 | KSh125.00 | KSh0.00 | KSh125 - KSh1251 |
| DAP | Kirinyaga | KSh120.00 | KSh0.00 | KSh120 - KSh1202 |
| DAP | Kakamega | KSh118.00 | KSh18.00 | KSh100 - KSh136 |
| DAP | Embu | KSh114.00 | KSh2.00 | KSh112 - KSh116 |
| DAP | Kisumu | KSh110.00 | KSh5.00 | KSh105 - KSh115 |
| 1 In Kitui, DAP retails at a fixed average price of Ksh125 per Kg - Ksh5 higher than the national average. | ||||
| 2 In addition to lower average price (Ksh120), the low deviation of Ksh2 means retail prices do not fluctuate that much compared to Kakamega (Ksh9). | ||||
| Source: Ministry of Agriculture & Livestock Development | ||||
Kitui records the highest retail price at Ksh125 per kg, which is Ksh5 above the national average. Kirinyaga aligns with the national figure at Ksh120, while Embu is slightly lower at Ksh115. Kakamega averages Ksh114, though with a wider deviation of Ksh9, indicating more fluctuation across outlets. Kisumu provides the lowest average price at Ksh110 per kg, Ksh10 below the national benchmark, and with a low deviation of Ksh2, suggesting relatively stable pricing.
This shows that while prices in some counties remain fixed or fluctuate only slightly, farmers in places like Kisumu currently benefit from the most affordable and consistent retail price.
3.2 Trend
3.2.1 Overall Trend
Retail prices of DAP and NPK have not been falling as quickly as farmers might hope.
From late 2021 into 2022, DAP prices spiked sharply, peaking around Ksh130 per kg — a steep increase from the 2021 average of Ksh80. NPK followed a similar upward trajectory, though consistently Ksh20 cheaper than DAP.
Since 2023, both fertilizers show signs of easing, but the pace of decline has been slow. By 2025, DAP stabilized at around Ksh120, only slightly lower than its 2022 peak, while NPK hovered near Ksh100. The year-over-year decreases are smaller than in past years, meaning farmers are still paying near-record prices. In practical terms, this “slower relief” means input costs remain a heavy burden despite the slight downward adjustments.
3.2.2 Year-Over-Year Change
Retail prices of DAP fertilizer have eased since their 2022 peak, but the pace of decline has been small compared to the earlier spike.
| Slower price relief for farmers | ||||
| as retail price show smaller year-over-year decreases compared to past years. | ||||
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Average Retail
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Change
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|---|---|---|---|---|
| Year | Fertilizer | Price | Price (Ksh) | Percent (%) |
| 20211 | DAP | KSh80.00 | KSh0.001 | 0.00%1 |
| 20222 | DAP | KSh130.00 | KSh50.002 | 62.50%2 |
| 2023 | DAP | KSh128.00 | −KSh2.00 | −1.54% |
| 2024 | DAP | KSh120.00 | −KSh8.00 | −6.25% |
| 2025 | DAP | KSh120.00 | KSh0.003 | 0.00% |
| 1 2021 acts as the baseline explaining the KSh0 and 0.00% values in year over year change. | ||||
| 2 On average, retail price in 2022 rose by 62.50%, that’s KSh50 more compared to 2021. | ||||
| 3 DAP retails at an average of KSh120 - same as last year | ||||
| Source: Ministry of Agriculture & Livestock Development | ||||
In 2021, DAP retailed at an average of Ksh80 per kg. By 2022, prices surged to Ksh130 — a 62.5% increase, the sharpest rise in recent years. The following years brought only limited relief. In 2023, prices fell slightly to Ksh128 (−1.5%), and in 2024 dropped further to Ksh120 (−6.3%). By 2025, the price remained unchanged at Ksh120, showing no additional reduction.
This trend reveals that while the steep increases of 2022 have moderated, the downward adjustments since then have been minimal. Farmers therefore continue to face high fertilizer costs, with retail prices essentially plateauing at near-record levels.
4 Discussion
The findings highlight two critical dynamics shaping fertilizer affordability this season.
First, geography matters. Nationally, DAP averages Ksh120/kg, but county-level variation is stark. Farmers in Kisumu benefit from lower prices (Ksh110/kg), while those in Kitui pay Ksh125/kg — a difference that compounds when scaled to the 50+ kilograms typically required at planting. For many households, this gap translates into thousands of shillings more in input costs, purely based on location.
Second, price relief is coming slowly. After the sharp 62.5% surge between 2021 and 2022, the easing since has been modest. From 2023 to 2025, prices dropped only Ksh8, plateauing at Ksh120. This sluggish decline means that, although farmers are no longer facing the 2022 shock, they are also not experiencing meaningful relief.
Together, these two factors create a tough landscape. Farmers in high-cost counties may reduce fertilizer use or turn to cheaper substitutes like NPK or organic manure, but these alternatives do not always deliver the same yield benefits. In short, while fertilizer prices are stabilizing, affordability remains out of reach for many farmers.
5 Conclusion
This case study shows that while DAP fertilizer prices are no longer rising, they remain elevated compared to pre-2022 levels. The current average of Ksh120/kg poses a challenge for farmers, especially those in higher-priced counties like Kitui. Although prices are trending downward, the pace of relief is too slow to provide meaningful financial breathing room this season.
For Kenyan maize farmers, the affordability of DAP is a balancing act:
Farmers in counties with lower retail prices (e.g., Kisumu) can maintain usage more easily.
Farmers in higher-cost counties may be forced to reduce fertilizer use or seek alternatives, potentially lowering yields.
Ultimately, the ability of farmers to afford DAP this season will depend not only on the national average but on where they farm and how quickly price reductions continue. Without faster relief, many will face tough trade-offs between input costs and food security — a challenge with ripple effects for every Kenyan household that depends on maize as a staple food.