Nutrient Management Flashcards
What are the essential nutrients obtained from the air as carbon dioxide and as water?
Carbon(C) Hydrogen(H) and Oxygen(O)
List the Macronutrients along with their symbol
Nitrogen(N), Phosphorus(P), Potassium(K), Calcium(Ca), Magnesium(Mg), Sulfur(S)
Which Macronutrients are Mobile in the Plant?
Nitrogen, Phosphorus, Potassium, Magnessium
Nitrogen’s Uptake forms in soil
Ammonium ion (NH4+), Nitrate ion (NO3-)
Phosphorus’s uptake forms in soil
Phosphate ion (H2PO4-, HPO42-)
Potassium’s uptake forms in soil
Potassium ion (K+)
Calcium’s uptake forms in soil
Calcium ion (CA2+)
Magnesium’s uptake forms in soil
Magnesium ion (MG2+)
Sulfur’s uptake forms in soil
Sulfate ion (SO42-)
List Micronutrients along with their symbol
Boron(B), Chlorine(Cl), Copper(Cu), Iron(Fe), Manganese(Mn), Molybdenum(Mo), Nickel(Ni), Zinc(Zn)
Boron’s uptake forms in soil
Boric Acid (H3BO3) or borate ion (H2BO3-)
Chlorine’s uptake forms in soil
Chloride ion (CL-)
Copper’s uptake forms in soil
Cupric ion (CU2+)
Iron’s uptake forms in soil
Primarily ferrous ion (Fe2+): some Ferric ion (FE3+)
Manganese’s uptake forms in soil
Primarily manganous ion (Mn2+)
Molybdenum’s uptake forms in soil
Molybdate ion MoO42-)
Nickel’s uptake forms in soil
Nickel ion (Ni2+)
Zinc’s uptake forms in soil
Zinc ion (Zn2+)
Describe the function of Nitrogen in plants
It is used in the synthesis of amino acids, proteins, enzymes; found in chlorophyll ((photosynthesis)Green), ADP and ATP(energy transfer)
Describe the function of Phosphorus in plants
important component of energy transfer system(ADP,ATP); important to photosynthesis and respiration; part of cell nuclear material important to cell division
Describe the function of Potassium in plants
accelerates growth of meristematic tissue; regulation of somatal opening (water loss); incolved in nitrogen and carbohydrate metabolism; catalyzes some enzymes
Describe the function of Sulfur in plants
is a component of several amino acids (cystine, cysteine, methionne) which are part of many proteins; involved in protein sythesis and enzyme activation; forms flavor compounds in mustard, garlic, and onions.
Describe of nutrient needs change as plant growth progresses from germination to maturity
During the seedling stage, plants are small and nutrient demand is small. As the plants become larger through the vegetative growth stages nutrient needs increase. Nutrient needs can be high in reproductive tissues, but much of that demand is met by redistribution of nutrients that are contained in vegetative tissues.
Describe soil solution
Soil solution is the water in soil that contains dissolved ions, molecules, and gases. Plant nutrients dissolved in the soil solution can be cations, anions, or uncharged molecules. These nutrients are absorbed by the plant roots through the processes of mass flow, diffusion, abd root interception
Describe cation exchange sites
Positively charged ions, cations, are held by cation exchange sites on soil clay and organic matter. These cations can move into the soil solution by cation exchange and be readily available to plants.
Describe organic matter
Soil organic matter can retain cationic nutrients by cation exchange and chelation, and can be a source of nutrients (N,P,S) when decomposed.
Describe soil minerals
Soils contain minerals that slowly dissolve to release nutrients to the soil solution. Some soil minerals (e.g. clays, carbonates, hydroxides) can also retain nutrients by adsorption on their surfaces
Describe plant residue
Plant residue contains the essential elements that are returned to the soil system as the plant residue decomposes and rainfall leaches soluble nutrients from the plant residue
Describe mineralization
Mineralization is the release of a nutrient when an organic material (e.g. soil organic matter, manure, biosolids) is decomposed by soil microorganisms. It is the conversion of a nutrient from organic to inorganic form
Describe immobilization
Immobilization is the reverse of mineralization(nutrient is converted from inorganic to organic form). During decomposition the nutrient is incorporated into microbial cells and soil organic matter.
Describe uptake antagonism between ions
Two or more ions may compete for plant uptake by various mechanisms. One ion is said to be antagonistic with regard to the uptake of another ion.
