Nutrient index value (Parker, 1952) is calculated from the number of soil samples falling in the category of low (\(\text{N}_l\)), medium (\(\text{N}_m\)) and high (\(\text{N}_h\)) nutrient status and represented by expression as given below:
Show Hint
To remember the weights, match the status with the numbers:
- Low \(\rightarrow 1\)
- Medium \(\rightarrow 2\)
- High \(\rightarrow 3\)
Sum the products of the sample counts and their weights, then divide by the total number of samples.