Spring Fertiliser Advice - Grassland

Transcription

1 February, 2016 Spring Fertiliser Advice - Grassland Contents Page No. 1. National soil fertility status & trends 2 2. Soil ph & liming advice 3 3. Nitrogen advice 5 4. N Sources Urea & CAN & Research Update 6 5. Building soil P & K fertility 9 6. Timing of P & K Application 9 7. Suggested Fertiliser Programmes for Dairy, Beef & Sheep Organic Manures Sulphur & grassland Fertiliser Product List Highlights Update on national soil fertility status & trends 2015 Importance of liming & Soil P availability Building soil P & K levels Fertiliser advice programmes for 2016 Urea advice, new products & research update More technical information Log on to Soil & Soil Fertility Website Prepared by Mark Plunkett, David Wall & Patrick Forrestal, Teagasc, Johnstown Castle. Page 1

2 1. Soil Fertility Status & Trends The latest Teagasc soil fertility results (i.e. soil samples taken during 2015) show that approximately 10% of grassland and 15% tillage soil samples have the optimum levels of soil ph, & K to maximise either grass and grain production annually. Over the last 10 years that soil fertility data base shows the continued decline of soil P levels on both grassland and tillage farms with 61% and 59% of soil samples at soil P index 1 and 2 (sub-optimal for production). Soil ph and liming continues to be ignored on Irish farms with 65% of all grassland soil samples below the target ph 6.3 required for optimum grass growth. While there has been a slight improvement in soil ph levels on tillage farms there are still 55% of soils below the target ph 6.5. In summary:- 64% of grassland soils are below the target ph % of tillage soils are below the target ph 6.5 Soil P levels continues to decline on grassland (61% index 1 and 2) and tillage (59% index 1 and 2). Soil K levels on grassland farms have stabilised over the last 4 years (54% index 1 and 2). Soil K levels on tillage farms are gradually improving (currently 47% index 1 and 2). Soil fertility levels have declined more rapidly over the last 10 years on grassland farms. Currently only 10% grassland samples analysed have optimum soil fertility. Figure 1 A. Grassland soils Soil fertility levels have declined more slowly over the last 10 years on tillage farms. Currently only 15% tillage samples analysed have optimum soil fertility. Figure 1 B. Tillage soils Figure 1. Proportion of Grassland (A) & Tillage (B) soils with optimum soil fertility (i.e. ph, P and K) levels. Page 2

3 2. Soil ph & Liming Advice Soil ph and the application of lime has a significant influence on the availability of stored nutrients in the soils (especially P) and the efficiency of freshly applied nutrients applied in either organic (manures) or chemical (fertiliser) forms. Maintaining soil ph in the optimum range for grassland (ph 6.3) or tillage crops (ph 6.5) is the starting point to correcting and optimising soil fertility. For example grassland soils maintained at the target ph: 1. Will potentially release up to 80 kg N/ha/year from soil organic matter 2. Will increase plant availability of both P & K compared to low soil ph levels (<ph 6.0). 3. Will provide a more hospitable environment for grass and crop establishment and longevity. 4. Together these beneficial effects will lead to increased grass and crop productivity. Lime Advice - Ground limestone Where soil ph is low and a large quantity of lime is required to increase the soil ph to the target range, ground limestone is most suitable. Apply lime to soils to achieve the target soil ph based on the soil test report (lime requirement (t/ha) provided). Apply Magnesium lime where soil Mg levels are Index 1 or 2. Don t exceed 7.5t/ha in a single application. Where the lime requirement is large (>7.5 t/ha [3 t/ac]) split the lime application (i.e. apply 50% now and the balance in year 3). On high molybdenum (Mo) soils maintain soil ph <6.2 to prevent negative effects on Cu uptake in ruminant animals On high molybdenum (Mo) soils, only lime a proportion of the farm each year (e.g. 20% of the farm annually) to reduce the risk of an acute copper deficiency in grazing animals arising from high Mo levels (related to high soil ph) in grass across the entire farm. Magnesium lime is slower to increase soil ph and therefore maybe more suitable on high Mo soils to reduce the incidence of copper deficiency. Leave at least 3 months between liming & silage harvest. Leave 7 days between applying urea / slurry application and applying lime afterwards?? Leave 3 months between applying lime first and following with urea / slurry application Lime Standards as per DAFM Specification (SI 248 of 1978) Product must have a Total Neutralising Value greater than 90 per cent 100% lime products must pass through a 3.35 mm sieve (i.e. very course limestone is less effective at increasing ph due to lower reactivity, needs additional time to break down and dissolve) Not less than 35% must pass through a 0.15 mm sieve (i.e. is finely ground). Therefore at least 350kg/tonne of limestone is fine and therefore very reactive and will begin to work immediately. The moisture content must be less than 3.0% specification Granulated Limes Granulated lime is composed of fine lime (i.e. <0.10 mm sieve) and therefore all very reactive (i.e. ~ 100% will react within the year of application). Treat granulated liming products like a fertiliser in that they should be applied annually. Where soil ph is close to the target level, granulated lime could be considered as a maintenance type liming product. o The rate of application form maintenance will depend on the level of lime loss and acid production (i.e. from N fertilisers and manure applications) annually, E.g. lime utilization and loss will typically range from 450 to 900kg/ha per year. o The industry recommends to apply granulated lime at a rate of ~1:3 (compared to ground limestone) this would equate to a granulated lime application of 150 to 300kg/ha annually to maintain soil ph in optimum range. Consider costs over the 3-5 year period when considering granulated limes. Page 3

