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Soil Fertility and Fertilizers

by: Mr. Olin Stracke

Soil Fertility and Fertilizers SSC 341

Marketplace > North Carolina State University > Soil Science > SSC 341 > Soil Fertility and Fertilizers
Mr. Olin Stracke
GPA 3.82


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This 43 page Class Notes was uploaded by Mr. Olin Stracke on Thursday October 15, 2015. The Class Notes belongs to SSC 341 at North Carolina State University taught by Staff in Fall. Since its upload, it has received 48 views. For similar materials see /class/223867/ssc-341-north-carolina-state-university in Soil Science at North Carolina State University.

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Date Created: 10/15/15
SOIL PRODUCTIVITY and ENVIRONMENTAL QUALITY I PRODUCTIVITY DECLINE Soul Conservmg Soil Degrading P Practices P0625565 Soil Erosion OM loss oxider39os Compuc ion Desertificafion Acidification Saliniza l39ion Nutrient Depletion Excessive Leaching Waterlogging Crop Rotation Reduced Tillage Strip Cropping Contour Farming Terracing Improved Drainage Nutrient Management Vegetative Buffers Following OM Nutrient soil structure In ltration Runoff Soil erosion in ltration Nutrient and Microbial biomass nutrient Forms of N mineralization mmobilization rates Bulk water and air lled volume for and nutrient or soil structure Available nutrients environmental hazard Explanation Where next u Primary causes of productivity decline 15quot E Erosion of surface soil 9 W Fuguvxeiysgs epondupnn W 8 S B DWHSBNF E OXIdatlon of organlc matter 9 nrlmpmve snilnroducuvny 20 E Deterloratlon of sod structure 9 5 7 E Reductlon 1n s011 m1crob1al act1V1ty 9 9 I00 Improved lechniuues and m agviculwra E areas have thus lar counlerbalancad the decline in soil productivin BO quotT D Z ema Conservation 5 gammy Longterm research experlments document 40 in effects ofpoor management 670 1890 1910 1920 1930 1940 1950 960 YEAH CORN WHEAT 00 E ac 5quot S 60 e E a i 40 C U E 5 20 U39 7 0 l l 0 l l l l o 20 no so an mo 0 20 40 so so Inc was 0F summon vans or cumwmom A u o pom nvn aa a x snowum wuxm A m w mmn w ml d Effefcts39o n Soil Pro p R S 15fo Color typical dark color caused by OM facilitate warming Water retention hold 20 times weight in water Helps prevent drying and shrinking improves moistureretaining properties of sandy soils Combination with clay materials Cements soil particles into aggregates Permits exchange of gases stabilizes structure and increases permeabili y Chelation Forms stable complexes with cations Cuz Mn 2 2 enhance availability of micronutrients to plants Solubility in water lnsolubility of OM due to association with clay Little OM is lost by leaching Buffer action Exhibits pH buffering Helps to maintain soil pH Cation exchange humus 3001400 meg100 g OM may increase soil CEC from 20100 yields CO and nutrients A source of nutrients for plant growth g gwnh organ Sizizrzzsatgi ey bloacnvny39 perSIStence Modi es pesticide rates for effective control a Rainiall 5 20 D 4 a T so 2 C A a o 3 2 A 5 20 B d 2 10 l l l l l l I l 0 2390 4390 6390 3390 150 1amp0 1330 1390 1900 19m 1920 1930 1940 1950 i960 1910 1930 YEARS YEAR A Reduced Tillage bP NH 9 0 Notill H 1970 lbsal l SOlL LOSS H ENHANCING PRODUCTIVITY WITH CONSERVATION PRACTICES Stubble mulch Plow 4000 u a o o m a o 0 i000 ORGANIC C lgkg soil 0 IS 30 45 60 75 l I l I l 75 7 E 8 I E 150 Lu 0 8 225 o NoTxllage o Plolellage 300 l l l I I Plow updown SwaeuruDdown a E Plowrconlour In Sweeprconlour Nomll 2 RAINFALL 1m B Rotations A Residue level E Soil structure improved W increased soil OM 9 increased quantity of residue returned to soil E Soil structure W grasses gt forage legumes gt grain legumes gt tap rooted crops gt fallow B Roots type E Root residue effective in improving soil structure increasing OM than above ground residue E 1 ton root residue m 3 ton above ground residue on increasing OM improving soil s c e E perennial forages gt Winter cereals gt grain com gt vegetables 9 differences due to neness of surface roots amp persistence during Winter early spring A 0 o 2 o 239 z E lt o g 2 a n o I o I a HOIlglIIal 6 level 16 u 160 2 a A 5 6 CORN OR ALFALFA RESIDUE Vay MORROW PLOTS 1904790 36 Unlerllllzad Sunplms Norm c 32 a 39 i 25 3yr Rolanon 5 quotquotK 4 dI 9 24 1 39 z 5 2 H t r c 20 Ar 0 39y39 me O x v o x a a I 9 0 16 comlnuous Com 12 I I I I I I I Is 4 1933 1955 less 1974 1962 1985 1958 1990 YEAR a 270 I NolenIlIzeI subplots NA a m Fertillzerslaned I I 4n 1955 In l 70 subplots NB I I g 339VrRDlallun g 39 ISO I 3 27yr Rulallon A A I E gt z w A conIInuouscom 5 U 50 I 0 I I I I I I I 19m 1913 was 1537 1945 1961 1973 1985 lsel YEAR 13 No image Management 35 a Tillage 7 decrease tillage should increase soil OM 30 E Manure particularly bene cial to s011 0 nven rona r age structure more bene cial than same weight of 2 crop res1due 1 5 o 5 i o i 5 2 o 2 5 u 3 5 wmmuew ewemmar mm CROP RESWE WW Pandiemn Oregon or u 301quot w damn E Fertilizer 7 increasing crop yield Will increase soil OM 5 1015quot m manure nannyaquot m Gib339 m u a runquot or N imsidus sumac r i851 1901 1921 mm 1951 user VEAR in S v 0715 onuzx so m Ilaquot olmanurs 6 N GRAlNVlELD wm al mximum 5 niba39HMN a o w DI N undue bullied N ina 1531 W41 195V mm v971 rear visa D Speci c crops the relative order of decreasing bene t to soil structure and OM is I erennial grasses I perennial le es Winter cereals spring cereals grain cornsorghum soybeans or silage cornsorghum dry beans peas vegetable crops summer fallow E Other considerations 9 Crop rotations can be justi ed on the basis of improved soil structure minimal erosion and higher yields Other bene ts include a reduced weedinschdisease pressure and subsequently reduced pesticide costs b improved distribution of labor equipment and ris c reduced purchased N W legumes and manures may not reduce N leaching potential 1 600 1 1 200 E Nutrient w exhaustion 3 30 Bensr rotations E Superphosphale legume 400 allowing mechanization new vanelias I n I I 1860 1900 1940 1980 YE R III ENVIRONMENTAL QUALITY A Soil Processes affecting water quality Soil Processes Affecting Water Quality Soil Processes Impact on Water Quality Soil erosion Transport of dissolved and suspended sediments in surface runoff Leaching Movement ofnutrients agricultural chemicals and dissolved organic r on in percolating wa er Macropore flow Rapid transport of water and pollutants from surface to subsurface and into a drainage system OM mineralization Release of readily soluble compounds leac e 0 that are easily washed away or ut B Best management practices 7 Ground water Principles Strategies tor Control Availability The concentration in the soil prolile determines its availability which ultimately determines the potential for loss to groundwater Detachment Detachment occurs when the nutrient or pesticide is desorbed and moves into the soil water Transport Water moving through the soil prolile to groundwater may transport pesticides and nutrients Deposition Deposrlion occurs when the nutrient or pesticide is deposited or removed before reaching groundwater karst topography Reduce concentration In the soil Limit quantity of nutrient or pesticide available for leaching loss by proper application rates and placement methods Limit exposure time in the soil Consrder persrstence when selecting pesticides and multiple or split