Explain Why Lime & Ammonium Fertilizer Should Not Be Added at the Same Time

Soil pH

• Soil pH is affected by lime and ammonium or ammonium sulfate. The pH scale ranges from 0 to 14. A measurement of 0 to 7 is an acidic soil, while 7 to 14 is alkaline. Adding fertilizer helps gardeners balance the pH of the soil and keep it at a healthy level for plants. Many plants prefer a mildly acidic soil. Raising or lowering the pH of the soil depends on the type of fertilizer and the initial soil pH.

Lime and Ammonium

• Lime, often derived from limestone, is used to increase the pH of the soil and make it more alkaline, according to the Clemson Cooperative Extension. Fertilizers that contain lime are used in situations where the soil is too acidic for the health of plants. Ammonium and ammonium sulfate fertilizers decrease the pH of the soil and make it more acidic. Adding ammonium to the soil helps make it healthier for plants that need an acidic soil for growth.

Adding Fertilizers

• The pH of the soil is affected by the type of fertilizer added. However, adding fertilizers that contain both lime and ammonium has an undesired effect on the soil. Equal amounts of lime and ammonium may balance out, leaving the pH of the soil unchanged. A slightly unbalanced amount of lime or ammonium leads to a pH that is not acidic or alkaline enough, depending on the needs of the soil and the plants growing in the garden.

Fertilizer Burn

• Another problem associated with adding lime and ammonium fertilizers at the same time is fertilizer burn, which results from the application of excess fertilizers. Salts and other chemicals in fertilizer dry out the soil and the plants they are placed on, which gives grass, trees, shrubs and flowers a dried-out and burned appearance. Heavy and simultaneous applications of these two types of fertilizers do more harm than good to the garden. Avoid adding too much fertilizer to the soil.