4 Importance of soil ph on nutrient availability Recent research from Johnstown Castle clearly shows the importance of lime in relation to the availability of soil P and the improved efficiency from P applied in bagged fertiliser. Figure 2 shows the benefits of lime in un-locking soil P and increasing the efficiency of freshly applied P. This shows that the application of lime for ph correction is the first step to consider when building soil P levels. Figure 2:- 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. (Sheil, et al, 2013) Lime Usage in 1970 to 2014 Figure 3. National lime usage ( 000 t/yr) between 1970 and 2014 Page 4

5 3. Nitrogen advice Over the coming days / weeks fertiliser programmes will be starting on many intensive grassland farms. The timing and rate of N will depend on a number of factors such as location, soil conditions / temperature and length of growing season. Apply N when soil temperatures reach 5 to 6 C (when grass will begin to grow). Check forecast and ensure at least 48 hours reasonable weather after application (i.e. rain < 15mm, ~10mm rain will help Urea move into the soil and reduce N losses through volatilisation). Aim to apply 23 units/ac in 1 st spilt in February, and have approximately 60 units/ac N applied by early April on highly stocked farms. Urea 46% N ( 0.75/kg N) is a cheaper source of N compared to CAN 27%N ( 1.00/kg N). Urea may be safer than ammonium nitrate based fertilisers (i.e. C.A.N.) for early N applications because there will be less nitrate-n, which is prone to leaching, in the soil. Don t forget P & K in spring. Where straight N as Urea or CAN is applied for the 1 st application of the year consider , , 27 s or 24 s etc. to supply P & K in the 2 nd round of fertiliser applications (4 to 6 weeks time). Target some low P and K soils (fields or paddocks) with slurry before or after the first grazing round to maximise the efficiency of slurry N and get some necessary P and K onto these soils. Target most productive swards / recently reseeded fields with early N first. Aim to apply P and K with 1 st or 2 nd N applications (esp. on Index 1 & 2 soils). Table 1:- Recommended rates of N fertilizer (kg/ha) for grassland during the year where approximately half of the farm is cut for first-cut silage and the amount of second-cut is kept to a minimum (0 30% of the grassland area) Stocking Rate (kg OrgN/ha) Jan/Feb March April May June July Aug Sept Total N rate (kg/ha) Source:- Teagasc Green Book Page 5

