Question

observation of crop rotational

Answer 1

There is an old farmer's adage that says "tomatoes follow corn", but it's much more than an old wives tale.  In this example, growing corn in a patch of ground starves out the root knot nematode that attacks the roots of tomato plants.  If you have observed an issue with root knot nematodes as you pull up your spent tomatoes, you can use this knowledge to address the issue by planting corn, or a related cereal grass such as annual rye, to starve them out naturally.
  
If you grew the same crop in the same row or space season after season, the soil borne pests and diseases that affect that crop would build up in the soil.  Pests and pathogens are opportunistic.  You would be providing them the perfect opportunity to take up permanent residence.  Moving the crop to a different row or space breaks the pest and disease cycle.

Of course, tomatoes and corn are both heavy feeders, so there is more than just one factor to consider for rotating crops.  It is usually preferable to have a light feeder follow a heavy feeder.  This reduces the demand for essential nutrients and gives the soil a chance to rest and recover.  Planting heavy feeders one after the other in the same place depletes the soil.  This results in having to rely more heavily on supplemental fertilizers, especially nitrogen.  

The more you know about crop rotation, the better your garden will be. You will be able to manage some problems naturally, without adding chemicals, and you will be able to build soil as you garden instead of depleting it in the process.

Answer 2

Crop rotation is a method used in fields of agriculture where the different crops will be grown according to the seasons. Crop rotation increases the feritlity of the soil and most helpful for the farmers as it also increase the soil erosion.