What is the meaning of addition, removal & alteration in agricultural science?

Question

What is the meaning of addition, removal & alteration in agricultural science?

Answer 1

In my experience, these terms are usually used in relation to soil management.  An addition usually refers to the application of a needed nutrient for a crop such as nitrogen, phosphorus or potassium.  It can also refer to irrigation, composting or any other addition of material to the soil.

Removal is the movement of nutrients off of the site with the harvest of the crop and subsequent utilization of the crop.  

Alteration is often the physical modification of a site usually to improve or allow crop production.  Alteration is often a modification of water.  Installation of drainage pipe across the mucky fields on Michigan and other areas allowed these areas to drain more quickly, and thus be farmed.  Installing raised beds allow many landscapers to grow specific plants around certain buildings.  Setting up a timed irrigation system, installing terraces, grassed waterways, etc, are all methods of altering the site to affect water input or water movement.   Alteration may or may not include altering the pH, the aluminium to calcium balance, etc.  This is a gray area as material is added, much like fertilizer, to correct a chemical problem, not a physical problem.