Application of diammonium phosphate starter fertilizer below and beside the seed while planting is called:

The application of diammonium phosphate starter fertilizer below and beside the seed during planting is referred to as banding. This method involves placing the fertilizer in a concentrated band, either directly beneath or alongside the seed. Banding enhances nutrient uptake efficiency because it positions the fertilizer in close proximity to the root zone, allowing the young plants to access the nutrients more readily as they grow.

In contrast, sidedressing involves applying fertilizer to the soil surface alongside growing plants, which is typically done later in the growing season. Fertigation refers to the practice of applying fertilizers through irrigation systems, ensuring an even distribution of nutrients directly with water. Topdressing involves spreading granular fertilizer on the surface of the soil after crops have emerged, which may not provide the same immediate access to nutrients as banding does. Each of these methods has its specific application timing and purpose, but for starter fertilizers like diammonium phosphate placed at planting, banding is the most effective approach.