Soil Biology CSS 360
Popular in Course
Popular in Soil Science
This 50 page Class Notes was uploaded by Rosalind O'Connell on Saturday September 19, 2015. The Class Notes belongs to CSS 360 at Michigan State University taught by Staff in Fall. Since its upload, it has received 68 views. For similar materials see /class/207207/css-360-michigan-state-university in Soil Science at Michigan State University.
Reviews for Soil Biology
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/19/15
Soil Organic Matter Why study soil organic matter foundation of agriculture major control on global carbon cycle key and relatively poorly understood element in terrestrial element cycling I the place where soil chemistry physics and biology meet Ll Klmbln and Fallu I What is soil organic matter 1 Unrecognizable partially decayed plant residues Soil microbes fauna and the byproducts of decomposition Chemically complex often novel compounds formed from secondary reac ons Heterogeneous Soil Organic Matter is Heterogeneous CENTURY MODEL SOIL HZO TEMPERATURE POTENTIAL PLANT PRODUCTION SOIL ORGANIC MATTER ACTIVE 5 to 1 y AVAILABLE SLOW NUTRIENTS 1050 yr N P s DEAD PAS awe P LANT 100045000 y MATERIAL STRUCTURAL METABOLIC Example ill Building Active Soil irgairliic Matter Pools provides most of the plant nutrients stimulates Active Sonc macroaggregate formation 10 yr CO I i In depleted agricultural soils lt7 2 of total soil C is active pool in Slow Soil C grassland and forest systems 50 yr gt15 of soil C is active pool CO Cation exchange capacity Passive Soil C microaggregation 1500 yr From Parton et al 1983 in Coleman et al 1984 0 C c 2 V L a 3 m E 9 lt0 on h 0 395 U 0 Start of cultivation Active SOM Pool Management change Passive or resistant SOM pool 0 10 20 30 40 50 60 70 80 90100110120130 Years since conversion Soil Fractionation by Density Decommsition Sguence less decomposed Light fraction LF density lt13 9 cm4 Heavy fraction HF density gt18 9 cmquot V older more decomposed There are 3 General Controls over SOM Tumover Biochemical controls inherent recalcitrance due to the chemistry of original litter inputs of SOM Physical contmls agl aggregation and sorption Chemical controls eggl secondary chemical reactions leading to the formation of complex largely ammatic malecules Biochemical controls related to abundance of lignin and N Lignin monomer precursors Phydroxyphenol Syringyl guaiacyl Polymerization coupling of subunits 4 C M H V C D U C O 395 39E 0 CL E O U CU D 3D 40 50 El 39ninznitroen Racgnt Advances in Understanding Ligni n Stability in Snails Undecomposed plant Protected soil residue Iignin Iignin Lost nonVSC Iignin products f3 uf I rm 1 JE ww n FAA gymx 0 nu an nnvgnggnw Early SOM models overemphasized the contribution of ligninderived phenols to SOMmineral complexes Amine 92 NH2 H OH N 39 R R1 OH b39R1 OH I R1 0 Polyphenol Condensation UXIdaSB reaction Phenolic Quinone Humus Aromatic COOH isolated l Aliphatic COOH Phenolic OH C O Hbonded Sugar Htl OH4 f H COOH COOH bro Quinone o I Aromatic COOH R 23H Peptide adjacent to a second C 0 COOH Phenolic 0H Oxygen as a bridge unbonded I NH Cyclic N Lignin decomposition 2 Kilt Microbial products Glycine nH CH2 l COOH Further reactions and condensation to larger molecular structure ltgtH2 COOH Condensation with amino acids and long chain aliphatic compounds F l G U R E l 2 l 6 Hypothesized formation of a humic substance by reaction of a phenol decom position product between an amino acid and an aliphatic substance Aggregate in uence Over C and 1N Cycling 0 S ng 1me 39r p nHWWQ N n o Am oUmiiml thU mm tor1eetal1988 Controls over aggregate Formation and Stabilization o Particulate organic matter organic matter gt 53 pm and light fraction organic matter polysaccharides Plant roots Fungalhyphae Inorganic mechanisms cation bridging between soil particles especially Caz al 2000 small aggregates a in a matrix of lamentous fungi f Parry et Conventional Low input Organic No till Alfalfa Poplar Early Success Mid Success NT Late Success Aggregate Mean Size mm M I Aggregate Susceptibiiity to Disturbance NH C l C RCH E m U 539 D ED Aliphatic compounds lipids waxes now emphasized Clay mineral Polyvalent ionic bond Van der Vaals interactions CH303 OH Aliphatic domain Phenol CN J CH304 Ci 20503 8 OH FIGU RE I 2 l 7 Idealized structure of humic acid showing high aliphatic content adapted from Schulten and Schnitzer 1993 showing physicochcmical interactions wi u a clay mineral Orgunorninera interactions M denotes various cations such as iron and calcium contact zone of hydrophobic I I I I I I a l kinetic zone interactions outer region low charge 21 mineral smectite with