Heavy use of copper based fungicides is a big source of soil copper contents. Uptake by plant is generally linked with pH and presence or absence of some micronutrients, such as Zinc, molybdenum. Some researchers suggest use of lime for tuning copper uptake. Question arises, what should be minimum and maximum copper level? When treatment, may be in the form of other micro nutrients, lime or other form of alkalinity is required to discourage its unwanted uptake?
This might be helpful: http://ceqg-rcqe.ccme.ca/download/en/263
Dear Nafees - good question. The problem of Cu pollution is very much there, but main source is anthropological activities in most of the cases and at some places pedo-geochemical sources may also be found.
The question you raised is what level of Cu and other nutrients for safe production food crops. Many organization have set limits for different situations, i.e site specific conditions (like crop type, soil characteristics, management, irrigation water, rainfall etc etc. Here in Pakistan, 2 ppm each of Cu, Mn, Fe and Zn were reported as the best concentration for rice and wheat in calcareous alkaline arid region Indus valley soils. Increase or decrease in anyone will affect the absorption of others.
In soils polluted through raw sewage irrigation, gypsum (as Ca source at different rates ranging from 2 to 16 ppm Ca) antagonized the absorption of divalents (Cu, Cd, Zn, Mn, Fe, Pb, Ni, K, P ------- Ph.D. thesis by Dr. M. Zia-ur-Rehman, Inst. Soil & Environ. Sci., UAF) much more compared to certain other amendments.
For many other nutrients, information is available in literature even you can consult one chapter on nutrition and interactions in our book "Salt-Affected Soil-Principles of Management" published by Allied Book Center, Urdu Bazaar, Lahore.
Thank you for your input. Almost half of the question is answered. The treatment aspects are not clear.
2nd part of the question is "how to discourage the uptake of Copper?". Add lime, add Zinc, add Molybdenum, and what about the dose (Kg/ha).
Adjustment in soil pH is one of the most prudent ways to ensure optimum availability of copper and uptake thereon...
Excess of Cu changes the status of the earth , it becomes more granular.
Try to precipitate the Cu excess with CaOto get a pH around 8.