Source

Farmers add fertilizers to their fields because it makes the crops grow larger and produce a higher yield. Yield is the quantity of crops that farmers harvest.

A fertilizer is a mineral or chemical compound that increases the nutrients available in a soil so that the plant can grow well to their full potential.

The minerals that would be discussed as regards the write-up here is magnesium and nitrate.

Magnesium

Magnesium is needed to make the green pigment(Chlorophyll). Lack of enough magnesium in plant makes a plant's leaf appear yellow.

Source

Moreover, it can't grow well because it cannot photosynthesise to make its own food due to lack of substantial amount of chlorophyll to trap energy from sunlight for photosynthesis to occur as much as it should for it to make its own food.

Nitrate

Nitrate contains nitrogen atoms. Nitrates are needed by plants to change carbohydrates to protein. Protein are important for making new cells.

Without enough nitrogen, leaves die and plants stay small such as a stunted growth maize plant.
Nitrogen is also needed to make Chlorophyll though not in similar amount as compared to magnesium.

Source

Farmers can test the soil in the field to know exactly which minerals are lacking in each part of the farmland. This allows farmer to know where exactly to add fertilizers and where they are not needed.

Farmers who can afford the latest technological advancements can use GPS Global Positioning Satellite with their farm machineries. The screen of the GPS attached to the front of the farm machineries allows the farmer to view the crops in the field and assess the soil particles for possible changes.

Source

Last but not least, soil fertility assessment with respect to location on the farm field allows the farmer to easily control how much fertilizer is needed in each part of the farm field.

That's all atleast for now on soil nutrients and the need for fertility assessment.
Reference
Reference
Reference

Happy Blogging and Reading 💥💥💥💥