pH Levels in Soil

We’re losing track of the basics!

Watson Seeds carried out a soil sampling project in autumn 2014 throughout areas in the South and East of Scotland from the Borders to Aberdeenshire.  130 samples were taken largely from rotational arable/grass fields.  One of the major revelations from this exercise was the lack of attention being paid to soil pH levels.  This is extremely concerning as lime application and pH level is one of the fundamental requirements for the success of any crop including long term grass.

In the aftermath of 2012, which most of us will remember as the horrendously wet year, many farmers attended soil clinics in an effort to find out how to get damaged ground back into good condition.  In many cases soil structure had been seriously damaged.  The speakers at the soil clinics highlighted the fact that drainage on many farms had been damaged or neglected over the years.  This also worsened soil structure problems.  At these clinics it was regularly pointed out that lime application was right up there with drainage as an absolute necessity to produce satisfactory crops.  The sad reality is that regardless of how much fertiliser and agrochemical is applied at whatever cost the crop yield is destined to be severely cut if the pH levels are too low.

Where high rates of N application are used, acidity can build up rapidly at the top of the soil profile, especially in high rainfall areas.  Because of the slow reactivity of liming agents, and their lack of mixing with the soil matrix, rates of change of pH down the soil profile are slow and regular liming is better than large infrequent doses.

From our soil sampling project the table below summarises our findings from 130 soil samples taken.


What is alarming is that 44.3% of samples taken were borderline or below satisfactory pH at 5.5 – 5.9 and staggeringly 14.2% were below 5.5 pH.  Therefore cumulatively 58.5% of the 130 samples taken were below pH6.  This is a concerning set of statistics as the consequences of this apparent trend in low pH’s result in heavy yield penalties for most crops including grass.  If a grass reseed is established in a borderline pH it may well yield satisfactorily in the first couple of years, but lime is depleted with high yielding crops and will soon fall below acceptable levels and the sward start to deteriorate from a number of angles: –

  1. Ryegrass/clover yields reduce,
  2. Indigenous less productive species of grass start to take over,
  3. Acid tolerant weeds such as buttercups and daisies establish,
  4. Response to fertiliser is significantly reduced,
  5. Nutritional value deteriorates rapidly,
  6. Growing season shortens significantly

At Watson Seeds we are going to great lengths to provide grass mixtures which will yield well, feed well, last as long as prescribed and withstand the rigours of modern farming practices.  Our deep concern is that if the very basics of crop husbandry, such as lime applications, are being mismanaged then our customers are unlikely to reap the benefits of using the best varieties of grass and clover.

Our message is loud and clear!

Do your best to ensure that you do not let soil pH levels fall below the optimum level (between 5.8 and 6.4) that way you will give your grass and consequentially your livestock the best chance to thrive.