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Grain · Soil & nutrition · Fallow

Fallow efficiency

31% of fallow rain stored

The proportion of summer-fallow rainfall captured and held as plant-available soil water at sowing. In a climate where the growing-season rain is unreliable, stored moisture is the insurance that carries a crop through a dry spring finish.

Worked example · Soil water stored ÷ fallow rainfall
31% Target 30% Stored 31% Lost 69%
Soil water stored ÷ fallow rainfall
The benchmark

Summer fallows in southern and central NSW typically store only 20–30% of the rain that falls as plant-available water; good stubble and weed management pushes the top of that range and beyond.

GRDC Water Use Efficiency ↗
What it signals

Fallow efficiency is the difference between a crop that finishes and one that pinches. Every extra millimetre banked over summer is roughly another 20 kg/ha of wheat potential — moisture the season may not otherwise provide.

Data required to calculate
Soil water at sowingmmSoil water at fallow startmmFallow rainfallmm

Silo pulls each of these from the sources the operation already uses, and keeps the figure current automatically.

How to improve it
01

Keep summer weeds controlled so fallow water goes into the soil, not weeds.

02

Retain standing stubble to cut evaporation and catch more rainfall.

03

Match the fallow length and rotation to the soil’s water-holding capacity.

Questions & answers

What is fallow efficiency?

The proportion of summer-fallow rainfall captured and held as plant-available soil water at sowing. In a climate where the growing-season rain is unreliable, stored moisture is the insurance that carries a crop through a dry spring finish.

What data do you need to calculate fallow efficiency?

You need: Soil water at sowing (mm), Soil water at fallow start (mm), Fallow rainfall (mm). Silo pulls each of these from the sources the operation already uses and keeps the figure current automatically.

What is a good fallow efficiency benchmark?

Summer fallows in southern and central NSW typically store only 20–30% of the rain that falls as plant-available water; good stubble and weed management pushes the top of that range and beyond.

How do you improve fallow efficiency?

Keep summer weeds controlled so fallow water goes into the soil, not weeds. Retain standing stubble to cut evaporation and catch more rainfall. Match the fallow length and rotation to the soil’s water-holding capacity.

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