Alternative Soil Amendments

800-346-9140
ALTERNATIVE
SOIL AMENDMENTS
A ppropri e Technol
at ogy Transf f R ural A reas
er or
HORTICULTURE TECHNICAL NOTE
www.attra.ncat.org
ATTRA is the national sustainable agriculture information center funded by the USDA’s Rural Business -- Cooperative Service.

ABSTRACT: This publication covers soil amendments that are not standard agricultural fertilizers. These include plant and
animal by-products, rock powders, seaweed, inoculants, conditioners and others. Much of the information is taken from research
reports by Iowa State University and the Rodale Institute Research Center, which cover the material in greater detail (2, 9). The
reader is referred to these works for additional information. Another ATTRA publication, Sources for Organic Fertilizers and
Amendments, serves as a companion piece to this document. It provides sources for the materials discussed herein.

Written by Bart Hall, July 1998
Revised by Preston Sullivan, April 2001

Table of Contents
Amendments in Proper Context...........................................................2
Plant & Animal By-Products ................................................................2
Manure & Compost Based Products ....................................................3
Rock and Mineral Powders ..................................................................4
Seaweed Products ...............................................................................7
Microbial Inoculants ............................................................................8
Soil Conditioners ..................................................................................10
Evaluate Products Carefully.................................................................10
References ...........................................................................................11

IS A PROJECT OF THE NATIONAL CENTER FOR APPROPRIATE TECHNOLOGY

Amendments In Proper Context amendment without ensuring that it was
approved by the program under which they
The sustainability of a farm system is only sought certification. Some alternative soil
marginally related to fertilizer and other inputs. amendments either contain ingredients that
Intrinsic soil factors such as slope, texture, and disqualify them from use in certified production,
local rainfall, along with management-related or contain "secret" ingredients that prevent a
factors such as a forage-based rotation, soil certification program from evaluating whether or
organic matter, aggregate stability, and tillage not that specific brand can be approved.
practices, have a much greater influence on the
sustainability of any given farm than does the ATTRA has additional information on organic
type or amount of soil amendments. Shifting certification, plus a list of certifiers, available
from conventional inputs to alternative ones does upon request. ATTRA has some good
little to increase overall sustainability. introductory material on sustainable soil
management; ask for ATTRA publications
For example, yields of most crops will be reduced Overview of Cover Crops & Green Manures and
in soils with poor or excessive drainage, and Sustainable Soil Management.
when soil pH is too acidic or alkaline for the
crop’s needs. Only if soil moisture, air, and Plant & Animal By-Products
acidity regimes are generally correct do the major
nutrients—nitrogen, phosphate, and potash— Assorted by-products of the food and fiber
begin to exert significant influence on yields. In industries are occasionally used as soil
other words, if a soil is excessively acid and amendments, returning to the land nutrients that
poorly drained it doesn't really matter how much might otherwise be wasted.
fertilizer (conventional or alternative) is applied; Many of these products are far too expensive to
yields will still be disappointing. justify their use in other than very specialized
horticultural applications.
In most cases, alternative products are
appropriate and effective as minor components Plant by-products
of a highly developed system of whole-farm
management. They are most effective in fine- Alfalfa meal (or pellets) contains around 3%
tuning a system that already functions relatively nitrogen and is commonly used as an animal
well. This fact is well worth remembering when feed. It is an excellent fertilizer material in
talking with vendors at a trade show or planning horticulture, and is said to contain unknown
a product purchase. It is wise to evaluate their growth factors which make its mineral content
potential usefulness in view of other use for the more effective as plant nutrients.
same money.
Cottonseed meal is a rich source of nitrogen (7%).
Farmers for whom organic certification is an Unfortunately, a substantial percentage of the
important element of marketing should check insecticides used in the U.S. are applied to
carefully with their certification program before cotton, and some of these tend to leave residues
buying any product that they do not positively in the seeds. Most organic certification programs
know is approved on a brand-name basis. restrict or prohibit the use of cottonseed meal.

