SULPHUR

Importance of sulphur (S)

• protein syntehises

• for photosyntehis

• strengthens cell walls

issues with S

• atmospheric depsositon = soil acidication

• air, water and soil pollution iwth S compounds

• organic S not availbe to plants

sources - PRESENT IN ROCKS (N IS NOT!!)

• organic residues

• weathering of minreals

• coal/oil buring

• precipation

• syntehitic fertilizer

losses

• plant uptake

• leaching

• erosion

• volatization

S vs N differnces

• no fixation done by microrganisms

• PRESENT IN MINERALS

  • sulphates - hypsum

  • sulphites- pyrite

S vs N similarites

• similar pathways of depsoiton

• both need mineralization to be avaialbe to plants

• last stage of minerlization both releases H+

• both can be lost as gas (volatization)

Dry and Wet Deposition of S from the Atmosphere  

SO2 GAS combines with water and can from sulforus and sulfuric acid = acid rain

• both acids dissociates quickly and realeases H+ ions into the soil = acidified

oxidation of S and its acidic effects - hydrogen sulphide oxidation

During the microbial decomposition of organic compounds that contain S, sulphides are formed - and oxidized by thioballicus (chemoautotrophs)

• forms H+ ions and so42 (avialble form of sulphur)

oxidation of S and its acidic effects- oxiation of pyrite (FeS2)

wheathering and oxidation of sulphide minerals releases H+ions

Environmental Considerations of Mining Impacts and Sulphur

• metal sulphites tailings depsoited in well drained, aerobic enviroment = sulphide minerals in the tailings are slightly soluble, so only a limited concentration of sulphide ions exists in the tailings "soil" solution at any time

• deposited in aerobic enviroment = aerobic S-oxidizing baceria oxidizes sulphide to sulfuric acid = acid mine drainage

violitization loss of sulphur

suspetple. when Organic materiasl burned

• burining oxidizes S to so2 gas = lost to atmosphere

S not commonly defifncet but whats the effect of adding N

can increase number of nutrient demands = sulphur then becomes litming factor in plant growth

sulphur oxidation

main sources of sulphur in soils: organic matter and sulphide minerals. Both are in a reduced state and need to be oxidized and made available to plants as sulphate (SO₄^-).

• Both the dissociation of H₂S and the oxidation of S result in the release of H⁺ ions.

soil fertility

ability of the soil to supply nutrients needed for plant growth.

A nutrient is deemed essential for plant growth when:

1. deficiency of an element makes it impossible for the plant to complete its life cycle

2. deficiency can be prevented or corrected solely by supplying this element

3. the element is directly involved in the nutrition of the plant in such a way that it is a constituent of a necessary metabolite such as an amino acid

macrontureints

P,C, H, O, N, K, Ca, Mg, and S.

amount needed of the macronutiernts

CHO- makes upplants

PNK- large amounts; their deficiencies are quite common

Ca Mg s - in moderate amounts; their deficiencies are less common.

Major types of reserve forms of nutrients in soils:

minerals (K, Ca, Mg and metals)

OM decay ( N and S and P)

negatively charged surfaces of soil colloids. - holds cations (Ca, Mg, K)

Law of the Minimum

plant growth and reproduction can be no greater than the level allowed by the growth factor present in the lowest amount relative to the optimum amount for that factor.