What are chelates and chelating agents?

Often in agricultural practice across mineral fertilizers in the form of chelates. Usually, trace elements are synthesized in chelated form to be easily soluble and more easily available to plants.
Chelates are compounds that “make” inaccessible chemical elements in the soil, especially trace elements available to plants. Many micro positively charged ions (cations), while pores of plant negatively charged. In this case the element can not enter the cell. However, by adding a chelate, trace elements such as iron becoming “bunched” (crisp) and a positive charge is changed in the negative or neutral, which allows the element to pass through the pores of the plant.
Synthetic chelating agents
EDTA is the most widely used chelating agent (broker).
A higher degree of quality is DTPA.
EDDHA is the highest quality chelating agent (broker).
Chelates have several points of attachment that they “clutched” micro elements. EDTA four points of connection, while DTPA has five, but most of the links does not have to mean greater advantage of Chelating agent. In some cases chelating agent with four points of connection can better “hold” micro elements, unlike the chelating agent with five points of connection. When the plants will receive the required element, plants remove the element (take), for example iron chelate and in this case the iron is absorbed by crop. chelate is not absorbed, but only the necessary trace element and chelate is back into solution. EDTA is effective best in slightly acidic pH, while the chelating agent DTPA is best effective in alkaline pH environment.
DTPA chelating expensive element unlike EDTA and DTPA often used in better market chelated fertilizer.
Natural chelating agents
Fulvic acid is one of the best natural chelating agents.
Plants that grow on soils with optimum percentage of organic matter, especially fulvic acid, better adopt trace elements and rarely suffer from chlorosis caused by deficiency, i.e. insufficient absorption of iron and other micro nutrients. Fulvic acid obtained by decomposition of organic matter into humus.
Like some of the synthetic chelating agents fulvic acid forms four points of connection with the chemical element, but unlike synthetic chelating agents fulvic acid is absorbed into the plant along with the entry.
Unlike synthetic chelating agents fulvic acid as a chelating agent retains its high efficiency at low and high pH.
Fulvic acid also facilitates the transport of fluids through the plant.