applications of pesticides and nutrients Consider nonapplication zones in sensitive areas Establish nonappiication or butter zones around sensitive areas such as wells sinkholes and into soil water Consider chemical properties when making a product decision Products that are more strongly absorbed are less likely to be desorer to surlaoe waters Reduce amount of water leaving soil profile39 Transport ol nutrients and pesticides in pe water is reduced it the amount of water teaching is reduced Irrigation management and cover crops can be used to reduce inseason and oilseason percolation losses Subsurlace drainage may reduce percolation losses but may redirect drainage water rcolatmg Create a sink or physical barrier to chemicals being transported Natural claypans or impermeable geologic formations may create a physical barrier and allow tor breakdown or removal from the soilgeologic formation Such barriers are often created in disposal srtes such as landfills C Best management practices 7 Surface water Principles Strategies for Control Reduce concentration at the 50quot surface Availability oncentration ma be lowered by reducing determines it to enter surface water Nitrate is soluble in water and can move in 0 surface water through lateral subsurface flow or drainage tile Detachment When nutrients and pesticides are dissolved in runoff ah the soil and moved oftSite Transport Runoff that contains both nitrates the carrier is overland p 3 es m 3 abs in overland flow is sediment Deposition Deposition occurs when the on sedimen s is sto ped before it reaches the receiving water body fertilizers Proper residue management Control soil erosionland structures 5 a ow surface often only 13 to 110 of an inch in thickness s potential application rates incorporation banding integrated ant and taller application For nitrate practices that optimize N use efficiency and limit t of nitrate available for overland flow subsurface lateral flow or tile drainage flow Limit exposure time at the soil surface Consider esticide persistence and multiple applications of pesticides and nutrients Consider nonapplication zones in sensitive areas Establish nonapplication or buffer zones around sensitive areas suc as elivery points into streams and field borders 2 m D M 9 395 N 1 i m 0 52 2 a n 3 Delay the onset of runoff after rainfall begins Allow time for nitrate and some pesticides to move below the soil surlace reducin de achmenl into overland flow Practices include no tillage mulch tillage contour farming and infiltration enhancement Reduce effect of raindrop splash Crop residue and gr cover can limit the effect of raindrop splash on the detachment of nutrients and pesticides Lit n pesticides to surface waters For many pesticides and Reduce soil erosion losses Reduce transport of ammonium phosphorus and pesticides attached to sediment Practices include no tillage mulch tillage contour cropping and terraces Reduce overland flow Reduce transport of both water an iment Practices include increased crop residue levels and contour larming transport of nutrients and pesticides in overland flow or em or nutrients pesticides to be deposited as the leave the field Deposition may be illicull to achieve lor nitrates or many pesticides especially when the flow beco e concent ated in small channels A control practice includes vegetative filter strips Traps a e most effective in reducing sediment and soilbound pollutants Create traps for dissolved pollutants and sediment Provide and Foliar applications Cover crops to scavenge N03 Single N Application I I I Split N Applications I I 100 7 75 N Subject 3 7 i0 LOSSES gt Z 4 so lt E Crop N Uptake 25 V Total N Applied 0 IUD 0 Crop Need I I I Cumulative N Applications no 7 75 N Subject 3 to Losses 50 Crop N Uptake 25 r Total N Applied 100 of Crop Need I l x I I vanNG SEEDING RAPKD MATUFlATlDN HARVEST enowm Rainlall llllll it Cropland T YT till Evapotranspiralion r4 MWMHH Aquifer recharge 1 D AGRICULTURAL SUSTAJNABILITY Surface 1 l I l I pmmm sazuws mmn MATURNlON vassr GRWH ill oreslland T T T T l l Confined aquiier The strength and longevity of any civilization depends on the ability to sustain andor increase the productive capacity of its agriculture Agricultural sustainability is the integration of agricultural management technologies to produce quality food and ber While maintaining or increasing soil productivity farm pro tability and environmental quality Humans greatly contribute to the degradation or conservation of agrrcultural product1v1ty Many criteria can be established to judge or evaluate Whether an agricultural production system is in a state of decay or is being enhanced Adopting conservation technologies Will generally result in improved agricultural productivity The dif culty in achieving agricultural sustainability increases With increasing climate constraints Projected Global Production of Food Commodities through 2060 Commodity 1980 2000 2020 2040 2060 Million Tons Wheat 441 603 742 861 958 Rice 249 368 480 586 659 Coarse grains 741 1022 1289 1506 1669 Animal products 82 108 138 164 184 Dairy 470 613 750 877 997 Protein feed 36 52 64 76 85 Total 1989 2766 3463 4070 4552 700 600 r a 500 r g lt 400 r c Oopland 9 300 n 7 7 7 7 7 7 7 7 e 7 PastureRange 7 7 7 7 7 7 7 7 7 7 7 7 E Forestland 43 U39ban 200 7 7 7 7 7 7 7 7 7 7 7 7 RecreationWldlife 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 100 r 0 i i i i i 1940 1950 1960 1970 1980 1990 2000 Year 8 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 67 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 77AcnssperFarm777 Farms millions hundreds 5 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 4 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 3 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 2 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 1 7 7 7 7 A p 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 Farmland millions 0 i i 1900 1920 1940 1960 1980 2000 Year NUTRIENT MANA GEMENT 1N TURF Ef cient nutrient management is important for turfgrass quality durability aesthetics Nutrient content of turfgrass similar to other crops Table 91 W bc grass residue left on eld applied nutrients remain in soilcrop system mostly As grass residues degrade nutrients will I cycle through soil OM immobilization and mineralization I adsorb to mineral exchange sites I precipitate as minerals I denitrify andor lost though leaching N Nutrients retained in soil pro le become plant available in subsequent years nutrient cycling surface soil OM increases W soilplant analyses essential for ef cient nutrient management Leaf samples collected by clipping slightly above soil surface 2days after regrowth Nutrient suf ciency ranges in Table 93 Nitrogen Adequate N maintains darkgreen leaf color proli c tillering shoot density tolerance to other stresses W Excessive N increases water use enhances susceptibility to diseases reduces tolerance to high temperatures Increased heatwater stress reduces root stolon and rhizome growth thin uneven turf N rates 918 lbl000 ft2 40 to 350 lb Na depending on turfgrass Splitting total N rate into 24 applications through season recommended to maintain high quality minimize N leaching I Coolseason grasses 9 34 applications of l lbl000 ft2 in late fall and early spring I Warmseason grasses 9 monthly 1 lb 1000 ft2 beginning midspring through early fall W Low N rates lt 15 lbl000 