Fertilizer Mix Ratio Calculator

Yes, urea (46-0-0) and DAP (18-46-0) can be safely mixed together. This combination is actually quite common and provides both nitrogen and phosphorus. However, there are a few important considerations:

• Mix them just before application to prevent moisture absorption and caking
• Ensure uniform mixing for even nutrient distribution
• When applied to soil, incorporate within 24 hours to minimize nitrogen losses through ammonia volatilization

This mix is particularly useful for early growth stages when plants need both nitrogen for vegetative growth and phosphorus for root development.

If you don't have all the fertilizers listed in our calculator, you have several options:

1. Use only the fertilizers you have available by unchecking the unavailable options in the calculator. The algorithm will attempt to create the closest possible match to your target ratio using only your selected fertilizers.
2. Consider alternative fertilizers with similar NPK content. For example, if you don't have DAP (18-46-0), you might use a combination of SSP (0-16-0) and urea (46-0-0) to achieve similar nutrient contributions.
3. Adjust your target ratio to something more achievable with the fertilizers you have on hand.

Keep in mind that when using fewer fertilizer types, it may be more difficult to achieve exact NPK ratios, but you can often get close enough for practical purposes.

To calculate the NPK of a fertilizer mix manually, follow these steps:

1. For each fertilizer in your mix, multiply its percentage of each nutrient by the weight of that fertilizer in the mix
2. Sum the total amounts of each nutrient (N, P, K)
3. Divide each nutrient total by the total weight of all fertilizers combined
4. Multiply by 100 to get the percentage

For example, if you mix 50kg of urea (46-0-0) and 50kg of DAP (18-46-0):

Nitrogen (N): (50kg × 46%) + (50kg × 18%) = 23kg + 9kg = 32kg

Phosphorus (P): (50kg × 0%) + (50kg × 46%) = 0kg + 23kg = 23kg

Potassium (K): (50kg × 0%) + (50kg × 0%) = 0kg

Total mix weight: 100kg

Final NPK ratio: (32/100 × 100)-(23/100 × 100)-(0/100 × 100) = 32-23-0

This is exactly what our calculator does automatically for you, while also optimizing the mix proportions to match your target ratio.

While our calculator is primarily designed for conventional fertilizers with standardized NPK values, it can be adapted for organic inputs with some modifications:

• You'll need to know the approximate NPK values of your organic inputs. For example, well-composted chicken manure might have values around 3-2.5-1.5.
• Enter these values manually in the calculator, understanding that organic materials have variable nutrient content depending on source, processing, and age.
• Remember that nutrients in organic materials are released more slowly over time compared to synthetic fertilizers.

For more precise organic calculations, consider that:

• Only a portion of nutrients in organic materials may be available in the first year
• Environmental factors significantly affect mineralization rates
• Organic inputs provide additional benefits beyond NPK that aren't accounted for in this calculator

Flowering crops generally benefit from fertilizer mixes with higher phosphorus (P) and potassium (K) relative to nitrogen (N). Ideal ratios often follow these patterns:

• Early flowering stage: Ratios like 10:30:20 or 5:10:10 are common, where phosphorus is emphasized to promote flower initiation and bud development.
• During flowering/fruiting: Ratios like 3:15:20 or 0:10:20 work well as plants need less nitrogen (which can promote vegetative growth at the expense of flowers) and more potassium for flower/fruit quality.

Common flowering crops and their preferred NPK ratios during flowering:

• Roses: 5:10:10 to 5:8:20
• Tomatoes (flowering stage): 5:10:15
• Strawberries: 2:8:10
• Orchids: 10:30:20
• Annual flowering plants: 7:22:8

Using our calculator, you can create custom mixes that achieve these ratios using commonly available fertilizers.