Modern laboratory testing developments mean soil and plant tissue sample results for a range of nutrients are available within days, allowing faster decision making and better targeting of fertilisers, according to Yara.
John Telfer, development manager at Yara Analytical Services, said there has been an increase in growers wanting to test for the whole nutrient spectrum. “For a lot of people there is a lot of intense P and K management, following RB209, but they are not always seeing the response they might wish from NPK and are realising it takes more to grow a crop.
“New techniques in the lab make it as affordable as it’s ever been. Twenty years ago a full soil test cost £37/sample and took three weeks. Now it costs less than that and results are ready in a few days.”
Interest in testing for organic matter has risen in the last 4-5 years but there are some discrepancies between test methods, said Mr Telfer. “We use the Dumas combustion approach which is the most accurate way to measure it. LOI is the most common method but does not always give reliable results on heavy clays, or brash.”
Growing numbers of farmers are also tissue testing, said Mr Telfer. “Growers are looking at what they spend and starting analysis, allowing the opportunity to spend appropriately.
“There is no point in throwing on more 20:10:10 – it is better to allocate nutrients where they are needed. This does not necessarily mean spending more.”
1 Address soil fertility. Nutrient availability, soil type and organic matter can all be tested
2 Opt for broad spectrum nutrient testing. As well as pH and major nutrients such as N, P and K, this will also assess key micronutrient reserves, ensuring one deficiency is not compromising yields
3 Understand your soil type. Soil type and variation across your farm will impact on how applied nutrients behave e.g. lighter soils are more prone to leaching which could affect timings of fertiliser applications. Heavy soils can lock up nutrients so it may be decided to adopt a foliar approach to by-pass soil problems. A lab laser diffraction analysis determines the sand, silt and clay portions defining a soil’s texture
4 Include organic matter (OM) analysis. OM provides the habitat for soil-borne organisms that convert soil-borne nutrients into a form available to a growing crop. OM analysis gives a clearer picture of soil levels and the effectiveness of any applied OM amendments.
5 Get a better insight with foliar analysis. As well as soil type, uptake of nutrients can also be affected by compaction, water availability, soil temperature, nutrient interactions and disease. A leaf sample analysis reveals nutrient deficiencies before they become visually apparent and the plant has become stressed.
6 Know your muck and slurry values. Actual results can vary enormously from book values quoted in RB209. If they do, this will build inaccuracies into nutrient management.
7 Act on your results. Discuss your results with your agronomist. By using a UKAS accredited lab, you can be sure the results you are working with are accurate and reliable.
Source: Jon Telfer, Yara