Climate and rainfall in pastures

Climate affects the characteristics of a land type and the pasture that grows there. Rain, heat, humidity, wind and frost all affect pasture composition, quantity and quality.

Rainfall

Annual rainfall averages can be used as the 'normal' amount to expect for a region. However, averages can be skewed from very high rainfall and extreme weather events.

Total rainfall figures may also be misleading because intense rain may have occurred over a few days rather than in steady rain events across a season. Intense rain usually runs off the soil instead of being absorbed, so it is less effective for pasture growth than steady gentle rain.

Use the AussieGRASS tool for data on regional rainfall and pasture growth.

Factors that affect rainfall and pasture growth include:

• ground cover (pasture condition and species)
• soil type and condition
• rainfall intensity
• evaporation
• slope
• tree cover.

Temperature

Consider local temperature averages and extremes as part of your pasture management plan or when selecting pasture species.

Temperature, rainfall and sunlight has a direct effect on pasture growth. Pastures grow well during warmer months if there is enough moisture. Growth in winter is minimal, however forbs (non-woody broadleaf plants) can be abundant, providing extra pasture quantity and protein for grazing livestock.

Climate change

Future impacts of climate change may make managing grazing lands even more complex.

There may be more intensive rainfall events but lower overall rainfall figures. Increases in temperature and evaporation rates may stress animals, pasture production and land health.

Potential damage may include:

• higher rainfall intensity
• more potential evaporation
• more soil evaporation
• less pasture growth in summer and less digestibility
• trees dying during droughts
• more animal heat stress in summer
• less grazing time and greater water demands
• more diseases and pests in hot and wet conditions
• increased stress on human health (including heat stress).