f tz used w soluble N sources to maximize N recovery minimize N leaching Higher N rates used with slowrelease N sources such as Scoated urea Chapter 4 OPTIMUM N APPLICATION RATES AND TIMING FOR TURFquot Annual NRate Number of Turf Species rm 1 mm m 1 2 e 4 Fineleaf fescue 12 EF EF ES EF ES LF EF ES MR LF Tall fescue Perennial ryegrass 24 EF EF ES EF ES LF EF ES MR LF Kentucky bluegrass Bermuda grass 48 ES ES MR ES ER LR ES ER MR LR Saint Augustine Zoysia 24 ES ES MR ES ER LR ES ER MR LR E earlyM mid L late S spn39ngR summer F fall liable 1071 Common N Sourtes Used in Turf and Imporlanl haraclerislics NRrImsc mean Lrnrlzfng NSzipphuithau N Smu39t l39 Gm 11 Rare l iirpnrr39nl I uurun39u Tunmurum Urcn 46410 high mndcmrc hing 4N0 3400 high high high LNHngso4 217070724 high high high 0 13044 high high high NIAP 11752 0 modcraf moderate high DP IS 4GO xnodm39atc modetart hi 1 TBDU 317070 niodu39a re low low modem h quotCU 22 to 3300 mm ow lnvr lnodm39atc Rosinruontcd urea 24 to 357070 Dug 0w IOVV moderate Ivlcrhylcnc urcas amp 3300 In dcl39nfc quotlong low low low urcuforumldchydc Liquid iiihniiics variable Inodcl39atc lcnlg low low low scwug c sludge Phosphorus I up Adequate P important for early seedling vigor stand establishment N utilization Figure 1034 Soil tests identify lowP soils 9 if Mehlich III P gt30 ppm fertilizer P not necessary Potassium up Micro up up Turf quality depends on adequate K where 21 NK in leaf insures good root stolon rhizome growth important for optimum turf density water use efficiency winter hardiness Low K increases susceptibility to disease and drought stress Fertilizers w ll NK will supply adequate K in most cases K fertilizers have higher salt indices than N P sources thus caution recommended at germinating and seedling growth stages Table 103 Like N K is mobile in soil K leaching can occur in sandy soils see Chapter 6 S essential for protein and chlorophyll synthesis 9 dark green color maximize NK uptake Table 102 Deficiency symptoms o en mistaken for N stress Annual S rates are 052 lb 1000 ftz applied once early spring or split applied with N in spring and fall Split applications reduce S leaching potential especially in sandy soils see Chapter 7 nutrients Soil testing identifies potential micronutrient deficiencies Darkgreen color depends on adequate Fe9functions in chlorophyll synthesis Earlyspring and midsummer applications recommended Soilapplied Fe and other micronutrients not efficient as foliar CONSERVA T 1 ON TILL1GB up Nutrients concentrate in upper 24 in Tillage ie every 56 years redistributes nutrients through tillage depth Soils low in fertility should be increased to mediumhigh fertility before initiating notill BC N in reducedtillage immobilized by surface residues To maximize N recovery place below residue BC P amp K effective but under lowfertility and or cool dry areas surface PK may reduce availability vs subsurface band Yield increases from bandapplied fertilizer generally greater under notill than under tilled systems Figure1035 Conservation tillage 9 gt surface residues9cooler wetter conditions at planting lt nutrient availability was We at ANR w I NRATEUbIa RESID UAL FERTILIZER A VAILABILITY crops do not recover all nutrients applied portion in soil after harvest Residual depends on rate yield recovered by crop proportion of crop harvested and the soil Longterm residual N except in arid regions small vs immobile nutrients Residual N availability related to soil OM buildup Residual P observed for years depends on P rate soil P xation potential FERTILIZA TION WITH MAN URE Manures contain valuable nutrients amp OM use small compared to fertilizers although increasing bc 0 increased use of large con ned animal feeding operations 0 increased interest in organic production systems Bene cial effects of manure use include 35 0 Increase soil OM moisture retention mm 30 buffer capac1ty BC and NH4 m M9 na39manwe N0 Regimen I V supply Improve soil structure increase in ltration rate decrease soil bulk density Greater movement availability of P and micronutrients due to OM complexation o Complexation of Al in acid soils 390 Nico in glee mo 9 YEARS O m o GRAIN YIELD Mg haquot 3 5 4 I I l I 1950 i960 1970 I950 1990 Animal Manure Composition Manure composition varies with animal type and age feed type and composition bedding type and composition waste handling system dry matter highest in solid wastes Q Waste Type Swine Beef Dairy Manure Handling e ects on Nutrient Composition W Historically common disposal method was manure collection w bedding spread on elds Newer liquid waste systems dilute waste with water by storage in open or closed pits or lagoons N losses during storage various greatly 1580 with storage system I P Manure Oxidation ditch Waste application method Four principal methods used for eld application of manure are 0 Field BC spreading of solid waste when weather soil and crop permit 0 Injecting slurry water amp manure below soil surface or sprayed on soil surface 0 Injection of slurry into sprinkler irrigation system 0 Surface band applied under crop canopy W N loss affected by application method 9 incorporate immediately after applied to minimize NH3 loss manure N availability depends time material remains on soil surface before incorporation Minimal N available if waste incorporated gt58 days after application Subsurface applied maximizes N availability Available season Producers interested in manure as a nutrient source to crops should consider 0 high transportation costs encourage manure application close to source where overapplication may increase N and P loss to surface and groundwater nutrient content highly variable which makes it dif cult to accurately apply variability of manure N mineralization limit available N at periods of high N demand Increased soil compaction can occur with manure application equipmentPossible nutrient imbalances e g S supplementation can be bene cial with lagoonstored hog waste Liquid Broadcast with cultivationT Solid Liquid Liquid MI CRON U YRIEN TS IRON ZINC MANGANESE COPPER I GENERAL INFORMATION A IRON Fe 4th most abmdant element in soil o si Al Fe total Fe ranges 0550 ave 34 gt no relation to Fe availability B ZINC Zn total Zn ranges 10300 ppm ave 50 ppm C MANGANESE Mn total Mnranges 2001000 ppm D COPPER Cu total Cu ranges 2100 ppm 11 mONerCrMANGANESErCOPI ER 1N PLANTS A Fe 1 FORMAN39D RmclloNs Plants absorb Fe and Fe 39 39 394 39 r Transferof chlorophyll synthesis or chlorosis symptoms ofFe stress 1quot I n nl llquotl compound ofthe photosynthetic electron transport chain D 2 VISUALDEFICIENCY SYMPTOMS The suf ciency level ofFe in plants ranges between 50 and 250 ppm Fe de ciency likely occurs lt50 ppm Fe in the dry matter A causing stunted growth Ulluu 1 FORM AND FUNCTIONS Plant roots absorb Zn as me cation zu2 eauses me shortming ofintemodes and smaller mmuomlal leaves 2 VISUAL DEFICIENCY SYMPTOMS Plant Zn concentration ranges between 25 and 150 ppm Zn de ciencies usually occur when leaon eoueeuuau39om lt 20 ppm Zn toxicities occur whm eaqu concentxa on gt 400 ppm T lm m n ll 39 39 chlomu39e leafmas 0 u I quot small uanow thickened and malformed leaves Early 1055 of foliage mma on offruit o m wlm lime or no yield levellng or by wlnd and Water eroslon Zn de c39 mcorn lune cuunesyw mm m ml lnsnn e t om AND mucrlous Cu mostly absorbed by plants as 03 y w enzymes that create complex