SOIL FERTILITY AND NUTRIENT MANAGEMENT

Transcription

1 NRCCA Sil Fertility & Nutrient Management Study Guide - 9/28/28 SOIL FERTILITY AND NUTRIENT MANAGEMENT Cmpetency Areas Cmpetency Area 1: Basic Cncepts f Plant Nutritin... 2 Cmpetency Area 2: Basic Cncepts f Sil Fertility... 3 Cmpetency Area 3: Sil Testing and Plant Tissue Analysis... 8 Cmpetency Area 4: Nutrient Surces, Analyses, Applicatin Methds Cmpetency Area 5: Sil ph and Liming Cmpetency Area 6: Nutrient Management Planning Authrs/Instructrs fr Sil Fertility and Nutrient Management Quirine Ketterings, Assciate Prfessr, Nutrient Management Spear Prgram, Department f Animal Science, Crnell University. Karl Czymmek, Senir Extensin Assciate, PRODAIRY, Department f Animal Science, Crnell University. Tm Bub, Extensin Educatr, University f New Hampshire Cperative Extensin. Dug Beegle, Prfessr, Department f Crp and Sil Science, Penn State University. Patty Ristw, Extensin Assciate, Nutrient Management Spear Prgram, Department f Animal Science, Crnell University. NRCCA bard review by Janet Falln, DairyOne. Last Updated

2 NRCCA Sil Fertility & Nutrient Management Study Guide - 9/28/28 Cmpetency Area 1: Basic Cncepts f Plant Nutritin 1. List the 18 elements essential fr plant nutritin. Nutrient Macr/micr Uptake frm Mbile in Plant 1 Carbn Macr CO 2,H 2 CO 3 2 Hydrgen Macr H +,OH -,H 2 O 3 Oxygen Macr O 2 4 Nitrgen Macr NO 3-,NH + 4 Mbile 5 Phsphrus Macr HPO -2 4,H 2 PO - 4 Smewhat Mbile 6 Ptassium Macr K + Mbile (very) 7 Calcium Macr Ca +2 Immbile 8 Magnesium Macr Mg +2 Smewhat mbile 9 Sulfur Macr SO - 4 Mbile 1 Brn Micr H 3 BO 3,BO - 3 Immbile 11 Cpper Micr Cu +2 Immbile 12 Irn Micr Fe +2,Fe +3 Immbile 13 Manganese Micr Mn +2 Immbile 14 Zinc Micr Zn +2 Immbile 15 Mlybdenum Micr MO - 4 Immbile 16 Chlrine Micr Cl - Mbile 17 Cbalt Micr C +2 Immbile 18 Nickel Micr Ni +2 Mbile 2. Classify the essential elements as macrnutrient r micrnutrients. See Table 1. The macrnutrients can als be gruped as primary nutrients (nitrgen, phsphrus and ptassium) and the secndary nutrients (calcium, magnesium and sulfur). This grup f nutrients is used in large quantities. The micrnutrients n the ther hand are used in much smaller quantities. 3. Recgnize the functins f N, P, and K in the plants. Nitrgen: fund in chlrphyll, nucleic acids and amin acids; cmpnent f prtein and enzymes. Phsphrus: an essential cmpnent f DNA, RNA and phsphlipids which play critical rles in cell membranes; als play a majr rle in the energy system (ATP) f the plants. Ptassium: plays a majr rle in the metablism f the plant, and is invlved in phtsynthesis, drught tlerance, imprved winter-hardiness and prtein synthesis. 4. Distinguish each macrnutrient as mbile r immbile in the plant. See Table 1. Nutrients that are mbile in the plant will mve t new grwth areas s the deficiency symptms will first shw up in the lder leaves. Nutrients that are nt mbile in the plant will nt mve t the new grwth s the deficiency symptms shw up first in the new grwth. 2

3 NRCCA Sil Fertility & Nutrient Management Study Guide - 9/28/28 5. List chemical uptake frms fr each macrnutrient. See Table 1. Sme f the nutrients are taken up in mre than ne frm. 6. Describe hw nutrient demands change at different plant grwth stages. In general, nutrient needs increase as the plant grws thrugh the seedling stage int the reprductive stage (silking and tasseling). Fr nitrgen, the rate f uptake increases very fast between V8 ( knee high) and R1 (silking). When the plants are yung and small, the need fr nutrients is lw. Once the plants get larger and start t grw rapidly, the needs increase dramatically. Cmpetency Area 2: Basic Cncepts f Sil Fertility 7. Recgnize the rle f the fllwing in supplying nutrients frm the sil: A. Sil slutin D. Sil minerals B. Catin exchange sites E. Plant residue C. Organic matter The sil slutin is the liquid in the sil and the plant nutrients disslved in the sil slutin can mve int the plant as the water is taken up. Catins (psitively charged ins such as calcium, magnesium and ptassium) are held n exchange sites in the sil. Catin exchange capacity (CEC) is a measure f the amunt f catins that can be held by the sil and released int the sil slutin. Sils with a greater catin exchange capacity (see #1) are able t hld nt mre nutrients. Organic matter cntains nutrients and releases nutrients fr plant uptake upn decmpsitin. As sil minerals (clays, carbnates, etc) weather (breakdwn) they release nutrients fr plant uptake. A gd example f this is ptassium. As plant residues breakdwn, the nutrients in them becme available t the grwing plants. Nitrgen is typically the ne we think f, but the ther essential nutrients in the plant residues will becme available fr plant uptake as well. 8. Describe the fllwing nutrient transfrmatins and interactins: A. Mineralizatin B. Immbilizatin C. Nutrient uptake antagnism Mineralizatin refers t the cnversin f rganic N surces (plant residues, manures, and bislids) t inrganic N surces. This is accmplished by a wide variety f micrrganisms. Immbilizatin is the reverse f mineralizatin as this refers t the cnversin f inrganic frms f nitrgen int rganic frms, such as micrbial cells and rganic matter. Nutrient uptake antagnism refers t the cmpetitin fr plant uptake by different nutrients. 3