Organic certification programs and their field Fruit pomaces are what remain after the juice is
inspectors have reported persistent problems extracted. They are heavy, wet products
with alternative soil amendments other than the normally available only locally, and best
better-known alternative fertilizer materials. composted before use.
Some farmers have been refused certification
because they took the word of a product Leaf compost is increasingly available as more
promoter and applied an alternative soil and more municipalities compost urban and

// ALTERNATIVE SOIL AMENDMENTS Page 2

suburban leaves. In principle, the product is a measured as 4-1-1. Fish emulsion may be
good one, but it is often contaminated with fortified with chemical fertilizer, so organic
"impurities" ranging from transmission fluid to farmers should be suspicious of any product with
trash bags. a nitrogen content in excess of 5%.

Soybean meal is, like alfalfa, most commonly Leather meal is ground tannery waste with 10%
used as a protein supplement for animal feeds. nitrogen. Unfortunately, most leather meal also
With about 7% nitrogen it can be a useful, but contains about 3% added chromium (a toxic
expensive, fertilizer material. heavy metal), and is thus prohibited in organic
agriculture.
Wood ash contains about 2% phosphate and 6%
potash, but may be contaminated with heavy Manure and Compost Based
metals or plastic and typically has a high salt
Products
content. Wood ash is rather alkaline, and
excessive use can be quite damaging to many One of the most common types of prepackaged
soils. Some organic programs restrict its use. alternative soil amendments is the manure- or
compost-based blended fertilizer. Several of
Animal by-products these products have national distribution, and
many more enjoy a loyal regional following. Such
Blood meal is dried slaughterhouse waste products are typically analyzed at 2 to 5% for
containing about 12% nitrogen. Unless used each nutrient. Dried compost is used as a
carefully, it can burn plants with ammonia, lose bulking agent, source of nutrients, and organic
much of its nitrogen through volatilization, or matter. It is blended with several of the materials
encourage fungal growth. In view of the discussed in this publication, including rock
extremely high cost of blood meal, farmers minerals and plant and animal by-products.
should be sure that it really is the best source of Nearly all products of this class sell for prices
nitrogen in a given situation. about three times greater than their conventional
fertilizer value, but may be quite effective in farm
Bone meal is discussed under phosphate sources, situations. However, farmers with access to other
in the section titled “Rock and Mineral Powders.” sources of manure or compost can realize
substantial savings by relying on local manure
Feather meal is a common by-product of the resources. Some manure-based, blended
poultry slaughter industry. Although total fertilizers contain ingredients prohibited by one
nitrogen levels are fairly high (7 to 10%), the or more organic certification programs and may
nature of feathers is such that they break down not be used in certified production; others may be
and release their nitrogen much more slowly disqualified because the manufacturer refuses to
than many products of similar price. reveal the "secret" ingredients.

Fish meal and fish emulsion are, like most animal Composted sewage sludge is marketed as a
by-products, rich in nitrogen. Fish meal contains fertilizer and soil amendment. This compost
about 10% nitrogen, along with about 6% provides organic matter and a number of
phosphate. It is most frequently used as a feed nutrients, and as marketed, is solid with little
additive, but can be used as a fertilizer. The odor. The greatest potential problems with using
fertilizer analysis of fish emulsion varies with composted sludge are heavy metals from
preparation method. Whole fish and fish parts industrial waste, along with assorted chemical
must be digested to form a slurry, a process contaminants (from household cleaners, latex
accomplished with the aid of either phosphoric paint, and other things people flush down their
acid or special enzymes. Acid-digested fish drains). Pathogens are controlled fairly easily
emulsion usually has an analysis around 4-4-1, through proper composting, which raises the
while enzyme-digested fish emulsion is usually temperature of the composting material