polymers suel as llgmn and melamn cl ls unlque ln lts mvolvementm enz mes andlt cannoth replaced by any othermetal lon 2 VISUAL Dmclwcv SYMPTOMS 39 r wlnle under In some crops Tu W H r w r n ale Stem melanosls ergot andtakerall rootrot dlseases occurln eenaln cl de clentwheat yaneaes In some vegetable crops leayes lack turgor and develop abluergreen cast Chlorosls andleaf eunlng occurs ln some crops and ower productlon ls o en reduced D MN 1 FORM AND FUNCTIONS To y chlorosls Cu toxicity o en resembles Fe de ererrcy Cu toxicities are rare oeeurrmg m areas k k k a Iudn mumnnal mu 1 mme wastes and Cu comarmrrg pesncrdes and fungrades were app1red Mn should be 2 to 3 ppm ando 2 to 5 ppmrespeaave1y Mn concentration m plants ranges from 20 to 500 ppm Mn concentrations lt 15 to 20 ppm are consrdered de cient Mquot L A Mn can substitute for Mgquot m marry ofuae phosphorylzuon reacnorrs zrhvutv ofmarry A 39 In the many enzyme sv m Mn zudhi h u U awe n of mdoleaceuc acd 2 VISUAL DEFICIENCY SYMPTOMS Like Fe Mn is a relatively immobile element in the plant and de ciency symptoms usually show up rst in the younger leaves In broadleaf plants visual symptoms appear as interveinal chlorosis see inside book cover Mn de ciency of several crops has been described by such terms as gray specie of oats marsh spot of peas and speckled yellows of sugar vets Wheat plants low in Mn are often more susceptible to rootrot diseases Mn toxicity causes crinkle leaf in cotton and is observed in highly acidic soils of the southern US Liming will readily correct this problem Wheat Cotton m Fe Zn Mn and Cu CYCLE Feis shnwn Zn Mn Cu are similarseetext Plant and animal rushing Plant Uptake mm Dissolullon pm 39tatinrl Minera zarion ORGANIC MATYER Immnbilmarion Adsurptinn Desnrpnan 1 Fe rmagneme ego 2 z r 39ankhmteanFezOQ mummanzsm 3 Mn rmanganesedmxldx MnOZ 4 Cu rcupmusnmde llo B mommy mm 1 a ante maghamte rezOZ rgnethn OH 7 F Dhydrnxlde FeOHz Fe 2 7 Fellhydrnx1de FeOH2 rFe carbnnate FeC03 rFenxxde Fee 0mm 4Fe0 o 6F3203 Redumnn 217320 4FeOOz 2 rnnnteZnO r mmhsnmte ch03 rhnp ate Zn 17002 rzmchydmxlde Znon 7 alsn called Sm39l Zn 3 Mn 2 rMnOHz MnSxO 4 Cu 2 rmal achne Cuz OH co 7 Euan hydran de moi1 C MICRONUTRIENT SOLUBILITY IN SOILS 1 General Relationships O Ca2 M921 5 6p 3 B 009 t 10 E 4 06 O lt v 8 4a k 99 4g 1 1 5 l I l J 4i 20 4 5 e 7 e 9 pH Mineral solubility the solubility of a mineral refers to the concentration of solution Fe for example supported or maintained by a specific Fe mineral Thus the amorphous Fe mineral common in most soils called soil Fequot exhibits a solubility of 10396 to 103924 M Fe3 depending on pH As pH increases the solution Fe concentration decreases solution Fe precipitates as soil Fe causing solution Fe concentration to decrease The following reaction shows this equilibrium relationship as H 39 39 FeOH3 mineral must increase by precipitation of Fe which p causes solution Fe3 to decrease FeOH3 soil 3H gt Fe3 3H20 For every unit increase in pH Fe3 concentration decreases 1000fold log SOLUBLE Fe molL 2 Iron Fe SOLUBILITY IN SOILS Plant requirement 1 level Tote soluble Fe I 4 5 6 pH 1 log ACTIVITY an 3 Zinc J o pH Fe solubiliyz is highly 2H degendent Zn Mn Cu solubility also is very DH 4 Manganese 5 Copper D EXCHANGEABLE AND ADSORBED MCRONUTRIENTS 39 very few micronutrients on the CEC or ABC 39 can have micronutrients adsorbed to FeAl oxide surfaces as shown below OH OH T i39 Pet OH Fe o O Cuz m 0 Cu2H Fe 0H Fe o OHA OHa IV Micronutrient Availability and De ciency A SOIL PH deficiency generally occurs in high pH calcareous soils very soluble in acid soils can be leached in acid sandy soils FeHMn 2 can be toxic soil pH lt 48 lime acid soils to reduce toxicity B SOIL OM 9 How does soil OM improve micronutrient availability in high pH soils 1 natural organic compounds 39CHELATE or bind micronutrient cations 2 the 39chelated39 micronutrients can not participate in the precipitation reactions 3 OM is an important source of micronutrients released to solution during mineralization CHELATE 4 high OM can bind micro39s causing deficiency OM gt30 Cu Mn most common OcOH O OH 9 a c cub g H OH 0 K sOH oc CU C OXIDATIONREDUCTION OX Re ducti on idation Fe O 9 Fe3 Fe3 9 Fe2 O FeS ZnS MnS can precipitate in waterlogged soil I plant root exudates create a reducing environment near root surface that causes reduction of Fe3 to 2 Fe2 Plants therefore take up Fe D ENVIRONMENT low soil temperature reduces mineralization of OM cool wet spring can enhance Zn de ciency E F l 2 a b c reduced microbial activity reduced root growth reduced diffusion NUTRIENT INTERACTIONS AND IMBALANCEs 1 Fe excess Zn Cu Mn and P can reduce Fe uptake 2 Zn high P and Fe reduces Zn uptake 3 Mn high Fe and Fe reduced Mn uptake 4 Cu high Fe and Mo reduced Cu uptake CROP SENSITIVITY 1 Fe sorghum gt soybean gt strawberry Each roses maple gt com gt wheat High Sensitivity Mild Sensitivity Low Sensitivity Berries Alfalfa Alfalfa Citrus Wheat Barley Barley Field bean Corn Corn FleX Cotton Cotton Forage sorghum Field Bean FlaX Fruit trees Field peas Grasses Grain sorghum FlaX Millet Grapes Forage legumes Oats Mint Fruit trees Potatoes Ornamentals Grain sorghum Rice Peanut Grasses Soybean Soybean Oats Rice Sugar beet Sundangrass Orchard grass Vegetables Vegetables Ornamentals Wheat Soybean Vegetables com gt soybeans gt veggies gt small grains gt fruits High Sensitivity Beans lima beans peas Castor beans Citrus Corn FlaX Fruit trees deciduous Mild Sensitivity Alfalfa Potatoes Sorghum Sugar beets Tomatoes Wheat Low Sensitivity Asparagus Carrots Forage grasses Mustard other cruci ers Oats Peas Peppermint Rye Saf ower Fruits 3 Mn soybeans gt small grains gt legumes gt corn H h Sensitivit Mild Sensitivit Low Se sitivitz Alfalfa Potatoes Barley Rye Citrus Sugar beet Corn Rice Corn Soybean Fruit trees Wheat Field beans Rye Cotton Vegetables Oats Fruit trees Soybean Field beans Wheat Onions Oats Vegetables Fruit trees Potatoes Wheat Rice Some crops are listed under two or three categories because of variation in soil growing conditions and differential response Of varieties of a given crop 4 Cu veggies gt forages Hi h Sensitivit Mild Sensitivity Low Sensitivit Wheat Carrots Barley Rye Rapeseed FlaX Lettuce Oats Canola Potatoes Peanuts Beets Corn Beans Peas Rice Spinach Timothy Soybean Lupine Alfalfa Citrus Clover Forage grasses 39 Onion IV MICRONUTRIENT FERTILIZERS A SULFATES l FeSO4397HzO 19 Fe precipitates rapidly as FeOH3 at high pH thus not a good soil applied Fe source dissolve in water and foliar apply may need repeated applications 2 ZnSO439HzO 36 Zn common source excellent residual value approx 24 years w210 lb Zna 3 MnSO4394HzO 24 Mn common source can be band applied at 510 lb Mna not with seed broadcast rate needs to be 6 times the band rate 4 CuSO4395H20 26 Cu lower band rate 715 lb Cua vs broadcast 2540 lb Cua B Chelates FeEDDHA o VG o H Name Formula Abbreviation lc cl Citric acid C6H807 CIT Oxalic acid CszO4 OX Pyrophosphoric acid H4PzO7 P207 3 Ethylenediaminetetraacetic acid C10H1508N2 EDTA 0 Diethylenetriaminepentaacetic acid C14H23010N3 DTPA ZHDTPA 3 Cyclohexanediaminetetraacetic acid C14H2208Nz CDTA H Ethylenediaminedio C18H2005N2 EDDHA 0 H w hydroxyphenlyacetic acid a5Zn diffusion to rootscpm 1 Chelate Stability EDTA 103 M 500 400 EDTA 10 300 M 200 HCl 102 10 quotCIT 103 M CIT 10 0 AH o o 2 4 6 8 Time days Crop 1 SOHGHUM YIELD 9430 2 