6 4. N Sources Urea & CAN Urea (46% N) is a less expensive source of N than CAN (27% N). Figure 4 below shows the forms of N which Urea and CAN are in when applied and a summary of how they change in the soil system. The ammonium and nitrate supplied by CAN are both available for plant up take at the time of application. Urea is converted first to ammonium by the activity of the urease enzyme (urea hydrolysis). This process is relatively rapid under Irish conditions. Plants may take up some urea but it will usually convert over a period of hours to days depending on soil temperature and soil moisture. The Urea hydrolysis process is slowed somewhat by drier and cooler conditions. Ammonia loss from urea is a concern from an agronomic and a national gaseous emissions perspective. Some practical guidance on practices likely to minimise ammonia losses is provided below. Once ammonia converts to ammonium it may be fixed to the soil and less prone to loss by volatilization to the air. Figure 4.Conversions of Urea N to ammonium and nitrate N in the soil Figure 5. N transformations and losses from the soil, gas (red up), leaching (red down) N losses and role of urease inhibitor in stabilising Urea. Page 6

7 Steps to reducing N losses when applying Urea Rainfall: 10 15mm in first day or several days reduces ammonia loss but be cautious of leaching and runoff N loss Avoid applying to wet soil/grass followed by windy, sunny conditions Urea applied into a crop canopy is more protected from wind and direct sun The proportion of N loss as ammonia gas tends to increase with increasing N rate e.g. grazing N rates (typically <40 kg N/ha) are potentially less risky than silage N rates (typically >80 kg/ha) Increasing ammonia N loss risk at ph > 7 Apply Urea before lime application (21 days) Wait at least 3 months after liming before applying Urea Wait 10 days after slurry application before applying Urea and vice versa Incorporating into soil will minimise ammonia losses but risk of toxicity to seedlings increases with rate, do not place urea with seed for this reason Using Urea stabilised with a urease inhibitor (e.g. NBPT reduced ammonia N loss in Teagasc grassland trials by c. 79% on average). Urea Research Update A 3 year project undertaken at the Johnstown Castle Research Centre to evaluate several existing and new fertiliser N products is currently coming to conclusion. Some of the products evaluated were new to the market in This project was focused on evaluating the ability of various N fertiliser types to optimize crop productivity, while having positive cost benefits, and lower environmental loss potential in grassland and arable cropping systems. The main N fertiliser sources compared were CAN (27%) and Urea (46%). In addition a number of N stabiliser technologies (which are added to Urea N fertiliser) were also evaluated. These are explained as follows; Urea (46% N) with N stabilisers: The new Urea based fertiliser N products can provide additional options for These stabilisers provide potential benefits when added to Urea fertiliser by either: A. Guarding against N volatilization loss (ammonia gas loss) by moderating the rate of urea hydrolysis. B. Guarding against N leaching (nitrate) and denitrification loss (including the greenhouse gas nitrous oxide) by slowing nitrification of ammonium to nitrate. Urea Technologies available Koch Advanced Nitrogen (KaN) which is Urea dressed with a urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) which claims to reduce N losses through volatilization Target Urea + AGRHO N Protect B is dressed with the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) which claims to reduce N losses through volatilization Goulding enhanced nitrogen (GEN) which is Urea dressed with a partial calcium salt of maleic itaconic copolymer, which claims to act as both a urease and a nitrification inhibitor. Teagasc trials indicate that CAN, Urea and Urea+NBPT (KaN) frequently give similar yields (fig 6), but Urea had the lowest N recovery due to ammonia gas loss. KaN effectively reduced ammonia emissions (N loss) compared with untreated Urea fertiliser and GEN had similar ammonia loss to untreated Urea. Page 7

8 Figure 6. Relative yield of Urea and Urea + NBPT compared to CAN (set at 100%) across 6 grassland sites, 5 N rates and 30 fertiliser applications dates. Table 2. Relative strengths of different N fertilisers in relation to different agronomic and environmental criteria CAN Urea Urea + NBPT (Urease inhibitor) Cost Yield N recovery Greenhouse gas Ammonia gas Table 3:- Urea products with inhibitors for 2016 Product N (%) K (%) S (%) KaN KaN + S KaN + K KaN + KS KaN + KS GEN GEN + S GEN +S AGRHO N Protect B Gaseous Emissions of N Greenhouse gas (GHG) The EU has committed to reduce agricultural greenhouse gas emissions by 30% by In research conducted under Irish conditions Urea based N fertilisers are showing promise for reducing emissions of the potent greenhouse nitrous oxide. Ammonia gas Ireland has committed to reduce ammonia gas emissions by 5% by This is a significant challenge for a growing agricultural sector which produces c. 98% of national ammonia emissions. When applied, Urea based fertilisers emit ammonia gas. In research conducted under Irish conditions ammonia loss from Urea was greatly reduced by stabilising it using a urease inhibitor. Page 8

