The Land

Testing program underpins science-based decisions

A comprehensive soil test plays a key role in managing inputs and understanding limitations to achieve a targeted outcome in all farming and pasture systems.
A comprehensive soil test plays a key role in managing inputs and understanding limitations to achieve a targeted outcome in all farming and pasture systems.

This is branded content for Incitec Pivot Fertilisers.

Farmers looking to address yield-limiting factors in farming or pasture systems can undertake a testing program to underpin science-based management decisions and eliminate any guesswork.

The importance of soil testing and the data it provides for managing input costs and optimising crop yields cannot be overstated. Equally valuable is soil health, grain, and plant tissue testing, in generating a complete picture.

Incitec Pivot Fertilisers Senior Agronomist, Jim Laycock, said it was important for farmers not to look at test results in isolation.

"Measuring to manage is important. By undertaking a range of key tests, farmers can identify any nutrient deficiency or toxicity that may impacting yield, and eliminate or minimise those that can be managed," Mr Laycock said.

"A comprehensive soil test plays a key role in managing inputs and understanding limitations to achieve a targeted outcome in all farming and pasture systems.

"Published critical values for most nutrients are available to assist in the decision-making process.

"Likewise, published critical concentrations for the Colwell phosphorous (P) test by crop type, location and soil type are available to support the decision-making process in cropping and pasture systems."

Looking at soil health, a new Soil Health Package is available through Incitec Pivot Fertilisers' Nutrient Advantage Laboratory enabling farmers to benchmark and improve overall soil health.

It measures aggregate slaking and dispersion; active carbon (Labile); total carbon and total nitrogen and C:N ratio; and soil respiration.

"Soil health testing is all about improving your organic matter/organic carbon levels in soils," Mr Laycock said.

"It's not something you would do every year, but rather every three to five years.

"Metrics from soil health testing will allow you to establish a baseline of your soil health and know where to go to, based on the optimum and above-optimum ranges and agronomic advice available as part of all test results."

A Soil Health Decision Support system called Nutrient Advantage Pro (NA Pro) is available, generating a report with advisor comments to help in management decisions.

Mr Laycock said grain testing is a useful tool to analyse how much goes out the gate at harvest time in a cropping system.

"Grain testing also assesses the viability of seed and its potential maximisation of root extension based on soil-P levels in grain," Mr Laycock said.

"Knowing grain nutrient removal offtake is useful in monitoring paddock nutrient status. We have seen a wide range of nutrient content in grain, particularly of P, N, sulphur (S), and potassium (K).

"As an example, Dr Rob Norton did an analysis in 2008 and 2009 of National Variety Trials (NVT) wheat grain samples from across south eastern Australia and reported that mean P concentration ranged from 2.3 to 3.6 kg P/t grain, which is a significant variation.

"So, if you're looking at that and you're harvesting a 3 to 4 t/ha crop, there's obviously a big difference in the amount of P that goes out the gate and what P range you're thinking about applying to that system for the next crop.

"In 2014, Dr Norton reported mean canola P concentrations from 54 NVT trial sites across southern Australia ranged from 3.6 to 7.2 kg P/t grain."

Mr Laycock said another tool that is underutilised in cropping and pasture systems is plant tissue testing to assess nutrient uptake.

"Plant tissue testing can assist in identifying plant nutrient deficiencies and/or toxicities that affect plant health. Again, there are published critical values established for a wide range of crop types and pasture species that farmers can use as guidance in their decision-making," Mr Laycock said.

As an example of the value of plant tissue testing, Mr Laycock said he had worked with a grower who had thought about spreading N to address poor performance.

"We undertook a plant tissue test and a comprehensive soil test, and those test results showed us conclusively that potassium was the problem and so we addressed that limitation," Mr Laycock said.

"For an investment of $150 for the tissue and soil tests, we were able to make recommendations about application of potassium in that system, leading to significant financial savings and increased biomass production and growth."

For more information on testing services go to: www.nutrientadvantage.com.au