4 NRCCA Sil Fertility & Nutrient Management Study Guide - 9/28/28 9. Describe hw the prcesses f mass flw, diffusin, and rt interceptin affect nutrient uptake. Mass flw f a nutrient ccurs when it is disslved in the sil slutin and flws with the water int the plant. This is the majr prcess fr uptake f nitrgen, calcium and magnesium. Diffusin is the mvement f a nutrient frm an area f high cncentratin t ne f lwer cncentratin. Typically the nutrient will mve frm the sil slutin (high cncentratin) t the rt surface (lw cncentratin). This is an imprtant prcess fr phsphrus and ptassium. This is the thery behind the use f banded r starter fertilizer. Rt interceptin ccurs when a rt grws in t an area r surface f clay r rganic matter and absrbs the nutrient. 1. Describe hw catin exchange capacity (CEC) influences nutrient mbility and uptake. Catin exchange capacity (CEC) is a measure f the amunt f catins (psitively charged ins) that can be held by the sil. As the clay cntent, rganic matter cntent and ph increase, the CEC will als increase. This results in increasing the sils ability t hld mre nutrients. Since much f the plant uptake (and leaching) f nutrients cmes frm the sil slutin, as the CEC increases, the nutrients in slutin decrease and becme les mbile in the sil. 11. Distinguish each macrnutrient as mbile r immbile in the sil. The mbility f nitrgen is dependent n the frm it is in. If it is in the nitrate frm (NO3-) it is very mbile with the sil water and can be easily leached. In the ammnium frm (NH4 + ) it can be held n catin exchange sites and is nt susceptible t leaching. Phsphrus is typically immbile in the sil unless sil test levels rise abve the sil s ability t bind it. Calcium, magnesium and ptassium are cnsidered immbile in sil since they are held n catin exchange sites. Sulfur (as sulfate SO 4 - is an anin and nt held n catin exchange sites) is mbile in mst sils. 12. Describe hw the fllwing sil characteristics affect nutrient uptake: A. Texture D. Misture B. Structure E. ph C. Drainage/aeratin F. Temperature Texture is defined as the prprtin f sand, silt and clay in the sil. As the clay cntent increases, s des the CEC, resulting in a greater ability t hld nutrients. Sils with mre sand and less clay have lwer CECs and cannt hld as many. Since these sandy sils als have large pre spaces, leaching f nutrients is greater than n a sil with mre silt and clay. Sil structure is defined as the arrangement f sil particles int aggregates. If these aggregates have large spaces between them, sil water (and nutrients) will mve mre freely resulting in leaching lsses. Destructin f gd structure, smetimes by cmpactin can result in an increase in runff since the water can nt mve dwn thrugh the sil prfile. Under pr drainage cnditins, nitrate nitrgen can be lst thrugh denitrificatin. With excessively drained sils (sandy) leaching lsses are mre imprtant. Sme nutrients like irn and manganese are mre sluble under very wet r flded cnditins. 4

5 NRCCA Sil Fertility & Nutrient Management Study Guide - 9/28/28 Sil misture is very imprtant fr rt grwth, s adequate misture will imprve uptake f nutrients by diffusin and rt interactin. Sil misture is als imprtant fr rganic matter decmpsitin (which releases N, P and S). Sil ph affects the availability f mst nutrients. Fr example, at lw ph and high ph phsphrus is less available than when the ph is arund 6.5. At a lw ph it is bund by aluminum and irn and at a high ph is bund by calcium. Many f the micrnutrients are als sensitive t ph, being mre available in slightly acid sils. At high ph s, mlybdenum can becme t available and be txic t plants. See #39 fr mre detailed infrmatin. Sil ph is imprtant in N transfrmatins including mineralizatin f rganic materials (bilgical degradatin), nitrificatin (bacteria respnsible fr this prcess are ph sensitive) and N fixatin. Temperature affects the plant s ability t grw and thus affects nutrient uptake. 13. Describe hw the fllwing affect the fate f N in sil: A. Fixatin by clay F. Immbilizatin B. Ammnificatin/mineralizatin G. Leaching C. Nitrificatin H. Plant uptake D. Vlatilizatin I. Symbitic fixatin E. Denitrificatin See #14 fr a schematic f the N cycle. A. Since the sil has a negative charge, the ammnium in (NH 4+ ) can be bund t the sil particle. Depending n the type f clay, this in can be trapped in the actual structure f the clay mineral and becme unavailable t plant uptake. B. Ammnificatin (the secnd step in the mineralizatin prcess) is the cnversin f rganic nitrgen t ammnium N by micrbes as they decmpse the rganic matter. If large amunts f nitrgen rich rganic materials with narrw C:N ratis (<15-2) is added, significant levels f ammnium can be prduced. This will then be cnverted t nitrate (nitrificatin), absrbed by plants, fixed r held by the sil r cnverted t ammnia and lst t the air (vlatilizatin). Mineralizatin readily ccurs in warm (68-95 F), well-aerated and mist sils. In New Yrk, abut 6 8 lbs f N per acre is mineralized n average frm sil rganic matter each year. R-NH 2 NH 3 + NH 4 rganic N ammnia ammnium R reflects the (undefined) rest f the mlecule. Ammnificatin C. Nitrificatin is a tw step prcess that cnverts the ammnium t nitrite (by ne species f bacteria) and then t nitrate (by a secnd species f bacteria). These bacteria are sensitive t temperature, misture and sil ph. Nitrificatin is mst rapid when sil is warm (67-86 F), mist and wellaerated, but is virtually halted belw 41 F and abve 122 F. + NH 4 - NO 2 - NO 3 ammnium nitrite nitrate Nitrificatin 5

