Our Organisation Search
Quick Links
Toggle: Topics

Solohead Farm

The research focuses on low input systems of milk production based on grass-white clover swards examining issues such as productivity, grazing management, persistency of clover is swards, nitrate leaching and emissions of nitrous oxide and ammonia.

Researcher - James Humphries  Farm Manager - Daniel Barrett

Rolling grassland at Solohead Research Farm with the Galtee Mountain Range in the background

The current research programme is focused on white clover and 50 of the 52 ha on the farm are clover-based swards with an average clover content of 20 to 25% receiving annual fertilizer N input of between 0 and 100 kg N/ha.

The clover content of swards is around 5 to 15% of pasture DM during April (left) and 35 to 45% in August/September (right)

Solohead Farm Profile

History: The farm is owned by Tipperary Co-operative Creamery. Teagasc uses the farm in partnership with Tipperary Co-op. to carry out applied research into systems of milk production and grazing management. This partnership began in 1976.

Location:The Solohead dairy research farm is located near Limerick Junction in Co. Tipperary (latitude 52° 51' N; 08° 21' W; altitude 95 m a.s.l.).

Area: 52 ha (effective)

Herd: The herd consists of 95 cows plus 28 replacement units.

System: Spring calving dairy herd supplying 575,000 litres milk. There is a relatively long grazing season extending from early February to late November. The slow-draining nature of the soil means that it can get saturated during and following periods of high rainfall and is very prone to damage by grazing cows. A flexible approach to grazing management is required to avoid this.

Soil Type: The soils on the farm are a mixture of heavy Gleys and Grey Brown Podzolics. The soil has a clay-loam texture, 25% sand and 42% clay in the upper 20 cm with increasingly massive structure and low permeability in lower horizons (poor drainage). However, a network of deep (2.5 m) open drains and underground feeder drains in the wetter fields has been installed to lower the water table. The soils at Solohead represent almost 23% of the soils of Ireland that are typically under permanent grassland management.

Paddocks: 37 paddocks

Dairy Infrastructure:

  • Milking parlour: 12 unit herring bone with ACR.
  • Accommodation: 109 cow cubicles and 18 weanling cubicles – extendible.

Farm Map

Solohead Herd Profile

Average annual milk production over the last 10 years has been 6,400 kg/cow. The fat and protein percentage in milk between 1997 and 2007 is shown in Table 1.

Table 1. Trend in average annual milk fat and protein

 percentage at Solohead between 1997 and 2007.

Year Fat % Protein %
1997 3.82 3.37
1998 3.85 3.34
1999 3.83 3.42
2000 3.94 3.48
2000 3.94 3.48
2001 4.02 3.55
2002 3.98 3.45
2003 4.07 3.57
2004 4.15 3.56
2005 4.28 3.57
2006 4.17 3.57
2007 4.154 3.60

This steady increase in fat and protein in milk can mainly be attributed to selection of bulls with high milk solids composition. The objective has been to produce an average of over 500 kg of milk fat and protein per cow.

Mean Calving Date: 20th Feb. 2008

Herd:The herd is mainly Holstein-Friesian with 15% cross-bred Holstein-Friesian x Montbelliarde cows. Crossbred cows are back crossed to Holstein-Friesian bulls. Montbelliarde bulls are crossed onto pure-bred Holstein-Friesian cows.

Sires of Cows: Bulls used in recent years include ILZ, KNW, HFL, RDU, RMW, OJI, GIO.

Concentrate Input: Average concentrate input has been 490 kg/cow.

Solohead Farm Current Experiments

MKDC-5676: Post grazing height and the productivity of white clover-based systems of dairy production

RSF07-516: Quantification of the potential of white clover to lower greenhouse gas emissions from Irish grassland-based dairy production.

RSF07-511: Productivity of clover-based grassland under simulated organic production and nitrate losses to ground water.

Post grazing height and the productivity of white clover-based systems of dairy production

Project Leader: James Humphreys


A considerable amount of information indicates that tight grazing favours the clover content of swards (Frame and Boyd, 1987; Acuña and Wilman, 1993; Schils and Sikkema (1999). In general cutting to 4 cm increased clover yield by 30% to 35% and combined grass and clover yield by in the region of 16 to 20%. Cutting to 8 cm at intervals of 4 weeks resulted in a severe reduction in clover content, almost eliminating it from the sward over a three-year period. However, grazing to approximately 4 cm is known to depress intake of herbage and lower milk yield and composition (Mayne et al., 1987; Maher et al., 2003). The objective of this experiment was to evaluate the impact of grazing intensity on the clover content, herbage production and milk production from cows grazing grass-clover swards.

