Why do we analyse plants?

Plant analysis is a great in-season tool to monitor nutrient uptake, ensuring that crops and pastures are adequately supplied with nutrients to optimise yield and returns. Plant analysis has multiple benefits.

Understanding deeper nutrient supply

When used with soil analysis, plant analysis can help us understand nutrient supply from deeper in the soil profile, which can also help assess the effectiveness of fertiliser recommendations.

Gauging trace element status

Plant sampling and NUlogic analysis is the most accurate way to determine the trace element status of a crop. Soil sampling is less reliable when testing trace elements.

Diagnosing hidden hunger

Timely plant sampling can also help identify ‘hidden hunger’, which is an indication of crop and pasture nutrient deficiency before symptoms are seen. If we wait until visual symptoms of a deficiency, the crop is already under stress and yield potential may be lost.

Diagnosing crop issues

In season biomass imagery or crop inspections can highlight areas not performing as well as expected. If the cause is nutritional, tissue testing will show which nutrients need adjusting with in-season top ups.

Refine fertiliser strategies for next season

Plant sampling can help identify if your fertiliser regime is matching crop nutrient needs. Marginal or low uptake of certain nutrients can allow us to choose fertiliser products that may better suit your crop (and pasture) requirements when making fertiliser decisions for next season.

Adapting your fertiliser program to match the season

Monitoring plant nutrient levels during the season will show if more nutrients are (or are not) required. This can easily pay for itself through yield improvements or by saving money on unnecessary fertiliser applications. Table 1. shows the nitrogen (N) (total N and nitrate N) and potassium (K) concentrations from plant tests (oats) taken from two treatments in a trial at mid-tillering.

Nitrogen, nitrate and potassium concentrations in oats at mid-tillering

Table 1. Nitrogen, nitrate and potassium concentrations in oats at mid-tillering from two treatments (average of three reps) in a CSBP trial at Wickepin in 2021. Green shading indicates adequate status, yellow marginal status.

The results show there was no need for K fertiliser — K was well above critical levels in the 0K treatment. The 52N treatment (106 kg/ha Agstar + 100 L/ha Flexi-N banded) provided adequate N.

While this trial showed some visual responses to N, there were no significant responses measured in what was a very high yielding crop. There was also no response to K. These results were not surprising given the results from plant testing.

Obviously, additional N and K fertiliser provides some insurance against deficiencies limiting returns in high yielding situations. However, this trial highlighted the value of plant testing as a way to limit fertiliser spend in situations where it is unlikely to be profitable.

How to choose plant sampling sites

It is a good idea to go back to existing soil sampling sites for in-season plant sampling. Soil and plant sampling sites can be identified using DecipherAg and can be logged into the DecipherAg mobile app, to make them easy to locate in the paddock.  

Find out more about DecipherAg here. 

Planning your plant sampling sites at the same time as your soil sampling sites can ensure that plant sampling can be conducted in a timely fashion in the season.

Given the high price of fertiliser inputs this year, there will be more value in plant testing to get the best returns and reduce risk.

Contact your account manager to start planning your plant sampling today. 


Luke Dawson
By Luke Dawson
- Senior Agronomist
Luke was raised on the family farm at Warralakin east of Mukinbudin before completing a degree at the Muresk Institute of Agriculture. 

Luke started with CSBP in 2005 as a trainee Area Manager and has since worked as an Area Manager based in Hyden, Esperance, and Dalwallinu and District Manager for the Central Midlands District, now based regionally as Senior Agronomist. 

Luke brings a strong nutritional background to the role, as well as a focus adding value through CSBP's services. 

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