Properties of Alluvial Soils
Alluvial soil is rich in nutrients and may contain heavy metals. These soils are formed when streams and rivers slow their velocity. The suspended soil particles are too heavy for the decreasing current to carry and are deposited on the riverbed. The finest particles are deposited at the mouth of the river, forming a delta. Alluvial soils vary in mineral content and specific soil characteristics depending on the region and geologic makeup of the area.
High Rate of Root Turnover
Increased wetting and drying cycles cause high root turnover in alluvial soil. Alfalfa root systems increase water flow and macroporosities in alluvial soils, according to Javed Iqbal, et al., in a 2005 report prepared for Purdue University's Agronomy Department. This property of alluvial soil is important in farming different types of grasses, rice, potatoes, wheat and other food crops.
Depending on the area where the alluvial soil is located, it will have different magnetic properties. Contaminants in the rivers and streams that create alluvial soil -- such as heavy metals and magnetic minerals -- create magnetic fields in the soil. Contaminants including lead, zinc and cadmium enter the waterways from lead ore smelters, factories and other sources of chemical pollutants. Scientists use these magnetic properties to determine pollution levels and map polluted and unpolluted areas, according to the September issue of the “Journal of Applied Geophysics.”
Alluvial soil is rich in minerals and nutrients -- highly fertile, and a good crop soil. It often contains gravel, sand and silt. The chemical content of the soil will depend on where it is located. The topography of the land will influence what runs off into the river that eventually forms the alluvial soil. One example is the volcanic pumice in the western part of Mexico's Nayarit state. The alluvial soils of the region are pumiceous and have unique physical and chemical properties that provide a good environment for vigorous plant growth, according to J.E. Gama-Castro, et al., in an article published in the June 2000 issue of “Soil and Tillage Research.”
Caroline Thompson is a professional photojournalist who has been working for print and online publications since 1999. Her work has appeared in the "Sacramento Bee," "People Magazine," "Newsweek" and other publications. She holds a Bachelor of Arts in photojournalism from California State University at Hayward and a personal trainer certification from the university's Health and Fitness Institute.