Agriculture Reference
In-Depth Information
At the other extreme, if your soil is dominated by clay, the resulting structure will likely
result in less than ideal infiltration and drainage. Water will puddle on the surface and
won't go down as deep and it will not drain as well because there are so many small pore
spaces near the top of the soil to hold it. Of course, that means it holds onto more water
and needs to be irrigated less often. The water-holding capacity is excellent, but some of
the water is held so tightly that plants and microbes can't get it. Also, with fewer big pore
spaces, there's less air in the soil and less resistance to compaction.
Silt falls somewhere in the middle. Water infiltrates and drains better in silt than clay
and this texture has an even better water-holding capacity because more of the water is ac-
tually available and accessible to plants. There are also more big pore spaces for air in the
soil.
What about organic matter? It turns out that it does everything right in terms of soil
structure. It infiltrates brilliantly and drains freely, but not before holding onto a tremend-
ous amount of water. It still allows for plenty of air in the soil, but it resists compaction.
Also, it plays a huge part in actually binding your sand, silt and clay into the aggregates
that give the soil structure.
So the amount of sand, silt, and clay in your soil is your soil texture. Soil texture along
with organic matter, the soil food web and the nutritional makeup of the soil influences
your soil structure, which is how it all clumps together. This in turn determines how much
water will infiltrate, drain and stay around, and how much air will be in there. It also de-
termines the potential fertility of the soil.
