Grassland P & K Advice Mark Plunkett Johnstown Castle, Wexford Mark Plunkett, Teagasc Grassland P & K Advice Mark Plunkett Johnstown Castle, Wexford Mark Plunkett, Teagasc

Mark Plunkett, Teagasc Presentation Notes This presentation can be used for either drystock or dairy training groups as there is double slides for either group. For example slides 3, 4 & 5, 6,7 & 8, 9 & 10 Mark Plunkett, Teagasc

Soil P for Grassland Soils Mark Plunkett, Teagasc Soil P - Drystock Soil P for Grassland Soils 64% Index 1 & 2 Target Index 3 Soil P fertility decreasing over time 64% of soils P Index 1 and 2 Aim for P Index 3 Soil P fertility continues to decrease Mark Plunkett, Teagasc, 2018

Soil K for Grassland Soils Mark Plunkett, Teagasc Soil K - Drystock Soil K for Grassland Soils 57% < Index 1 & 2 Target Index 3 Soil K fertility decreasing over time 57% of soils K Index 1 and 2 Aim for P Index 3 Soil Kfertility continues to decrease Mark Plunkett, Teagasc, 2018

Soil P & K Trends - Drystock Farms Mark Plunkett, Teagasc Soil P & K Trends - Drystock Farms P and K Trends over time 42,646 Soils Mark Plunkett, Teagasc, 2018

Soil P for Grassland Soils Mark Plunkett, Teagasc Soil P - Dairy 61% < Index 1 & 2 Target Index 3 Soil P fertility decreasing over time Soil P for Grassland Soils 61% of soils P Index 1 and 2 Aim for P Index 3 Soil P fertility continues to decrease Mark Plunkett, Teagasc, 2018

Soil K for Grassland Soils Mark Plunkett, Teagasc Soil K - Dairy 54% < Index 1 & 2 Target Index 3 Soil K fertility similar to P declining slowing over time Soil K for Grassland Soils 54% of soils K Index 1 and 2 Aim for P Index 3 Soil K fertility continues to decrease Mark Plunkett, Teagasc, 2018

Soil P & K Trends - Dairy Farms Mark Plunkett, Teagasc Soil P & K Trends - Dairy Farms P and K trends overtime 16,650 Soils Mark Plunkett, Teagasc, 2018

Soils with Optimum Fertility Mark Plunkett, Teagasc Soils with Optimum Fertility “90% of soils sub-optimal for Major Nutrients – pH, P or K” 91% of soils sub optimal for pH, P & K Mark Plunkett, Teagasc, 2018

Soils with Optimum Fertility - Dairy Mark Plunkett, Teagasc Soils with Optimum Fertility - Dairy “90% of soils sub-optimal for Major Nutrients – pH, P or K” 89% of soils sub optimal for pH, P & K Mark Plunkett, Teagasc, 2018

Step 1 - Reliable Soil Results Mark Plunkett, Teagasc Step 1 - Reliable Soil Results “Soil results are only as good as the sample on which it is based on” “Greatest potential for error is in field sampling” Take a representative soil sample Establish an accurate estimate of the soils nutrient status 10cm sampling depth represents a volume of approx. 1,500 tonnes/ha of soil Sample every 4 to 5ha Take soil samples as per soil sample guidelines to ensure reliable results = 6,000 to 7,500t Soil Mark Plunkett, Teagasc, 2018

Role & Function of P Rooting & Tillering Mark Plunkett, Teagasc Role & Function of P Rooting & Tillering Kick starts spring grass growth Extra 1.5t DM/ha Animal health 0.35% P in Grass Meat & Milk Function and role of P in grass production Mark Plunkett, Teagasc, 2018

Irish Soils & P Fixation Mark Plunkett, Teagasc Irish Soils & P Fixation Effect of soil pH on soil P availability – Aim for pH 6.3 to 6.5 to maximise soil P availability Mark Plunkett, Teagasc, 2018

Irish Soils & P Fixation Mark Plunkett, Teagasc Irish Soils & P Fixation Irish soils are naturally acidic High levels of Aluminium & Iron Fix P applied to soils Response to applied P very poor Lime increases soil pH & unlocks soil P Building Soil P will take time depending on the soil type and level of P fixation Applying P to acidic soils results in P fixed by Al & Fe Mark Plunkett, Teagasc, 2018

Al Acidic Soils Fix P Fe P Fertiliser Mark Plunkett, Teagasc Acidic Soils Fix P P Fertiliser “Acidic soils competes for freshly applied P & its is Fixed by Al & Fe” “Manure P more available in acidic soils” P Al Explains soil P fixation Fe P Acidic Soil Mark Plunkett, Teagasc, 2018

Unlocking Soil P with Lime! Mark Plunkett, Teagasc Unlocking Soil P with Lime! Average change in soil test P (Morgan’s) across 16 soils (av. pH 5.5) 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 Lime will increase soil P availability and freshly applied P is more available Mark Plunkett, Teagasc, 2018

Role & Function of K N & P Efficiency Prevents Lodging Mark Plunkett, Teagasc Role & Function of K N & P Efficiency Prevents Lodging Silage Production Extra 3t/ha 2 cut silage removes 250kg/ha Slurry excellent K Potassium vital role to play in N efficiency and water regulation in the plant K vital in grass silage production. Ideally recycle slurry back to silage fields Mark Plunkett, Teagasc, 2018