4 6 Fe ADDED Darn RATIO OF CHELATED Fe T0 TOTAL CHELATE Crop 2 2 4 6 Fe ADDED ppm 2 Commercial che1ated micronutIients I very expensive use on high value crops mostly foliar applied mixed w uid N or P fertilizers when banded with the seed Fe FeEDDHA 6 Fe gt FeDTPA 10 Fe gt FeEDTA 514 Fe ZnDTPA or ZnEDTA 6 14 Zn excellent residual availability Mn MnEDDHA or MN EDTA 12 Mn Cu CuDTPA 6 Cu 51057 N 1 8 RECOVERY OF ADDED M10RONUTR1ENTS 1 FeSO k Oal crop Ccm amp H a 6 9 12 SOIL FEHTILIZER REACTION PERIOD WEEKS B OTHER MICRONUTRIENT FERTJLIZERS 1 Oxides ZnO 80 Zn only common one dissolve in 10340 2 Chlorides few available inorganic source and thus will precipitate at high pH 3 Others organic matter manure municipal wastes V MICRONUTRIENT APPLICATION A SOIL APPLICATION I no practical economic fertilizer practice for Fe I banded rates ltltlt broadcast rates B FOLIAR APPLICATION I one application generally not effective for entire growing season I maybe too late when the de ciency is diagnosed and foliar spray app1ied I apply foliar treatment before de ciency symptom appears I may eliminate Fe chlorosis wo yie1d advantage except w severe Fe chlorosis C OTHER STRATEGIES I plant nonsensitive crops I add OM manure etc D GENERAL RECOMMENDATIONS Fe APPLICATION CROP FE SOURCE RATE METHOD REMARKS Vegetables Fe chelates 0510 lbac Fe Foliar Wet foliage repeat as needed Citrus Fe chelates 1224g Fetree Broadcast Grain sorghum FeSO47H20 07012 lb Fe100 L H20 Foliar Three sprays of 125Lac and corn Field dry beans FeSO47H20 595 g Fe100 L H20 Foliar 2week intervals until 80125 Lac symptoms disappear Deciduous fruits Fe polyflavonoid 60100 g Fe100 IHZO Foliar Wet foliage repeat as needed Soybeans FeEDDHA 015 lbac Fe Foliar Spray band over row at second trifoliate 280 lha Cotton FeSO47H20 10 lb Fe1OO L H20 Foliar Wet plants repeat as needed Listings of particular iron fertilizers are not intended to be exclusive 2 Zn APPLICATION CROP ZN LBAC SOURCE METHOD COMMENTS com 410 ZnSO4 ZnO ZnNH3 Broadcast or banded Use lower rates for 12 Zn chelate Banded higher soil test values Sorghum 39 ZnSO4 ZnO ZnNH3 Broadcast or Use lower rates for 12 Zn chelate banded higher soil test values Banded Soybean 23 ZnSO4 ZnO ZnNH3 Broadcast or banded Use lower rates for 12 Zn chelate Banded higher soil test values Rice 710 ZnSO4 ZnO ZnNH3 Broadcast preplant Use lower rates for 1 Zn chelate Banded higher soil test values Dry beans 34 ZnSO4 ZnO ZnNH3 Broadcast or banded Use lower rates for 053 Zn chelate an ed higher soil test values Citrus 06 kg Zn ZnSO4 Foliar Wet foliage repeat until 100 L H20 symptoms disappear Pecans 3060 g Zn100 L ZnN032 Foliar Five applications start H20 400 Lac ing at bud break then of trees repeated weekly Snap beans 0611 Zn chelate Broadcast Repeat foliar until onions lima 0205 Zn chelate Banded symptoms disappear beans potatoes 01 Zn chelate Foliar or leaf analysis con firms adequate Zn 3 Mn Application Crop Mn Source Rate lb ac Method Comments Soybeans MnS044H20 1560 Broadcast Annual application MnS044H20 520 Banded Repeat as needed during season MnSO44H20 12 Foliar MnEDTA 0205 Foliar Sugar beets MnS044H20 2080 Broadcast Annual application Onions MnS044H20 or Mn0 4070 Broadcast Annual application check via soil test and plant analysis MnS044H20 or Mn0 1020 Banded Annual application Citrus nuts MnS044H20 or Mn0 0204 lb Mn Foliar Repeat as needed 100 L H20 Vegetables MnS044H20 or Mn0 810 Banded Annual application Snapbeans Spinach Cauliflower Celery Lettuce Corn oats MnS044H20 or Mn0 1560 Broadcast Annual check soil test 520 Banded Annual application Potatoes MnS044H20 1015 Banded Annual application 4 Cu APPLICATION CROP CU SOURCE RATE LBAC METHOD COMMENTS Small grains CuS045H20 or Cu0 15 Banded Higher rates on organic soils 312 Broadcast quot Cu chelates 052 Banded quot Corn CuS045H20 or Cu0 312 Broadcast quot 12 Banded quot Cu chelates 0204 Banded quot Vegetables CuS045H20 or Cu0 212 Broadcast quot 13 Banded quot Cu chelates 082 Broadcast quot 0208 Banded quot Soybeans CuS045H20 24 Broadcast quot 12 Banded quot Citrus CuS045H20 520 Broadcast Repeat in 5 years Citrus CuS045H20 90 g Cu1OO L H20 Foliar Annual applications Small grains Cu chelates 50 g Cu1OO L H20 Foliar Annual applications Some recommendations call for 20 to 60 lbac copper in initial applications on organic soils 4O lbac Cu is considered to be a maximum allowable treatment on mineral soils to avoid Cu toxicity BORON MOLYBDENUM CHLORIDE I BORON A B in pl A N ants Forms and functions B is absorbed predominately as boric acid H3BO3 Other forms in solution exist but generally in much lower concentrations Although it is required for higher plants and some algae and diatoms B is not needed by animals fungi or microorganisms Plants require B for 1 cell development in meristem tissue 2 proper pollination and fruit or seed set 3 translocation of sugars starches N and P 4 synthesis of amino acids and proteins 5 nodule formation in legumes and 6 regulation of carbohydrate metabolism B concentration varies from 6 to 18 ppm in monocots and 20 to 60 ppm in dicots Most crops are usually adequate if B is gt 20 ppm in mature leaf tissue B toxicity is uncommon in most soils unless it has been added in excessive amounts In arid regions B toxicity may occur naturally or may develop because of a high B content in irrigation waters Visual deficiency symptoms B is not mobile in the plant thus the rst visual de ciency symptom is cessation of terminal bud growth followed by death of young leaves In Bdef1cient plants youngest leaves turn pale green losing more color at the base than the tip Basal tissues break down and if growth continues the leaves have a onesided or twisted appearance Flowering and fruit development reduced by B deficiency Sterility and impaired seed set are lateseason symptoms in both Bsensitive rapeseed and clover and insensitive wheat crops B deficiency symptoms often appear in the form of thickened wilted or curled leaves a thickened cracked or watersoaked condition of petioles and stems and a discoloration cracking or rotting of fruit tubers or roots see color plates inside book cover The breakdown of internal tissues in root crops gives rise to darkened areas referred to as black heart Some conifers exhibit striking B deficiency symptoms including distorted branches and main stems resin bleeding and death of major branches Peanuts Low Sen sitivity Alfalfa Asparagus Pea Cauli ower Barley Wheat Peppermint Celery Table beet Bean Potato Rapeseed Turnip Blueberry Rye Oat Conifers Corn Sweet Corn Sorghum Canola Grasses Spearmint Onion Soybean Cucumber 39 B B m 50H 1 B CYCLE Adsorhed er sauna HA5 2 GENERAL INFORMATION total B m sells 15 very small 20 2 pnmary mmeral some of m s e 00 ppm 011515 TOURNLALJNE boloslllcate very lnsoluble TN and l we l n l l B 15 complexedby OM andls amajol some ofB to plants OM mineralization supplles B 3 AVAILAEle ANDDEFICIENCY lower CEC Thls 15 especlally true In acld 50115 len low 0 M B avallablllty lncleases Wltn lnmeaslng o M Dry condltlpns generally reduce B avallablllty B de clency k t D B contalns gt 1 ppm B can produce B toxl lty In NC B deflclency can occur In sandy splls s 115 Wlth pH gt5 5 and under droughty Eondltlons Common crops that exlnblt B deflclency ate cotton peanut tobacco and apple C B FERTILIst 1 Borax NaaB30710 H20710711 n B Rates generally lt 3 lbsa do notleapply wlthout 5011 testing folB 