organic food

Are organic fertilizers necessary or even wise in organic agriculture?
By: J.P.van Kooijk (1)



Nowadays a lot of noise is being made about organic agriculture even here in Mexico, where a large project has recently been initiated with the objective to grow 300,000 has (720,000 acres) of organic crops for local consumption and export. Most of the people involved above, all consumers, don't know much about agriculture and (unfortunately) less about fertilizer use and nutrient (fertilizer, manure, chemical compounds) cycles in plant and soil. This caused the idea that chemical fertilizers are part of the environmental contamination problem and that organic cropping systems should not use them. Chemical fertilizers, however, only contaminate if they are used in huge quantities and even then they only cause nutrient contamination or temporary pH changes which are generally harmless unless they cause extreme increases in water plants and algae growth in drainage channels, ponds and lakes which might cause them to clog. The same can happen with excessive use of certain organic fertilizers like cow or pig manure, which caused countries like The Netherlands to apply strict control over amounts allowed to be spread over any given field per year.

To be able to produce intensive organic agricultural and horticultural crops, instead of chemical fertilizers, other more "natural" sources of plant nutrition are used which can cause no end of dangerous situations, for example the spinach-human disease problems (E Coli bacterial infection of consumers) in California. Plants can only take up nitrates, phosphates, potassium, magnesium, etc. as pure chemical elements mostly in the form of ions, and therefore in exactly the same forms independent of source. This means that, whether you use organic or chemical fertilizers, any compound will have to be broken down to its chemical building blocks before those blocks (ions) can be absorbed and used by the plants. The questions are: 1) How efficient is your fertilizer whether they are organic materials as manure, leather industry residues, bone meal, any other organic materials or chemical fertilizer, 2) how fast the nutrients become available, 3) which part of these nutrients can be taken up by the plant or stored in the soil (adhered to CEC, etc.) and 4) which part of the nutrients will be washed out and contaminate the ground water table. Most important however, is the question: What are the byproducts? Purely chemical fertilizers well chosen and adapted to crop and soil should not contaminate at all since byproducts are mainly harmless ions like H+, PO4³-. Ca²+, Cl-, etc., common under natural conditions, and easily dealt with in nature through biological buffers , while residues of many organic matter compounds will have an enormous additional effect in changes of fungus, bacteria and virus populations in the soil while these compounds decompose ( read, rot slowly) in top soil.

Essentially, the basic idea is wrong and should be seriously re-evaluated before we go forth on this very dangerous track. Organic fertilization, or the use organic compounds to provide nutrients for crops , sounds nice to the layperson but does not reduce contamination risks and could cause serious health problems. Chemical fertilizers judiciously applied should not contaminate at all, even less with fertigation and chemigation systems in which minute amounts of nutrients are fed to the crops mixed with the irrigation water of trickle or other irrigation systems.

Some glaring examples of dangerous organic manures: "Night soil" (human manure very much used in China and other Asian countries) is an organic fertilizer, but what happens if even only one person providing the manure has a contagious disease? The E. coli infections in California probably don’t stem from use of human manure or the use of waste (gray) water, but if you use large amounts of organics in top soil you might easily get an E. coli population explosion while the manure decomposes in the fields ( Estrichia coli is a common bacteria in the environment including the human intestines, coli is plural for colon or large intestine where it is abundant under normal balanced conditions) Another example: What happens if large amounts of organic residue hitherto rare in natural soil conditions are added to fields? What might happen in soil bacterial, fungus, etc. populations while they adjust, adapt their populations, and maybe evolve, cannot be foreseen but the “mad cow disease” caused by feeding bovines “organic” animal residue like sheep offal, should be a warning, next a "mad soil disease", a “crazy strawberry disease”, a “diabolical asparagus”, “degenerated nerve system beans” disease or maybe “optical illusion apples” ? We might even discover some new recreational drugs, don’t forget that LSD is a low concentrate of a substance naturally found in a wheat fungus!



1) The author, Johannes P. van Kooijk, holds a M. Sc. degree in both Tropical Crop Production and Soil Science from the National Agricultural College, Tropical and Subtropical Division, in The Netherlands. He lives currently in Mexico and has worked in many countries on plant nutrition, organic agriculture, organic horticulture, organic manure research, integrated pest management, development of alternative innovative crop production systems, agro-forestry research and intensive alternative cropping system evaluation.