6 NRCCA Sil Fertility & Nutrient Management Study Guide - 9/28/28 D. Vlatilizatin is the lss f ammnium N by its cnversin t ammnia. Vlatilizatin lsses are higher fr manures and urea fertilizers that are surface applied and nt incrprated (by tillage r by rain) int the sil. Manure cntains N in tw primary frms: ammnium and rganic N. If manure is incrprated within ne day, 65% f the ammnium N is retained; when incrprated after 5 days the ammnium N will have been lst thrugh vlatilizatin. Organic N in manure is nt lst thrugh vlatilizatin, but it takes time t mineralize and becme plant available. + H 2 N-C-NH 2 NH 4 NH 3 Urea ammnium ammnia Vlatilizatin E. Once nitrgen in the sil reaches the nitrate (NO 3- ) frm, several things can happen. Under waterlgged r flded (anaerbic) cnditin nitrate can be cnverted t gaseus frms f N. Under typical cnditins the majrity wuld be in as N 2 gas. This prcess is called denitrificatin. - NO 3 - NO 2 NO N 2 O N 2 nitrate nitrite nitric nitrus nitrgen xide xide gas Denitrificatin F. If the sils are nt wet (aerbic), the nitrate can be used by micrbes t breakdwn mre rganic materials. Immbilizatin refers t the prcess in which nitrate and ammnium are taken up by sil rganisms and therefre becme unavailable t crps. Incrpratin f materials with a high carbn t nitrgen rati (e.g. sawdust, straw, etc.), will increase bilgical activity and cause a greater demand fr N, and thus result in N immbilizatin. Immbilizatin nly temprarily lcks up N. When the micrrganisms die, the rganic N cntained in their cells is cnverted by mineralizatin and nitrificatin t plant available nitrate. + - NH 4 and/r NO3 R-NH 2 ammnium nitrate rganic N R reflects the (undefined) rest f the mlecule. Immbilizatin G. If sufficient rain ccurs the nitrate can be lst t the grundwater by leaching thrugh the sil prfile belw the rts f the plants. H. If the cnditins are aerbic (nt wet f flded) the nitrate can be taken up by the plants. I. Symbitic fixatin f nitrgen is a mutually beneficial prcess between a legume plant and the assciated micrrganism (Rhizbium sp.). The plant prvides the micrbe with an energy surce t cnvert N 2 frm the atmsphere t ammnium that can be utilized by the plant. Nitrgen fixatin requires energy, enzymes and minerals, s if a plant available frm f N is present, the crp will use it instead f fixing N frm the air. N 2 NH 3 R-NH 2 nitrgen gas ammnia rganic N R reflects the (undefined) rest f the mlecule. N fixatin 6

7 NRCCA Sil Fertility & Nutrient Management Study Guide - 9/28/ Describe hw the fllwing sil factrs affect symbitic nitrgen fixatin: A. ph D. Nitrgen level B. Misture E. Aeratin C. Ppulatin f crrect Rhizbia species F. Organic matter The Nitrgen Cycle See als: 7

8 NRCCA Sil Fertility & Nutrient Management Study Guide - 9/28/28 The micrbes that are respnsible fr symbitic nitrgen fixatin are very sensitive t ph. As the ph drps, fixatin will slw. Very little will ccur belw a ph f 5. The Rhizbia species that are respnsible fr fixatin perate under gd misture cnditins. If it gets t wet r dry micrbial activity will slw dwn. Under drught cnditins, fixatin will stp. There are numerus species f Rhizbium, and they each require a specific hst. The inculatin f the legume seed with the crrect species (especially the first time this legume has been in the field) is extremely imprtant t btaining gd levels f fixatin. Fr example, the symbitic bacteria fr sybean will nt fix nitrgen with alfalfa. As readily available nitrgen frm ther surces (fertilizers, manures, bislids, rganic matter) increases, the amunt f nitrgen fixed decreases. Since the Rhizbia are aerbic bacteria, aeratin is very imprtant. Under very wet cnditins they will nt fix as much nitrgen. Under wet cnditins, leaching and denitrificatin lsses may increase as well. If the rganic matter cntent is very high, and the supply f available nitrgen is plentiful, the bacteria will nt fix as much nitrgen. Cmpetency Area 3: Sil Testing and Plant Tissue Analysis 15. Cnvert fertilizer analysis frm elemental t xide frm and frm lbs/acre t ppm and vice versa. 1 ppm = 1 mg/kg = 2 lbs/acre (assuming 2 millin lbs f sil in ne acre furrwslice) 1 lb K = 1.2 lb K 2 O 1 lb K 2 O =.83 lb K 1 lbs P = 2.29 lb P 2 O 5 1 lb P 2 O 5 =.44 lb P 16. Recgnize hw the fllwing affect sil sampling methds: A. Methd f previus fertilizer applicatin B. Tillage system C. Nutrient stratificatin D. Within-field sil and crp variability A. Banding f fertilizer applicatins and manure spreading are knwn t increase spatial variability within a field. Nt every inch f surface area receives the same amunt f fertilizer and/r manure and the mre variability in the field, the mre sub-samples shuld be taken. If the lcatin f the bands is knwn, avid sampling directly in the band. B. Tillage can impact distributin f nutrients ver a field and ver depth (deep tillage, zne till, etc.). The mre tillage there is the less variable the nutrient distributin will be and minimum recmmended sub-sampling guidelines can be fllwed. C. In n-till systems, nutrient stratificatin is usually greater than fr cnventinally tilled fields. Cnsistent sampling t the recmmended depth is critical in n-till systems. Fr sil ph in n-till 8

9 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 systems, tw sil samples will be needed, ne representing -1 inch (fr seeding) and anther fr 1-6 inches. If the surface sample (-1 ) ph is belw 6 a limestne applicatin shuld be made even if the deeper sample des nt call fr liming. D. Fr the best sampling prtcl, take 2-3 subsamples per acre and cmpsite. One cmpsite sample shuld nt represent mre than 1 acres (unless past sampling shws minimal differences). Als the area t be sampled shuld be relatively unifrm, ie. similar sil prperties and past management. If there are knwn significant differences within the area t be sampled eg. ld fence rws, manure r lime stckpile areas, wet spts, etc, a mdified sampling strategy shuld be fllwed. If the areas are t small t manage separately, avid taking any subsamples frm these areas. If they are large enugh fr the farmer t practically manage them separately, take a separate sample frm these areas. Remember: yur sil testing results and the fertility recmmendatin yu make based n the sil test can never be mre accurate that the sil sample yu take. 17. Indicate hw the fllwing may cause variability in sil test results: A. Time f sampling E. Type f extractin methd B. Depth f sampling used (Mrgan, Mehlich-3, C. Number f samples taken Bray, Olsn) D. Sample handling T btain a sil sample: Nutrient cntent f the sil slutin and sil matrix vary depending n the time f year. T minimize variability and build the strngest histric recrds take samples in the same time f the year. Take samples ver a cnstant depth t minimize additinal variability and build the strngest histric recrds. Depth f sil samples depends n tillage used n the field. Samples are nrmally taken frm the surface t the tillage depth (usually 6-8 inches deep). This depth is imprtant because lime and fertilizer are mixed within the tilled layer. Fr lime recmmendatins fr n-till r minimum-till crps, take a sample frm the -1 inch depth and ne frm -6 inches. The tw samples shuld be placed in separate plastic bags labeled clearly with - 1 inch and -6 inch. Fr the best sampling prtcl, ne sample shuld nt represent mre than 1 acres. One sample shuld represent ne management unit (cnsider sil type and past management). Test at least nce in 3 years r twice in a rtatin. Use the right sampling tl: Prbe r auger and a clean plastic bucket. Take 2-3 subsamples per acre acrss a unifrm field. Mix subsamples and take a 1 cup subsample. Label the sample and keep a recrd f the sample and its lcatin. Avid sampling when the sil is very wet. Scrape away surface litter. Take equal amunts fr each subsample. Take cres t plw depth (n-till: r 8 ). Sample between rws, avid fence rws. Remve stnes, wd, trash. Have the analyses dne by the same labratry (same extractin methd). Cnversin equatins between different extractin methds and labratries are nt 1% crrelated and errrs are intrduced when cnversin equatins are used. Furthermre results frm ne lab cannt be cmbined with anther t create a histrical recrd. Remember: yur sil testing results and the fertility recmmendatin yu make based n the sil test can never be mre accurate that the sil sample yu take. 9

