How Does Canola Get Its Nutrients? C.A Grant Agriculture and Agri-Food Canada Brandon Research Centre

Transcription

1 How Does Canola Get Its Nutrients? C.A Grant Agriculture and Agri-Food Canada Brandon Research Centre

2 Canola Needs a Total of 17 Elements C H O K N P 17 Essential Elements Ca S Mg B Cl Cu Fe Mn Mo Zn Ni

3 Some come from the air or water C H O K N P 17 Essential Elements Ca S Mg B Cl Cu Fe Mn Mo Zn Ni

4 Others are usually present in adequate amounts in prairie soils C H O K N P 17 Essential Elements Ca S Mg B Cl Cu Fe Mn Mo Zn Ni

5 N, P and S are most often limiting for canola production C H O K N P 17 Essential Elements Ca S Mg B Cl Cu Fe Mn Mo Zn Ni

6 Nitrogen is Critical for Crop Growth Usually most limiting nutrient Largest fertilizer input Required for optimum yield and protein

7 How Much Nitrogen is Removed by a Canola Crop? A 40 bu/acre canola removes about 85 lb N per acre About 40 lb more taken up but recycled in residue About 125+ needed for growth

8 Daily Uptake of N By Canola Reaches 6 to 8 lb per acre per day About 6-8 Weeks after Seeding (6 leaf stage) Carstairs Biomass accumulation rate, lb/acre/day Rosser 6 leaf stage 7 Biomass accumulation rate, lb/acre/day leaf stage Nitrogen uptake rate, lb/acre/day 40 N uptake rate, lb N/acre/day Weeks after Seeding Weeks after Seeding Biomass accumulation rate, lb/acre/day 250 Olds Budding stage 6 leaf stage Biomass accumulation, lb/acre/day Petersfield 6 leaf stage Nitrogen uptake rate, lb N/acre/day 3 N uptake rate, lb N/acre/day Weeks after Seeding Weeks after Seeding (Courtesy Rigas Karamanos)

9 Plants Access N from Soil Fertilizer additions make up the difference between crop demand and soil supply Mineralization Nitrate and ammonium in solution and on exchange Immobilization

10 Nitrogen Reactions Influence Availability from Soil and Fertilizer Manure & Crop Residues (75%) NH 3 Volat n Crop Removal N 2, N 2 O Denit n NO Soil Organic N Mineralization Immobilization Ammonium NH + 4 Nitrate NO - 3 Leaching & runoff

11 Reactions and Losses Depend on Environment and Management Nitrogen losses can be high, with poor management or under bad conditions Management practices can be used to minimize losses

12 Volatilization can be high with broadcast urea if not incorporated Fertilizer N NH 3 volatilization 40-90% of urea-n under hot, dry conditions NO N 2 N 2 O Ammonium NH 4 + Nitrification Nitrate NO 3 - Denitrification Leaching, runoff

13 Banding Reduces Ammonia Losses to Extremely Low Levels -1 ) Ammonia (g N ha Fall Brandon ZTF CT-Control CT-Uncoated RT-Control RT-Uncoated Spring preseeding After Seeding If urea bands were sealed, losses were no higher than from the control grams per hectare Some losses occurred under RT when band did not seal

14 Denitrification can be high on warm, saturated soils Fertilizer N 2-4 lb N/ac/day under saturated soil conditions NO N 2 N 2 O Ammonium NH 4 + Nitrification Nitrate NO 3 - Denitrification Leaching can be high on sandy soils with excess rain or irrigation Leaching, runoff

15 Banding an Ammonium-Producing Source Reduces Leaching and Denitrification Losses Ammonium must convert to nitrate before it is susceptible to loss Slows conversion of ammonium to nitrate Lowers nitrate concentration in the solution Reduces the risk of loss

16 Supported by data from U. of Manitoba that showed losses from fall-banded N fertilizer were minor on welldrained soils 120 Grain yield (% of spring) r = 0.11 ns r = 0.66* Crop harvest Upper slope Lower slope Soil freezes Sep 20-Sep 30-Sep 10-Oct 20-Oct 30-Oct Date of application Highs Lows Linear (Lows) Linear (Highs) Thiessen et al. U. of Manitoba

17 Much of our N Loss may be Cycling via Immobilization-Mineralization immobilization - tie up of N mineralization - release of N N mineralized (k g /ha) May 13 June 8 June 30 July 21 Aug 10 Sept 8 N tie-up N release Sampling date Selles Durum Stubble Pea Stubble

18 In-Soil Banding Reduces Immobilization Recovery of fertilizer N % straw incorp N bcst Fall recovery of fertilizer N in crop and soil straw on surface N bcst straw removed N bcst straw incorp N band straw on surface N band Tomar and Soper, 1981 Immobilized N Plant N straw removed N band

