Focusing on Phosphate with Agrii's Nutrition Specialists

Today we are going to be talking with National Fertiliser Manager Tom Land, and John Charlton, Crop Input Specialist in the North East. 

This episode focusses on phosphate across various crops from cereals to maize. We'll delve into the critical role of phosphate in crop production, exploring its nutritional requirements, the importance of tissue analysis, and strategies to correct deficiencies to enhance crop quality and farm profitability.

Current Trends in Phosphate Use on Farms

What's the current trend in phosphate use on farms?

Tom Land:
We're observing that growers are becoming increasingly cautious about their inputs, driven by price and economic factors. Statistics show that phosphate use is declining. This can be positive if managed correctly through precision farming and the use of organic manures.

However, overuse of phosphate is detrimental to the environment. While reduced phosphate use can indicate efficiency, data also suggests declining grain P concentrations, which raises concerns about nutrient management. 

Impact of Declining Grain P Levels

What is the impact of declining grain P levels, and why should growers take note of this trend?

John Charlton:
Declining grain P indicates reduced phosphate availability to the crops during the growing season. This can lead to yield penalties because phosphate is essential for routine and energy transfer within the crop. If phosphate levels aren't maintained, it can negatively affect yield and overall crop health.

Mitigating Yield Penalties from Phosphate Deficiency

What can growers do to mitigate the risk of yield penalties due to phosphate deficiencies?

Tom Land:
Understanding your soil's limitations is fundamental. Using the P index system helps determine phosphate needs based on soil type. Factors like soil depth, root systems, organic matter, and soil biology also play crucial roles. Proper crop establishment and maintaining good soil structure and biology are essential to prevent yield reductions.

John Charlton: 
This principle applies across various crops. Any crop requiring significant energy, like maize, relies heavily on phosphate for maximizing output from sowing onwards. Ensuring phosphate availability is key to achieving optimal yields.

Key Sources of Phosphate on Farm

What are the key sources of phosphate on farm?

Tom Land: 
Traditional fertilizers such as Triple Super Phosphate (TSP) and Diammonium Phosphate (DAP) are commonly used. However, over the last four years, many growers have been switching to more organic manures. These include ash-based sources from electricity production, farmyard manure, sewage cake, and other products containing various sources of P. Organic manures offer additional benefits like improving soil biology and organic matter content.

Trends in Phosphate Pricing

You mentioned the cost of phosphate earlier. Can you talk us through some of the trends and what is happening with the price of phosphate?

Tom Land:
Phosphate prices have been rising significantly, reaching up to £600 per tonne. This increase makes it challenging for growers to decide whether to invest in phosphate fertilizers. If growers can obtain organic materials at a relatively low cost, it often makes economic sense to use them instead of traditional phosphate fertilizers.

Organic materials not only provide phosphorus but also improve soil biology and organic matter, offering additional benefits. However, there's a concern when growers apply phosphate fertilizers without seeing a direct yield response.

Despite the dropping P index or grain P levels, some growers may choose not to purchase phosphate fertilizers if they don't observe immediate benefits, making informed decision-making crucial.

Assessing Phosphate Levels

Where do you advise farmers and growers to start in terms of checking their phosphate levels and when?

John Charlton:
The principal approach is conducting soil analysis. Start by testing your soil during the autumn or early spring, well ahead of harvest time. If you're applying organic manure, it's also beneficial to test these inputs to understand exactly what you're adding to the soil.

From there, you can develop a nutrient management plan and supplement with conventional fertilizers or other phosphate sources as needed. There is a range of phosphate sources available to suit different situations and costs.

Phosphate Management Plans

You've spoken about nutrient management plans before. How important are they?

Tom Land:
Nutrient management plans are crucial. They allow us to discuss not just how much phosphate to apply but also how to maximize its efficiency. By using soil analysis data, growers can make informed decisions about their phosphate applications.

Many growers are now testing for more than just P and K; they also assess pH and organic matter levels to better understand soil health and optimize nutrient responses based on current best practices.

Developments in Phosphate Products

What developments have you been focusing on at Agrii over the last few years?

John Charlton:
We've been developing and trialling various phosphate fertilizers, focusing on improving nutrient insufficiency. On the economic side, we're exploring cheaper phosphate sources like ash-based products.

We're also working with growers who use organic manures to enhance phosphate availability through better placement and application technologies. 

One notable product is Agrii-Start Release, a soil phosphorus activator designed to unlock phosphate and other vital nutrients in the soil.

Tell us about Agrii-Start Release and its benefits for growers.

Tom Land:

We've been trialling Agrii Start Release over numerous years with different phosphate fertilizers. We began by coating traditional fertilizers like TSP and DAP to increase their solubility, allowing us to potentially reduce the amount of phosphate applied.

Through trials, we observed that even without phosphate fertilizers, Agrii-Start Release increased grain P levels by enhancing the availability of soluble P in the soil, which plants uptake effectively.

This product is particularly beneficial for high-index soils where fresh phosphate application isn't feasible and for soils with high calcium levels that cause phosphate lock-up.

Case Study: Phosphate Management in Heavy Clay Soils

Can you share a case study demonstrating effective phosphate management?

Tom Land: 
Certainly. On a heavy clay soil farm in the North East, high cation exchange capacity led to phosphate lock-up, reducing availability. We applied Agrii-Start Release* in the autumn and monitored phosphate levels monthly.

Compared to the control group, we saw a significant increase in available phosphate over the winter period, which translated into better crop yields.

Top Tips for Growers

What are your top tips for growers regarding phosphate management?

John Charlton: 
The more data you have, the better decisions you can make. Conduct thorough soil and tissue analyses regularly to understand your nutrient status and adjust your management plans accordingly.

Tom Land: 
Grain analysis is essential. Despite its low uptake among growers, it provides valuable insights into soil phosphate levels and helps target your inputs effectively, ensuring you get the best return on investment.

Unlock phosphate and other vital nutrients in your soil with Agrii-Start Release.

For detailed trial results, usage recommendations and tank mix compatibility, visit www.agrii.co.uk/our-services/fertiliser/agrii-start/release/