A soil conditioner is a product which is added to soil to improve the soil’s physical qualities, usually its fertility (ability to provide nutrition for plants) and sometimes its mechanics. In general usage, the term "soil conditioner" is often thought of as a subset of the category soil amendments (or soil improvement, soil condition), which more often is understood to include a wide range of fertilizers and non-organic materials. In the context of construction soil conditioning is also called soil stabilization.
Soil conditioners can be used to improve poor soils, or to rebuild soils which have been damaged by improper soil management. They can make poor soils more usable, and can be used to maintain soils in peak condition.
Composition
A wide variety of materials have been described as soil conditioners due to their ability to improve soil quality. Some examples include biochar, bone meal, blood meal, coffee grounds, compost, compost tea, coir, manure, straw, peat, sphagnum moss, vermiculite, sulfur, lime, hydroabsorbant polymers, and biosolids.
Many soil conditioners come in the form of certified organic products, for people concerned with maintaining organic crops or organic gardens. Soil conditioners of almost every description are readily available from online stores or local nurseries as well as garden supply stores.
Polyacrylamides
Polyacrylamides have been widely investigated as soil conditioners. They were introduced as "linear soil conditioner" in the 1950s by Monsanto Company under the trade name Krilium. The soil conditioning technology was presented at a symposium on "Improvement of Soil Structure" held in Philadelphia, Pennsylvania on December 29, 1951. The technology was strongly documented and was published in the June 1952 issue of the journal Soil Science, volume 73, June 1952 that was dedicated to polymeric soil conditioners. The original formulation of polyacrylamide soil conditioners was difficult to use because it contained calcium which cross-linked the linear polymer under field conditions. Krilium was abandoned by Monsanto. Water-soluble soil conditioners offer the following benefits:
increase pore space in soils containing clay
increase water infiltration into soils containing clay
prevent soil crusting
stop erosion and water runoff
make friable soil that is easy to cultivate
make soil dry quicker after rain or irrigation, so that the soil can be worked sooner
Consequently, these translate into
stronger, larger plants with more extensive root system
earlier seed emergence and crop maturity
more efficient water utilization
easier weed removal
more response to fertilizers and to new crop varieties
less plant diseases related to poor soil aeration
decreased energy requirement for tillage
The cross-linked forms of polyacrylamide, which strongly retain water, are often used for horticultural and agricultural under trade names such as Broadleaf P4 and Swell-Gel. In addition to use on farm lands, these polymers are used at construction sites for erosion control, in order to protect the water quality of nearby rivers and streams. As an nonionic monomer it can be co-polymerize with anionic for example Acrylic acid and cationic monomer such as diallyldimethyl ammonium chloride (DADMAC) and resulted co-polymer that can have different compatibility in different applications.
Polyacrylamide is also used in some potting soil. Another use of polyacrylamide is as a chemical intermediate in the production of N-methylol acrylamide and N-butoxyacrylamide.
Purpose
Soil structure
The most common use of soil conditioners is to improve soil structure. Soils tend to become compacted over time. Soil compaction impedes root growth, decreasing the ability of plants to take up nutrients and water. Soil conditioners can add more loft and texture to keep the soil loose.
Soil nutrients
For centuries people have been adding things to poor soils to improve their ability to support healthy plant growth. Some of these materials, such as compost, clay and peat, are still used extensively today. Many soil amendments also add nutrients such as carbon and nitrogen, as well as beneficial bacteria.
Additional nutrients, such as calcium, magnesium and phosphorus, may be augmented by amendments as well. This enriches the soil, allowing plants to grow bigger and stronger.