19 Immobilized Nitrogen is not a Loss Builds soil organic matter Improve soil quality Cycles back to following crops Improves soil s ability to buffer N supply in years when yield potential is high Need to consider both soil nitrate and mineralization to predict soil N supply Mineral N

20 Soil Testing For Available N Provides indication of residual nutrient in soil Nitrate in the bank Does not necessarily consider mineralization Interest on organic matter

21 Older Systems May Rely More on Stored Soil Nitrate Soil nitrate released and stored over fallow period Mine organic matter to release N Intensive tillage increases mineralization and amount of nitrate in soil at seeding Continuous cropping and reduced tillage reduce the stored nitrate N fertilization and higher yield increase residue return to the soil May increase the importance of N mineralization from SOM and crop residues over the growing season

22 Can We Test for Mineralization? Specific tests predict potential mineralization Mason Jar test Long-term incubation Have not been very useful so far in the prairie environment for routine testing Tests measure release under ideal temperature and moisture Actual mineralization depends on environmental conditions

23 Potential Mineralization Increases with Soil Organic Matter Content More organic matter gives more potential for N release under the right conditions Acts as buffer for N rate Conditions that promote high crop yield promote N release As crop demand increases, the ability of SOM to release N increases Pot Min N (ppm) y = 43.02x R 2 = Soil Organic C (%)

24 Past Management Can Affect N-Supplying Power of the Soil Long-Term Building Continuous Cropping Diversified Crop Rotation (cereal-oilseed- cereal-pulse) Good N fertilization Some forages before start of zero tillage ( ) As of 2008, 30 years of no-till Long-Term Depleting 50/50 summerfallow/crop rotation prior to 2001 Minimal N fertilizer Conventional tillage Crop Rotation (cereals mainly) No-till since 2001 Courtesy of Guy Lafond

25 Spring Wheat (3 years) Grain Yield 60 Yield (bus/acre) ~30 kg/ha Building Depleting Nitrogen (kg/ha)

26 How to Improve Nitrogen Use Efficiency? Soil nitrate test is still a good indicator of available N for crop growth in annual cropping systems Improve estimates of soil N supply to fine-tune application rates in modern systems Consider past inputs of legumes, manures and other soil building practices Modelling or measurement of mineralization Match management practices to environment Select proper rate, source, timing and placement of N fertilizers Enhanced efficiency fertilizers and split applications may have role where environmental conditions promote losses We may be underestimating nitrogen use efficiency if we don t consider N balance over the long-term

27 Canola has a High Demand for P

28 Adequate P is needed for full response to N fertilizer Hybrid Canola Westco Yield (t/ha) P 2 O 5 kg /ha N (kg/ha)

29 Principles of Phosphorus Nutrition that Affect Fertilizer Management Choices Soil will supply P to the crop Fertilizer tops up soil supply for optimum yield P availability varies with environmental conditions P is needed early in growth Plants must have adequate supply in first 3-6 weeks Need to apply at or before seeding P is not very mobile Ties up with Ca, Mg, Al and Fe Doesn t move far in the soil Roots must intercept P since P won t move to roots 29

30 How Much Phosphorus is Needed by a Crop? 40 bu/acre canola removes 38 lb/acre Additional 20 lb/acre is cycled in the residue Total of around 58 lb for growth Without an adequate P supply, crop yield will be reduced But not all crop requirement has to come from fertilizer 30

31 Plants Access P from Soil Solution Fertilizer additions make up the difference between crop demand and soil supply weathering Adsorption desorption dissolution 31 precipitation Soil solution phosphorus HPO -2 4 H 2 PO -2 4 Immobilization Mineralization

32 Factors that Restrict P Availability Low soil P reserves (soil test P) Cold soil temperature Excessively wet or dry soils High or low ph (ph 6-7 ideal) Fine soil texture (eg. clay) Restricted rooting Compacted, poorly aerated soils Crops with poor root systems for P uptake Need for P fertilizer will be higher if P availability is restricted

33 Phosphorus is Relatively Immobile in the Soil Has important effect on P management decisions

34 Phosphorus Should be Banded Banding slows tie-up of P in soil Having ammonium N in the band slows reactions further MAP, DAP and APP are effective P sources because they contain ammonium Adding urea to MAP bands increases fertilizer P uptake when fertilizer is banded away from seed However, excess N can delay P uptake due to band toxicity 34

35 Phosphorus Should be Banded Some plant roots proliferate in bands Ammonium in the band may also increase root proliferation Uptake increases with P concentration and rooting Fertilizer bands provide high concentration More roots in the band increase uptake 35

