Soil Fertility Management By Allah dad Khan Objectives Understand objectives of soil fertility management Understand objectives of soil fertility management.

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<ul><li> Slide 1 </li> <li> Slide 2 </li> <li> Soil Fertility Management By Allah dad Khan </li> <li> Slide 3 </li> <li> Objectives Understand objectives of soil fertility management Understand objectives of soil fertility management Philosophies/techniques of precision farming Philosophies/techniques of precision farming Using &amp; obtaining valid soil samples Using &amp; obtaining valid soil samples Considerations in making/following fertilizer recommendations Considerations in making/following fertilizer recommendations Knowledge of fertilizer quality Knowledge of fertilizer quality How to calculate fertilizer blends How to calculate fertilizer blends Fertilizer application methods Fertilizer application methods Benefits/limitations of manure use Benefits/limitations of manure use </li> <li> Slide 4 </li> <li> Introduction Fertilizer is one management option used almost universally Fertilizer is one management option used almost universally Must replace soil nutrients lost by harvest Must replace soil nutrients lost by harvest Over-fertilization can result in dangerous pollution Over-fertilization can result in dangerous pollution Technology has increased fertilizer efficiency Technology has increased fertilizer efficiency </li> <li> Slide 5 </li> <li> Goals &amp; Concerns in Fertility Management Goals regarding fertility Goals regarding fertility Increase yield Reduce costs/unit production Improve product quality Avoid environmental pollution Improve environmental health &amp; aesthetics </li> <li> Slide 6 </li> <li> Goals &amp; Concerns in Fertility Management Efficient land managers: spend 50% increase in yields 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 factor Other growth hindrances insects, diseases, acidity, extreme cold Increased yield has less market value than the cost of buying/app of fertilizer </li> <li> Slide 7 </li> <li> Goals &amp; Concerns in Fertility Management Fertilizers generally most profitable farm input Fertilizers generally most profitable farm input Soil fertility problems usually the easiest to solve Soil fertility problems usually the easiest to solve Soil nutrients typically present in finite amounts, dont replenish themselves Soil nutrients typically present in finite amounts, dont replenish themselves Crops typically contain: (in rank of amount found in the plant) N, K, Ca, P, Mg, S Crops typically contain: (in rank of amount found in the plant) N, K, Ca, P, Mg, S </li> <li> Slide 8 </li> <li> Goals &amp; Concerns in Fertility Management Utilizing fertilizers may help cut unit cost of production by maximizing yield Utilizing fertilizers may help cut unit cost of production by maximizing yield Improved fertility = improved yields, improved aesthetic appeal Environmental concerns abound Environmental concerns abound Fertilizer laws viewed as lax by some Farmers may be the primary cause of non-point-source pollution </li> <li> Slide 9 </li> <li> Goals &amp; Concerns in Fertility Management Three common pollutants: Nitrates Nitrates Percolate through to groundwater Not safe to drink Cause Blue-baby syndrome inhibits oxygenation of blood Becoming common near heavily fertilized fields, feedlots, dairies Phosphates Phosphates Pollute surface waters by runoff Promotes algae growth in rivers/ponds Depletes available oxygen in the water for fish </li> <li> Slide 10 </li> <li> Goals &amp; Concerns in Fertility Management Wise use of fertilizers must be encouraged, actually improve the environment Crops, trees, etc. - remove more CO2, decrease sediment, dust, erosion Crops, trees, etc. - remove more CO2, decrease sediment, dust, erosion Plays important role for future of the planet Plays important role for future of the planet </li> <li> Slide 11 </li> <li> Scale of Land Management Large- &amp; Medium-Scale Management Large- &amp; Medium-Scale Management Large-Scale Low levels of operational precision, little reliance on sophisticated technology Low levels of operational precision, little reliance on sophisticated technology May be most feasible/profitable for some May be most feasible/profitable for some Simple &amp; low-tech Simple &amp; low-tech Some shy away from high tech for other reasons Some shy away from high tech for other reasons </li> <li> Slide 12 </li> <li> Scale of Land Management Disadvantages Disadvantages Some parts of field may receive too much/little fertilizer or pesticide Less than optimal yields Inefficient use of fertilizers &amp; pesticides Higher cost of production/unit Environmental pollution due to over application Advantages Advantages Minimal technological training &amp; instrumentation needed Field operations can be performed w/ standard, readily available, cheaper equipment </li> <li> Slide 13 </li> <li> Scale of Land Management Medium-Scale Subdivide field into two+ management units Subdivide field into two+ management units Delineation