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Soil Nutrients
Olga S. WalshAssistant Professor
Soil Nutrient ManagementMontana State University
Western Triangle Agricultural Research Center
Nutrients and plant growth
o Plant’s sufficiency range = range of nutrient necessary to meet plant’s nutritional needs and maximize growth
o Nutrient levels outside of a plant’s sufficiency range cause crop growth and health to decline due to either a deficiency or toxicity
Mc Cauley et al., 2009
Mobile and Immobile Nutrients
BLA BLA
BLA BLA
Roger Bray, “A Nutrient Mobility Concept or Soil-Plant Relationships. 1954. Soil Science.
MT soils:Common deficiencies /toxicities
• Most common: N and P• Sometimes – K, S
• Micronutrient deficiencies are fairly uncommon with deficiencies of B, Cl, Fe, and Zn occurring most often
• Toxicities – uncommon, result of over-fertilization
Essential plant nutrientsTotal of 16 essential nutrients
3 Macronutrients from air and water: Carbon, Hydrogen, Oxygen (C, H, O)
13 MACROnutrients from soil:3 Primary nutrients - Nitrogen, Phosphorus and Potassium
(N, P, K)3 Secondary nutrients - Calcium, Magnesium and Sulfur
(Ca, Mg, S)7 MICROnutrients - Iron, Manganese, Zinc, Copper, Boron, Molybdenum, and Chlorine (Fe, Mn, Zn, Cu, B, Mo, Cl)
Essential plant nutrients
Deficiency disrupts plant’s growth and reproduction
Deficiency can be prevented or corrected only by supplying the element
Nutrient is directly involved in the nutrition of the plant
Macronutrients
Nutrients from air and waterCarbon, Hydrogen, Oxygen
Base of all organic molecules, building blocks for growth Absorbed as CO2
Combined with H and OTransformed into carbohydrates in leaves in the process of photosynthesis
Essential Macronutrients
N, P, K
Needed in greater amounts for growth
Lacking from soil firstGreater response
N deficiency Light green upper (young) leavesYellow lower (older) leaves
Essential Macro nutrients: P Catalyses biochemical reactions
Component of DNA (genetic memory)
Component of energy molecules Key element in photosynthesis
P deficiency Dark purple discoloration on the leaf tips, advancing down the leafStunted plants with fewer shoots
Essential Macro nutrients: K Photosynthesis and movement of nutrients
Protein synthesis
Activation of plant enzymes
Regulation water use
K deficiency Marginal chlorosis and necrosis on older leavesShorter internodes, stunting
Essential Secondary nutrients Ca, Mg, S
Needed in moderate amounts
Essential Secondary nutrients: Ca Cell structure, membranes
Nutrient uptake
Reaction to negative environmental factors
Defense against disease
Ca deficiency Poor root growth, stunted dark rotting rootsSymptoms – in new growth (necrotic spots in young leaves), leaves collapse before unrolling
Essential Secondary nutrients: Mg
Chlorophyll formation
Light-absorbing pigments
Amino acids and proteins
Resistance to drought and disease
Mg deficiencyPale green, chlorotic young leavesFolded or twisted leavesSymptoms similar to drought
Essential Secondary nutrients: S
Component of amino acids and proteins
Component of enzymes and vitamins
Formation of Chlorophyll
S deficiencySeedlings: pale yellow chlorosis on young leaves
S deficient leaf (left) normal (right)
Micronutrients
Micronutrients
Fe, Mn, Zn, Cu, B, Mo, Cl
Needed in very small amounts
Involved in metabolic reactions as part of enzymes (reused, not consumed) Can be corrected with a fraction of pound per acre rate
Iron (Fe)
RespirationPhotosynthesisEnzymatic ActivatorChlorophyll Synthesis
Fe deficiencyFailure to produce sufficient chlorophyllInterveinal chlorosis, green/yellow stripesNew leaves turn white
Manganese (Mn)
Component of various enzyme systems for:• energy production• protein synthesis, and• growth regulation
Mn deficiencyInterveinal chlorosis Brown necrotic spots on leavesWhite/gray spots on leaves Premature leaf drop and delayed maturity
Zinc (Zn)
RespirationPhotosynthesisEnzymatic ActivatorChlorophyll Synthesis
Zn deficiencyFirst appear on middle-aged and old leavesMuddy gray-green leaf colorLeaves appear drought stressed, with necrotic spots
Copper (Cu)Catalyst in photosynthesis and respirationConstituent of enzymes Involved in building and converting amino acids to
proteins Carbohydrate and protein metabolism Plant cell wall constituent
Cu deficiency Leaf tip die-back followed by a twisting or wrapping of the leaves Delayed maturity Stunted, misshapen heads
Boron (B)
Cell wall strength and developmentCell divisionFruit and seed developmentSugar transport
B deficiency Saw tooth effect on younger leavesPale, “water-soaked” new shootsHead sterility
Molybdenum (Mo)
Conversion of nitrates (NO3 ) into amino acids in the plant
Conversion of inorganic P into organic forms in the plant
Protein synthesisSulfur metabolism
Mo deficiency Stunted plantsFlowering/Seed formation affectedHollow stemsBrittle, discolored leaves
Chloride (Cl)Photosynthesis
Stomata regulation
Gas and water balance in cells
Nutrient transport (K, Ca, Mg)
Disease resistance
Cl deficiencyPhysiological Leaf Spot SyndromeWhite to brown spots on leavesStarts in lower leaves at tilleringSimilar to tan spot, smaller spots, no “halo”
Micronutrient deficiencyHigh soil pH (uptake decreases as pH increases) – all but MoMT typical pH = 7-8, varies from 4.5 to 8.5
Low organic matter MT typical OM = 1-4%
Cool, wet weather
Micronutrient products
Citri-Che Crop Mix 1 (N, S, Cu, Mn, Zn)Gainer High Phos (N Nitrogen, Phosphate, Potash, Sulfur, Boron, Copper, Iron, Manganese, Molybdenum and Zinc
Acknowledgements
• Information is based on Montana State University’s Extension Module 9 by McCauley et al, 2009: http://landresources.montana.edu/NM/Modules/Module9.pdf