36 Some crops can increase rooting when they contact a fertilizer reaction zone Roots in Reaction Zone (% ) Flax Unfertilized Soil P Reaction Zone Wheat Strong and Soper Rapeseed Buckwheat Canola is very good at increasing rooting in the fertilizer band Very good at using fertilizer P Also very good at using residual soil P Excretes organic acids to mobilize P 36

37 Banding P Near the Seed-Row Ensures that Roots Will Contact the P Granule Early in Growth Broadcast Banded At 25 Kg P 2 O 5 /Ha and 18 cm row spacing have a granule every 2.3 cm ( ) The large difference between banded and broadcast applications is POSITION Courtesy Geza Racz 37

38 Phosphorus Should be Banded P will not move to roots so roots must contact bands Bands must be placed where roots will contact them early in season Near the seed-row Seed-placed Side-banded 38

39 Effect of rate and placement of MAP on stand density and grain yield of canola Too much fertilizer close to the seed can damage the seed and reduce yield Damage is from the nitrogen in the MAP Grain Yield (kg /ha) P2O5 Rate (kg/ha) Yield-In Row Stand-In Row Nyborg and Hennig p lants p er 6.1 m

40 Canola Canola is highly responsive to P on very low P soils Can use soil P well if soil test P is moderate to high Yield will usually be optimized with 15 to 20 lb P 2 O 5 ac -1 Place as starter near or in the seed-row Response to starter more likely on cold soils, with early seeding No Starter P 25 bu/acre 25 lb P2O5 applied as MAP 35 bu/acre lb NW MKP per ac, equiv. to ~ 7 ppm Olsen P

41 Sulphur Deficiency is Very Common In Canola Sulphur removal (kg/ha) Wheat 4 Canola 12 Peas 8 Alfalfa 34 Canola requires more S than cereal and pulse crops.

42 Plants Access S from Soil Solution Rain,irrigation, atmospheric deposition As with other nutrients, fertilizer additions make up the difference between crop demand and soil supply Immobilization dissolution Gypsum Mineralization Soil solution SO 4-2 precipitation 42

43 Sulphur Deficiency Sulphur is not mobile, so does not move from old to young tissue Yellowing of younger leaves is early symptom Often the S deficiency results in a reddish-violet color, similar to P and N. Cupping of younger leaves is a symptom of critical S stress,

44 Sulphur Deficiency Symptoms Sulphur deficiencies are usually patchy in a field, since S supply is normally highly variable

45 Adding N without S Can Depress Canola Yield on an S-deficient soil Canola Yield (t/ha) Control N banded N broadcast Increasing N with No S Increasing N with S Grant 1994

46 Adequate S is Needed, But Specific N:S Ratio May Not Be That Important High N:S ratio can indicate an S deficiency However, once a S deficiency is corrected there is little or no response to adding more S with increasing N rate.

47 Sulphur Sources Sulphate Sources Ammonium sulphate Ammonium thiosulphate Gypsum Microessentials S-15 Elemental Sources Elemental S Bentonite blends Tiger 90 Microessentials S-15 Manage sulphate and elemental sources differently

48 Sulphate Sources Are Immediately Available so Timing of Application is Flexible Ahead of seeding Will not volatilize May immobilize or leach Near seeding Readily available Post-seeding Can be effective, even when delayed

49 Sulphate Sources Are Mobile in the Soil so Placement Options Are Flexible Banding Broadcast Dribble-band Seed-placement Avoid excesses that could cause toxicity

50 Elemental Sources Must Oxidize to Sulphate Apply far before crop requirement Use finely divided product Broadcast rather than band Want to maximize contact with microbes Leave on surface to weather Incorporate after weathering Part of long-term program

51 Canola yield as affected by placement of applied sulphur Control Tiger 90 Am. Sulph Seed Yield (kg/ha) Broadcast Seedplaced PP Band

52 Canola yield as affected by residual S applied the previous year Control Tiger 90 Am. Sulph Seed Yield (kg/ha) Broadcast PP Band

53 Effect of a single year s application of S sources on canola yield over three years on a sandy loam soil Treatment Year 1 Year 2 Year 3 Total Control Sp. Brd T Sp. Brd AS Banded T Banded AS Seedrow T

54 Conversion of S to Sulphate is not Reliable Under Canadian conditions, we cannot rely on elemental sources to provide enough available sulphate on deficient soils during the following crop year May be beneficial in long-term planning

55 Summary Canola is effective at accessing nutrients from the soil Also good at using fertilizer nutrients Need to consider soil nutrient supply when assessing fertilizer demand Immediately available nutrients and potential mineralization Select proper rate, source, timing and placement Match management practices to environment to minimize losses and maximize efficiency

56 Thank You For your Attention