Measuring pasture mass

Whether you are a scientist running feed trials or a farmer managing pasture and feed supplies, measuring pasture mass is an important part of the job. Pasture mass is the amount of pasture per hectare and is usually measured in kilograms of dry matter per hectare (kgDM/ha). Dry matter is the plant material left behind when the water in it is removed. Dry matter per hectare is a unit for measuring pasture production.

A dairy cow at the peak of her production consumes around 18 kg of dry matter (around 100 kg of fresh pasture weight) per day. A ewe with a single lamb consumes 2–3 kg of dry matter per day.

In this activity, students explore a few of the ways in which scientists and farmers measure pasture mass – the fresh weight in the paddock and the dry matter it produces.

This activity follows on from Observing pasture composition.

By the end of this activity, students should be able to:

• use some of the terminology associated with measuring pasture mass
• talk about why farm managers and/or scientists measure pasture mass
• use a quadrat cut to observe fresh pasture
• use a microwave to convert a fresh sample to dry matter
• use simple formulas to determine pasture mass – kgDM/ha for a local pasture or school field sample.

Download the Word file (see link below).