Ag Slag – The Product

After a gap of some 30 years, the new modern day Slag is once more available to farmers around the country. Production methods have changed and the Basic Slag is not the same product it was – in many ways it’s even better.

This product, now called Ag Slag, is a by-product of the steel industry and is the ore that remains after the iron has been taken out. We do not want the iron, however we do want the phosphates, calcium, manganese and other trace minerals including selenium that are in this product.

In the ‘good old days’ Basic Slag was a high phosphate, black dusty product, that was available in 1 cwt bags – about the same size and density as cement and very difficult to spread accurately – but we loved it! It worked to produce high quality forage with high sugars and high nutritional value. The grass tasted sweet, with high sugars, high mineral content and was highly nutritious.

Later on, it was sort of granulated and mixed with potash to form ‘K Slag’ – a lot more money but still worked well and maintained the potash levels.

In the 1970/80′s many of the steel works closed down including one of the biggest at Corby where around 100,000 tonnes per year of slag was produced. With the introduction of intensive high nitrogen systems, farmers moved away from natural clover based swards and because of this slag was forgotten about as specialist grassland fertilisers were produced.

Today most grass tastes foul, it is bitter and mostly ‘gunpowder’ grass i.e. high in potassium nitrate. Your animals don’t like it – but don’t have a choice and vets bills are high because mineral levels are too low.

For optimum results, Ag Slag needs to be used on acid soils. Provided that it is tipped onto hard standing, the Ag Slag product does not require immediate use. As it does not deteriorate in the open, it can be kept for use when circumstances allow.