Whether you have recently acquired land or had it a long time, changes in seasonal conditions, crop input expenses and commodity prices mean your soil nutrition strategy will always need adaption.
Given last year’s exceptional rainfall, farmers could be forgiven for scratching their heads about the nutrient levels in their soils. How much did my 2016 crop remove? Did the nutrients leach to a deeper level and can the 2017 crop access them? How much will the heavy stubbles lock up? How much will burning stubbles remove?
It’s important to have a soil monitoring program with testing to determine your nutrient starting point to prevent in-season deficiencies.
Early 2017 soil test results conducted by BCG for growers across the Wimmera and Mallee are showing, on average, moderate to low phosphorous (P) levels following cereals and canola. Nitrogen (N) levels to 70cm are ranging from 40kg N/ha following wheat, to over 100kg N/ha following fallow.
Soil samples should be sent to a reputable laboratory and growers should also be careful with the interpretation of their results, seeking advice from a good agronomist if they are unsure.
The critical values offered in some reports are a guide only and may not be relevant to your soil type or to the depth of the soil sample.
Soil tests can often suggest more nutrients should be applied, however a response to fertiliser application is not always observed.
Recent GRDC-funded research suggests critical soil test levels can be the first point of inaccuracy and interpretation needs to be refined for different soil types associated with your paddock. One way to validate your soil tests and to assess the most cost-effective rate of fertiliser for your crop is to use paddock strip trials, and sowing is a good time to plan your on-farm trial.
The key is to keep it basic by testing one variable, such as fertiliser rate or seeding rate, and set up the trial with a number of treatments.
Where possible, it is best to replicate your test strips so you can rule out any influencing factors.