sufficiently to kill many microorganisms. The on-farm experimentation. A general
U.S. Environmental Protection Agency has understanding of the principal phosphate
established strict guidelines for pathogen control, products, however, will give some indication of
which most sewage composting facilities follow. how they are likely to act in different
circumstances. Of particular importance is soil
Heavy metal contamination is a significant risk pH; phosphates will be released more quickly in
wherever industrial facilities contribute to moderately acid soils than in neutral or alkaline
sewage. Contamination by heavy metals and soils.
many other chemicals is limited as much as
possible with current technology, but composted Colloidal phosphate consists of clay particles
sludge often contains levels that make it surrounded by natural phosphate. Total
unsuitable for use on food crops. Before using phosphate is around 20% and “available”
any composted sludge or other treated municipal phosphate about 2–3%. An efficient use of
waste product in crop production, the grower colloidal phosphate is to add it directly to
must know the chemical composition of the livestock manure in the barn or lot, where the
product and whether it is safe to apply to food manure acids dissolve much of the total
crops. Have the sludge tested. It is important to phosphate and the phosphate stabilizes the
note that at least 38 states regulate the production nitrogen in the manure. Many of the same
of sewage compost. Its use is prohibited in all advantages can be had by adding 20–50 pounds
certified organic production. of colloidal phosphate to one ton (two cubic
yards) of manure when composting. The ATTRA
Rock And Mineral Powders publication Farm-scale Composting Resource List
directs the reader to many useful resources on
Phosphate sources composting. When direct land application of
rock phosphate is the only possibility, spreading
There are a number of alternative phosphate rates between 500 and 2,000 pounds per acre are
sources on the market, but it can be difficult for appropriate, depending on phosphorus status,
growers to determine which is the most soil acidity, and finances.
appropriate for their operation. Much of the
difficulty stems from confusion about the Rock phosphates are usually derived from
difference between “total” and “available” ancient marine deposits. They have a different
phosphate. Chemical phosphate fertilizer is sold composition than collodial phosphate, generally
on the basis of available phosphate expressed as making them less available. Total phosphate is
P2O5. In fact, “available phosphate” is the only around 30% and available phosphate 1–2%. They
allowable claim for fertilizer value. are best used in the same manner as colloidal
phosphate, and it is worth paying for several tests
Available phosphate designations are determined to determine how effectively this phosphate
moves into manure and soil. It may or may not
by measuring the amount of phosphate that
be a better buy than colloidal, depending greatly
dissolves in a weak citric acid solution believed to
on conditions and circumstances.
imitate conditions near plant roots. This test
provides a standard means of comparing
Hard-rock phosphates are usually derived from
different phosphate sources. Unconventional igneous volcanic deposits and consist almost
phosphates, because of their slow release, are totally of the mineral apatite. Although apatite
often promoted on the basis of total phosphate contains about 40% total phosphate, because of
content. Neither available nor total phosphate the mineral's composition, this phosphate is
analyses give a particularly accurate picture of largely unavailable. In most circumstances it is
how different phosphate materials will perform not a good buy, but in some situations is the ideal
in natural systems, hence the importance of product; again, trial and observation are the keys
developing good powers of observation through to a wise purchase.


Bone meal is so well known, especially in Sulpomag® and K-Mag® are two brand names for
horticulture, that it can hardly be considered an langbeinite.
alternative product. Typically it contains about
27% total phosphate, and nearly all of that is The salt content and solubility of potassium-
available. There is a great deal of confusion bearing sulfates dictate well-considered use, but
about the phosphate content of bone meal their high potash content (22% for langbeinite
because much of it is sold as a feed additive. In and 50% for potassium sulfate) does allow for
the feed industry, phosphorus is expressed on the good plant response from relatively modest
label as elemental phosphorus, while in the application rates. Although soluble salts, these
fertilizer industry it is expressed as phosphate. products are considerably less salty and less
Phosphate gives a much bigger number (2.3 times soluble than either kainite (a mixture of
as big) for the same actual phosphorus content. potassium sulfates and common salt) or muriate
Twelve percent phosphorus is the same as 27% of potash, the most common conventional
phosphate, and bone meal is sold under either of potassium fertilizer.
those (or similar) numbers; it's the same good,
but expensive, product in either case. Granite dust is often sold as a "slowly available"
potash source for organic production. Total
A by-product of the smelting industry, basic slag potash contents in granite dust typically vary
may, if finely ground, be a source of phosphorus from 1 to 5%, depending on overall mineral
and minor elements. Use of basic slag in organic composition of the rock, but granite is mostly
production is restricted. feldspar, a mineral with low solubility.
Therefore, little potash fertility is derived from
Potassium from rock and mineral powders this material.

