Grain data analysis: nutrient content vs critical values
NRM
Agriculture
Whether farmers invest in soil, plant tissue, or grain data analysis, it’s important that we interpret the results accurately and understand what they mean. The best way to understand your results is to compare them with a benchmark. For GrainCheck, our innovative grain analysis service, these benchmarks are the critical values published by ADAS and confirmed by accredited labs like NRM. These values give growers context on their grain nutrient content to help measure progress and take informed action for improved productivity.
NRM’s work with the science community is collaborative, ensuring that the critical values published alongside analytical results are the best they can be. However, some critical nutrient values are more certain than others, and in some cases, no data exists because the work hasn’t been done.
As the UK’s leading provider of soil analysis, NRM is on the case. The lab was established in 1990 and analyses thousands of samples every year, allowing us to gather more and more data for the critical values that have less certainty, and they are becoming more definitive every year.
Certainty around critical values is also crop-specific. The most certainty in values exists for wheat because most of the experimental work conducted over the last few decades has been concentrated on that crop. The data is limited for other combinable crops, so NRM is working hard to not only improve the critical values for wheat, but to also take the lead in understanding what they might be for other crops.
Grain data analysis: crop nutrient recovery
Each year, NRM reviews all the grain results from the previous year to assess the national picture and understand how well crops recovered and utilised the nutrients they were supplied.
As we all know, each season brings weather challenges, and 2023 was no exception. It was a season of rain, cooler spring temperatures, and more rain. We then saw exceptional heat throughout June, followed by persistent rain from July through the autumn. This resulted in 8.1t/ha grain yield; 5.2% lower than 2022.
We understand the difficulties these conditions create, including the system resilience required to navigate them, and that there are several reasons why crops may struggle to recover nutrients. For instance, there might be an adequate or excess of nutrients in the soil, but very wet or dry weather combined with poor soil conditions can hinder overall root and shoot development, leading to poorer nutrient uptake and utilisation efficiencies. The best approach to dealing with these conditions and emerging victorious is to ensure that the soil is in optimal condition, with good structure, biology, and chemistry.
More than 40% of grain samples were below the target range for nitrogen and phosphorus
Grain data analysis of the more than 3000 samples tested in 2023 shows the impact of those challenging conditions. For example, we discovered that over 40% of the wheat grain samples had nitrogen and phosphorus levels below target. Interestingly, 30% of the samples exceeded the target for nitrogen, and only a quarter met the nitrogen target (see figure below). From all the samples analysed, potassium uptake seemed the best of all the major nutrients, with most samples hitting the target 62% of samples contained at target, 27% were above target and 11% were below target.
Figure. Winter wheat grain samples at, below, or above target range for different nutrients
Grain data analysis: key lessons from 2023
As we have alluded, the changing climate is bringing more erratic seasonal conditions, and it’s crucial to consider how our agronomic choices can affect nutrient utilisation and potentially complicate crop recovery. The farming industry needs to become more resilient despite all these challenges. For instance, if we ignore or miscalculate the supply of soil nutrients, use inappropriate fertiliser analysis that provides nutrients in the wrong ratio, or fail to account for nutrients from livestock and other organic inputs, crop recovery can be challenged. In addition, a lack of planning in combination with unpredictable weather can create a perfect storm of inefficiencies that accumulate from when the crop is drilled to when it is harvested.
Excess nutrients found in the grain can indicate an overapplication of nutrients earlier in the spring, or it may result from fertilising for a higher yield that was not achieved. In such cases, there may be an excess in the system, which could be at risk of loss over the winter if an autumn-sown crop is not planted. Cover cropping is an excellent solution to address this issue if the field is scheduled for a spring-sown crop. It helps reduce the risk of nitrogen leaching into groundwater and protects the soil from erosion, minimising the loss of phosphorus bound to soil particles escaping into the wider environment.
Accounting for any carryover nutrients for the following crop is essential. The following crop can benefit if nutrients are retained in the soil system over autumn and winter. Measuring soil nitrogen in spring, for example, will give you a good estimate of what remains in the soil from the season before and can help you manage your costs as the spring advances. Fertiliser prices have reduced from the highs of 2022, but why apply excess just because the price per kilo is lower than the previous year? Optimising nutrient rates from the outset is the best approach to managing nutrient supply throughout the spring.
Grain data analysis: improving the critical values for winter wheat
The significance of accurate ‘grain critical values’ to compare analytical results cannot be overstated. At NRM, we can update our GrainCheck critical values regularly because of our extensive dataset. This process involves rigorous data analysis and validation, ensuring that the values we determine are reliable and accurate. Access to this data allows us to have more confidence in the values determined for trace elements like copper and zinc, and can help us determine critical values for boron, calcium, and iron, which are currently under review.
NRM is currently working to improve the existing critical values for wheat. Based on our dataset, we have observed that the current critical value for grain phosphorus is higher than required and needs to be revised. Moreover, we aim to establish critical values for nutrients such as boron, calcium, and iron, for which values have not been determined previously. Stay tuned for updates!
Critical values for winter barley and oilseed rape
Our GrainCheck report contains the critical nutrient values and their reliability for wheat, even when analysing grain from other crops. However, these values may not be entirely applicable to other crops. So, we are working on a plan to address this by publishing crop-specific critical values. To do this, we need even more samples to be submitted to the lab for analysis. By analysing more samples, we can establish new critical values tailored to specific crop species.
NRM: here to help
To understand more about the GrainCheck service and how it can help you use nutrients more effectively, get in contact by clicking here or speak to your agronomist about more advice. We also have an offtake nutrient calculator to help you get even more out of your data.
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