Contamination occurs when there is more nitrate in the soil than plants can absorb. Sources of the contamination, may include: soil containing nitrate-bearing minerals, fertilizers, raw animal wastes or sewage leachate from septic tanks, and surface water runoff. Excess nitrate is carried through the soil into groundwater suppliers by rainwater and irrigation. Because of the use of fertilizer and presence of animal wastes, agricultural areas where heavy farming is performed, tend to have more nitrate-contaminated water supplies than other areas. Because of these factors, well waters containing Nitrogen Nitrate should be checked periodically by local or state health authorities.
What does "heavy farming" mean in the above passage? Does it mean literally 'excessive farming' where people do farming regardless of soil recovery? Or, does it mean 'farming using heavy equipment' to increase the total farm output? I found an example where ,I guess, heavy farming meaning farming using heavy equipment is used, that is, 'heavy farming baling hay'. Am I right??
