At Terra Safi, we often get asked two questions:
“What’s in your organic fertiliser?” and “How does it compare to chemical fertilisers?”
The short answer: while chemical fertilisers deliver a quick boost of nutrients, Terra Safi’s organic fertiliser feeds your soil first — and that makes all the difference.
Let’s dig a little deeper into the chemistry, biology, and practical use of organic fertiliser.
When most farmers think of fertiliser, they think of DAP (Diammonium Phosphate) and CAN (Calcium Ammonium Nitrate) — the two most widely used chemical fertilisers in Kenya. Both deliver nutrients quickly, but their chemistry makes them poorly suited for sandy coastal soils, where water moves fast and organic matter is low.
DAP provides both nitrogen (in the ammonium form) and phosphorus. However, when DAP dissolves in soil, it temporarily raises the pH around the granule, causing a chemical reaction that can make phosphorus bind tightly to iron and aluminium oxides in acidic soils. Once that happens, it’s no longer available to the plant. In other words, much of the phosphorus applied as DAP is lost within days — especially in our coastal soils, which tend to be acidic and low in buffering capacity.
Buffering capacity refers to the soil’s ability to resist sudden changes in pH. Soils with high organic matter or clay content can buffer — or stabilise — their pH when fertilisers or other inputs are added. Sandy soils, like those at the coast, have very low buffering capacity, meaning their pH changes quickly and nutrients can become locked up or washed away.
CAN, on the other hand, is mainly used as a top dressing. It supplies nitrogen in both the ammonium (NH₄⁺) and nitrate (NO₃⁻) forms, which plants can absorb directly. But because nitrate is water-soluble, it’s also easily leached below the root zone in sandy soils — meaning the nitrogen ends up in the groundwater instead of in the crop. This not only wastes money but also contributes to nutrient pollution in nearby streams and coastal ecosystems.
Organic fertilisers like Terra Safi’s work differently. The nitrogen and phosphorus are bound in organic compounds that must first be broken down by soil microbes. This slow, biological release synchronises with plant needs, minimising leaching losses and pollution. Moreover, the organic matter improves soil structure and moisture retention, which helps retain nutrients that would otherwise wash away.
Over time, this approach builds a living soil that stores nutrients naturally — turning your field or garden into a self-sustaining ecosystem rather than one that constantly needs chemical inputs.
Nitrogen drives leaf and stem growth. In chemical fertilisers like CAN or urea, nitrogen usually comes in highly soluble forms that dissolve quickly and can easily leach out of sandy soils or volatilize into the air as ammonia gas.
In Terra Safi’s organic fertiliser, nitrogen is bound in organic molecules — from decomposed plant and animal matter. Microbes in the soil gradually convert this nitrogen into ammonium (NH₄⁺) and then nitrate (NO₃⁻) through the nitrogen cycle.
This slow process:
The result? Stronger, more resilient plants — and cleaner groundwater.
Phosphorus (P) is essential for root development, flowering, and fruiting. In DAP and other chemical fertilisers, phosphorus is provided in mineral forms like phosphate salts, which can quickly react with iron and aluminium in acidic soils to form insoluble compounds that plants can’t use — a common issue in coastal Kenya.
In contrast, the phosphorus in Terra Safi organic fertiliser is tied up in organic matter and mineralised slowly by soil microbes. These microbes release organic acids that help dissolve bound phosphorus, making it available when the plant actually needs it.
By feeding soil life, Terra Safi fertiliser ensures that phosphorus stays in a natural, usable cycle instead of being locked away.
Potassium (K) regulates water movement, enzyme activity, and stress resistance in plants. Chemical potassium sources (like potassium chloride) are immediately available but can increase soil salinity over time.
Organic matter in Terra Safi fertiliser holds potassium in a cation exchange complex — a kind of nutrient “bank” that releases K⁺ ions slowly. This is particularly important in sandy soils with low cation exchange capacity, where nutrients tend to wash away easily.
While chemical fertilisers often focus on N-P-K, plants also need micronutrients like calcium, magnesium, zinc, iron, copper, and boron — in tiny amounts but with massive importance.
These trace elements:
Terra Safi’s organic fertiliser naturally contains a spectrum of these micronutrients — released slowly and buffered by organic matter to prevent toxicity or imbalance.
When planting seedlings, mix a handful (about 50–100 g) of Terra Safi organic fertiliser into the hole with the topsoil.
This ensures that nutrients and microbes are right where the young roots need them most.
After plants are established, use Terra Safi fertiliser as a top dressing around the base of the plant (but not touching the stem).
– For vegetables or flowers: 50–100 g every 2–3 weeks.
– For fruit trees: 500 g to 1 kg, depending on size, once every 1–2 months.
Lightly water after application to help nutrients filter into the root zone.
Because it releases nutrients gradually, there’s no risk of burning the plants — unlike chemical fertilisers.
Each handful of organic fertiliser does more than feed your crops — it feeds the soil ecosystem that supports them.
Healthy soil is the foundation of a thriving ecosystem
Microbes, fungi, and earthworms transform organic matter into humus, improving water retention, aeration, and nutrient holding capacity. Over time, your soil becomes more fertile, resilient, and productive — even in the sandy coastal regions where fertility is often a challenge.
In Summary
| Aspect | Chemical Fertiliser (DAP, CAN) | Terra Safi Organic Fertiliser |
|---|---|---|
| Nutrient Release | Immediate, short-term | Slow, sustained |
| Soil Impact | Degrades structure, kills microbes | Builds structure, feeds microbes |
| Risk of Leaching | High (especially in sandy soils) | Low |
| Micronutrients | Often missing | Naturally included |
| Long-Term Fertility | Declines over time | Improves over time |
Healthy soil grows healthy plants — and healthy communities.
That’s why at Terra Safi, we believe in feeding the soil, not just the crop.