Alternative potash (potassium) sources are Another source of slowly available potash,
similar to alternative phosphates in that there are popular in alternative agriculture, is the clay-type
a variety of sources, with differing availability mineral, glauconite, commonly sold as
and fertility value. As with phosphate, there is a greensand. Total potash content of greensand is
difference between available potash and total around 7%, all of which is deeply locked into the
potash; similarly, there is a difference between mineral and only slowly available. Greensand is
pure potassium and potash, with the potash also said to have desirable effects on soil
number being 1.2 times higher than potassium structure. Its high price, however, limits its use
for the same amount of nutrient. solely to high-value horticultural applications.

Two sources of potash, potassium sulfate and Feldspar is one of the major potassium-bearing
potassium magnesium sulfate (langbeinite), are minerals of granite. Feldspar powder is fairly
commonly enough used in conventional easily obtained through the ceramics trade.
agriculture that they can hardly be considered Unfortunately, most feldspar potash is as tightly
alternative, save for the fact that both are bound within its mineral structure as is the
regularly used in certified organic agriculture. potash in greensand. Unless particular
There are two forms of potassium sulfate on the circumstances provide a clear indication that
market. One is derived by reacting sulfuric acid feldspar is the most appropriate source of potash,
with potassium chloride. It is a good fertilizer, it is proabably not cost-effective.
but not acceptable in certified organic
production. Natural potassium sulfate, from Certain micas, particularly biotite (black mica),
Great Salt Lake, is extracted by a differential contain several percent total potash, which,
evaporation process lasting three years. It can be because of mica's physical structure (quite
used in organic farming. Langbeinite goes from different than feldspar or glauconite), is relatively
mine to field with minimal processing. available in microbially active environments. If
pure biotite can be obtained at a reasonable price,
it may be cost-effective and useful.


A by-product of the cement industry, kiln dust Zeolites
can be an affordable limestone substitute and
potash (about 6% soluble) source in areas where Zeolites are mined alumino-silicate materials,
it is available. Some cement kilns are fired using containing only insignificant levels of plant
assorted industrial wastes, sometimes including nutrients. Their use in crop production stems
hazardous wastes. Dust from these kilns may primarily from high nutrient-exchange capacities,
itself be a hazardous product, and in several which allow them to absorb and release plant
states is legally treated as such. Sources should nutrients and moisture without any change in the
be verified carefully, and state regulations nature of the zeolite. This action results from the
checked. To date, the product is sold only in mineral’s porous-but-stable chemical structure.
bulk. It is generally prohibited in certified
organic production. Zeolites enhance the performance of fertilizers by
making them resistant to leaching,
Secondary and minor nutrients from rock immobilization, and gaseous losses. They are of
powders particular use in reducing leaching in sandy soils.
In one study, 4 to 8 tons of zeolite per acre was
A number of other rock dusts and powders are applied (1). Yield increases were reported for
occasionally available in various parts of the wheat (14%), eggplant (19–55%), carrots (63%),
country; sometimes the results from local trials and apples (13–38%). Zeolites are widely used in
are reported in national or international eastern European and Japanese agriculture, but
publications, but it is important to remember that their use in the U.S. at this time is very limited.
what applies in one region may not be pertinent
in another. Additionally, when dealing with Humates
natural materials like rock, there is very little
product consistency from one batch to another; Humates are commercial products usually
results from one trial may not be transferable to prepared from leonardite, an oxidized form of
other situations. lignite coal and clay. Leonardite may contain up
to 60% humic and fulvic acids, which mimic the
Basalt dust, if available at a reasonable cost, can "active" part of soil humus. Soil scientists use
provide a wide range of trace minerals to very broad definitions to describe soil organic
agricultural systems over a period of several matter components; "fulvic acids" and "humic
years; as with most rock powders, transportation acids" are terms lumping complex families of
costs are a major factor in determining cost- organic compounds together on the basis of how
effectiveness. Most of the rich volcanic soils of they can be most easily extracted from soil. For
the world are derived from basalt, which gives the most part, however, the organic acids
some indication of basalt's agronomic value, and extracted from leonardite bear little resemblance
even when too expensive for land application, to the humic or fulvic acids in soils. Although
basalt dust can benefit farm systems when mixed extremely useful and cost-efficient in certain
with manure in the composting process. situations—as nutrient substrates in soilless
greenhouse production for example—humates
Any rock, of course, can be ground into powder, and similar products are less clearly helpful in
if the price is right. Various people have many field situations.
proposed additions to the soil of assorted rock
dusts, or even powdered gravel. One rationale The sheer volume of organic matter in even
for this is the paramagnetic property that some moderately rich soils suggests that agronomically
rock minerals add to the soil—a factor believed to affordable applications of humates may not
be associated with high fertility. ATTRA has produce significant improvements. The top six
additional information on paramagnetism in soils inches of soil weigh approximately 1,000 tons per
for those interested. acre; each percent of organic matter, therefore,
weighs ten tons. Even assuming that the organic
matter in humate products actually is similar to


