We always had great pea crops until a few years ago. All of a sudden our peas quit coming up. Out of four double rows, we only get about ten plants. We rotate our crops and garden organically. When I dig down to see if the seeds have rotted or failed to germinate, I can't find any seeds at all. Could something be eating the seeds? What would eat them and why all of a sudden? We had ten years of successful pea crops and then almost nothing for the last five years. The few plants that grow are strong and healthy, and the nearby crops germinated just fine.
Mice or birds love to feed on pea seeds. Most birds can be scared off by placing flash tape or predator balloons in the garden. Placing fake snakes in the area may also help. This article will help with mice: https://www.gardeningknowhow.com/plant-problems/pests/animals/garden-mouse-control.htm