10 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/ Cmpare and cntrast the fllwing appraches fr making fertilizer recmmendatins: A. Sufficiency level C. Catin saturatin ratis B. Sil buildup and maintenance A. Sufficiency level: Methd used by mst land grant universities. In this apprach, the fertilizer rate is based n expected crp respnse (increased yield) based n the limiting factr cncept. The agrnmic sil test is an index that can be used, based n a large amunt f lcal field studies, t determine (1) if a respnse t extra fertilizer is t be expected and if s, (2) hw much f that fertilizer needs t be added. Field calibratins are needed t develp a recmmendatin system. B. The Sil buildup and maintenance apprach is based n building the sil test level int the ptimum range if it is belw ptimum and then maintaining it in the ptimum range. The buildup part f the recmmendatin is determined by the expected crp respnse t the added nutrients similar t the sufficiency level apprach. The maintenance part f the recmmendatin is based n replacing the amunt f nutrient expected t be remved by the crp. This shuld keep the sil test level frm becming belw ptimum between sil testing. When the sil test reaches a level where crp remval will nt reduce the sil test t belw ptimum, n additinal nutrients are recmmended. The crp is allwed t draw the nutrient levels dwn int the ptimum range. C. The catin saturatin rati apprach assumes an ideal rati f Ca, Mg, and K n the CEC. Ca ++ Mg ++ Sil slutin H + K + NH 4 + Ca ++ Mg ++ K + NH 4 + Fe ++ Al +++ Fe ++ Mn ++ H + Mn ++ The mst cmmnly applied rati is: 65% Ca, 1% Mg, 5% K, 2% misc. Hwever, studies by e.g. Liebhart (1981), McLean (1977) and McLean and Carbnell (1972) suggest n relatinship between %K and Mg saturatin and yield. Especially fr calcareus sils, adjustments t particular ratis can be very expensive and saturatin estimates based n summatin f catins can be inaccurate. Generally, if the sil ph and the sil test K and Mg levels are ptimum, the balance f catins n the CEC will be 1

11 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 acceptable fr ptimum crp prductin and further adjustments in catin saturatins n the CEC are nt necessary. Liebhardt, W.C Sil Science Sciety f America Jurnal 45: McLean, E.O ASA Special Publicatin n. 9. McLean, E.O., and M.D. Carbnell SSSA Prceedings 36: Recgnize hw the fllwing affect sil test interpretatin: A. Prbability f crp respnse t added D. Within-field variability nutrients E. Labratry chice B. Estimate f nutrient sufficiency level F. Envirnmental risk C. Results reprted as ppm r lbs/acre G. Extractin methd It is imprtant t recgnize that an agrnmic sil test = INDEX f nutrient availability. Lcal field research is needed t calibrate an agrnmic sil test fr its ability t (1) identify likeliness f a respnse t additinal nutrients, and (2) accurately predict the amunt f nutrient needed t reach sufficiency levels. This research needs t be cnducted under lcal cnditins t be applicable s fertility recmmendatins are state-specific and smetimes even regin specific. The agrnmic critical sil test level is defined as the sil test level beynd which a respnse t additinal fertilizer is highly unlikely. Keep in mind, sil testing fr fertility management requires lcally applicable crp respnse studies that link sil test levels t prbability f a crp respnse and actual nutrient needs. Risk f envirnmental lss increases with sil test increase beynd the critical sil test and applicatins beynd the ptimum ecnmic applicatin rate will result in lw nutrient use efficiency and envirnmental lss. Within-field variability needs t be taken int accunt in sil sampling prtcls (see #2). As a first requirement, a gd sil testing labratry needs t have a gd quality cntrl system in place. Hwever, als high quality labratries can give different results if yu were t split samples and send subsamples t different labratries. This is because sil testing labratries can differ in: 1) Nature f the extract used (e.g. Mrgen, mdified Mrgan, Mehlich-3, Bray-1, ammnium-acetate). 2) Shaking time. 3) Slutin t sil rati. 4) Analytical prcedure/instruments used. 11

12 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 5) Way f reprting results (ppm r lbs/acre, P r P 2 O 5 ): 1 ppm = 2 lbs/acre 1 lb P/acre = 2.3 lbs P 2 O 5 /acre; 1 lb K/acre = 1.2 lbs K 2 O/acre Mst cmmn extractin methds used in the Nrtheast include Mrgan (sdium acetate), mdified Mrgan (ammnium acetate), Mehlich-3, and fr P als Bray-1 and Olsen. These varius methdlgies were develped fr specific purpses (Bray fr lw ph sils, Olsen fr calcareus sils, etc.) and results frm methd can nly be equated t anther if reliable cnversin equatins exist. 2. Describe sil sampling strategies: A. Randm sampling B. Grid-based C. Sil type based sampling Sil type and management impacts sil nutrient levels and crp prductin. Fr mst accurate results, take 2-3 samples per acre in a randm pattern that cvers the field and limit field size t n mre than 1 acres t reduce the risk f sampling multiple sil types within a field. See #16 abve fr mre n sampling methds. Grid sampling will be helpful if there is large within-field variability, if that variability is within the respnsive range fr nutrients and ph, and if the farmer has the ability t manage based n this variability. In grid sampling a field is divided int small (usually 1-4 acres) blcks (grid cells) and a separate sil sample is taken frm each f these grid cells. The sample may be 6-1 subsamples taken frm a small area at the center f the grid cell r it may be 6-1 subsamples taken randmly (see abve) frm thrughut the grid cell. Sample results are cmpiled either directly int a map shwing the different sil test levels and recmmendatins fr each grid cell r the test results may be statistically smthed t create a map. 21. Recgnize factrs that influence the results f the pre-sidedress nitrgen test: A. Rtatin D. Depth f sampling B. Manure type and histry E. Field variability C. Timing f sampling relative t F. Sample prcessing weather patterns The Pre-sidedress Nitrate Test (PSNT) is an in- seasn sil nitrate test that can be used t determine if additinal fertilizer nitrgen (N) is needed fr crn. This test is taken at sidedressing time just befre the perid f majr N demand by crn. It is mst useful fr fields with a histry f manure and/r sd incrpratin. The PSNT is designed t: 1) estimate the sil s nitrate supplying ptential, and 2) decide if that is enugh N t meet crp needs. The PSNT is particularly useful when it is unclear whether 12

