Agriculture Reference
In-Depth Information
at any one time is just a fraction of that needed by plants over the course of the year,
the water-soluble nutrient mix must be continually replenished with minerals and organic
matter. Over time, especially with monocropping and the use of toxic pest and weed
control agents, the availability of soil nutrients diminishes over time. To get around this,
many growers manually amend their soils by adding in readily available fertilizers once
or more each year. A growing trend is the movement towards the use of organic nutrients
(compared to the addition of just nitrogen, phosphorous or potassium) in various forms
ranging from well-conditioned mulches and composts, to cover crops as well. Generally
speaking, soil particles and plant residues are made of large quantities of nutrients that
are nutritionally-unavailable, soother means oftransformation (e.g.bacteria andfungi)are
needed to break them down into forms that plants can take in and use. Over time, plant
residues eventually decompose into soil particulates, mineral ions, or reform into humus.
Forms of Plant Nutrients
Source: Based on Univ. Minnesota Extension
Whileclayandhumusarenotabsorbedbyplants,theyholdnutrientsintheformofmineral
ions on their surfaces. The number of places that are available to hold nutrients is called
the exchange capacity, or more specifically, the Cation Exchange Capacity (CEC) of the
soil.Cations,orpositivelychargedionicelements,areheldtogetherbyelectrostaticforces.
Cationic elements include:
Common Soil Cations
Search WWH ::




Custom Search