When it comes to boosting milk production in dairy cows, some farmers immediately think of genetics, feed quality, and pasture management. But there’s another key player that often gets overlooked: fertilizer.

Choosing the right fertiliser can do a lot for improving pasture quality — and better pastures mean healthier cows and higher milk production. Here’s how it works, and what you can do to make the most of your farm’s potential.

Healthier Grass = More Milk

Great milk starts with great feed. When pastures are rich in energy, protein, and essential minerals, cows can easily meet their nutritional needs without costly supplements. Fertilisers help by:

• Boosting grass growth — giving cows more to eat.
  
• Increasing pasture quality — promoting high-protein grasses and clovers.
  
• Improving soil health — leading to long-term, sustainable productivity.
  

A cow grazing on a nutrient-rich, well-fertilised pasture can produce significantly more milk than a cow grazing on poor-quality grass.

From my own experience, I’ve seen firsthand how much difference the right fertiliser makes. Good fertiliser choices have led to healthier pastures, higher milk yields, and stronger cow condition throughout the season. When I used a balanced fertiliser program tailored to my soil’s needs, milk production noticeably increased — and the cows were happier too.

Choose Fertilizers That Add Key Nutrients

Not all fertilizers are made equal. For maximum milk production, focus on fertilisers that:

• Increase nitrogen levels: Nitrogen is essential for leafy, protein-rich pasture growth.
  
• Add phosphorus: Helps strengthen root systems and improve pasture resilience.
  
• Provide potassium: Supports overall plant health and improves pasture drought tolerance.
  
• Include sulfur: Enhances protein production in grasses and clovers.
  

Many farmers also use lime to adjust soil pH, creating a better environment for nutrient uptake.

Support Clover Growth

Clover is a natural powerhouse for milk production because it’s high in protein and fixes nitrogen into the soil naturally. Using the right fertilizer blend — and avoiding excessive nitrogen ,which is better for the environment anyway,— encourages clover to thrive in your pasture, cutting fertiliser costs and boosting cow performance.

Tip: Look for fertilisers that are clover-friendly or work with your local agronomist to create a custom fertilisation plan.

Timing Is Everything

Applying fertiliser at the right time makes a big difference. Best practices include:

• Fertilising after grazing to stimulate regrowth.
  
• Applying early in the season to set pastures up for strong spring and summer growth.
  
• Splitting applications throughout the season to avoid nutrient losses and support consistent pasture quality.
  

Healthy pastures mean cows don’t need to work as hard to get what they need — which translates directly into more milk in the vat.

Don’t Forget Soil Testing

Before you invest in fertiliser, test your soil. Knowing exactly what your pasture needs prevents over-fertilisation, saves money, and protects the environment. Regular testing helps you adjust your fertilizer plan over time and keep your pastures performing at their best.

Final Thoughts

In dairy farming, small changes can make a big impact. Choosing the right fertiliser and applying it at the right times boosts pasture quality, supports cow health, and naturally increases milk production.From my own farming journey, I can say without hesitation: good fertiliser is an investment that pays off — in healthier cows, stronger pastures, and fuller milk vats.The bottom line? If you want more milk — start with the soil.

You might also want to read our blog post How to increase milk production in grass-fed cows

For more on fertilizer nutrients, see DairyNZ’s guide to pasture management.