Describe mass flow
Mass flow occurs when a nutrient moves to a plant root with the water that is being absorbed by the plant. This is important nutrient uptake process for nutrients such as nitrogen, calcium, and magnesium
Describe diffusion
Diffusion is the movement of a nutrient to a plant root due to a concentration gradient between the soil solution and the root surface. The nutrient concentration is higher in the soil solution than at the root surface and, thus, the nutrient moves to the root surface. This is an important nutrient uptake process for nutrients such as phosphorus and potassium.
Describe root interception
Root interception occurs when a root grows next to clay or organic matter surface and absorbs the nutrient. Root interception usually means the root has grown near a soil colloid and absorbed the nutrients on or near the colloid surface. This is usually a minor way nutrients are absorbed
Descibe how cation exchange capacity (CEC) influences nutrient mobility of cations and anions
Cation exchange is the process whereby cation(s) in the soil solution change places with cation(s) on a negatively charged soil colloid (clay and organic matter) *This is an important reaction because the cations in solution are the ones that are absorbed by the plant and the ones than can leach.
Ca2+ + k+[soil colloid] = 2k+ + Ca2+[soil colloid]
Describe CEC
is the amount of positively charged cations that can be held by a given weight of soil. Units are cmaole + charge per kg soil which is equivalent to meq/100 g soil.
What happens as Cation exchange capacity increases?
The mobility of cations decreases as they are held on the CEC. Increases in 2:1 clay minerals, organic matter, and soil pH are generally related to increases in CEC
List the three cations that are largely retained on the CEC of a soil and are immobile
Calcium (Ca), Magnesium (mg), and Potassium (K)
If routine additions of cations occur (e.g. fertilization, liming, or acidification), the added cation(s) can change place with
Ca, Mg, or K on the CEC bringing Ca, Mg, or K into the soil solution. Any cation in the soil solution is mobile and subject to leaching
What type of anions are not evenly distributed in soil water and why?
Soluble anions (nitrate, chloride, and sulfate) because they are excluded from water nearest negatively charged clay and organic matter. The water that contains the excluded anions also moves fastest in soil. The net effect is that soluble anion leaching is increased
Nitrogen is mobile as what and immobile as what?
Mobile as nitrate(NO3-) immobile as ammonium (NH4+)
Phosphate (H2PO4-, HPO42-) is immobile in soil except
where P sorption capacity has been exceeded
Is Sulfate (SO42-) mobile or immobile in most soils?
Mobile
Calcium Magnesium and Potassium are immobile in what and mobile in what?
Immobile in CEC and Mobile in soil solution
Describe how texture affects nutrient uptake
Texture is the proportion of sand, silt, and clay in a soil. **Available plant nutrients are generally held in the clay fraction, so the more clay in a soil the more likely there will be available nutrients.* Leaching of nutrients increases as soils become more sandy because sandy soils have large pores that allow freer water movement. Sandy soils also have only a small capacity to retain ions due to small cation and anion exchange capacities
Describe how structure affects nutrient uptake
Soil structure is the arrangement of soil particles into aggregates. Soil structures that create large pores will increase the potential for nutrient leaching. Lack of structure can lead to increases in runoff and erosion.
Describe how drainage/aeration affect nutrient uptake
Iron and manganese solubility increases in flooded soils (anaerobic = no oxygen). Nitrate is lost from anaerobic soils by dentrification. Nutrient losses are associated with excessive drainage.
Describe how moisture affects nutrient uptake
Adequate soil moisture is especially important for nutrients that move to roots by diffusion (e.g. P). Adequate soil moisture favors decomposition and release N, P, and S from the material undergoing decomposition. As soil moisture decreases, insoluble compounds containing nutrients can form.
Describe how pH affects nutrient uptake
Soil pH affects the availability of most nutrients due to physical (leaching, volatilization), chemical (adsorption, desorption, precipitation) and biological processes (mineralization, immobilization) that change with pH. Extremes in soil pH can alter absorption of nutrients by roots by changing root metabolism,
Describe how temperature affects nutrient uptake
Temperature can be through plant metabolism where a minimum, optimum, and maximum temperature for nutrient uptake exists and can change with plant growth and development. If the nutrient source is a decomposing organic material, then temperature also can affect the rate of that process.