protein conditioning 21 mlneral with coating of hydrous iron oxide VAVAVA AVAVAVAVA AVAVAVAVAVA quotAVAVAVAVAVAVAV unchar ed 1 g octahedral charge Siloxane 39 tetrahedral charge kaoli nite 39 metal cation Microbial Communifies Primari y Control 0 Structure microbial biomass aromatics N carbohydrates aliphatics Plant litter C Lignin amp Iignin subunits Lipids waxes aliphatics Carbohydrates Proteins amino acids Particulate C gt53 mm Lignin amp Iignin subunits Lipids waxes aliphatics Carbohydrates Proteins amino acids Silt associated C Lignin amp Iignin subunits Lipids waxes aliphatics Carbohydrates Proteins amino acids Clay associated C Lignin amp Iignin subunits Lipids waxes aliphatics Carbohydrates Proteins amino acids Molecular Soil Organic Matter Dynamics Plant derived C r Microbial derived C Ncontaining compounds Lipids waxes atha cs co 0 C 5 390 C 3 o to a 2 lt 5 a n carbohydrates aromatics litter Biochemical PhysicalChemical PrOteCtion Protection Grandy and Neff 2006 in review Management Factors that Influence SOM Increase C inputs to soil Vegetation management Compostmanure Decrease decomposition rates Aggregation Vegetation management Reduce soil disturbance Campast and Manure Ammdmem Effth an 050 Remvary 0f 50 C and N in Degradgdi Fata m 0005 at Mama 35 iAmendment Program quot035 None a 3D 7 1Year a 739 4Year b 03930 I5year 25 quot025 A d A 20 r quot020 5 0 2 E 15 quot015 E U U 10 quot010 0395 quot005 00 000 SOII C Soil N Effects of Legume Manure and F39ertiilizernaased Soii Management on Soii c 6000 W 67 5000 Soil C at onset E of experiment 9 4000 Soil C after 15 y of 5 management 0 e 8 3000 Why did soil C Change Residue quantity 0 2000 Cnv Manure gt Legume 1000 conventional manure legume Source Drinkwater et a1 1998 Nature 396262 265 Clmjppiimg System Effch cm Saw Aggmgat m and S M at am KBS MEIR E g g 35F 35 3 u 30 30 8 25 0V 25 L S u 5 0 7 8399 20 H 20 T lt D T 71 i 15 2 U 15 3 O T39 0 10 g 10 a E 05 l 05 O O l I l I 00 g r0 39 39 39 v9 6quot 0 gt 4 00 0 400 0qu 0620 SKQ 90 6300 000 0 9 SK 606990 00 90 9 lt5 Grandy and Robertson 2007 Overall Concwsons in lNil gtstilHi can be Vil i iht wr yieikdi if w l g Wrai iea is ii Willi ii ngzctemm met in senile immeQiieiteily ma iwses mm QJQiT CSXQlE KE QQ levels mmmcanliy Mumfde in dij e lcgsm gu iguiiiwai in ngiirtega ticnn sell mmism fi quotevents lieecai if quot N imiinertraiiize 39 LekC mg is ELL n iii 0121 i 1i anti times N263 emissim Pk 350 300 gt10 times more C 250 lost annually from tillage than sequestered in no till i 200 150 10039 50 g C m392 y391 Annual C sequestration rate in Midwest 30 g C m392 y391 2003 2004 and 1R ibxe1 i m mmal l xaimg e BEW H W Tilliage E e cs on C and N Cycling 69 Light Fraction SOM I Sand C Clay 0 Bacteria K Fungi N20 NH4 NIt NO3 Colonization Soil quality and Disease Suppression See httpzllattrancatorgfattrapublsoilbomehtml What are Soil Quality and Soil Health Soil Quality the capacity of a specific kind of soil to function within natural or managed ecosystem boundaries to sustain plant and animal productivity maintain or enhance water or air quality and support human health and habitation Doran and Zeiss 2000 Soil Health the continued capacity of soil to function as a vital living system within ecosystem and l an duse boundaries to sustain biological productivity maintain the quality of air and water environments and promote plant animal and human health Doran eta 1996 Plant diseases occur when a susceptible host and a disease causing organism meet in a favorable environment if V The Soil Food Web b 4 Arthropods Skadam Nematodes Haunt92262 A hrapuds yr Mair aim ti Nematodes Funga and tMIIrmlhmdear39i 39 r I V Mymnmzalrung 7 lv g y Sapllml39mii 1mm Ema tad ES Kl ants Pmclaaurs t m 5hnnh amt FDEDIS a gigs 4amp3 r2 Organic Protozoa Matter Hagu atzs Wham mgltkm and 7 lm melabnliles Ier 5 Animals dams animals am Banana mimihgs First trnphic Second Third tru phin Fourth trophic Fifth and tevel trophic level level level higher twphic thoyynr nnsizms Dncnmpnwrs ShraddErs HighEI ievel leve1s Mutual39sst Fredalors pradurur Hith We Pathagans panama Grazers predatun HucHeac st httpIsoilsusdagovsqilconceptssoiLbiologyimagesA 3jpg Current potato soils in MI Potential for potato soils in MI ow overall biological activity High overall biological activity 0w diversity of soil organisms high diversity of soil organisms peak soil activity out of synch with peak soil activity better synchronized with times when potatoes are susceptible times when potatOes are susceptible to to disease disease Highly conducive Highly suppressive Disease suppression continuum How do we get there Could declines in 80M and soil quality