may be based on: Soil types Soil types Past management differences Past management differences Farmers observations Farmers observations Ex. High, medium, low N application areas in the field Ex. High, medium, low N application areas in the field Same equipment/technology needs as for large-scale management farmers Same equipment/technology needs as for large-scale management farmers </li> <li> Slide 14 </li> <li> Scale of Land Management Does improve efficiency of farm inputs Does improve efficiency of farm inputs Can reduce excessive applications of chemicals/fertilizers Can reduce excessive applications of chemicals/fertilizers May do spot treatments/applications w/in a field due to field observations Small-Scale Management (Precision Farming) Small-Scale Management (Precision Farming) Global Positioning System (GPS) network of U.S. satellites w/ a signal detection system used to locate positions on the ground </li> <li> Slide 15 </li> <li> Scale of Land Management Soil sample fields on a grid Data collection points no more than a few feet apart Each sample site mapped using GPS Custom applicators can custom apply fertilizers at variable rates that change constantly as the applicator travels the field variable rate application, site- specific management, precision farming </li> <li> Slide 16 </li> <li> Scale of Land Management Potential to substantially decrease fertilizer/chemical application rates Potential to substantially decrease input costs Does require expensive technology, equipment &amp; extensive technical knowledge </li> <li> Slide 17 </li> <li> Soil Tests Law of the Minimum: growth of the plant is limited most by the essential plant nutrient present in the least relative amount (first-limiting) Soil Acidity Evaluation Soil Acidity Evaluation pH measured w/ electrode &amp; solution Lime requirement amount of lime required to achieve desired pH Reported as buffer pH Reported as buffer pH </li> <li> Slide 18 </li> <li> Soil Tests Soil Test for N Soil Test for N No good tests for soil available N Most states provide N recommendations based on yrs of field plots trials on various crops, soils, management, fertilizers N recommendations consider: Previous crops Previous crops Estimates N carryover Estimates N carryover N needed to decompose residues N needed to decompose residues Projected yields Projected yields Climate Climate </li> <li> Slide 19 </li> <li> Soil Tests Lab N tests accurate, but nearly impossible to interpret Some will discourage N testing Some will discourage N testing Behavior of carryover N unpredictable can make analyses invalid Leaching Leaching Denitrification Denitrification Mineralization Mineralization Climate Climate </li> <li> Slide 20 </li> <li> Soil Tests N recommendations based on yield goals rather than soil reserves Corn Rule 1.2-1.4#N/bu of yield goal How much N should be recommended for corn following corn, expected yield 120 bu/ac? How much N should be recommended for corn following corn, expected yield 120 bu/ac? How much N should be recommended for corn following soybeans, expected yield 195 bu/ac? How much N should be recommended for corn following soybeans, expected yield 195 bu/ac? </li> <li> Slide 21 </li> <li> Soil Tests Soil Tests for P &amp; K Soil Tests for P &amp; K Widely used to predict probability of crop response to fertilization Survey: 47% soil tested medium to low for P 47% soil tested medium to low for P 43% soil tested medium to low for K 43% soil tested medium to low for K P &amp; K soil levels declining in many states P &amp; K soil levels declining in many states P testing Quite reliable soil P is very stable from yr to yr Quite reliable soil P is very stable from yr to yr </li> <li> Slide 22 </li> <li> Soil Tests Most soil P unavailable to crops Most soil P unavailable to crops Soil test extracts &amp; measures what may actually be available Soil test extracts &amp; measures what may actually be available K testing Tests both exchangeable &amp; soluble reserves Tests both exchangeable &amp; soluble reserves Conflicting testing procedures over which is most accurate Conflicting testing procedures over which is most accurate Some estimate upper threshold needs ~159- 246#/ac (above which no response to K fertilizer) Others - 335#/ac on clay soils (calculated based on soil CEC higher CEC = decreased available K) Some experimentation w/ soil probes checking K, NO 3, PO 4, SO 4 </li> <li> Slide 23 </li> <li> Soil Tests Soil Test for Ca &amp; Mg Soil Test for Ca &amp; Mg Related to need for lime Well-limed soils rarely Ca &amp; Mg deficient Mg deficiency more common than Ca Coarse-textured or acidic soils Coarse-textured or acidic soils Many yrs using non-Mg containing lime Many yrs using non-Mg containing lime Mg testing for: Exchangeable soil Mg Exchangeable soil Mg % Mg saturation of soil colloids % Mg saturation of soil colloids Ratio of K:Mg Ratio of K:Mg </li> <li> Slide 24 </li> <li> Soil Tests Soil Test for S &amp; B Soil Test for S &amp; B S testing inaccurate acts much like N Can test but must take variability into account Can test but