Shooting in the dark in the absence of a soil test

Teagasc’s Stan Lalor was keen to emphasise the importance of soil testing when making decisions in regards to soil fertility at a recent ASA technical event on the Nitrates Directive.

He said: “Have a soil analysis for the whole farm. You are shooting in the dark if you don’t know where you are starting from in terms of building a fertiliser programme.”

Lalor stressed that it is key for farmers to have that information about what their lime requirements are where they are in terms of P and K indexes.

He cited the worrying statistic that 90% of grassland soils were sub-optimal for either pH, P or K in 2013. For Lalor this highlights the danger in working without soil test results.

He commented: “If you’re in a situation in the absence of a soil test result you are assuming everything is ok for P, K and lime. However there is a 90 per cent chance the recommendations for that field will be wrong.”

“Farmers are very keen on managing grassland, herd health, cow fertility. What we are trying to get across is that soil fertility should be right at the top of that list. Our message is to put soil fertility management in a series of steps.

Steps to Soil Fertility Management

  1. Soil test. This is a key first step.
  2. Soil pH should be a priority from the results and farmers should aim to have the whole farm between 6 and 6.5.
  3. The third step is about P and K indexes. Farmers should be targeting to get all fields in index 3.
  4. Index 4 is a resource. Farmers should be exploiting it. It is very important to be repeating soil tests to pick up if fields have fallen out of index 4 into index 3.Farmers need to back to that maintenance rate again. In index 1 and 2 farmers need to identify and nourish.
  5. Optimise slurry first – then top up with fertilizer as required. Very important to maximise the efficiency of the return from slurry. He said: “Take something like slurry it is in the tank and it is a cost anyway. It is important to try and get the best value out of that potential nutrient source.”
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