that in soil, it requires two tons of humates per Seaweed Products
acre to increase soil organic matter by 0.1%.
Most seaweed fertilizers come from kelp that has
Research by the Rodale Institute determined that: been harvested, dried, and ground. Kelp meal is
suitable for application directly to the soil, or for
commercial humates...are not products that addition to the compost pile. It flows easily and
can substitute for adequate mineral is readily applied with most dry fertilizer
nutrients.... Humates do contain high applicators. It is easily mixed with other dry
percentages of humic acids and organic fertilizers and amendments.
matter, but at their recommended, or
economically feasible rates it is likely they
Soil application rates for kelp meal commonly
may not significantly increase soil organic
range from 150 to 250 lbs/acre for pastures,
matter. Likewise, the humic acids in
forages and small grains. Two hundred to 400
commercial humates may have the ability
lbs/acre are advised for corn, horticultural crops,
to...provide growth-stimulating effects, but
and gardens. Since it is expensive, kelp meal is
in the soil they comprise only a minute
most commonly used only on high-value crops.
fraction of the total soil humic acid content
(2).
Dried raw seaweed tends to contain about 1%
Additionally, the results indicated that humates nitrogen, a trace of phosphorus, and 2% potash,
containing unrefined leonardite can immobilize along with magnesium, sulfur, and numerous
soil phosphorus under some conditions, creating trace elements. Raw seaweeds are prepared by
a negative effect on plant performance. various methods and sold under a number of
brand names.
The Rodale report also concluded that:
More often, compounds from kelp and other
[while] humate products are based on seaweeds are extracted by various methods in
sound principles and the potential for order to concentrate both micronutrients and
their beneficial action does exist...the naturally occurring plant hormones into a
economics and time involved to increase soluble, easily transported form. Such kelp
organic matter through commercial extracts are sometimes applied as a foliar spray
products, rather than through more by farmers seeking a natural source of
traditional organic-matter-building micronutrients. For the most part, none of the
programs, should be seriously considered micronutrient levels in kelp extracts is high
(2). enough to correct a deficiency, but as a "tonic"
providing a broad array of micronutrients and
Despite such determinations, many farmers other trace elements, seaweed extracts have won
report significant benefits from the use of a measure of acceptance among organic farmers.
humates and related products. Where humates Note that while most kelp products are allowed
have shown the most promise is as natural soil in certified production, a few have been
amendments in areas with alkaline, low-organic- supplemented with commercial forms of potash
matter soils. Such soils are common across a and other nutrients and are prohibited.
wide range of agricultural production zones in
the southern and western U.S. Leonardite and Microbial Inoculants
similar products are generally consistent with
organic production practices, given that they are Inoculants, which are dry or liquid preparations
natural products with proven benefit in certain of one or more species of microorganism, fall into

situations. Some extracts, however, are not three broad groups: 1) those that inoculate
acceptable in certified organic production, individual plants with symbiotic organisms
depending on the extraction process used. (chiefly Rhizobia spp.), 2) those that inoculate the


soil with desirable organisms, and 3) those that from plant association by taking nutrients and
are used as “cover crops” (algae). carbohydrates from the plant roots they live in.

