Managing Soil Fertility. Teagasc Soil Fertility Management Spring 2015

Transcription

1 Managing Soil Fertility Teagasc Soil Fertility Management Spring 2015

2 Outline Key Questions What s happening to soil fertility? What steps can be followed to manage it? What are the benefits? Is there a return on investment to managing / improving fertility? What Targets can be set for soil fertility? 2

3 Soil Fertility Data Teagasc analyse c. 35,000 samples per year Individual results never disclosed to third party Database provides good overview of national soil fertility Not a random sample Not fully representative Not validated Gives overview 3

4 Lime Usage in Ireland Source : DAFM 4

5 Soil ph Grassland soils Grassland target = % of grassland soils with ph < 6.2 Liming is very important 5

6 Soil ph Tillage soils Tillage crop target = % of tillage soils with ph < 6.5 Liming is very important 6

7 Fertilizer N P K Usage in Ireland N K P N Fertilizer usage ('000 tonnes) 500 P & K Fertilizer usage ('000 tonnes) National Fertilizer Usage DAFM 7

8 Soil Test P & K National (All) What does this mean for you? - ~ % of soils are in Index 3 - If you don t soil test, you don t know what you are dealing with - Are your soil fertility levels declining as well? - You don t know unless you soil test 8

9 Grassland Soils With Optimum Soil Fertility ) 9

10 Tillage Soils With Optimum Soil Fertility 10

11 Steps to Soil Fertility Management Index Description Very Low Low Target High 11

12 Steps to Soil Fertility Management 12

13 Soil Testing Why? Indicator of background soil fertility levels Tool to help plan nutrient applications Fertilizer Slurry / FYM Monitor change in soil fertility levels overtime Soil ph and Lime requirement P&K Mg and trace elements Adjust fertilizer / manure management practices Derogation requirement 13

14 Soil Testing How? Area: one sample per 2-4 ha (5 ha with derogation) Sampling pattern: Soil type; slope; cropping history; drainage; experience Practical management units Representative sample from entire field Avoid unusual spots (Gates, Feeders, old fences, ditches, dung/urine patches, FYM heaps) Avoid lines of normal fertilizer / slurry application traffic No. of cores: Minimum 20 cores per sample Mix and sub-sample cores if necessary 14

15 Soil Testing Sampling Depth Critical especially for P P tends to stay near the surface Full 10 cm deep sampling is critical Ground sampling Wear on soil corer Regularly ploughed Soil P level Permanent Pasture Soil Depth Less of an issue Re-test after ploughing 15

16 Soil test for ploughing / reseeding Permanent Grassland P concentrated in top few cm of soil Ploughing P displacement Young seedlings High P requirement for germination & establishment P supply delayed until roots get down Soil sample after ploughing Can be an issue for min-till crops as well P concentrated at surface 16

17 Soil Testing When? How often: Every 3-5 years (4 years if in derogation) Fertilizer P & K 3-6 months Timing: For comparison, sample at same of year Avoid extremes (Very dry / waterlogged) Late Autumn / Early Spring ideal Results ready for fertilizer planning for the coming year Slurry / FYM 3-6 months Lime 2 years (for accurate soil ph) 17

18 Soil Testing Cost / Benefit ~ 25% of soils are in Index 3 If no soil test and assume Index 3, then you are likely to be wrong in 75% of fields!! Cost Consider relative to fertilizer cost? N P K Fertilizer = / tonne??? 18

19 Steps to Soil Fertility Management 19

20 Soil ph and Liming P Soil P reserve less available N Fertilizers less available K Optimum ph for grassland = Maximum nutrient release from soils Soil biological activity ~67% of grassland soil < 6.0 Response to fertilizer P on acid soils???? 20

21 Lime in grassland Offtake N fertiliser 1 bullock 25 kg of Lime 1,000 L milk 3kg of lime 100 kg = kg lime 1 ha 5 t/ha silage DM 75 kg of Lime Grassland Example Up to kg/ha/yr of lime in drainage 150 kg/ha N 300 kg 2 bullocks 50 kg Lime loss in drainage kg Total lime required kg/ha/yr 1-2 ton/acre every 5 years 21

22 Lime and P availability Lime increased the STP Additive benefits of P and lime Sheil et al, 2013 Average change in soil test P (Morgan s) across 16 soils treated with P (100 kg/ha of P), Lime (5 t/ha of lime), and P + Lime and incubated over 12 months in controlled conditions.