13 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 enugh manure was actually applied. Over the curse f a few years, carefully cmpare PSNT results with fertilizer and manure inputs and crp perfrmance. When t use: In crn fields, 2 nd year r mre after a sd and/r where the manure rate is uncertain. If nt enugh manure was applied t meet the expected N needs f the crp. Where nt t use the PSNT: The test is useless fr crn fields that received pre-plant r early pst-plant bradcast fertilizer N applicatins (ther than <4 lbs starter N/acre). Any leftver nitrate frm bradcast fertilizer will be picked up by the PSNT, resulting in an verestimatin f the true rganic N supply. First year crn after a grass and/r alfalfa des nt need additinal N beynd a small starter N applicatin (2-3 lbs N/acre). S, it is a waste f time and mney t sidedress N fr first year crn s it is als nt necessary t take a PSNT. In additin, PSNT results f first year crn fields have shwn t be unreliable as indicatrs f sil N supply. Hw t take samples? Limit sample t areas f 15 acres r less and take a separate sample fr areas with different crn stands (different ppulatin densities, stage f develpment, and/r clr), crp histries, fertility management, significant changes in slpe, etc.). Sample between crn rws t a depth f 12 inches (stay away frm the starter band). Sample when the crn is 6-12 inches tall. D nt sample t clse t a rain event that culd have resulted in nitrate leaching (wait fr 2-3 days after significant rainfall). Samples shuld be dried immediately (spread the sample thinly and dry in the sun r under a fan) t stp N mineralizatin and sent t the labratry. Interpretatins can be state-specific. The PSNT guidelines fr New Yrk are: PSNT ppm Likeliness f an ecnmic respnse t N guideline nitrate-n extra N 25 Lw N additinal N needed Abut 1% If uncertain, cnsider sidedressing 25-5 lbs N/acre <21 High Apply sidedress N accrding t the Crnell N guidelines fr crn* *The N guidelines fr crn as well as the NYS Crn N Calculatr can be dwnladed frm the NMSP website: (nmsp.css.crnell.edu/nutrient_guidelines). Fr fields with <21 ppm: If yu tk a PSNT n a field that yu expected t need sidedress N (fr example a field that received less manure than needed t meet N needs), add the extra N. If yu tk a PSNT n a field that yu expected t nt require sidedress N (fr example where manure applicatins shuld have supplied sufficient N), make sure the field actually received the planned manure applicatin and that the field histry is crrectly recrded. Check N needs with the NYS Crn N Calculatr. If under the lwest manure applicatin estimates, the calculatr still shws that n additinal N is needed, despite the PSNT being <21 ppm, rganic-n mineralizatin rates early in the seasn were likely lwer than average but n additinal N is needed because the field is expected t supply sufficient nitrgen frm rganic surces nce mineralizatin cnditins 13

14 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 imprve (warm and mist sils). If the calculatr shws that additinal N is needed and the PSNT is <21 ppm, cnsider adding the extra N. 22. Describe hw t use plant tissue analysis fr: A. Prblem slving/diagnsis B. Nutrient prgram mnitring C. In-seasn nutrient management Analyzing plant tissue can indicate the success f a sil fertility prgram and uncver ptential prblems. Plant tissue analysis cmplements sil testing by measuring the nutrients actually taken up by the plant. In additin, secndary nutrients and micrnutrients that currently are nt rutinely measured in sils can be measured reliably in plants. It shuld be nted, hwever, that plant nutrient cntent represents the effects f nt nly sil nutrient status but als all the factrs cntrlling plant grwth. Therefre, a single year s infrmatin may nt be useful fr planning a sil fertility management prgram. But as results are accumulated ver a perid f years, the infrmatin will becme mre valuable. Nutrient Mnitring Sample cllectin is very imprtant. The nutrient cncentratin in a plant varies with the plant s age and the part f the plant sampled. If plant analyses are t be meaningful, the apprpriate plant part must be cllected fr the age f the plant, and a number f plants must be included t btain a representative sample. Specific directins n plant sampling generally are available with each sampling kit frm the plant analysis labratry. Diagnsing Nutrient Prblems Plant tissue analyses may be useful in diagnsing crp nutritinal prblems. Take samples frm the prblem area and a nearby nrmal area fr cmparisn. Then, use all available infrmatin t interpret the plant analysis fr diagnsing a nutrient deficiency. Lk carefully at symptms n the plants, nte any patterns in the field, and cnsider the timing f the prblem s appearance. Keep in mind that nt all nutrient deficiencies in plants are the result f nutrient deficiencies in the sil. Sil testing and plant analysis can cnfirm each ther, but they als can indicate when the cause f the prblem is smething ther than a nutrient deficiency in the sil. If the sil test level is adequate but the plants are deficient, sme ther factr is limiting the plant s ability t take up available nutrients. Sme areas t cnsider include: pssible interactins with ther cultural practices such as tillage r pesticide use; pest injury such as rtwrm feeding; differences in varieties r hybrids; r sil physical cnditins such as cmpactin. Leaf symptms are nly guides t the surce f the truble - dn t use leaf symptms alne. Usually under field cnditins mre than ne deficiency symptms is present; therefre, symptms are cmplicated. Diseases may enhance nutrient deficiencies and vice-versa. Stress f any type can prduce r enhance plant symptms, i.e., the purple clring f crn in spring is brught n by cld stress, t deep cultivatin; thus pruning the plant rts can result in K deficiency. Zn deficiency is ften the result f pr rt grwth. 14