Irish Soils & K Good levels of K 5% of total K is available Mark Plunkett, Teagasc Irish Soils & K Good levels of K 5% of total K is available K found in the clay component Soil test very reliable Easy to improve soil K compared to P Soil type (light v heavy) Some K fixing soils (for example Athy) Irish soils have good levels of soil K. Soil K will respond / change faster than soil P Mark Plunkett, Teagasc, 2018

Soil Test Results Mark Plunkett, Teagasc, 2018

Soil P & K Index System Basis to Index System Mark Plunkett, Teagasc Soil P & K Index System Basis to Index System Index 4 – Very Fertile Soils Index 3 – Soil Feeding the crop & Replacing off-takes Index 1 & 2 – Building soil fertility Soil P & K Index system Basis to Index system Mark Plunkett, Teagasc

Why Build Soil Fertility? Mark Plunkett, Teagasc Why Build Soil Fertility? Index 3 Low response to fertilizer Index 4 Soil supply sufficient to meet demands Large variation between soil types! Index 1 & 2 Yield response to increased soil P levels ~ 1.5 t/ha Cost of not knowing soil is in Index 1 is approximately 1.5 t/ha of grass DM per year Large variation around this average estimate (0-5 t/ha) Average of response curves from 8 sites over 4 years. (32 repeated experiments). K – Similar response in silage (1-3 t/ha/yr)

How much P and K to replace offtake? Mark Plunkett, Teagasc How much P and K to replace offtake? P (kg) K (kg) Milk (1,000 litres) 0.9 - 1 1 - 1.5 Meat (Live wt.) (100 kg) 1 0.5 - 1 Silage (1 ton DM) 3 - 4 25 Grain (1 ton grain + straw) 3.8 10-15 P and K offtakes for milk / meat / silage / grain Mark Plunkett, Teagasc Lalor – ASA Conference, Killeshin Hotel, Portlaoise 20 Mar 2014

How much P & K Removed? Stocking Rate / ha Product P (kg) K (kg) Mark Plunkett, Teagasc How much P & K Removed? Stocking Rate / ha Product P (kg) K (kg) 10,000L Milk 10 15 15,000L Milk 23 1,200 kg Meat 12 X 24 1,100kg 11 P & K Off takes by stocking rates Mark Plunkett, Teagasc Lalor – ASA Conference, Killeshin Hotel, Portlaoise 20 Mar 2014

P & K advice – replacing offtake Mark Plunkett, Teagasc P & K advice – replacing offtake Stocking Rate (LU/ha) 1.5-2.0 2.0-2.5 2.5-3.0 > 3.0 Dairy P – K advice kg/ha 14 – 30 19 – 35 23 – 40 27 – 45 units/acre 11 – 24 15 – 28 18 – 32 22 – 36 Stocking Rate (LU/ha) 1.0-1.5 1.5-2.0 2.0-2.5 2.5-3.0 Beef/Sheep P – K advice kg/ha 7 – 10 10 – 15 13 – 20 16 – 25 units/acre 6 – 8 8 – 12 10 – 16 13 - 20 P and K advice for dairy & drystock P and K rates for drystock are low Mark Plunkett, Teagasc

P & K Advice – Off takes Grass Silage Mark Plunkett, Teagasc P & K Advice – Off takes Grass Silage Cut 1st 2nd P – K advice kg/ha 20 – 125 12 – 75 units/acre 16 – 100 10 – 60 P and K advice for 1st & 2nd cut silage Mark Plunkett, Teagasc

P & K – Build Up Rates Build-up Index 2 Index 1 P – K advice kg/ha + Mark Plunkett, Teagasc P & K – Build Up Rates Build-up Index 2 Index 1 P – K advice kg/ha + 30 – 30 50 – 60 units/acre 24 – 24 40 – 48 P and K build up rates P increased by 30kgP/ha at Index 1 P increased by 20kgP/ha at Index 2 Mark Plunkett, Teagasc

How long does it take to change Index ? Mark Plunkett, Teagasc How long does it take to change Index ? P Generally takes time to increase/decrease (5 to 10 years) Lighter soils tend to move quicker Organic matter content % Clay Advice 1st Correct Soil pH Apply fertilizer as per fertiliser plan for a number of years Re-test every 3-5 years to monitor changes over time K Will change faster than P Index 1 & 2 Apply off takes + build-up until next soil test Index 4 Omit K for one year, then revert to Index 3 advice (off takes) On av. 50kgP/ha req. for 1mg/L P On av. 1kgK/ha req. for 1mg/L K Changing soil P takes time while soil K will change faster Mark Plunkett, Teagasc

New Fertiliser P Allowances Mark Plunkett, Teagasc New Fertiliser P Allowances Grassland Stocking Rate (kg/ha) P Index 1 2 3 4 131 - 170 63 43 13 171 - 210 66 46 16 211 - 250 >250 69 49 19 50kg P/ha @ Index 1 30kg P/ha @ Index 2 1. Adjust for Conc. Feed (5kg/ton) 2. Slurry Removed from calculations New P allowances Complete Farm Fertiliser Plan to Determine P Allowances Mark Plunkett, Teagasc

Mark Plunkett, Teagasc P & K advice – In Summary Take good soil samples for reliable P & K results Correct soil pH before building soil P Determine P & K advice Takes time to increase soil P while K will increase quicker New Nitrates allow extra P for build up Summary Mark Plunkett, Teagasc