How do you know that they are deficient?May i know with what do you compare the indices or the benchmark for comparisons?

Thank you in advance.

Nur, what we do is look at recommended levels of a given nutrient in the soil and compare that with the actual soil nutrient. If the actual soil nutrient falls below then its is inadequate. We have further investigated on the different dosages of the potassium nutrients against available commercial fertilisers and found that the potassium levels in soil plays key role in maize yield

Thanks