A crop planted to protect the soil from erosion, add nitrogen to the soil, and "trap" nutrients is called a:

A crop that is specifically planted to protect the soil from erosion, enhance soil nitrogen content, and "trap" nutrients is known as a cover crop. Cover crops are typically grown during the off-season or alongside main crops, serving multiple purposes such as preventing soil degradation, improving soil health, and enhancing nutrient availability for subsequent crops.

The primary benefits of using cover crops include their ability to form a protective canopy that reduces the impact of raindrops on the soil, thereby minimizing erosion. Additionally, many cover crops, particularly legumes, have the ability to fix atmospheric nitrogen through their root systems, enriching the soil with this essential nutrient, which can benefit future crops planted in the same area.

In contrast, a fallow crop refers to land that is left uncultivated to restore its nutrients, while intercrops involve growing two or more crops in close proximity to maximize land use and improve yield. Pulse crops are specific legumes cultivated for their edible seeds, which can also contribute nitrogen to the soil but are not primarily intended for erosion control in the same manner as cover crops.