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Tillage Update - Tillage farms show largest increase in soil sample numbers in 2021

While Tillage farms show largest increase in soil sample numbers in 2021, a drop (-6%) in soil fertility was noted. Mark Plunkett, Tillage Specialist Johnstown Castle Research Centre, reminds tillage farmers that they should aim to maintain soil fertility by fertilising to grain yield potential

In 2021 Teagasc analysed a total 33,876 soil samples comprising of dairy, drystock and tillage enterprises. Overall soil sample numbers increased by 13% in 2021.

On tillage farms 3,794 soil samples were taken, which represents ~ 17% increase in soil samples compared to 2020.  This was primarily driven by the significant increases in the cost of N, P and K fertilisers projected mid-2021 and the drive to maintain crop margins in 2022.

Summary of soil pH, P and K for Tillage Farms in 2021

The following is a summary of the main changes for soil pH, phosphorus (P) and potassium (K) in 2021 on tillage farms:-

  • 18% of soils have optimum pH >6.5, P & K – Index 3 (6 % Decrease)
  • 61% of soils with a soil pH >6.5 (13% Decrease)
  • 57%of soils at P index 1 & 2 (7% Increase)
  • 32% of soils at K Index 1 & 2 (2% Decrease)

The data set reveals a drop (-6%) in soil fertility for the first time in 10 years on tillage farms.  We cannot look at one year in isolation as soil fertility trends need to be assessed over a 3 to 4 year time frame to establish real soil fertility trends. Since 2011 soil fertility on tillage farms has steadily increased which reflects fertiliser practices and use with annual improvements of approximately 1% per year.  Building soil fertility takes time so it is important to take stock of this one-year emerging trend in the tillage soils database.   

This emerging trend of a drop in soil fertility on tillage farms is mainly driven by a decrease (-13%) in soil pH and soil P (-7%) results. Soil K levels continue to improve (+2%) with less soils testing at K Index 1 & 2.  This is a reflection of fertiliser use practice change to higher K compounds over the last 10 to 15 years.  

Recently released DAFM fertiliser use figures for 2022 indicate that P and K use has reduced by 30%, which is a concern, as reduced P and K applications will run down valuable soil fertility reserves built up over the last decade.

What you can do

With indications of escalated fertiliser prices remaining for the coming season we should aim to maintain soil fertility by fertilising to grain yield potential.  

Soil fertility is an asset as it is a key driver of nitrogen use efficiency, grain yield development and reducing GHG emissions from tillage soils.

In 2022, overall yields reported to date are above the national average for the majority crops.  This will have resulted in increased off takes of P and K’s, so very important to now assess crop P and K offtakes and soil fertility over the coming weeks.

Take action now

  • Assess field P & K balances after the harvest
  • Take fresh soil samples where P and K applications were reduced or omitted in 2022
  • Apply lime over the coming weeks to build / maintain soil pH levels
  • Update records / farm fertiliser
  • Plan fertiliser requirements for 2023

Click here to read full soil fertility report

Find out more about Soil & Soil Fertility

Find out more information and advice from the Teagasc Crops team here.   The Teagasc Crops Specialists issue an article on a topic of interest to tillage farmers every Thursday on Teagasc Daily.  If you have further queries you can talk to your Teagasc tillage advisor. Find your local Teagasc office here