23 Lime requirements Advice is to apply lime in a 3-5 year cycle Grassland typically requires between t/ha/yr Exceptions High Mo soils and grassland don t exceed ph 6.2 Lime requirements reduced by 5 t/ha Where advice is > 7.5 t/ha Split application 7.5 t/ha now Remainder after 2 years Precaution to reduce risk of trace element problems 23

24 High Mo higher risk where: High soil ph (>6.2) Avoid over-liming Poor drainage (or wet weather) Species: Clover > Yorkshire fog > Meadow grass > Fescue > Timothy Low Nitrogen inputs (Higher N higher yields Dilution of Mo in herbage + less clover) 24

25 Lime types Ground limestone Apply as per Lime requirement Calcium based Magnesium based Standard product Use where Magnesium in the soil test is low Granulated limes Same material, just more finely ground More expensive Granulated Lime 50 kg Quick fix (e.g. tillage crops after sowing) Rented ground 25

26 Lime Quality Quality Standards in place for Ground Limestone (SI 248 of 1978) Statement should contain the following details: Criteria Minimum standard Fineness - 100% must pass through 3.35mm sieve - 35% must pass through 0.15 mm sieve Moisture Content - Must be < 3% TNV - Must be > 90% (Total Neutralising Value a measure of the strength of the lime) 26

27 Lime for reseeding Incorporate lime into the seedbed Apply after ploughing (or after spraying if direct drilling) Till the lime into the soil Avoid applications over 7.5 t/ha (3 t/acre) Where more lime required, wait 2 years to apply more lime ) 27

28 Steps to Soil Fertility Management Index Description Very Low Low Target High 28

29 P&K Convert test result into soil Index Target = All soils in Index 3 for P and K! Only ~ 25% at present Soil Index Description Very low Low Medium High Soil test P (mg L-1) ) Soil test K (mg L-1)

30 Soil Index & Advice Index 1 & 2: Requires additional nutrients to build soil reserves Target Index 3: Maintain balance Index 4: Draw on soil reserves Build up Advice Build up Nutrient offtake Maintenance Maintenance Maintenance Replace offtake 1 Replace offtake Replace offtake 2 3 Soil Fertility Week Soil Index (4-8 February 2013) 4 30

31 Maintenance rates P & K offtakes Milk (1000 litres) Liveweight (100 kg) Silage (1 ton DM) Leaching (1000 mm rainfall) ) P (kg) K (kg) ~ 10 31

32 Soil P and K build up - Grassland P K 10 kg/ha (8 units/acre) 30 kg/ha (24 units/acre) Index 2 16% P Muriate 50% K 25 kg 25 kg Apply forup 5 years Apply build + or until soil maintenance intest shows increase Index 1 and 2 Index 1 20 kg/ha (16 units/acre) 60 kg/ha (48 units/acre) 16% P Muriate 50% K 50 kg 50 kg ) 32

33 How long does it take to change Index? P Normally takes a number of years to increase/decrease Lighter soils tend to move faster Advice Lower organic matter Less clay Apply fertilizer as per soil test for a number of years Re-test every 3-5 years to monitor changes over time K Will change more quickly than P Index 1 & 2 Apply maintenance plus build-up until next soil test Index 4 Skip application for one year, then revert to maintenance 33

34 Save Money in Index 4 - Dairy Example Dairy 2 cows / ha Index 3 advice (grazing) = 14 kg/ha P & 30 kg/ha K Cost of P and K = 58 /ha Soil Test shows Index 4 Save 58 /ha/yr until drops to Index 3 ) 34

35 Save Money in Index 4 - Drystock Example Drystock 2 LU / ha Index 3 advice (grazing) = 10 kg/ha P & 15 kg/ha K Cost of P and K = 35 /ha Soil Test shows Index 4 Save 35 /ha/yr until drops to Index 3 35

36 Lost production in Index 1 & 2 - Dairy Same Example Production loss in Index 1 vs. Index 3 Dairy 2 cows / ha Index 3 advice (grazing) = 14 kg/ha P & 30 kg/ha K Approximately 1.5 t/ha/yr of grass DM Worth 400 /ha/yr Additional P and K for build up = 20 kg/ha P & 60 kg/ha K Additional Cost = 100 ha/yr until soil P / K increases Long-term investment benefits of increasing to Index 3 Soil ph needs to be right as well! 36