be linked to increased disease severity in potato systems Would it be possible to increase 80M and soil quality to increase disease suppression Speci c suppression speci c effects of individual organisms or a group of organisms antagonistic to the pathogen General suppression related to the total amount of microbiological activity at a time critical to the pgthgen Not due to a single organism but collective effects and due to competition for C and N substrates and possibly direct forms of antagonism Mycorrhlzal Fungi and Disease Suppression Among the most bene cial rootinhabiting organisms myoon39hizal fungi can cover plant roots forming what is known as a fungal mat The mycorrhizal fungi protect plant roots from diseases in several ways By providing a physical barrier to the Invoding pathogen A few examples of physical exclusion have been reported Physical protection is more likely to exclude soil insects and nematodes than bacteria or fungi Hwever some studies have shown that nematodes can penetrate the fungal mat By providing antagonistic chemicals Mycorrhizal fungi can produce a variety of antibiotics and other toxins that act against pathogenic organisms By competing with the pathogen By increasing the nutrientuptake ability of plant roots For example improved phosphorus uptake in the host plant has commonly been associated with mychorrhizal fungi When plants are not deprived of nutrients they are better able to tolerate or resist diseasecausing organisms By changing the amount and type of plant root exudates Pathogens dependent on certain exudatee will be at a disadvantage as the exudatea change t Green manures and campostlmanura release carbon and nutrients that are feedstock far soil organisms provide energy that supports the complex web of soil crganisms that compete with parasite and disease organisms tip the balance in favor of bene cial organisms and against parasites and pests mm at at 2007 EBullertln 22994 What are the mechanisms of general suppression Antibiosis Competition for substrates Competition for root infection was Induced systemic resistance enhanced plant defenses Microbiastasis energy stress Microbial oolanizationideslruaiun of pathogen propagules SoilGardTM is a39 technological breakthrough and captures the pathogen supprejssiveness of the fungus Gliocladium virens GL2 1 in a39 convenient stabe and highly effective form When incorporated into potting media SolGardTM controls plant pathogens through a variety of mechanisms including parasitism antibiosis competition and exclusion Gliocladium virens is known to parasitize some soil pathogens such as R solan39i The Gliocladium will actually wrap itself around the pathogen and release enzymes that destroy the pathogen s cuticle leaving the pathogens susceptible to attack GL21 also produces a broad spectrum antibiotic caled39gliotoxin which kills many soil pathogens Gliotoxin is not found in the SoilGardTM formulations but when the spores of GL21 begin to grow in the soil GL 21 produces the antibiotic httpwwwarsusdagov snpmba an96 umsdenhtm Evidence for Disease Suppression 0 C c 2 V L a 3 c0 2 9 lt0 on h 0 395 U 0 Start of cultivation Active SOM Pool Management change Passive or resistant SOM pool 0 10 20 30 40 50 60 70 80 90100110120130 Years since conversion Brady and Weil2002 OJ 0 C U 390 C 5 Q lt O 392 4 E G n W MW 0 Fine POM O Mid size POM Coarse POM v Total POM c E o E D C E c 9 E E a o c o O E O o R 1 00 200 300 400 500 Duration of Decomposition d FIGURE 51 Changes in total and sizefractionated POM concentration during decomposition in sand Suppressiveness to Pythium dampingoff was sustained from Day 53 to Day 375 Stone et al 2004 1 60 200 ppm Carbonyl Carboxyl Compost Day 4 4 Compost PONI Day 83 7 Com Ht POM Day 391 7 post POM Day 506 IO 1 10 1 60 ppm Aromatic 12 20 20 a 45 1 10 ppm OAlkyl 7O 5 4 I Suppressiveness or 1 0 45 Compositional Similarity ppm to Suppressive or Alkyl Conducive POM Less decomposed than PONI Suppressive Suppregtsivc Conduc ive Stone et al 2004 Potato Cropping System Challenges o amdy rug I SEEM WW milky o Mag 2 o ngch mimng mm mm mch o Miam mc gmg CQBHI Emma Soil Quality Declines are Accompanied by Intense Disease Scab Pressure httpvegetablemdonline ppath cornelledu httpwww potatodiseases org Are SOM losses and Isease pressure d Ie Early D Vertioillium dahliae In conjunction with the root lesion nematode a co a I v uan n I quotno a VA onl mlo n I o I l l 331 wolopmonmt quotmaximum in unanimous direct pon 39llion I meow o cmulumnahu n 07 n his O U M E O O O U 0 396 O p U E 0 C o x 09 Treatment Q 10 Days after residues incorporated
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'