3.soil fertility management By Allah Dad Khan

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<ol><li> 1. Soil FertilitySoil Fertility Management ByManagement By Allah dad KhanAllah dad Khan </li><li> 2. ObjectivesObjectives Understand objectives of soil fertilityUnderstand objectives of soil fertility managementmanagement Philosophies/techniques of precision farmingPhilosophies/techniques of precision farming Using &amp; obtaining valid soil samplesUsing &amp; obtaining valid soil samples Considerations in making/following fertilizerConsiderations in making/following fertilizer recommendationsrecommendations Knowledge of fertilizer qualityKnowledge of fertilizer quality How to calculate fertilizer blendsHow to calculate fertilizer blends Fertilizer application methodsFertilizer application methods Benefits/limitations of manure useBenefits/limitations of manure use </li><li> 3. IntroductionIntroduction Fertilizer is one management optionFertilizer is one management option used almost universallyused almost universally Must replace soil nutrients lost byMust replace soil nutrients lost by harvestharvest Over-fertilization can result inOver-fertilization can result in dangerous pollutiondangerous pollution Technology has increased fertilizerTechnology has increased fertilizer efficiencyefficiency </li><li> 4. Goals &amp; Concerns inGoals &amp; Concerns in Fertility ManagementFertility Management Goals regarding fertilityGoals regarding fertility Increase yieldIncrease yield Reduce costs/unit productionReduce costs/unit production Improve product qualityImprove product quality Avoid environmental pollutionAvoid environmental pollution Improve environmental health &amp;Improve environmental health &amp; aestheticsaesthetics </li><li> 5. Goals &amp; Concerns inGoals &amp; Concerns in Fertility ManagementFertility Management Efficient land managers: spend 50% increase in yields Fertilizers may not be profitable if:Fertilizers may not be profitable if: Water is the most limiting factorWater is the most limiting factor Other growth hindrances insects,Other growth hindrances insects, diseases, acidity, extreme colddiseases, acidity, extreme cold Increased yield has less market valueIncreased yield has less market value than the cost of buying/app of fertilizerthan the cost of buying/app of fertilizer </li><li> 6. Goals &amp; Concerns inGoals &amp; Concerns in Fertility ManagementFertility Management Fertilizers generally most profitableFertilizers generally most profitable farm inputfarm input Soil fertility problems usually theSoil fertility problems usually the easiest to solveeasiest to solve Soil nutrients typically present in finiteSoil nutrients typically present in finite amounts, dont replenish themselvesamounts, dont replenish themselves Crops typically contain: (in rank ofCrops typically contain: (in rank of amount found in the plant) N, K, Ca, P,amount found in the plant) N, K, Ca, P, Mg, SMg, S </li><li> 7. Goals &amp; Concerns inGoals &amp; Concerns in Fertility ManagementFertility Management Utilizing fertilizers may help cut unitUtilizing fertilizers may help cut unit cost of production by maximizing yieldcost of production by maximizing yield Improved fertility = improved yields,Improved fertility = improved yields, improved aesthetic appealimproved aesthetic appeal Environmental concerns aboundEnvironmental concerns abound Fertilizer laws viewed as lax by someFertilizer laws viewed as lax by some Farmers may be the primary cause ofFarmers may be the primary cause of non-point-source pollutionnon-point-source pollution </li><li> 8. Goals &amp; Concerns inGoals &amp; Concerns in Fertility ManagementFertility Management Three common pollutants:Three common pollutants: NitratesNitrates Percolate through to groundwaterPercolate through to groundwater Not safe to drinkNot safe to drink Cause Blue-baby syndrome inhibitsCause Blue-baby syndrome inhibits oxygenation of bloodoxygenation of blood Becoming common near heavily fertilized fields,Becoming common near heavily fertilized fields, feedlots, dairiesfeedlots, dairies PhosphatesPhosphates Pollute surface waters by runoffPollute surface waters by runoff Promotes algae growth in rivers/pondsPromotes algae growth in rivers/ponds Depletes available oxygen in the water for fishDepletes available oxygen in the water for fish </li><li> 9. Goals &amp; Concerns inGoals &amp; Concerns in Fertility ManagementFertility Management Wise use of fertilizers must beWise use of fertilizers must be encouraged, actually improve theencouraged, actually improve the environmentenvironment Crops, trees, etc. - remove more CO2,Crops, trees, etc. - remove more CO2, decrease sediment, dust, erosiondecrease sediment, dust, erosion Plays important role for future of the planetPlays important role for future of the planet </li><li> 10. Scale of LandScale of Land ManagementManagement Large- &amp; Medium-Scale ManagementLarge- &amp; Medium-Scale Management Large-ScaleLarge-Scale Low levels of operational precision, littleLow levels of operational precision, little