15 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/ Recgnize hw the fllwing terms relate t plant nutrient level: A. Critical value D. Luxury cnsumptin B. Sufficiency range E. Txicity level C. Optimum, belw ptimum and abve ptimum sil nutrient levels The critical value (r mre ften range) f a specific nutrient is the sil r tissue cntent belw which, the plant mst likely was deficient in that specific nutrient and prductin culd have been enhanced by additin f the nutrient. Thus, belw the critical value, the nutrient levels are belw ptimum. Luxury cnsumptin ccurs when plants take up mre f a specific nutrient than needed fr ptimum functining and prductin. An example f a nutrient that is ften cnsumed in excess f crp needs is ptassium. Sil test results will be classified as lw r medium if the sil test levels are lwer than the critical agrnmic value, ptimum/high when in the sufficiency range, and excessive r very high when additin f fertilizer r ther nutrient surces is n lnger needed r desirable. Deficiency Sufficiency Txicity 24. Recgnize hw the fllwing affect plant tissue analysis results: A. Crp species D. Crp stress level B. Grwth stage E. Time f day sampled C. Plant part sampled F. Sample handling 15

16 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 Plant tissue nutrient interpretatin depends n (1) species sampled, (2) plant part, and (3) time f sampling. Sampling is nt recmmended when the plant part is sil r dust cvered, mechanically injured, damaged by insects, r diseased, r under misture r temperature stress (early mrning sampling is preferred). Plants under lng perids f stress can develp unusual cncentratins which can be misleading. Samples shuld be cleaned t remve surface cntaminatin. The washing shuld be quick t avid leaching f nutrients like ptassium and calcium. Always lk up specific sampling instructins prir t sampling. Examples are: Tree fruits: Time: between 6 and 7 days after average petal fall day Part: the middle f the current seasn s terminal shts Strawberries: Time: within the first 6 weeks after harvest Part: healthy leaves, well expsed t light Alfalfa: Time: bud t 1% blm Part: leaves frm the tp 1/3 f the plant Cmpetency Area 4: Nutrient Surces, Analyses, Applicatin Methds 25. Describe the rle f the fllwing in prviding plant nutrients: A. Sil rganic matter E. Cmpsts B. Cmmercial fertilizer F. Sludges C. Sil minerals G. Plant residue D. Animal manures Sil rganic matter and rganic amendments such as animal manures, cmpsts and sludges release nutrients ver time thrugh mineralizatin. Sil minerals and rganic matter create negatively charged surfaces that attract nutrient catins (catin exchange capacity). Sils differ in their mineral cmpsitin and rganic matter cntent, resulting in differences in their capabilities f prviding essential minerals t plants. Cmmercial fertilizer is recmmended nly when ther nutrient surces insufficiently supply nutrients t the crps. Plant residues release nutrients back t the sil. Residue cverage f the sil can furthermre result in misture cnservatin and s indirectly influence plant nutrient available. 26. Describe the physical frm and analysis f each f the fllwing nitrgen surces: A. Anhydrus ammnia D. Urea/ammnium nitrate B. Urea slutin (UAN) C. Ammnium nitrate E. Ammnium sulfate See

17 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/ Describe the physical frm and analysis f each f the fllwing phsphrus surces: A. Rck phsphate D. Diammnium phsphate B. Triple superphsphate E. Ammnium plyphsphate C. Mnammnium phsphate See Describe the physical frm and analysis f each f the fllwing ptassium surces: A. Ptassium chlride C. Ptassium nitrate B. Ptassium sulfate D. Ptassium magnesium sulfate Cmmn frms f N, P and K fertilizers (sme have ranges. E.g. UAN is 28-32% N) N: anhydrus ammnia (gas) urea (granular) ammnium nitrate (slid r liquid) urea ammnium nitrate (UAN) slutin ammnium sulfate (slid) NH 3 (NH 2 ) 2 CO NH 4 NO 3 Urea+ NH 4 NO 3 (NH 4 ) 2 SO 4 N P 2 O 5 K 2 O P 2 O 5 : rck phsphate (slid) triple super phsphate (slid) mnammnium P (slid) diammnium P (slid) ammnium plyphsphate (liquid) K 2 O: Ptassium chlride (muriate f ptash) (slid) Ptassium sulfate (slid) Ptassium nitrate (slid) Sulfate f ptash + magnesia (slid) Ca(H 2 PO 4 ) 2 Ca(H 2 PO 4 ) 2 NH 4 H 2 PO 4 (NH 4 ) 2 H 2 PO 4 Ca(NH 4 H 2 PO 4 ) 2 KCl K 2 SO 4 KNO3 K 2 SO 4 MgSO % Mg 29. Describe the physical frm and analysis f each f the fllwing calcium and/r magnesium surces: A. Calcitic lime C. Gypsum B. Dlmitic lime D. Ptassium magnesium sulfate Chemical name Cmmn Name Chemical Frmula Physical frm Calcium carbnate calcitic limestne, CaCO 3 slid Ca,Mg carbnate dlmitic limestne CaMg(CO 3 ) 2 slid Calcium xide lime, burned lime, quick lime CaO slid Calcium hydrxide hydrated lime, slaked lime Ca(OH) 2 slid 17

18 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 3. Define the fllwing cmmercial fertilizer terms: A. Nutrient use efficiency D. Guaranteed analysis B. Ttal availability E. Salt effect C. Water slubility Nutrient use efficiency is the yield utput per unit input (e.g. bushels f crn per lb f applied N). Ttal availability is the ttal amunt f a nutrient that is eventually expected t becme plant available (culd be ver many years). Water slubility reflects the prtin f that disslves in water (mre immediately available). Guaranteed analysis is the minimum amunt f N, P 2 O 5, and K 2 O (etc.) in the fertilizer material. Sluble salts are salts in the sil slutin, in direct cntact with rts. High sluble salt cntent (resulting frm e.g. large applicatins f N (ammnium salts) and K surces) can cause seedling damage (dehydratin). 31. Define the fllwing nutrient terms: A. Ttal Kjeldahl nitrgen (TKN) B. Organic N C. Inrganic N D. Organic P E. Inrganic P F. Disslved P G. Particulate P Ttal Kjeldahl nitrgen (TKN) Ttal N analytical methd that includes rganic fractin fr sils, plants and waters. Sils range frm.5 t.3 % typically, but can be several % fr mucks. Plants are nrmally.2 t 4 % depending n species, age, plant part, etc. Organic N Nt water sluble, rganically bund (prtein), slw t becme available. Inrganic N e.g. ammnium, urea, nitrite, nitrate. Organic P: P bund in rganic frm, nt sluble, mst cmmnly fund as phytate. Largest P fractin in animal manure, availability based n mineralizatin f rganic matter. Inrganic P: P nt assciated with carbn (usually P disslved in slutin as PO 4 3-, HPO 4 2-, H 2 PO 4- ). Disslved P: P in the sil slutin (PO 4 3-, HPO 4 2-, H 2 PO 4- ). Particulate P: P attached t sil particles. 32. Calculate fertilizer applicatin rates frm fertilizer analysis infrmatin. Example 1: Needed: 45 lbs N, 45 lbs P 2 O 5, 45 lbs K 2 O per acre Determine rati: 1:1:1 (N: P 2 O 5 : K 2 O) Apply (example): e.g. 3 lbs/acre f

