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 O’Brien

Characteristics of 50 dairy farms Average farm size: 66 ha Average no. dairy cows: 98 Average milk sales: 525,000 litres Milk solids per farm: 40,500 kg Milk solids per cow: 415 kg Concentrates fed: 645 kg/LU Fertilizer N use: 230 kg/ha Fertilizer P use: 8 kg/ha Fertilizer K use: 29 kg/ha

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 Dairy cows as a percentage of total livestock on farms 74 72 Dairy cows (%) 70 68 66 64 More dairy cows → less beef cattle 62 2002 2004 2006 2008 2010 2012 2014

Soil fertility on dairy farms 551 samples – silage and grazing areas Soil pH greater than 6.0 Index 3 & 4 for soil P and soil K 54% of fields with low soil pH 39% of fields with low soil P 25% at 39% of fields with low soil K optimum Fertilizer use 75% deficient in lime, P or K Fertilizer N P K Actual (kg/ha) 230 8 29 Required (kg/ha) 230 17 70

The relationship between soil P and soil K on farms No relationship 400 350 R 2 = 0.042 300 Soil K (mg/L) 250 200 150 100 50 0 0 5 10 15 20 25 30 Soil P (mg/L)

Soil fertility on dairy farms 551 samples – silage and grazing areas Soil pH greater than 6.0 Index 3 & 4 for soil P and soil K 54% of fields with low soil pH 39% of fields with low soil P 25% at 39% of fields with low soil K optimum Fertilizer use 75% deficient in lime, P or K Fertilizer N P K Actual (kg/ha) 230 8 29 Required (kg/ha) 230 17 70

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 25 20 Grass DM (t/ha) Proportion of farms (%) Average Range 15 9.8 7.5 to 11.5 10 5 0 <10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 Proportion of fields that are optimum (%)

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

Soil K in fields plotted against average soil K on each farm 350 300 Soil K (mg/L) per field 250 200 150 100 50 - 60 80 100 120 140 160 180 Farm average soil K (mg/L)

Soil K in fields plotted against average soil K on each farm 350 300 Soil K (mg/L) per field 250 Index 4 200 150 Index 3 100 50 Index 1 & 2 - 60 80 100 120 140 160 180 Farm average soil K (mg/L)

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

The cost of compound fertilizers relative to straights (CAN, Super P and Muriate of K) 100 80 60 Relative cost (€ per t) 40 20 0 -20 -40 -60 -80 -100 Fertilizer

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

The cost of muriate of potash and annual fertilizer K use 160,000 R 2 = 0.85 140,000 Annual fertilizer K use (t) 120,000 100,000 80,000 60,000 40,000 20,000 150 250 350 450 550 650 Muriate of K (€/t)

N, P and K use between 1990 and 2011 relative to 1990 Highest fertilizer N allowance and most restrictive P allowance in Europe 120 N 100 Relative use (%) 80 K 60 P 40 20 Running down soil reserves 0 1990 1993 1996 1999 2002 2005 2008 2011 2014

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

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” The relative cost of grass, silage and concentrates 300 Grass DM (t/ha) 250 Cost per UFL (€) 200 Average Range 150 8.9 7.5 to 11.5 100 50 Need to maximise grass growth through optimum soil fertility 0

Conclusions Widespread deficiency in lime, P and K on dairy farms → running down of soil reserves K → 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

Recommendations Need farmer engagement with fertilizer planning to get the best outcome Need a simplified planner that works on a per-field basis → adjust regulations to accommodate this Farmers are more likely to under-use than over-use fertilizers (cost sensitive) P and K use is self- correcting when accompanied by soil testing Get soils tested and make use of results → identify fields with deficiencies → calculate lime and fertilizer requirements Improving soil pH is the first step → Ground limestone Identify fields low in K and recycle slurry to these fields Compounds or straights (muriate of potash) to balance the remainder