3 Seed appllcatlons often lesult m seedlmg toxmty u MOLYBDENUM A MOINPLANTS 1 FoRMANDHvN l CT ONS Mo ls anonmetal anlon absorbed as molybdate Moan Ma cantentm plants lt 1 ppm Ma de clentplants Bantam lt 0 2 ppm Ma 39 ll hm n rquot m nl m s hawever Ma levels may exceed 1000 ppm 39reductasE redueupn pr None No h V n mm ll w Ma may 2150 be lmpartant m Fe absarpnan and translneaunn m plants 2 v u v ld ll n ean fad m farm leaves wlll became mm elangated and nppled General yellawlng pr alderleaves wlth llght green calm pr atherleaves y p s lg rs rs ccnh Brussels spmuts Legumes semen when M Ar N Equot wwrz GENERAL INEOMATION total Mo is small in soils 05 30 ppm plants need little Mo39 lt 01 ppm most crops39 0305 ppm legumes Some legumes accumulate Mo 10 20 ppm and may cause molybdenosis in ruminants This is a nutrient imbalance corrected by adding Mo to the diet Mo minerals are the primary source ofplant available Mo MoOI2 is adsorbed on clay and FeAl surfaces and is held stronger than SO4392 but lt PO4393 Excessive Mo can be toxic to grazing cattle or sheep High Mo forage may occur on wet neutral to alkaline soils Peat or muck soils may also exhibit high Mo Molybdenosis Mo toxicity is caused by an imbalance of Mo and Cu usually when Mo in the forage is gt 5 ppm Mo toxicity causes stunted growth and bone deformation and can be corrected by oral feeding of Cu Cu injections or increasing plant Cu by CuSO4 fertilization VAlLABlLlTY AND DEFICIENCY Mo solubility increases with increasing pH thus Mo de ciencies occur w soil pH lt 6065 Liming acid soils generally increases Mo availability OM contains some Mo and can be a valuable source ofplant available Mo 0 FERTJLIZERS Na or NH4 molybdates are usual Mo sources 54 Mo Rates are generally between 2 oz to 2 lb broadcast foliar or seed applied Mo fertilizers have a long residual and need be applied only every few years 111 CHLORIDE A CL IN PLANTs l N FORM AND FUNCTIONS 0 Cl is absorbed by plans as Cl39 through both roots and leaves Cl is mobile in plants 0 Cl levels in plans ranges from 02 to 20 although 10 Cl levels can be observed Chloride is not a true metabolite in higher plants The essential role of Cl is in is biochemical inertness which enables it to participate in osmotic balance which may have impor1ant biochemical consequences Cl is a counter ion during rapid K uptake contributing to leaf turgor VISUAL DEFICIENCY SYMPTOMS 0 Loss o leaf turgor is a symptom of Cl de ciency High Cl levels increase leaf water potential an cell sap osmotic potential Cl fertilization can improve moisture re ations 0 Cl involved in 02 evolution in photosynthesis Cl concentrations of N10 in chloroplasts o Chlorosis in younger leaves and wilting are the common Cl de ciency symptoms see color plates in book Necrosis in some plants leaf bronzing and reduction in root growth al 39 observed Tissue Cl concentrations lt70700 ppm are usually indicative of de ciency 0 Cl toxicity exism although crops varyi their tolerance to high Cl see below Leaves thicken and roll with e cessive Cl Hi h Cl adversely affects storage quality of tubers High Cl increases d b li t X g osmotic pre sure an lowers water availa i ty x 39 Soybean Sensitivity of Crops to Low Levels of Available Cl High Sensitivity Mild Sensitivity Low Sensitivity Avacado Potatoes Sugar beet Peach Wheat Barley Legumes Oats Corn Tobacco Soybean Spinach Lettuce Cotton Tomatoes B CL IN SOIL 1 CL CYCLE minerals Adsorbed or labile Cl 2 GENERAL INFOMATION The original source of Cl39 is primary minerals C1 in soils behaves very similar to N0339 very soluble and readily leaches some low Cl39 soils reported in the Great Plains 3 AVAILABILITY AND DEFICIENCY few de ciences reported Cl39 is bene cial in supression of some crown root rot and some leaf diseases Cl responses reported in Oregon North South Dakota Kansas on wheat barley and potatoes High NO339 levels can reduce Cl39 uptake C CL FERTILIZERS l The primary source of Cl39 is KCl 47 Cl39 OTHER MICRONUTRIENTS I COBALT IN PLANTS A CO B CO Co concentration in plant dry matter ranges from 002 to 05 ppm Co is essential for growth of symbiotic microorganisms such as rhizobia freeliving Nzfixing bacteria and bluegreen algae Co forms a complex with N important for synthesis of vitamin B12 coenzyme Co is also important in the synthesis of vitamin B12 in ruminant animals thus soil is an important source of plant Co for animals Because Co behaves similarly to Fe or Mn excess Co produces similar visual symptoms IN SOILS Total soil Co content ranges from 1 to 70 ppm avg 8 ppm Co Co de ciencies in ruminants are associated with forages produced on soils containing lt 5 ppm total Co Co de cient plants can commonly occur on 1 acidic highly leached sandy soils with low total Co 2 some highly calcareous soils and 3 some peaty soils Co is adsorbed on exchange sites and occurs as clayOM complexes similar to other metal cations Solution Co is very low lt05 ppm C FACTORS AFFECTING CO AVAILABILITY D CO FeAIMn oxides have a high adsorption capacity for Co and can adsorb soilapplied Co Co can replace Mn on adsorption sites of these minerals Co availability is favored by increasing acidity and waterlogging conditions which solubilize Mn oxide therefore liming and drainage reduce Co availability SOURCES Co deficiency of ruminants can be corrected by 1 adding Co to feed salt licks or drinking water 2 drenching 3 using Co bullets and 4 fertilizing forage crops with Co Co fertilization withl5 to 3 oza as CoSO4 is recommended Soils low in Co require 05 to 2 oz a of Co as CoSO4 for nodulation and N2 fixation by legumes II SODIUM IN PLANTS A NA Na is essential for plants that accumulate salts to maintain turgor and growth halophytes The increased growth produced by salt in halophytes is due to increased turgor Growth response from Na can be observed on lowK soils Nal can partially replace Kl Na is absorbed by plants at levels from 001 to 10 in leaftissue Sugar beet petioles frequently contain levels at the upper end of this range Many C4 plants require Na as an essential nutrient in uencing water relations Many C4 plants naturally occur in arid semiarid tropical and saline conditions where closure of stomata to prevent excessive water loss is essential for growth Sugar beets are responsive to Na where Na increases drought resistance In low Na soils the beet leaves are dark green thin and dull in hue The plants wilt more rapidly and may grow horizontally from the crown There may also be an interveinal necrosis similar to K deficiency Crops have been categorized according to their potential for Na uptake see below Na Uptake Potential of Various CroLs Medium Low Very Low Fodder beet Cabbage Barley Buckwheat Sugar beet Coconut Flax Maize Mangold Cotton Millet Rye Spinach Lupins Rape Soya Swiss chard Oats Wheat Swede Table beet Potato B NA IN SOILS 39 Soils contain 01 to 1 Na Low Na indicates weathering of Na from Na bearing minerals Very little exchangeable and mineral Na occurs in humidregion soils whereas Na is common exists in most arid and semiaridregion soils as Nasilicates NaCl NazSO4 and NazC03 Solution Na ranges from 05 to 5 ppm in temperateregion soils In humidregion soils exchangeable Ca2 gt Mg2 gt K Na Exchangeable Na can be utilized by crops Sugar beets respond to fertilization when exchangeable Na lt005 meq 100 g In arid regions exchangeable Na exceed those of K Na salts accumulating