Materials and Methods

There were three treatments involving three different post-grazing heights (PGH) maintained throughout the grazing season (February to December; Fig. 1). Each treatment received annual fertilizer N input of 100 kg/ha and was stocked at 2.0 cows/ha.

There were 27 cows per treatment. Cows were divided into four main groups on the basis of lactation number (1, 2, 3 & ³4) and then sub-divided into sub-groups of three on the basis of calving date. From within each sub-group one cow was randomly assigned to each herd. Herds were randomly assigned to each treatment. Milk production in the third whole week of lactation was used as covariate in analysis of variance. Mean calving date was 22 February. Clover stolon production was measured in February, May, August and November.

Results and Discussion

There were no (P >0.05) differences in production of milk, fat, protein or lactose, although each of these tended to decline with lower PGH (Table 1). Likewise there were no (P >0.05) differences in live-weight or body condition score (BCS) at the end of lactation (Table 1).

There were no (P >0.05) differences in stolon mass between PGH treatments. There were differences (P <0.001) between sampling dates (s.e.m. = 57.0) with stolon dynamics showing typical annual cyclicity: lowest masses in spring and highest in the late autumn. Low masses in February 2007 compared to February 2008 can be attributed to one-third of the paddocks on each treatment containing no clover at the start of the experiment. Grazing to 4 cm increased herbage production and, hence, carrying capacity by 12%.


Lowering PGH from 6 to 4 cm did not increase stolon mass and clover content of swards and did not have a detectable impact on milk output or on cow live-weight or BCS although there were trends towards lower milk production and lower live-weight and BCS associated with lower PGH. This needs further investigation.

White clover stolon, roots (with nodules) and leaves

Table 1. Annual production (kg/cow) of milk, solids-corrected milk (SCM), fat, protein and lactose, cow live weight & body condition score (BCS) at end of lactation
PGH 6 cm 5 cm 4 cm P value s.e.m.


Milk 6183 6039 5896 NS 160.3
SCM 6032 5820 5746 NS 162.0
Fat 257 248 247 NS 7.6
Protein 225 217 210 NS 5.7
Lactose 283 274 270 NS 7.7
Live Weight 635 635 620 NS 8.0
BCS 2.93 2.97 2.84 0.06 0.038


Acuña P., G.H. and Wilman, D. (1993) Effects of cutting height on the productivity and composition of perennial ryegrass-white clover swards. Journal of Agricultural Science, Cambridge, 121, 29-37.

Frame I. and Boyd A.G. (1987) The effect of fertilizer nitrogen rate, white clover variety and closeness of cutting on herbage productivity from perennial ryegrass/white clover swards. Grass and Forage Science, 42, 35-96.

Maher J. Stakelum G. and Rath M. (2003) Effect of daily herbage allowance on the performance of spring-calving dairy cows. Irish Journal of Agricultural and Food Research, 42, 229-241.

Mayne C.S. Newberry R.D. Woodcock S.C.F. and Wilkins R.J. (1987) Effect of grazing severity on grass utilization and milk production of rotationally grazed dairy cows. Grass and Forage Science, 42, 59-72.

Schils R.L.M. and Sikkema K. (1999) The effect of cutting height and management system on the performance of a grass/clover sward. In: Frame, J. (ed.) Developments in White Clover. FAO REUR technical series no. 29.

Nodules on white clover roots containing Rhizobia bacteria capable of supplying 150 kg N/ha in the soil each year.

