Laundry load soil level detection system

A laundry washing machine and method of operating same for the purpose of automatically determining a soil level of a laundry load from two turbidity readings taken before a washing cycle commences, such as during a pre-wash, filling phase. The machine is configured to detect a load size, add a first amount of water and take a first turbidity reading. A first dose of detergent is then added, a second amount of water added and the wetted load is gently tumbled/agitated before taking a second turbidity reading. A value based upon a ratio of the turbidity readings can determine the soil level of the load in order to choose a wash-related parameter, such as how much detergent to use for the subsequent complete wash cycle and/or the duration thereof.