Think carbon before nitrogen

What is the one thing you can’t afford to run out of? The answer is carbon. Look at the cartoon and you will see that only the right hand side of the fence has carbon available for livestock to consume.

A person running a grazing operation can afford to supplement nitrogen (protein) when it is in short supply. However, it is not commercial to supplement carbon when it is short. Hay is expensive.

A bare paddock has no carbon while a paddock of frosted or rank grass has carbon but little nitrogen.

It is often stated that nitrogen (protein) is the limiting factor. However, this is only true when you are assessing what has grown.

Correctly manage carbon flows from the atmosphere to your paddock and you will still have options when it has  not rained for a while.  

It has been suggested that with average pastures, removing animals for three to eight weeks after rain increases pasture production by 50-80%. Given pasture is 45% carbon on a dry basis, this is a lot of extra carbon coming into the paddock for future use.    

For anyone who doubts the importance of allowing plants to grow after rain and build up the supply of carbon, try feeding lick blocks to sheep or cattle in a totally bare paddock.

How much carbon is in your pasture?

Getting back to basics, carbon is the main building block of grass and everything else that grows in a pasture, so the reality is that nitrogen will not be present if carbon is not present.

With grasses, there are approximately 20 to 25 parts of carbon for every part of nitrogen.

The ratio will vary depending on the species of grass, the stage of growth, or whether there has been a frost.

With wheat/oats stubble, the ratio is 90 to 160 parts of carbon to each part of nitrogen.

When grass is analysed to assess feed value, the figure for nitrogen is multiplied by 6.25 to arrive at the protein level. The first thing to understand about pasture plants is that carbon remains fairly constant from one plant to the next or between leaves and stems.

It is the nitrogen content that varies.

After a frost, it is the nitrogen, not the carbon that is lost.

The atmosphere is 0.03 percent carbon dioxide and 78 percent nitrogen.

However, this is reversed when we look at pastures, with carbon being the main component.

Alan Lauder