Soil Properties Part 3

Tillage Pans and Traffic Pans Tillage pans - areas of compacted soil in the plant root zone caused by repeated plowing at the same depth.  Tillage and traffic pans are serious problems in many parts of the country because the area of root restriction is generally in the topsoil.   reduces the movement of air, water, and roots and therefore limits crop yields. Fragipans  Fragipans (silt pans) and clay pans can occur naturally in or near the subsoil. A fragipan is the result of too much silt in or near the B horizon, and is not the result of mans actions. Alleviating Traffic or Tillage Pans Subsoiling breaks up or shatters compacted layers using deep plowing equipment.  Reduced or minimum tillage means less movement over the soil which results in less compaction of the soil. Deep Subsoiling should precede reduced or minimum till operations.  No till reduces the formation of traffic pans because planting is done directly in the stubble of the previous crop.  Biological Properties of Soil   refers to the living organisms found in the soil includes both the micro and macro plants and animals. Plants  Micro     Bacteria Fungi Actinomycetes Macro – roots of higher plants Biological Properties of Soil Animals  Micro    Nematodes Protozoa Macro     Earthworms Rodents (prairie dogs, moles, gophers, etc.) Arthropods (mites, insects, spiders, etc.) Gastropods (slugs, snails, etc.) Biological Properties of Soil – Food Web Chemical Properties of Soil   The ability of soil to provide the essential elements needed for plant growth includes: the availability of these elements other chemical properties     clay minerals present humus content cation exchange soil reaction (pH). Objective 3: TERMS TO KNOW:      Homogenous mixtures – soil mixtures that contain the same type of soil particles Heterogeneous mixtures – soil mixtures that contain different types of soil particles Aerobic – occurring only in the presence of free oxygen Algae – soil plant microorganisms capable of photosynthesis Anaerobic – growing or occurring in the absence of free oxygen Objective 3: TERMS TO KNOW: (cont’d)     Bacteria – single-celled soil plant microorganisms, some of which are responsible for organic matter decomposition, while others are responsible for nitrogen fixation Fungi – soil plant microorganisms responsible for organic matter decomposition, especially the cellulose, lignin and gum Microorganisms – life forms too small to be seen with the unaided eye or barely visible Nematodes - soil animal microorganisms that are responsible for the decomposition of organic mater, consumption of other animal microorganisms and parasitism on the roots of certain higher plants Objective 3: TERMS TO KNOW: (cont’d)        Nitrogen cycle – the biochemical changes undergone by this atmospheric gas from its use by living organisms to decomposition and conversion back to the atmosphere Organic matter – soil materials including plant and animal residues at various stages of decomposition Rodents – small gnawing animals such as rats and mice Acid soil – one having a pH below 7.0 on a scale from 0 to 14 Alkaline soil – one having a pH below 7.0 on a scale from 0 to 14 Ion – charged atoms or groups of charged atoms pH – a numerical measure of the degree of acidity or alkalinity of the soil solution Homogenous Soil Mixtures    Sand Silt Clay Heterogeneous Soil Mixtures  Any combination and proportion of sand, silt, or clay