in poorly drained soils of the arid and semiarid regions will be contributors to soil salinity and sodicity see Chapter 2 C NA SOURCES Responses to Na have been observed in crops with a high uptake potential The Na demand of these crops appears to be independent of and perhaps even greater than their K demand The important Nacontaining fertilizers are K fertilizers with various NaCI contents and NaNO3 about 25 Na III SILICON A SI IN PLANTS Si is absorbed by plants as silicic acid H4Si040 Cereals and grasses contain 02 to 20 Si while dicots contain 002 to 02 Si Concentrations of up to 10 occur in Sirich plants Si contributes cell wall structure in grasses sedges nettles etc 2 to 20 Si Si impregnates cell walls of epidermal and vascular tissues where it appears to strengthen the tissues reduce water loss and retard fungal infection Where large amounts of Si are accumulated intracellular deposits known as plant Opals can occur Si in roots likely contributes to drought tolerance of some crops ie sorghum Although no biochemical role for Si has been identified it has been proposed that enzymeSi complexes that act as protectors or regulators of photosynthesis and enzyme activity Si can suppress the activity of invertase in sugarcane increasing sucrose production A reduction in phosphatase activity may provide increased supply of high energy precursors needed for optimum cane growth and sugar production The beneficial effects of Si have been attributed to correction of soil toxicities arising from high levels of available Mn Fe and Al plant disease resistance greater stalk strength and resistance to lodging increased availability of P and reduced transpiration Freckling necrotic spots on leaf is a symptom of low Si in sugarcane Si responses rice have been observed Si maintains rice leaf erectness which increases photosynthesis due to better light interception resulting in greater resistance to diseases and insect pests The oxidizing power of rice roots and accompanying tolerance to high levels of Fe and Mn are dependent on Si High N applications render rice plants more susceptible to fungal attack because of decreases in Si concentration in the straw To correct this Si materials are added B SI IN SOILS Si is the second most abundant element in the earth39s crust averaging 276 while Si in soils ranges from 23 to 35 Unweathered sandy soils can contain nearly 40 Si compared with as little as 9 Si in highly weathered tropical soils Major sources of Si include primary and secondary silicate minerals and quartz SiO2 Quartz is the most common mineral in soils comprising 90 to 95 of all sand and silt fractions LowSi soils exist in intensively weathered highrainfall regions Properties of the Stdef1cient soils include low total Si high Al low BS low pH and high Pfixing capacity due to their high ABC and AlFe oxide content Soil solution predominately contains silicic acid H4SiO40 Si concentrations of less than 09 to 2 ppm are not sufficient for proper nutrition of sugarcane By comparison 3 to 37 ppm Si in solution are common in soils Si levels adequate for rice production are gt100 ppm Si is adsorbed on the surfaces of FeAI oxides Si leaching in highly weathered soils will reduce solution Si and Si uptake C SI FERTILIZERS Primary Si fertilizers include calcium silicate slag CaAIzSiZOS and calcium silicate CaSiO3 In sugarcane at least 5000 Iba of CaSi03 are broadcast applied and incorporated before planting Annual CaSi03 applications of 500 to 1000 Ib a applied in the row also improved sugarcane yields Lime added to increase Ca levels and decrease soil acidity do not produce similar dramatic improvements in the growth of sugarcane Rates of 15 to 20 tha of silicate slag usually provide sufficient Si for rice produced on lowSi soils IV SELENIUM A SE IN PLANTS Se is an essential plant nutrient but it is essential for animals Livestock nutritional disorders caused by low Se can occur after cold rainy summers High summer temperatures are amenable to increased Se concentration in forages Plant species differ in Se uptake Certain Astragalus species absorb much more Se than other plants grown on the same soil Plants such as the cruciferae eg cabbage mustard and onions which require large amounts of S absorb intermediate amounts of Se while grasses and grain crops absorb low to moderate amounts of Se B SE IN SOILS Se occurs in very small amounts in nearly all materials of the earth s crust avg 009 ppm in mainly in sedimentary minerals Se is similar to S however it has five oxidation states 2 0 2 4 and 6 Total Se concentration in soils is from 01 to 2 ppm Areas ofhighSe soils in western North America and in other semiarid regions produce vegetation toxic to livestock High pH calcareous soils in arid regions lt 20 in precipitation are usually high in Se Se in soil occurs as selenides Sez39 elemental Se selenites Se4 Selenates Se5 and organic Se compounds The predominant species depends on redox potential pH and solubility Selenides See Selenides are largely insoluble and are associated with S2 in semiarid soils low weathering They contribute little to Se uptake because of their insolubility Elemental Se Seg Se0 is present in small amounts in most soils Significant amounts of Se0 may be oxidized to selenites and selenates by microorganisms in neutral and basic soils Selenites Se03k Se in acidic soils may occur as soluble complexes of selenites with hydrous Fe oxides Low solubility of Feselenite complexes is likely responsible for the nontoxic levels of Se in plants growing on acidic high Se soils Plants absorb selenite but generally to a lesser extent than selenate Selenates SeO L Most of the watersoluble Se in soils probably occurs as selenates Selenates are frequently associated with SO4239 in arid region soils and are stable in many wellaerated semiarid soils Other forms of Se will be oxidized to selenates under these conditions Selenate occur in minute quantities in acidic and neutral soils Selenates are highly soluble and readily available to plants and are responsible for toxic accumulations in plants grown on high pH soils Organic Se Organically complexed Se can constitute up to 40 of the total Se in some soils Soluble organic Se compounds are liberated through the decay of seleniferous plants Se in residue is stable in semiarid areas and much of it remains available in soil Organic Se is more soluble in basic than acidic soils which would enhance availability to plants in semiaridregion soils C FACTORS AFFECTING SE AVAILABILITY Low Se uptake is usually caused by low total Se in the soil parent material or low availability of Se in acidic and poorly drained soils Se uptake is greater in highpH soil than in acidic soils Solution Se is lowest at slightly acidic to neutral pH and increases under both more acidic and basic soil pH High soil pH facilitates the oxidation of selenites to more readily available selenates Increased yields with N and S fertilization may lower Se concentrations in crops through dilution Although Se de ciency disorders such as muscular dystrophy or white muscle disease in cattle and sheep can be corrected by therapeutic measures there is interest in Se fertilization to produce forages adequate in Se for grazing animals rather than to satisfy any particular plant requirements Se fertilization is acceptable if proper precautions are taken 1 At no stage should herbage become toxic