9 5. Building Soil Fertility ( P & K) Building soil P and K levels is a great topic of discussion on many dairy farms in light of the need to increase grass production to meet the feed demands of higher stocking rates. Aim for soil P and K index 3 to maximise grass production. Building soil P and K levels will take a number of years depending on the soil type. In general it will take approximately 50 kg P/ha to increase Morgan s P by 1 mg/l (Range 30 to 300 kg P/ha to increase a soil Index (3mg/L) depending on soil type light v heavy soil types). It is advised to apply recommended P and K rates annually and build soil P and K over time. This will spread the extra cost incurred while increasing the production potential of soils. Soil P tends to be slower to improve compared to soil K levels depending on the soil type. Table 3 below shows the typical build up rates of P and K (kg/ha) required on grassland soils annually. Table 4:- Recommended rates of P and K for build-up (kg/ha) Build Up P kg/ha (units/ac) K kg/ha (units/ac) Cost /ha ( /ac) Index 1 20 (16) 60 (48) 100 (40) Index 2 10 (8) 30 (24) 50 (20) Fertilisers such as / / / / 16% P (Super P) / 50% K (MOP) etc. are ideal for building / supplying P & K (see fertiliser product list). Remember that K can be applied at any time of the year while P applications have to be completed by the 14 th September. For grazing see suggested fertilizer programmes see pages 9 to 11. Organic manures are another effective route to replenishing / building soil P and K levels (for example cattle slurry is an excellent source of K). Target applications to low fertility fields (Index 1 & 2) and high demanding crops (grass / maize silage fields). See table 11 for a range of organic manures and available nutrient vales. 6. Timing of P & K Application Phosphorus (P) Apply (maintenance + build up rates) during the growing season as follows:- Apply 50% of P in spring to meet grass yield requirements 50% during the growing season in 2 to 3 application s to satisfy grass herbage P requirements Potassium (K) Apply maintenance rates of K during the growing season and apply build up rates in the August / September to reduce issues with nutrient imbalances. Page 9

10 7. Suggested Fertiliser (N, P & K) Programmes for Dairy, Beef & Sheep 1. Dairy Table 5:- Simplified P & K requirements (kg/ha) of grazed swards for dairy farms. (Rates shown are total P requirements, before deductions for concentrate feeds or organic fertilisers). Grazed Swards Farm Stocking Rates (kg Org N/ha) Soil P & K Index < >210 P K P K P K P K (kg/ha x 0.8 =units/ac) Table 6:- Suggested Fertiliser N, P & K programmes for dairy grazing stocked at 131 to 170kg Org N/ha¹ N Advice kg/ha 201 (161 units/ac) ( )= units/ac Soil P & K Index P kg/ha K K/ha Fertiliser Programme* (bags/ac) 1 34 (27) 90 (72) 2.7 bags x bag bags CAN 2 24 (19) 60 (48) 1.9 bags bags CAN 3 14 (11) 30 (24) 1 bags bags CAN bags CAN ¹ Rates shown are total P requirements, before deductions for concentrate feeds or organic fertilisers Consult farm fertiliser plan for whole farm N & P allowances Page 10

11 2. Beef Table 7:- Simplified P & K requirements (kg/ha) of grazed swards for dairy farms. (Rates shown are total P requirements, before deductions for concentrate feeds or organic fertilisers). Grazed Swards Farm Stocking Rates (kg Org N/ha) < Soil P & K Index P K P K P K P K (kg/ha x 0.8 =units/ac) Table 8:- Suggested Fertiliser N, P & K Recommendation s for beef grazing stocked at 131 to 170kg Org N/ha N Advice kg/ha 201 (161 units/ac) *Adjust N rate based on farm requirements ( )= units/ac Soil P & K Index P kg/ha K K/ha Fertiliser Programme* (bags/ac) 1 30 (24) 75 (60) 2.4 bags x bags CAN 2 20 (16) 45 (36) 1.6 bags bags CAN 3 10 (8) 15 (12) 3 bags bags CAN bags CAN ¹ Rates shown are total P requirements, before deductions for concentrate feeds or organic fertilisers Consult farm fertiliser plan for whole farm N & P allowances Page 11