19 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 Example 2: Needed: 15 lbs N, 3 lbs P 2 O 5, 12 lbs K 2 O per acre fr crn Apply (example): K preplant (bradcast) 15 lbs/acre 61 = 91 Starter 2 lbs/acre = Sidedress UAN* 37 gallns 3 = 12 This gives us: * Fr liquid fertilizers where the rate is given in gallns per acre the density f the fertilizer must be knwn t determine the amunt f nutrients applied per acre. In this example, UAN 3-- weighs 1.85 lb/gal. Therefre, 37 gallns/acre equals 37 x 1.85 = 41 lb f UAN/acre and thus at 3% N, this equals 41 x.3 = 12 lb N/acre. 33. Calculate manure applicatin rates frm manure analysis infrmatin. Althugh cncepts f N availability ver time are accepted in all states in the Nrtheast, actual N credits might differ frm state t state. We refer t Land Grant University guidance fr state specific guidance. The fllwing examples and the figure belw are frm wrk by Stu Klausner and clleagues at Crnell University and represent current New Yrk guidelines fr manure N. Manure cntains varius N pls that can be separated int an ammnium-n fractin and an rganic N fractin (see figure frm Klausner, 1997). Bth N pls behave very differently (with differences in N release fr plant grwth) and a manure analysis shuld therefre include an estimate f bth majr N pls. These tw pls are generally listed as rganic N and inrganic N r ammnium- N n manure test reprts. Ttal Manure Nitrgen Decay series fr stable rganic N in manure by animal type. T determine the amunt f N that will be available t the present crp yu must accunt fr the N frm the applicatin t the present crp plus any residual N that will be available frm manure applicatins in recent past years. The table belw prvides the factrs t estimate the N frm the present applicatin and frm past applicatins. The present year factr wuld be taken times the amunt f rganic N applied in the present year. A last year factr f 12% indicates that an estimated 12% f the rganic N applied in the manure last year is expected t be utilized by the present crp a year after applicatin. Therefre, this factr wuld be taken times the amunt f rganic N applied in the manure last year. Likewise, if manure was applied 2 years ag. Urine Ammnium N (fast N) Mineralized slwly during the year f applicatin Feces Organic N (slw N) Ammnium N Mineralized Available N = frm present + rganic N frm + applicatin present applicatin Residual mineralized very slwly during future years Mineralized rganic N frm past applicatins 19

20 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 Crnell guidance fr manure rganic N release by animal type (Klausner, 1997, derived frm wrk by Klausner et al., 1994). Release rate fr rganic N in manure (%) Surce Dry Matter Cntent (%) Present Year Decay_current Last Year Decay_lastyr Cws < Cws Pultry < Pultry Swine < Swine Hrses < Hrses Sheep < Sheep Tw Years Ag Decay_2yrs Crnell guidance fr estimated ammnia-n lsses as affected by manure applicatin methd (Klausner, 1997, derived frm wrk by Lauer et al., 1976). Manure Applicatin Methd Ammnia-N lss (%) Ammnium N utilized by the Crp (%) Injected during grwing seasn 1 Incrprated within 1 day Incrprated within 2 days Incrprated within 3 days Incrprated within 4 days Incrprated within 5 days N cnservatin/injected in fall Describe advantages and limitatins f the fllwing fertilizer placement methds: A. Injectin F. Fliar applicatin B. Surface bradcast G. Sidedress C. Bradcast incrprated H. Tpdress D. Band applicatin I. Seed placement E. Fertigatin Methd Advantages Limitatins Injectin Reduce lsses Slw, expensive Surface bradcast Fast, ecnmical Higher lsses Bradcast incrpratin Reduce lsses Slw, ersin Band applicatin High nutrient use efficiency Cstly, Slw Fertigatin High nutrient use efficiency Irrigatin equipment needed Fliar Rapid uptake Phytxicity, expensive, limited t small and/r repeated applicatins Sidedress High nutrient use efficiency Timeliness, slw Tpdress High nutrient use efficiency Lsses likely 2

21 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 Methd Advantages Limitatins Seed Placed Lwer equipment csts, starter effect greater than just meeting nutrient requirements 35. Recgnize certifiable rganic nutrient surces. Check with the apprpriate rganic certificatin agency. Phyttxicity Cmpetency Area 5: Sil ph and Liming 36. Define: A. Sil ph B. Buffer ph C. Exchangeable acidity D. Alkalinity Sil ph ph is the negative lg f the H+ in cncentratin ph = -Lg H + = lg 1/H + ph 7. = -lg.1 H + r (H + ) = 1 x 1-7 ph 6. = -lg.1 H + r (H + ) = 1 x 1-6 Prperties f ph: ph 7 is neutral - neither acid r basic (alkaline). ph < 7 is acid and > 7 is basic (alkaline). 1 ph = A 1 fld increase in acidity. ph 5 is 1 times mre acid than 6, 1 times mre acid than 7 Sils range between ph 3.5 and 9. a. Hydrgen and aluminum ins and cmplexes are the tw primary surces f sil acidity. b. ph Nrtheastern mineral sils c. ph Nrtheastern muck sils Exchangeable acidity is a measure f the sil s ability t withstand a change in ph upn lime additin. The higher the exchangeable acidity f a sil, the mre lime is needed fr a particular ph change. Buffer ph is used t estimate a sil s exchangeable acidity; the amunt f change in buffer ph is related t lime needs. Alkalinity is the term used t describe the amunt f base in a sil when the ph is abve Describe the lng-term change in sil ph frm applying N. Nitrificatin r the cnversin f ammnium N t nitrate N prduces acidity: 2 NH O 2 2 NO H + + H 2 O 21