Quantification of the potential of white clover to lower greenhouse gas emissions from Irish grassland-based dairy production

Project Leader: James Humphreys

Project Abstract

This project aims to quantify the change in greenhouse gas (GHG) emissions from Irish dairy production when mineral fertilizer N (MFN) is replaced by white clover-biologically fixed N (BFN). This will be quantified using lifecycle assessment (LCA) on a whole farm basis, initially using existing data sets of N flows within both MFN-based and white clover-BFN-based systems of dairy production measured over the last four (2003-2007) years at Teagasc Research Farm at Solohead. Gaps in existing knowledge in terms of nitrous oxide and ammonia emissions will be filled by on-site measurements and compared with model predictions. An appropriate LCA methodological framework will be developed and questionnaire detailing the key inputs needed to conduct the LCA of dairy farms will be drawn up. This questionnaire, which will include indicators of economic performance, will be used in the collection of data from approximately 20 farms on a range of soil types around the country that have switched from MFN-based to white clover-BFN-based grassland in recent years. This will give a broad-based interpretation of the likely change in GHG emissions associated with the wider use of white clover for dairy production that can be linked into the national emissions inventory. This study may provide justification for payments for white clover in rural environment protection schemes.

Start date: 01/11/07

Completion date: 31/01/11

Collaboration: Bioresources Research Centre, UCD School of Agriculture, Food Science and Veterinary Medicine Earlsfort Terrace, Dublin 2: Nick Holden. Teagasc, Johnstown Castle, Wexford: Gary Lanigan Civil and Environmental Engineering, University College Cork: Paul Leahy

Funding Agency: Department of Agriculture and Food

Measuring nitrous oxide emissions farm clover-based and fertilized grassland at Solohead Research Farm using (i) manual closed chambers (left) and (ii) auto-chamber (right) to measure temporal variability of nitrous oxide fluxes over periods of 24 hours.

Productivity of clover-based grassland under simulated organic production and nitrate losses to ground water.

Project Leader: James Humphreys

Project Abstract

Manufacturers of fresh organic dairy products offer a price premium of 157% to dairy producers that supply >55% of their milk during the winter. Grazing cows on clover-based grassland is a key component of profitable organic milk production. Ireland’s climate is conducive to production from clover swards over a long growing season. Organic systems of production operate at low stocking rates compared with conventional systems. Low stocking rates offer the potential to extend the grazing season throughout the autumn, winter and early spring. This project aims at substantially lowering the cost of feed for organic winter milk production by supplying a large proportion (>50%) of the diet from grazed clover swards during the autumn and winter. However, grazing during the winter, albeit at low stocking rates, carries the risk of losses of nitrate to groundwater. One objective of this project is to investigate the productivity of white clover-based grassland under different management regimes for dairy production: (i) conventional spring calving; (i) simulated organic non-fertilizer-N (NFN) spring calving; (iii) NFN winter production, with particular emphasis on autumn-winter production from clover-based swards. The other objective is to measure the impacts of these three systems on nitrate losses to groundwater.

Sub-project: Aspects of the survival of white clover in grassland

The objective is to study the impacts of shading and hoof-damage during the autumn and winter on clover abundance measured in terms of clover stolon mass and clover herbage content of sward herbage DM. These factors will be examined in two experiment: (i) sward canopy structure during the autumn and winter, abundance of clover stolon and sward productivity and (ii) Hoof-damage during the autumn and winter and clover stolon survival and abundance. Experiment (i) will be a plot-scale experiment where different canopies of herbage of grass-clover swards will be established by different harvesting regimes during the autumn and winter. Canopies will be described in terms of sward height and herbage mass. The extent of shading will be determined by light interception at the base of the sward recorded using an Accupar® Lp-80 ceptometer. These measurements will be used to establish a relationship between light interception at the base of the sward during the autumn and winter and clover stolon abundance during the following spring and summer. Experiment (ii) examine the impact of hoof-damage on clover stolon abundance within system-scale experiment examining different systems of milk production, including one system involving grazing during the winter. There will be six paddocks per system. Within each paddock stolon abundance will be determined in strips (1 m x 20 m) that are either unprotected or protected from hoof-damage. The effect of hoof-damage in each strip will be assessed using (a) ground-scoring index, (b) photographs analysed using Photoshop® and (c) a ground penetrometer.

Start date: 01/11/07

Completion date: 31/04/11

Collaboration: Department of Chemical & Life Sciences, Waterford Institute of Technology Cork Road, Waterford. Eddy Fitzgerald and I.A.Casey.

Funding Agency: Department of Agriculture and Food

Shallow wells installed to a depth of between 1.0 and 2.5 m for measuring nitrate losses to groundwater from clover-based dairy production