must take variability into account Boron level recommendations 5.0 ppm excess/toxicity risks </li> <li> Slide 25 </li> <li> Soil Tests Soil Test for Micronutrient Needs Soil Test for Micronutrient Needs Difficult to develop accurate tests due to relatively infrequent need for field supplementation Can be done, if requested for a specific need Adds expense to soil analysis </li> <li> Slide 26 </li> <li> Soil Tests How Good Is Soil Testing? How Good Is Soil Testing? Analyses recalibrated regularly based on field trial studies Validity of analysis related directly to accuracy of sample, information provided to the lab Soil analyses generally very valid for: P, K, soluble salts, pH, lime Other tests should only be used on as-needed basis Other tests should only be used on as-needed basis Extra cost Less accurate </li> <li> Slide 27 </li> <li> Analysis of Plants Only way to be sure of soil nutrient availability Plant Analysis vs. Soil Testing Plant Analysis vs. Soil Testing Plant most accurate report on what nutrients are actually available Plant analysis leaves little to no room for amendments to the soil When deficiencies are acknowledged, yield usually already affected </li> <li> Slide 28 </li> <li> Analysis of Plants When is plant analysis most helpful? Treatment of an easily-corrected deficiency Treatment of an easily-corrected deficiency Long-growing crops: turf, tree fruits, forests, sugar cane Long-growing crops: turf, tree fruits, forests, sugar cane Quick Tests in the Field Quick Tests in the Field Can test for N, K status in plants Collect ~20 leaves for sample Collect ~20 leaves for sample Must be random from different locations Dont select only affected-looking leaves </li> <li> Slide 29 </li> <li> Analysis of Plants Chop/mix, squeeze sap &amp; test Chop/mix, squeeze sap &amp; test Most effective for greenhouse/nursery growers Most effective for greenhouse/nursery growers Amendments can easily be made High possible economic losses Total Plant Analysis Total Plant Analysis Done in a lab Should be tested by stage of development Random sampling key </li> <li> Slide 30 </li> <li> Analysis of Plants Indicate part of plant sampled &amp; be consistent Dry to prevent spoilage (confounds results) Wrap in paper and mail w/ complete report complete history, information critical </li> <li> Slide 31 </li> <li> Analysis of Plants Interpreting Plant Analyses Interpreting Plant Analyses Accurate interpretation difficult if not all critical information provided Element classified as deficient if below threshold nutrient levels Levels change through season, stage of development, etc. Levels change through season, stage of development, etc. Some general disagreement from scientists on what threshold levels are </li> <li> Slide 32 </li> <li> Analysis of Plants Critical Nutrient Range Critical Nutrient Range CNR ranges at which nutrients are: Visually deficient Visually deficient Hidden deficient Hidden deficient Slightly deficient Slightly deficient Sufficient supply Sufficient supply Toxic Toxic </li> <li> Slide 33 </li> <li> Analysis of Plants Visual Nutrient Deficiency Symptoms Visual Nutrient Deficiency Symptoms Chlorosis yellowish to whitish appearance to foliage, stem Necrosis dead tissue Causes: disease, insect damage, salt accumulation, stress, nutrient deficiencies Some visual symptoms same for many diseases/deficiencies </li> <li> Slide 34 </li> <li> Analysis of Plants Nutrients are relocated in the plant by two pathways Xylem water-carrying vessels Xylem water-carrying vessels All nutrients can pass through Phloem sugar-carrying vessels Phloem sugar-carrying vessels Not all nutrients can relocate Mobile nutrients travel freely Immobile nutrients cant be moved from their location in the plant Mobile nutrient deficiencies tend to occur on older leaves plant sacrifices old for new tissue </li> <li> Slide 35 </li> <li> Analysis of Plants Immobile nutrient deficiencies symptoms on shoot/root tips, fruits Cant be treated from the soil w/ fertilizer plant cant send Ca (ex) to the ripening fruit Cant be treated from the soil w/ fertilizer plant cant send Ca (ex) to the ripening fruit Mobile nutrients: N, P, K, Cl, Mg, S N, P, K, Cl, Mg, S Immobile nutrients: Cu, Mn, Zn, Fe, Mo, S Cu, Mn, Zn, Fe, Mo, S Very immobile nutrients: B, Ca B, Ca </li> <li> Slide 36 </li> <li> Fertilizer Recommendations Different labs make different recommendations Traditional philosophies being challenged P application rates P application rates Yield-based N recommendations Yield-based N recommendations </li> <li> Slide 37 </li> <li> Fertilizer Recommendations Developing a Fertilizer Recommendation Developing a Fertilizer Recommendation Must have sufficient plot data to correlate yields &amp; nutrient needs Once a general amount of fertilizer is known: Subtract for manure application Subtract for manure application Subtract for residual P or N Subtract for residual P or N Add/subtract for N, P, S because of soil organic matter levels can count on them supplying some Add/subtrac...</li></ul>

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