reliance on sophisticated technologyreliance on sophisticated technology May be most feasible/profitable for someMay be most feasible/profitable for some Simple &amp; low-techSimple &amp; low-tech Some shy away from high tech for otherSome shy away from high tech for other reasonsreasons </li><li> 11. Scale of LandScale of Land ManagementManagement DisadvantagesDisadvantages Some parts of field may receive too much/littleSome parts of field may receive too much/little fertilizer or pesticidefertilizer or pesticide Less than optimal yieldsLess than optimal yields Inefficient use of fertilizers &amp; pesticidesInefficient use of fertilizers &amp; pesticides Higher cost of production/unitHigher cost of production/unit Environmental pollution due to over applicationEnvironmental pollution due to over application AdvantagesAdvantages Minimal technological training &amp; instrumentationMinimal technological training &amp; instrumentation neededneeded Field operations can be performed w/ standard,Field operations can be performed w/ standard, readily available, cheaper equipmentreadily available, cheaper equipment </li><li> 12. Scale of LandScale of Land ManagementManagement Medium-ScaleMedium-Scale Subdivide field into two+ management unitsSubdivide field into two+ management units Delineation may be based on:Delineation may be based on: Soil typesSoil types Past management differencesPast management differences Farmers observationsFarmers observations Ex. High, medium, low N application areas inEx. High, medium, low N application areas in the fieldthe field Same equipment/technology needs as forSame equipment/technology needs as for large-scale management farmerslarge-scale management farmers </li><li> 13. Scale of LandScale of Land ManagementManagement Does improve efficiency of farm inputsDoes improve efficiency of farm inputs Can reduce excessive applications ofCan reduce excessive applications of chemicals/fertilizerschemicals/fertilizers May do spot treatments/applications w/in a fieldMay do spot treatments/applications w/in a field due to field observationsdue to field observations Small-Scale Management (PrecisionSmall-Scale Management (Precision Farming)Farming) Global Positioning System (GPS)Global Positioning System (GPS) network of U.S. satellites w/ a signalnetwork of U.S. satellites w/ a signal detection system used to locate positionsdetection system used to locate positions on the groundon the ground </li><li> 14. Scale of LandScale of Land ManagementManagement Soil sample fields on a gridSoil sample fields on a grid Data collection points no more than a fewData collection points no more than a few feet apartfeet apart Each sample site mapped using GPSEach sample site mapped using GPS Custom applicators can custom applyCustom applicators can custom apply fertilizers at variable rates that changefertilizers at variable rates that change constantly as the applicator travels theconstantly as the applicator travels the field field variable rate application, site-variable rate application, site- specific management, precision farmingspecific management, precision farming </li><li> 15. Scale of LandScale of Land ManagementManagement Potential to substantially decreasePotential to substantially decrease fertilizer/chemical application ratesfertilizer/chemical application rates Potential to substantially decrease inputPotential to substantially decrease input costscosts Does require expensive technology,Does require expensive technology, equipment &amp; extensive technicalequipment &amp; extensive technical knowledgeknowledge </li><li> 16. Soil TestsSoil Tests Law of the Minimum:Law of the Minimum: growth of the plantgrowth of the plant is limited most by the essential plantis limited most by the essential plant nutrient present in the least relativenutrient present in the least relative amount (first-limiting)amount (first-limiting) Soil Acidity EvaluationSoil Acidity Evaluation pH measured w/ electrode &amp; solutionpH measured w/ electrode &amp; solution Lime requirementLime requirement amount of lime amount of lime required to achieve desired pHrequired to achieve desired pH Reported asReported as buffer pHbuffer pH </li><li> 17. Soil TestsSoil Tests Soil Test for NSoil Test for N No good tests for soil available NNo good tests for soil available N Most states provide N recommendations basedMost states provide N recommendations based on yrs of field plots trials on various crops, soils,on yrs of field plots trials on various crops, soils, management, fertilizersmanagement, fertilizers N recommendations consider:N recommendations consider: Previous cropsPrevious crops Estimates N carryoverEstimates N carryover N needed to decompose residuesN needed to decompose residues Projected yieldsProjected yields ClimateClimate </li><li> 18. Soil TestsSoil Tests Lab N tests accurate, but nearlyLab N tests accurate, but nearly impossible to interpretimpossible to interpret Some will discourage N testingSome will discourage N testing Behavior of carryover N unpredictable Behavior of carryover