Soil Fertility and Plant Nutrients

Nutrients required in small amounts by plants, measured in parts per million (ppm).

Nutrients required in large amounts by plants, essential for plant structure (e.g., carbohydrates, hydrocarbons).

Plant growth is limited by the scarcest essential nutrient.

Nutrients crucial for plant growth, at least sixteen types are essential for plant growth.

The process by which plants absorb nutrients from the soil.

The measure of the soil's ability to provide essential nutrients for plant growth.

A unit of measurement for expressing the concentration of micronutrients in soil.

Carbon, hydrogen, and oxygen; the building blocks of plant structure and come from water & carbon dioxide.

Using plants to remove contaminants from the environment.

Nutrients that can move from older plant parts to younger, growing parts when needed.

Nutrients that cannot easily move from older plant parts to younger, growing parts.

The ability of a nutrient to move within a plant.

If a deficiency symptom first appears in older plant parts, the deficient nutrient is likely mobile.

If a deficiency symptom first appears in younger plant parts, the deficient nutrient is likely immobile.

The process by which water carries dissolved nutrients from the soil profile.

A measure of a soil's ability to hold onto positively charged nutrients (cations).

A measure of a soil's ability to hold onto negatively charged nutrients (anions).

Phosphorus, potassium, magnesium, and molybdenum are examples of mobile nutrients.

Calcium, sulfur, boron, copper, iron, manganese, and zinc are examples of immobile nutrients.

The process where water-soluble ammonium (NH₄⁺) is released from decaying organic matter in soil.

The ratio of the mass of organic carbon to the mass of nitrogen in organic matter.

The uptake of ammonium (NH₄⁺) and nitrate (NO₃⁻) by microorganisms from the soil pore water due to a lack of nitrogen in organic matter.

Soil moisture reaching 60% water-filled pore space.

Soil moisture, temperature, soil type, cropping system, soil management, C:N ratio, and pH.

pH from 6 to 7.5.

Decaying organic matter, fertilizers (like ammonium sulfate, urea).

The breakdown of urea into ammonium by the urease enzyme.

Indicates organic matter is rich in carbon and low in nitrogen, tending to cause immobilization.

Indicates organic matter is rich in nitrogen, tending to mineralize, increasing ammonium in the soil.

Phosphorus (P) in soil is adsorbed by clay particles, especially smectite. Iron and aluminum oxides also bind P, making it unavailable for plant use.

Animal urine contains urea, a nitrogen compound.

The process by which sulfur moves through soil, involving various forms and transformations.

A significant portion (80%) of nitrogen in chicken manure is in the form of uric acid.

The process where sulfur is converted to a different chemical form (e.g., SO4).

Phosphorus can precipitate (form solids) with iron, aluminum, calcium, forming various compounds, reducing its availability for plants.

Uric acid takes several days to weeks to transform into NH3 in warm, moist soil.

The amount of water present in soil pores.

In alkaline soils, phosphorus precipitates with calcium. In acidic soils, phosphorus compounds may remain soluble, meaning it may leech out.

Phosphorus can be lost from soils through leaching (water movement) or erosion. The amount lost depends on the soluble phosphorus and erosion.

Pig manure stored as a liquid, containing a high proportion of NH3.

A measure of the acidity or alkalinity of soil.

Ways sulfur enters the atmosphere and, eventually, the soil (e.g., dust, gases, sea spray).

A large amount of water-soluble ammonia (NH3) in pig manure comes from urea hydrolysis and protein breakdown in storage.

Sulfur availability comes from rock weathering, atmospheric deposition, and the breakdown of organic matter.

Tiny living organisms that catalyze sulfur oxidation in soil.

Elemental sulfur in rocks (like pyrite) is oxidized to SO4 during weathering. This oxidation is mainly done by bacteria like Thiobacillus.

Chicken manure and liquid pig slurry are classified as fast-release nitrogen fertilizers because of their high proportion of readily degradable nitrogen.

Prokaryotes (bacteria and archaea) that possess amo and hao genes, responsible for oxidizing ammonia (NH3) to nitrite (NO2).

Minerals like CaSO4·2H2O that release sulfur when dissolved in soil water.

Prokaryotes and eukaryotes with the nxr gene that convert nitrite (NO2) to nitrate (NO3).

Rapid processes in soil during the growing season converting ammonia to nitrate.