Rhizobia In soils where mychorrhizae have been killed off,
an inoculation may be beneficial. In healthy soils
The most clearly beneficial microbial where they already exist there will be little or no
preparations for agricultural use are the different benefit to adding more. There are dozens of
strains of Rhizobia used to inoculate legumes. mychorrizae species in nature. Additionally, the
Specific strains of these bacteria live in a mutually species found on plant roots may change as the
beneficial (symbiotic) relationship with specific plant matures. If those that are available are of
species of legumes. The bacteria penetrate the the correct species, and are handled properly at
plant roots, causing the formation of root nodules all stages, they offer interesting potential benefits
containing both plant tissue and bacteria. In very to farmers in well-managed systems. Generally it
simple terms, the plant supplies the physical is preferred to inoculate with several species
environment and certain nutrients to the bacteria; rather than a single one. For information on
the bacteria "fix" nitrogen from the air into rhizobial and mycorrhizal inoculation for disease
compounds that then become available to the suppression, request the ATTRA publication
plant. Typical nitrogen fixation rates vary from Sustainable Management of Soil-borne Plant
50 lbs/acre to over 300 lbs/acre, depending on Diseases.
climate, species, and soil conditions. On most
farms these rates make it possible to harvest good Free-living soil organisms
crops without purchasing additional nitrogen.
A great many of the products in this category are
Mycorrhizae designed to be sprayed on the soil surface or on
crop residues in order to inoculate the topsoil
The mycorrhizae (my-cor-ry-‘zee) group of fungi with desirable microorganisms. Manufacturers
live either on or in plant roots and act to extend of these products make numerous and varying
the reach of root hairs into the soil. Mycorrhizae claims about their beneficial effects, which fall
increase the plant's uptake of water and into three broad categories:
nutrients, especially in less fertile soils. The
superfine, root-like structures of these fungi are • The microbes will fix enough nitrogen from
more extensive and more effective than plant root the air to allow the farmer to eliminate much
hairs at absorbing phosphorus, and other or all fertilizer.
nutrients as well. Phosphorus moves slowly in • The product improves soil organic matter and
soils but the fungi can absorb it much faster than "releases" soil nutrients to the crop.
the plant alone can. This enhanced root feeding • The product produces better yields, especially
makes it possible to reduce fertilizer rates for during times of drought.
plants having a healthy colony of mychorrhizae.
Some plants including citrus, grapes, avocados, Many microbial products do indeed contain free-
and bananas, are dependent on mycorrhiza living (as opposed to symbiotic) microbes that are
fungi. Others that benefit from having them are known to fix nitrogen in certain circumstances.
artichokes, melons, tomatoes, peppers, and Those species, however, work best in wet,
squash. oxygen-poor conditions that most farmers and
their crops would prefer to avoid. Rice paddies
Roots colonized by mycorrhizae are less likely to are a notable exception. In the vast majority of
be penetrated by root-feeding nematodes since cropping situations other than rice production,
the pest cannot pierce the thick fungal network. the amount of nitrogen fixed by such free-living