N unpredictable can make analyses invalidcan make analyses invalid LeachingLeaching DenitrificationDenitrification MineralizationMineralization ClimateClimate </li><li> 19. Soil TestsSoil Tests N recommendations based on yield goalsN recommendations based on yield goals rather than soil reservesrather than soil reserves Corn RuleCorn Rule 1.2-1.4#N/bu of yield goal 1.2-1.4#N/bu of yield goal How much N should be recommended forHow much N should be recommended for corn following corn, expected yield 120corn following corn, expected yield 120 bu/ac?bu/ac? How much N should be recommended forHow much N should be recommended for corn following soybeans, expected yield 195corn following soybeans, expected yield 195 bu/ac?bu/ac? </li><li> 20. Soil TestsSoil Tests Soil Tests for P &amp; KSoil Tests for P &amp; K Widely used to predict probability of cropWidely used to predict probability of crop response to fertilizationresponse to fertilization Survey:Survey: 47% soil tested medium to low for P47% soil tested medium to low for P 43% soil tested medium to low for K43% soil tested medium to low for K P &amp; K soil levels declining in many statesP &amp; K soil levels declining in many states P testingP testing Quite reliable soil P is very stable from yr toQuite reliable soil P is very stable from yr to yryr </li><li> 21. Soil TestsSoil Tests Most soil P unavailable to cropsMost soil P unavailable to crops Soil test extracts &amp; measures what maySoil test extracts &amp; measures what may actually be availableactually be available K testingK testing Tests both exchangeable &amp; soluble reservesTests both exchangeable &amp; soluble reserves Conflicting testing procedures over which isConflicting testing procedures over which is most accuratemost accurate Some estimate upper threshold needs ~159-Some estimate upper threshold needs ~159- 246#/ac (above which no response to K fertilizer)246#/ac (above which no response to K fertilizer) Others - 335#/ac on clay soils (calculated basedOthers - 335#/ac on clay soils (calculated based on soil CEC higher CEC = decreased availableon soil CEC higher CEC = decreased available K)K) Some experimentation w/ soil probesSome experimentation w/ soil probes </li><li> 22. Soil TestsSoil Tests Soil Test for Ca &amp; MgSoil Test for Ca &amp; Mg Related to need for limeRelated to need for lime Well-limed soils rarely Ca &amp; Mg deficientWell-limed soils rarely Ca &amp; Mg deficient Mg deficiency more common than CaMg deficiency more common than Ca Coarse-textured or acidic soilsCoarse-textured or acidic soils Many yrs using non-Mg containing limeMany yrs using non-Mg containing lime Mg testing for:Mg testing for: Exchangeable soil MgExchangeable soil Mg % Mg saturation of soil colloids% Mg saturation of soil colloids Ratio of K:MgRatio of K:Mg </li><li> 23. Soil TestsSoil Tests Soil Test for S &amp; BSoil Test for S &amp; B S testing inaccurate acts much like NS testing inaccurate acts much like N Can test but must take variability intoCan test but must take variability into accountaccount Boron level recommendationsBoron level recommendations 5.0 ppm excess/toxicity risks </li><li> 24. Soil TestsSoil Tests Soil Test for Micronutrient NeedsSoil Test for Micronutrient Needs Difficult to develop accurate tests due toDifficult to develop accurate tests due to relatively infrequent need for fieldrelatively infrequent need for field supplementationsupplementation Can be done, if requested for a specificCan be done, if requested for a specific needneed Adds expense to soil analysisAdds expense to soil analysis </li><li> 25. Soil TestsSoil Tests How Good Is Soil Testing?How Good Is Soil Testing? Analyses recalibrated regularly based onAnalyses recalibrated regularly based on field trial studiesfield trial studies Validity of analysis related directly toValidity of analysis related directly to accuracy of sample, information providedaccuracy of sample, information provided to the labto the lab Soil analyses generally very valid for: P,Soil analyses generally very valid for: P, K, soluble salts, pH, limeK, soluble salts, pH, lime Other tests should only be used on as-Other tests should only be used on as- needed basisneeded basis Extra costExtra cost Less accurateLess accurate </li><li> 26. Analysis of PlantsAnalysis of Plants Only way to be sure of soil nutrientOnly way to be sure of soil nutrient availabilityavailability Plant Analysis vs. Soil TestingPlant Analysis vs. Soil Testing Plant most accurate report on whatPlant most accurate report on what nutrients arenutrients are actuallyactually availableavailable Plant analysis leaves little to no room forPlant analysis leaves little to no room for amendments to the soilamendments to the soil When deficiencies are acknowledged,When deficiencies are acknowledged, yield usually already affectedyield usually already affected </li><li> 27. Analysis of PlantsAnalysis of Plants When is plant analysis most helpful?When is plant analysis most helpful? Treatment of an easily-corrected deficiencyTreatment of an easil...</li></ol>