Basics of Soil Science

Explore the basics of soil science through eight topics, from soil chemistry to soil genesis, building a foundation for higher level courses in soil science and agriculture.

Understand how soil air and temperature affect microbial activity, plant growth, and nutrient cycling through oxygen and carbon dioxide balance and diffusion.

Classify soil organisms by environment and energy source, from microflora to fauna. Describe fungal roles in cellulose and lignin decomposition, humus formation, and mycorrhizal associations that aid nutrient uptake.

Explore soil bacteria, unicellular drivers of nutrient cycling. Learn how symbiotic and free-living nitrogen-fixing bacteria, nitrifying bacteria, cellulose-decomposers, and sulfur-oxidizing bacteria transform nitrogen, carbon, and sulfur in soil.

Discover how soil algae, especially blue-green algae, fix nitrogen in rice fields, while lichens and actinomycetes contribute to soil formation, antibiotics, and rain-smelling compounds.

Explore how soil fauna, from macro-fauna to termites and earthworms, function as ecosystem engineers that modify soil structure, drive organic matter decomposition, and promote nutrient cycling and humus formation.

Explore soil nutrient cycling, detailing the nitrogen and phosphorus cycles driven by microbes, plants, and fauna, and how atmospheric inputs balance removals to sustain forests.

Identify essential plant nutrients and their classifications into macronutrients, secondary nutrients, and micronutrients, noting carbon, hydrogen, and oxygen as non-mineral constants; examine soil sources and roles in growth.

Determine soil nutrient availability by testing soluble and exchangeable nutrients, using ammonium acetate and DTP extractions, then analyzing with atomic absorption or ICP, while noting pH and organic matter effects.

Learn to design field trials with randomized block designs and replicate treatments to test fertilizer needs, and analyze nutrient uptake and yield with statistics to assess significance.

Explore nitrogen, phosphate, and potash fertilizers, including urea, ammonium, DAP, MAP, DSP, SSP, and KCl, plus complex and liquid forms, with slow-release coatings and inhibitors to reduce losses.

Examine secondary nutrients such as calcium, magnesium, and sulfur, their sources and soil interactions, plus micronutrients like zinc, manganese, iron, copper, molybdenum, and boron and foliar application.

Explore organic fertilizers from plant and animal residues, farmyard manure, green manures, and biofertilizers that enhance soil nitrogen, phosphorus, and potassium through nitrogen fixation, solubilization, and growth-promoting rhizobacteria.

Soil formation arises from weathering of rocks into primary and secondary minerals through physical and chemical processes, including oxidation, hydrolysis, and biological weathering, shaped by climate, relief, time, and biosphere.

Shows how soils form through addition, losses, translocation, and transformation of materials, creating dynamic horizons—from humus-rich organic layers to mineral A, E, B, C, and bedrock R.

Explore the USDA soil taxonomy, a six-level system—orders, suborder, great group, subgroup, family, and cities—that classifies soils by diagnostic horizons, moisture regime, and temperature.