Mycorrhizae also produce hormones and microbes is not generally considered
antibiotics, which enhance root growth and economically significant (3). In other words, the
provide disease suppression. The fungi benefit value of any fixed nitrogen may be less than the
cost of the product. Far greater nitrogen fixation,

for example, can be obtained via symbiotic surface is necessary. On most soils this would
Rhizobia on a legume sod or cover crop, for much require irrigation.
lower cost.
Where weed management is a concern, a
Soil microbes, like all living things, will thrive traditional cover crop will be more effective than
only in the presence of their preferred algae. The algal mat is very thin and will not
environmental conditions—moisture, oxygen, suppress weeds adequately. The constant surface
temperature, pH, food, and shelter. When moisture required by the algae tends to
conditions are not within favorable ranges, the encourage weed seeds to sprout. It can also
microbes cease reproduction or die. Natural encourage disease problems in the crop.
microbial populations will be abundant if soil
conditions are right. Adding a microbial Enzyme-Based Amendments
amendment in such circumstances may not be
cost-efficient, because the naturally occurring Enzymes are involved in a number of soil
individuals will typically outnumber the same reactions, particularly as catalysts in the
species supplied in a product by 10,000 to 1, or microbial breakdown of organic matter, but very
more (4). little research has been done on the effects of
adding enzyme products to the soil.
If soil conditions are not right, inoculant Nevertheless, commercial enzyme treatments for
organisms will reproduce just as slowly as their soils are often advertised as having a large
naturally occurring colleagues, which is to say, number of beneficial effects, including improved
not at all. The consensus among agronomists soil structure, nutrient "activation," greater
appears to be that these products perform best nutrient availability, "detoxification" of the soil,
when the soil is at or near optimum conditions to better drainage, better water retention, and
begin with. greater microbial activity.

Algal mats In nature, the microorganisms that process soil
organic matter produce the enzymes they need to
Another group of inoculants, sold as "cover do the job. Those enzymes, being proteins, are
crops," are commercial preparations of themselves broken down by microbial action (5).
soil-inhabiting algae advertised as providing Enzymes added to the soil would probably suffer
many benefits, including reduced soil crusting, a similar fate in short order.
improved soil structure, increased soil organic
matter, improved drainage, and better moisture As with free-living soil organism products, the
retention. A solution of the algae mixed with circumstances where enzyme products are likely
water is sprayed on the soil surface. In theory it to perform the best are in soils, that are already
then establishes itself to form a continuous mat well-balanced and in good condition.
over the soil surface. If natural algae populations
have not been observed to populate a particular Vitamin products are also sold as soil treatments
soil already, management practices will have to on occasion, but more often as sprays for the
be adjusted to get successful growth of an algal plants themselves. Plants might absorb some of
cover crop. the vitamin through leaves or roots, but much of
the applied vitamin is broken down into simple
Algae are susceptible to the vast majority of components before being absorbed by the plant
herbicides in use today and would therefore be (6, 7). Generally, plants in favorable
essentially incompatible in a conventional row environments synthesize all the vitamins they

crop system. Mat establishment could only occur need from the resources at hand. The most likely
in the absence of soil disturbance. Therefore, benefit of applying a vitamin product would be
application would need to be made only after a as a “quick fix” measure for plants grown under
final cultivation. Lastly, a continuously moist poor conditions, provided it is possible to


determine just which vitamins happen to be structure. Note, too, that many wetting agents
deficient. are not acceptable in certified organic production.