12 3. Sheep Table 9:- Simplified P & K requirements (kg/ha) of grazed swards for dairy farms. (Rates shown are total P requirements, before deductions for concentrate feeds or organic fertilisers). Grazed Swards Farm Stocking Rates (kg Org N/ha) Soil P & K Index < P K P K P K P K (kg/ha x 0.8 =units/ac) Table 10:- Suggested Fertiliser N, P & K Recommendation s for sheep grazing stocked at 130 to 170kg Org N/ha (10-13 ewes/ha) N Advice kg/ha Soil P & K Index P kg/ha K K/ha Fertiliser Programme* (bags/ac) 145* (116 units/ac) *Adjust N rate based on farm requirements 1 30 (24) 75 (60) 3 x bags /ac 2 20 (16) 45 (36) 2.5 bags bags CAN/ac 3 10 (8) 15 (12) 3.2 bags bags CAN/ac bags CAN/ac ( )= units/ac ¹ Rates shown are total P requirements, before deductions for concentrate feeds or organic fertilisers Consult Farm fertiliser plan for whole farm N & P allowances Page 12

13 8. Organic Manure Management Aim to maximise the application of slurry / FYM in the spring to increase the recovery of nitrogen. Spring application of cattle slurry will increase N recovery by 3 units/1,000gallons Trailing shoe / band spreader will further increase N recovery by 3 units/1,000gallons Slurry dilution will increase N efficiency but decrease P & K value per 1,000 gallons Apply slurry to field with a large demand for P & K e.g. Grass / maize silage etc. On soil index 1 & 2 reduce manure P availability to 50% To maximise N recovery apply on cool, calm, misty days. Aim to have 70% of slurry applied before April and 100% applied by mid-june. Table 11: Available N, P & K values for a range of organic manures Units/1,000 gallons Manure type N P K Cattle slurry (7% DM) Dilute cattle slurry (3.5% DM) Pig slurry (4% DM) Units/tonne FYM SMC Poultry Manures Broiler/Deep Litter Layers (30% DM) Layers (55% DM) Turkeys Page 13

14 9. Sulphur Sulphur (S) is an important nutrient for grassland, and is closely associated with N uptake and efficiency. There is currently no soil test or soil Index system for S. Herbage analysis is the best predictor of S deficiency. Current research shows that S deficiency is not just confined to light textured soils and S deficiencies are occurring on heavy textured soil sin early spring. Sulphur fertiliser advice The response to S fertiliser increases as the rate of N fertiliser increases. Apply 20 kg/ha per year for grazed swards in early spring. For silage swards apply 20 kg/ha of S per cut. Avoid over application of S can trigger copper and selenium deficiencies in livestock can be applied by using any of a number of straight or compound fertilisers that contain S Page 14

15 10. Table 12:-Fertiliser Products and Guide Prices 2016 Product Nitrogen % Phosphorus % Potassium % Sulphur% Price/tonne ( ) Nitrogen (N) CAN 27 Sulfa CAN 27 5 Super Net 27 3 Gran Urea 46 KaN 46 GEN 46 Sulfa Sul of Amm.(Pr) Sul of Amm.(Gr) ASN Selenigraze/grass (0.002%Se) 25 Seleniboost/start (0.002% Se) 42 P s K s Super P (16%) 16 MOP (50% K) 50 SOP (42% K) N, P s / N, K s S N, P, K s B B S S S S S Nutrigraze/Sweetgrass 23 2S/1-2Mg/5 Na S S Granulated Limes Granucal (34% Ca & 1.5% Mg) Gran Lime (38% Ca & 1% Mg) Physolith (26% Ca & 2.3% Mg) Page 15