What helps agronomists and agriculture specialists increase yield and keep track of how crops grow and develop in general?

Actually, this is an area that really interests me, because I can imagine how to increase yield, say, in a small garden in my parents' backyard. Even then, it doesn’t always work out. Weather conditions, forgetting to water, pests and insects can really affect it. And if the scale reaches huge fields, I can't even imagine how and what can be controlled there.