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Fertilizer use on the commercial dairy farms James Humphreys, Eimear - - PowerPoint PPT Presentation
Fertilizer use on the commercial dairy farms James Humphreys, Eimear - - PowerPoint PPT Presentation
Fertilizer use on the commercial dairy farms James Humphreys, Eimear Ruane, Andy Boland and Donal OBrien Characteristics of 50 dairy farms Average farm size: 66 ha Average no. dairy cows: 98 Average milk sales: 525,000 litres Milk solids
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62 64 66 68 70 72 74 2002 2004 2006 2008 2010 2012 2014 Dairy cows (%)
Dairy cows as a percentage of total livestock on farms
Farm characteristics
Average Range Stocking rate (LU/ha) 2.45 1.62 to 2.89 Grass DM production (t/ha) 8.9 7.5 to 11.5 More dairy cows → less beef cattle
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75% deficient in lime, P or K 25% at
- ptimum
Soil pH greater than 6.0 Index 3 & 4 for soil P and soil K
Soil fertility on dairy farms
551 samples – silage and grazing areas
54% of fields with low soil pH 39% of fields with low soil P 39% of fields with low soil K
Fertilizer use
Fertilizer N P K Actual (kg/ha) 230 8 29 Required (kg/ha) 230 17 70
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50 100 150 200 250 300 350 400 5 10 15 20 25 30 Soil K (mg/L) Soil P (mg/L) R2 = 0.042
The relationship between soil P and soil K on farms
No relationship
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75% deficient in lime, P or K 25% at
- ptimum
Soil pH greater than 6.0 Index 3 & 4 for soil P and soil K
Soil fertility on dairy farms
551 samples – silage and grazing areas
54% of fields with low soil pH 39% of fields with low soil P 39% of fields with low soil K
Fertilizer use
Fertilizer N P K Actual (kg/ha) 230 8 29 Required (kg/ha) 230 17 70
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5 10 15 20 25 <10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 Proportion of farms (%) Proportion of fields that are optimum (%)
Distribution of soil fertility per farm
80% of farms had less than 40% of fields at optimum 2% of farms had greater than 70% of fields at optimum Grass DM (t/ha) Average Range 9.8 7.5 to 11.5
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Grass growth is determined by the most limiting nutrient
Need to maximise grass growth through optimum soil fertility → Savings on lime, P and K are often a false economy
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100 150 200 250 300 350 60 80 100 120 140 160 180 Soil K (mg/L) per field Farm average soil K (mg/L)
Soil K in fields plotted against average soil K on each farm
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100 150 200 250 300 350 60 80 100 120 140 160 180 Soil K (mg/L) per field Farm average soil K (mg/L)
Soil K in fields plotted against average soil K on each farm
Index 1 & 2 Index 3 Index 4
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Fertilizer management on farms
Since 2006 dairy farms in the study stopped importing pig slurry Reduction in fertilizer P and K use – primarily due to costs (false economy) Very variable levels of engagement with fertilizer planning → current requirements are very complicated due to regulations → disappointment with the results – particularly with P → some plans exist only to meet regulatory requirements → disconnect between drawing up (planner) and implementing the plan (farmer) → farmers need to understand and control the plan to get the best outcome Many farmers are carrying on as they have always done except more focus on fertilizer N
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- 80
- 60
- 40
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20 40 60 80 100 Relative cost (€ per t) Fertilizer
The cost of compound fertilizers relative to straights (CAN, Super P and Muriate of K)
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Fertilizer management on farms
Since 2006 dairy farms in the study stopped importing pig slurry Reduction in fertilizer P and K use – primarily due to costs (false economy) Very variable levels of engagement with fertilizer planning → current requirements are very complicated due to regulations → disappointment with the results – particularly with P → some plans exist only to meet regulatory requirements → disconnect between drawing up (planner) and implementing the plan (farmer)
→ farmers need to understand and control the plan to get the best outcome
Many farmers are carrying on as they have always done except more focus on fertilizer N
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20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 150 250 350 450 550 650 Annual fertilizer K use (t) Muriate of K (€/t)
The cost of muriate of potash and annual fertilizer K use
R2 = 0.85
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20 40 60 80 100 120 1990 1993 1996 1999 2002 2005 2008 2011 2014 Relative use (%) Running down soil reserves
N, P and K use between 1990 and 2011 relative to 1990
N K P
Highest fertilizer N allowance and most restrictive P allowance in Europe
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Trends in P and K fertilizer use on farms
Fertiliser K use has declined substantially despite no change in the recommendations Relationship between P recommendations/allowances and use is partly coincidental Farmers are using far less fertilizer P & K than allowed/recommended Therefore Cost has been the major factor governing fertilizer use and regulation has a lessor role → Farmers are more likely to under-use than over-use fertilizer P & K
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50 100 150 200 250 300 Cost per UFL (€)
The relative cost of grass, silage and concentrates
What farmers want in 2015
To grow 14 t of grass DM per ha per year “Simplified on-line planner to let us know how much P and K we can use” Need to maximise grass growth through optimum soil fertility Grass DM (t/ha) Average Range 8.9 7.5 to 11.5
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Conclusions
Widespread deficiency in lime, P and K on dairy farms → running down of soil reserves → inefficient use of fertilizer N → curtailing grass production on farms Cost is the major disincentive to fertilizer K and P use on farms (false economy) Fertilizer planning is complicated → this is compounded by the regulations We know how to optimise soil fertility → the problem is at the implementation stage Very variable levels of farmer engagement with fertilizer planning
The key is for farmers to understand and control the plan
K
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