22 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 2 H + are prduced fr every N in the ammnium-n frm (NH 4+ ). This reactin ccurs regardless f the surce r the NH 4+. This acidity is ften the largest single surce f acidity in fertilized agricultural sils. The net amunt f acidity created when N fertilizer is applied depends n ther reactins that ccur with the fertilizer. The acidity created by different fertilizer materials is summarized in the table belw. As an example, if 15 lb N/acre is applied as urea, this will prduce the equivalent f 27 lb f lime requirement (15 x 1.8 = 27). Similarly if 15 lb N/acre is applied as ammnium sulfate, 81 lb f lime requirement (15 x 5.4 = 81) will be created. N Surce Theretical lb CaCO 3 /lb N Official (AOAC) lb CaCO 3 /lb N Anhydrus Ammnia Urea Ammnium Nitrate Ammnium Sulfate Mnammnium Phsphate Diammnium Phsphate The fllwing reactins explain why there are differences in the amunt f acidity per pund f N fr the different N fertilizer materials: Ammnia: NH 3 + H 2 O NH OH - This reactin prduces 1 OH - /N which neutralizes ½ f the acidity prduced by nitrificatin. Urea: NH 2 CONH2 + H 2 O 2NH 3 + 2H 2 O 2NH OH - This reactin prduces 1 OH - /N which neutralizes ½ f the acidity prduced by nitrificatin. Ammnium Nitrate: NH 4 NO 3 nly cntains 1 N as NH 4 + the ther N is already NO 3 - s nly 1 H + is prduced fr each N in ammnium nitrate. There is n OH - prduced when this fertilizer reacts. Ammnium Sulfate: There is n OH - prduced when (NH 4) ) 2 SO 4 fertilizer reacts therefre all f the acidity prduced by nitrificatin is present. Mnammnium Phsphate (MAP): There is n OH - prduced when NH 4) H 2 PO 4 fertilizer reacts therefre all f the acidity prduced by nitrificatin is present. Diammnium Phsphate (DAP): (NH 4) ) 2 H PO 4 + H 2 O 2NH HPO H 2 O H 2 PO OH - This reactin prduces 1 OH - /2N which neutralizes ¼ f the acidity prduced by nitrificatin. 38. Describe hw CEC, sil texture, exchangeable acidity and sil rganic matter affect lime requirements. Lime requirements increase with CEC and a sil s CEC increases with rganic matter cntent and clay cntent. Thus, clay sils with high rganic matter cntent require mre lime fr a similar ph change than sandy sils lw in rganic matter. In ther wrds, high CEC sils tend t be well-buffered, requiring mre lime t change the ph while sandy sils are prly buffered, requiring less lime per unit ph change. Als, because f the greater buffering, the sil ph will decrease slwer n higher CEC sils than in prly buffered sandy sils. 39. Describe hw sil ph affects the availability f each nutrient. Plants usually grw well at ph values abve 5.5. Lwer ph increase slubility f Al, Mn, Fe. a. In excess Al, Mn, Fe are txic t plants. 22

23 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 b. A critical effect is that rt grwth is slwed r stpped by excess sluble Al. Extreme ph values decreases the availability f mst nutrients. The effect f sil ph n nutrient availability is summarized in the figure belw. Lw ph reduces the availability f the macr and secndary nutrients. High ph reduces the availability f mst micrnutrients. Sil ph arund 6.5 is usually cnsidered ptimum fr nutrient Micrbial activity may be reduced r changed. ph versus availability f nutrients Strngly Acid Med. Acid Slightly. Acid Very Slightly Acid Very Slightly Alkaline Nitrgen Slightly Alkaline Med. Alkaline Strngly Alkaline Phsphrus Ptassium Sulfur Calcium Magnesium Irn Manganese Brn Cpper and Zinc Mlybdenum Describe hw liming materials increase sil ph. Limestne is calcium carbnate and magnesium carbnate CaCO 3 and MgCO 3 The limestne disslves in water t frm carbnic acid (H 2 CO 3 ) and Ca(OH) 2 : CaCO 3 + HOH H 2 CO 3 + Ca(OH) 2 H 2 CO 3 is unstable and cnverts t carbn dixide and water - the CO 2 gas escapes H 2 CO 3 CO 2 + HOH The remaining Ca(OH) 2 dissciates int Ca 2+ and OH - The Ca 2+ replaces 2 H + frm the sil; increasing the sil base saturatin The OH anin reacts with the sil acid catin H+ frming water H + + OH - HOH (water) 23

24 NRCCA Sil Fertility & Nutrient Management Study Guide 9/28/28 Aglime Reactins in Sil Acid Sil H + Al 3+ + CaCO 3 (Calcium Carbnate) Exchange Step 1 Neutral Sil + H + + Al 3+ + CO 2-3 Ca 2+ Neutralizatin Step 2 Al(OH) 3 + CO 2 + H 2 O Neutral Cmpunds 41. Describe hw purity, fineness, and Calcium Carbnate Equivalent (CCE) affect the neutralizing ability f liming materials. Calcium Carbnate Equivalent (CCE) - The neutralizing value f a liming material cmpared t pure calcium carbnate. A CCE f 1% wuld indicate the material will neutralize the same amunt f acidity per pund as pure calcium carbnate. Fineness - the finer a limestne is grund, the faster it will react in the sil. Fineness is reprted as a particle size distributin usually as the percentage f the material that will pass a 2, 6, and 1 mesh screens. An example f the size distributin fr a typical gd quality limestne is: 95% passing 2 mesh; 6 % passing 6 mesh; 5% passing 1 mesh. A distributin such as the ne abve is a gd cmprmise between cst and practical agrnmic effectiveness. Material larger than 2 mesh reacts t slw t be f much value as a liming material. All very fine, less than 1 mesh material, will react quickly but it will be much mre expensive and may be difficult t handle. Fineness des nt increase the ttal neutralizing value f a limestne, just hw fast it will react. Effective neutralizing value (ENV) f a limestne is determined by its calcium carbnate equivalent (CCE) multiplied by its particle size distributin expressed as fineness Limestnes react at rates prprtinal t the surface area f the particles The surface area f the particles is related t the size f lime particle 1% f lime that passes 1 mesh screen will react in 1 yr 8% f lime that passes 6 but held n 1 mesh will react in 1 yr 4% f lime that passes 2 but held n 6 mesh will react in 1 yr The Calcium Carbnate Equivalent prtin f the lime will react 24