37 Lost production in Index 1 & 2 - Drystock Same Example Production loss in Index 1 vs. Index 3 Drystock 2 cows / ha Index 3 advice (grazing) = 10 kg/ha P & 15 kg/ha K Approximately 1.5 t/ha/yr of grass DM Worth 400 /ha/yr Additional P and K for build up = 20 kg/ha P & 60 kg/ha K Additional Cost = 100 ha/yr until soil P / K increases Long-term investment benefits of increasing to Index 3 Soil ph needs to be right as well! 37

38 Variation in Soil test results Not all the farm is the same different fertilizers needed in different fields Often higher close to farmyard slurry High P does not always mean high K Phosphorus Potassium Fu et al

39 Steps to Soil Fertility Management 39

40 Slurry Value 1000 gallons =?? Soiled Water Cattle Slurry (Splashplate) All Year Spring N P K Summer N P K N P K Trailing Shoe units N / 1000 gallons 50 kg 50 kg 50 kg In spring or summer 5 / 1000 gals 24 / 1000 gals Pig Slurry FYM (1 ton) N P K N P K kg 50 kg Soil Fertility Week 28 / 1000 gals (4-8 February 2013) 22 / 1000 gals 10 / ton 40

41 Contribution to Slurry Value Cattle Slurry Majority of the value is in P and K N 12% P 19% K 69% Aim to get best use of both P and K in slurry Timing or method No effect on P and K Big effect on N 41

42 Slurry Variability - Hydrometer Beware of average values Soil Fertility Week (4-8 February 2013) 42

43 Decisions with slurry 1. Where to spread P & K requirements Target fields with: 2. low soil P and K High requirements (e.g. silage) When to spread Maximise N availability Weather as important as season, but spring generally best Trailing shoe / bandspreader will also increase N value Soil Fertility Week (4-8 February 2013) 43

44 Steps to Soil Fertility Management 44

45 Nutrient Balance What is the Weakest Link? Nutrient in shortest supply limits determines yield Especially true with P and K Fertilizer Planning Soil tests & Cropping Slurry & fertilizers Straight K N-P products N-K products N P K N P K Fertilizer Fertilizer Fertilizer Buy what you need - Not what you re being sold!! Soil Fertility Week (4-8 February 2013) 45

46 Sulphur >30% of Irish soils require S for optimum yield No soil test Soil texture Light texture (>50% sand) Low organic matter (<3% org C) On deficient soils: Silage 20 kg/ha of S per cut Grazing 20kg/ha per year 46

47 Spreading fertilizer accurately Application rate is affected by: Forward speed Regulator setting Bout width Fertiliser type and quality Agitator action, flow rate Spreader maintenance is very important N P K Replace vanes regularly Fertilizer Consult spreader manual for different products / settings ) It s too expensive to be spread badly!! 47

48 Timing P and K application P Autumn restricted by nitrates rules (15 Sept) Index 3 - apply little and often through the year Index 1 and 2 Apply some in spring Remainder apply little & often K No nitrates timing restrictions (straight K) Avoid > 90 kg/ha in spring Can reduce Mg in grass K Fixing soils: No build up Little and often 48

49 Lime, Slurry and Urea interactions Lime and Slurry P and K no major issue N Lime and Fertilizer N CAN no problem Urea Slurry before lime no problem Lime before slurry avoid slurry for 3-6 months High ph (Lime) increases ammonia (NH3) volatilisation Urea before lime no problem Lime before Urea avoid urea for 3-6 months Fertilizer N and slurry Delay fertilizer N for 4-7 days Slurry is a carbon source for denitrification allow 3 days for carbon to stabilise CAN vs. Urea No difference 49

50 Fertilizer Planning A fertilizer Plan brings everything together Field by field recommendations Compliance with regulations 50

51 Soil Fertility Management Targets Have soil analysis for whole farm Soil ph between 6 and 6.5 in all fields where high Mo (grassland) P and K Index 3 in all fields Index 4 is a resource Exploit it Index 1 & 2 should be increased to Index 3 Optimise slurry first then top up with fertilizer as required Nutrient inputs in proper balance Fertilizer planning is key to this 51

52 Thank you for your attention 52