Soil Conditioners Evaluate Products Carefully
Wetting agents and surfactants break the natural Some non-traditional soil treatments are based on
surface tension of water, overcoming its tendency sound biological or scientific principles.
to form droplets, and allowing it to penetrate a Unfortunately, a number of studies cited in the
variety of materials. Common clothes-washing Compendium (9, 10) and in the Rodale report
solutions, shampoos, and detergents rely on Novel Soil Amendments (2) show that using many
wetting agents or surfactants to function of the non-traditional products mentioned here
effectively. Similar compounds are also sold as results in negative net income for the farmer. The
soil conditioners and are heavily promoted as supposed beneficial effects of the products tested
improving water penetration, drainage, and soil in these studies do not increase yields sufficiently
structure. They are also advertised as aids in to offset the cost of applying the product. In
controlling erosion and reducing compaction or many studies, the product tested had no
hardpans as a result of increased water measurable effect on either the crop or the soil.
penetration of the soil.
Advertisements for these products often cite
In general, wetting agents are effective where a studies which the sellers claim prove the
soil's water-repellency is caused by turf or effectiveness of their products. Those results,
grassland cover, by ash from the burning of however, are usually taken out of context,
organic matter, or by single-grain soil structure obscuring the fact that the claimed yield increase
(soil particles all of one size and not aggregated,
is due not to the tested product, but to normal
as occurs in some sands). Conditions
random fluctuations in yield caused by
in which wetting agents have little or no effect
include poor drainage due to hardpans, environmental conditions within the study.
compaction from tillage or traffic, and “tight” or In other words, the product doesn't really do
fine-textured soils that have very small pores what the vendors claim it does. Though
(such as some clays). In other words, wetting governments do require companies to guarantee
agents are likely to have some effect where water analyses and to back up sales claims for
infiltrates a soil slowly because the soil surface conventional fertilizers, alternative products are,
repels water, but not where water penetrates for the most part, unregulated and uncontrolled.
slowly because there are no large pore spaces (8).
Most soils with good structure have good At the same time, prejudice against alternative
infiltration rates. Soil structure can be products and practices has often resulted in
maintained and improved by a good rotation,
testing that has been less than honest, and some
regular additions of organic matter, and normal
off-the-cuff rejections by researchers and
conservation practices. Beneficial effects should
not be expected on soils that are already wetable. Extension. As a result, farmers benefit the most
by evaluations done within the context of their
Commercial wetting agents can be quite own farm operations. On-farm research trials
expensive, especially when used to treat large take some effort but are not difficult to perform.
areas, and any results may not justify the cost of Contact ATTRA for a copy of the Sustainable
the product. Some farmers attempt to economize Agriculture Network's publication entitled How
by applying something like dishwashing soap or to Conduct Research on Your Farm or Ranch.

shampoo instead of commercial wetting agents, References
but caution is advised since other ingredients in
household products may be detrimental to plant 1) Mumptom, Fredrick A. 1985. Using zeolites
growth or may cause a breakdown of soil in agriculture. p. 125–158 In: Innovative


Biological Technologies for Lesser Developed 7) Allison, F.E. 1973. Soil Organic Matter and its
Countries. Congress of the United States, Role in Crop Production. Elsevier Scientific
Office of Technology Assessment. Publishing Co., New York, 639 p.
Washington D.C. 246 p.
8) Sunderman, H. D. 1983. Soil Wetting Agents:
2) McAllister, J. 1987. A Practical Guide to Their Use in Crop Production. North Central
Novel Soil Amendments. Rodale Press, Regional Extension Publication 190, 4 p.
Emmaus, Pennsylvania. 124 p.
9) NRC-103 Committee. 1986. Compendium of
3) Huang, P. M. and M. Schnitzer, (eds.) . 1986. Research Reports on Use of Non-Traditional
Interactions of Soil Minerals with Natural Materials for Crop Production, Cooperative
Organics and Microbes, Special Publication Extension Service, Iowa State University,
17. Soil Science Society of America, Madison, Ames. Varied pagination.
Wisconsin. 606 p.
10) Ibid. Supplement 1.
4) David Patriquin
Department of Biology, Dalhousie Univ.
Halifax, Nova Scotia By Bart Hall, July 1998
Revised by Preston Sullivan, April, 2001
5) Stevenson, F. J., (ed.) . 1982. Nitrogen in
Agricultural Soils. American Society of NCAT Agriculture Specialists
Agronomy. Madison, Wisconsin. 940 p.

6) Vitosh, M. L. 1984. Biological Inoculants
and Activators: Their Value to Agriculture.
North Central Regional Extension
Publication. 168. 4 p. The electronic version of Alternative Soil Amendments
is located at:
http://www.attra.org/attra-pub/altsoil.html

The ATTRA Project is operated by the National Center for Appropriate Technology under a grant from the
Rural Business-Cooperative Service, U.S. Department of Agriculture. These organizations do not
recommend or endorse products, companies, or individuals. ATTRA is located in the Ozark Mountains
at the University of Arkansas in Fayetteville at P.O. Box 3657, Fayetteville, AR 72702. ATTRA staff
members prefer to receive requests for information about sustainable agriculture via the toll-free
number 800-346-9140.


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