Fertilizers in Organic Farming

Before I go on about the use of fertilizers in organic farming, you must first understand what organic farming is. The simplest way to describe organic agriculture is agricultural production without the use of synthetic chemicals (fertilizers, pesticides, antibiotics, etc). For crop production, organic materials such as compost and manure are used to maintain soil organic matter and as sources of nutrients. Nitrogen-fixing as well as pest resistant plant varieties are utilized. The incorporation of soil management techniques such as mulching, inter-cropping and crop rotation are integral components of an organic farming system.

Organic farming is a farming system that promotes, among other practices, the use of organic fertilizers. Organic matter is an essential component of healthy soils, and all sound farming practices integrate and available organic materials to maintain or improve soil fertility. However, because of organic fertilizers are low in nutrient content, high application rates are needed to meet crop nutrient requirements. In many countries, particularly in developing countries, the availability of organic sources of fertilizers is simply insufficient for crop needs, partly due to competitive uses such as energy production. “The nutrient content, composition and release rate of some organic fertilizers is variable with makes it extremely difficult to ensure a steady supply and the correct balance of all the essential elements for healthy plant growth.” (www.wikipedia.org) Nutrient imbalances and declining soil fertility usually show up only several years after conversation to organic farming systems, due to progressively declining residual nutrients in the soil.

The use of some inorganic sources of plant nutrients in organic farming systems is recognized by the International Federation of Organic Agriculture Movements (IFOAM) and Codex Alimentarius. According to IFOAM, any substances to be added to the list of products authorized for organic farming shall “Be essential for achieving or maintaining soil fertility or to fulfill specific nutrient requirements. The ingredients are of plant, animal, microbial or mineral origin which may undergo mechanical/thermal, composting/digestion, their use does not result in, or contribute to unacceptable effects on, or contamination of the environment. Including soil organisms and their use has no unacceptable effect on the quality and safety of the final product.” The Codex guidelines on organic farming state that “Any substances used in organic systems for soil fertilization…should comply with relevant national regulations.”

Nearly all commercial inorganic fertilizers meet the above-mentioned requirements, except the one on acceptable transformation processes. Only those inorganic fertilizers that comply with the processing requirement (Wide range of products, except for nitrogen fertilizers) are listed as authorized products by IFOAM and Codex Alimentarius.

Mineral substances for use in soil fertilization and conditioning in organic farming

Substances allowed by the Codex Alimentarius Substances allowed by IFOAM

Natural phosphate rock Natural phosphates

Basic slag Basic slag

Rock potash, mined potassium salts Mineral potassium

Sulphate of potash

Calcium carbonate of natural origin Limestone, gypsum, marl, maerl, chalk, sugar beet lime, calcium chloride

Gypsum (Calcium Sulphate)

Magnesium rock Magnesium rock, kieserite and Epsom salts

(Magnesium Sulphate)

Epsom salts (magnesium Sulphate)

Calcareous magnesium rock Calcareous and magnesium amendments

Sodium chloride

(Only mined salt) Sodium chloride

Stillage and stillage extract

(Ammonium stillage excluded) -

Aluminum calcium phosphate -

Trace elements Trace elements

Sulphur Sulphur

Stone meal Pulverized rock, stone meal

Clay (bentonite, perlite, zeolite) Clay (bentonite, perlite, vermiculite, zeolite)

Vermiculite

The list of codex Alimentarius authorized products places additional requirements on some inorganic fertilizers, such as; the chlorine content of potassium salts must be less than 60%, while sodium chloride has no restrictions. These