to grazing animals topdressing must be avoided 2 High levels of Se in edible animal tissue should be prevented 3 Protection against Se deficiency should be provided for at least one grazing season following application during the dormant season D SE SOURCES Fertilization with selenites is preferred over selenates because they less soluble and less likely to produce excessive Se levels in plants Selenates are effective for rapid Se uptake The addition of Na selenite at l oza of Se is satisfactory for forages Foliar application of Na selenite at 6 ga of Se is suf cient to increase plant Se Se is present in phosphate rocks and in fertilizer P products produced from them Superphosphate containing 3 20 ppm Se provide sufficient plant Se to protect livestock from Sedefrciency V NICKEL Ni was recently established as essential to higher plants Ni in plants ranges from 01 to 10 ppm and is taken up as Ni2 Ni is a component of urease that catalyzes urea hydrolysis Chapter 4 Nidefrcient plants accumulate toxic urea levels in leaf tips due to reduced urease activity Ni may be involved in plant disease resistance due to changes in N metabolism Ni is essential to small grain crops High levels of Ni may induce Zn or Fe deficiency because of cation competition Application of some sewage sludge may result in elevated levels of Ni in crop plants VI VANADIUM Low V concentrations are beneficial for the growth of microorganisms animals and higher plants V is essential for green alga Scenedesmus There is no complete evidence that V is essential for higher plants V may partially substitute for Mo in N2 fixation by microorganisms such as the rhizobia Responses to V have been observed in asparagus rice lettuce barley and corn The V requirement of plants is lt 2 ppb where normal V level is about 1 ppm 1 Biological tests A Fzzld tests 1 replicated small plot studies with various treatments ie p rate o lo 20 40 80 lbs pzo5 per acre 2 results can be applied to similar soils with similar climatic conditions 3 time and labor intensive B Stnp tests 7 narrow strips of elds undergoing different treatment than the rest ofthe eld Figure 915 1 Useful in verifying the accuracy ofnutrient recommendations from soil analysis 2 Results must be interpreted carefully ifthey are unreplicate Phosphorus rate lbs P205 ac Tveatmem 1 Rep 1 u 20 to 40 so Trestmermz Rep 2 2o 40 to u so atmeni 3 Rep 3 40 u so to 20 lam 4 Rep 4 20 so 40 u to Field plot experiment c Laboratory and greenhouse tests 1 simpler and more rapid 2 Use many soils under a controlled climate 3 Useful in determining ifsoil tests are related to yield response to nutrient addition 11 Soil analysis A obyeeaves ofsorz tests To provide an index ofnutrient availability or supply in a given soil To predict the probability of obtaining a pro table response to lime and fertilizer To provide abasis for recommendations on the am ime and fertilizer to apply To evaluate the fertility status ofsoils on a county soil area or statewide basis by the use of soil test summaries PP Nt B Sotl tzsungm nutrtertt reeommertdattort system 1 2 3 4 c Colleetmg the sample 7 The largest source of error in the system ll 1 Fiel average sam lin dividing the eld into units that have similar management history and can be managed differently for the current crop 2 Site speci c sampling a Grid sampling dividing the eld into a grid with cells from 15 a in size i cell sampling ii point sampling b Directed sampling using other soil properties color texture etc to determine locations for soil samples ISell Sample I I G Field 1 61790 Samplea randomly 3904 quot collected from cell V LOW I spot i a Sam ple 3 Sample 4 I 1 quotsam39pl equot Sample 1 1 i 39 Gentle slo in IQ Q Q Sample 10 Sample 7 909 I 3 39 E Samples randomly p p quot7quotquot 5 II mllected llrom VO 4 39 quot 603 l i E I 39 Wall clrele amund I l quot grid palm Bottomland Sample 9 Sample 8 Point Sample h 39 GEE a ll 5 3 SJ 3 75 a Bray l P ppm ll lD l4 Soil Color Elevation Sell Dllvll Brawl P W Infiuu r r E 715 119 t 2339 5 0 l i r5 3 P235 Band 3 7395 lbs FEDS Elrna east D 45 lbs P235 Band D 45 lbs P235 Ermadcast I Unle rlllizecl 40 3 Management e ects on soil sampling a banded nutrients Will cause a localized increase in nutrient concentration around the band therefore band location must be considered When taking samples ERAY l lF ppm I l E 4 E D 2 4 B DISTANEE AGHDSS HOW ill m r y m depth ofsampling nutrient ent 39 immlmm numeuepm mobility andmanagem Within the soil pro le D Suzl test Table 910 PlavVNrm Lcm Common Extracmms Himm Sallytr No 101 CaClz Solution NH KC SolutionCEC HlPo Hgl Of NHFHCI BrayPl FcAIP mummi solubility NWTCHcoonENGg MchliclirPl lieALP mulm ul solubility Nauco3 Olsenl7 M mineral sol illry lt NHpAt so2 Gnu1112002 one SolutionABC Zn Fe Mn Cu DTPA EDTA Zn Fe Mn Cu mineral solubilty 1431303 Hot water Solution CI Wnrm Solution 1 Nitrogen 1 or 2 MKCI Kl removes N39Hf from exchange sites and Cl39 removes any NOg39 held by OM or anion exchange a presidedress N test to determineN availability during growing season b MostN recommendations based on crop yield potential 2 Phosphorus acidic soils rBray and Mehlich 111 soil tests remove P bound to Al hydroxides and precipitated as Alphosphates Primary extractant is N39HAF b neutral r p p p Pn39mary extractant is NaHC03 U Potassium extractedWith NH4OAc ammonium acetate Where NHLr removes Kir from exchange site Similarly NHLr in Mehlich Ill extracts K 4 Sulfur Because 804239 is mobile and S mineralization is a major source ofplant available S 804239 soil tests are not reliable 5 Micronutrients Fe Zn Mn Cu Extracted With chelates such as EDTA and DTPA E Calibrating soil tests 7 soil tests are calibrated to do the following 1 2 Hemnve sources m numems Sumo enny m dr elem sail les levels e lev l 00 Soil Fmquot n W Nutrrents requlred ll Timmy ml at m lsvskme m starter a mamaname moses 110 40 100 L1 0 D v 30 a so a gt E J 50 5 7D a g a E 60 v 10 50 l l I 1 I 0 W 10 20 so 40 so 0 20 30 40 50 BRAY 1 P SOIL TEST ppm BRAY 1 P SOIL TEST ppm F Interpretation of results and recommendation 1 Soil test data are interpreted based on the probability of a yield increase to additional fertilizer m 2 E D Z m a E a u a 0 a E E L 2 g l PROBAB 2 Goal is to maintain plant nutrients at a level for sustained productivity and pro tability P HATE FOR MAX VIELD lba 3 Mobile nutrients NOg39 804239 Cl39 crop yield is proportional to the total quantity of nutrient present in the root zone Figure 958 a recommendation is based on nutrient present ie N inthe pro le and a yield goal Float system Root summe on 2 sorption zone MOBILE NUTRIENTS IMMOBILE NUTRIENTS 4 Irnmobile nutrients 7 crop yield is proportional to the quantity of nutrient near the root surface Figure 958 a build up 7 When soil test levels are below the critical level nutrients should be added to increase soil test leve maintenance iwhen soil test levels are above the critical level nutrients are added to replace the nutrients removed by the harvested crop ST Snil Tst Level RELATIVE YIELD 3 mum Mam Fenm39zer A u iciency or m recommen applmm da on manure ions Maintenance or sinner recommenda Ian I r mummm um 01 V70 wudnm v 5 max 50 annuai o A W H mm 79 no 5 e2 VFAR Manure No nmriem applicauons applicauons E E E m E E c o 9 a 2 i W High BRA H P ppm Starter only recommendation Very High Excessive


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