Archive: Season overview

Published 12 December 14

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2014 Grass season overview

Following a challenging 2013 season, with rehousing in spring and drought conditions curbing growth in July, grass management in 2014 has been considerably more stable but not without its own challenges. As we now collate the last of the grass figures for 2014 from the Forage for Knowledge (FfK) grass measurement farms, DairyCo R&D manager Dr Debbie McConnell takes a look back at what has turned out to be a less volatile and more productive season for grass production across the FfK farms.

Grass growth rates

Total grass production across our FfK farms this year was approximately 800kg DM/ha greater than our 2010-2013 average, with the10 farms producing, on average, 12,612kg DM/ha between 1 March and 31 October (Figure 1). 

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Figure 1: Daily grass growth rates in 2014 compared to the 2009-2013 average throughout the growing season.

The season got off to a good start with daily grass growth rates averaging 48kg DM/ha between March and May. As a result, grass growth in Spring 2014 was 23% higher (4,442kg DM/ha) than the 2010-2013 average (3,626kg DM/ha) and 50% greater than Spring 2013 (2,923kg DM/ha). This was predominantly due to higher mean temperatures, which were on average 3oC higher than 2013 and 1.3oC higher than the long term average (Table 1).

Table 1: Seasonal mean air temperature, rainfall and sunshine hours in 2014. (Source: Met Office, 2014)

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 * Difference from 1981-2010 average.

Growth over the rest of the  season remained comparable with seasonal averages, with Summer growth 99% of the 2010-2013 average at 5,457kg DM/ha and Autumn growth 102% of the 2010-2013 average at 2,712kg DM/ha. However, a dry and warm Autumn (Table 1) has meant that soil conditions have facilitated extended grazing and higher regional growth in some areas.

Grass quality

Grass dry matter (DM) and crude protein (CP) content remained relatively comparable with the longer term 2010-2013 records (Figures 2 and 3). Average grass DM content throughout the season was 18.0% (2010-2013 average = 18.8%), while mean CP content was 23.5% compared with a 2010-2013 average of 23.9%. There was a small but notable dip in both DM and CP content in May 2014, most likely due to a reduction in sunshine hours during the month (only 80% of the long-term average).

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Figure 2: Grass dry matter content from the FfK farms during the 2010-2013 and 2014 growing season

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Figure 3: Grass crude protein, content from the FfK farms during the 2010-2013 and 2014 growing season

Grass metabolisable energy (ME) content was 0.6 ME lower on average throughout 2014, compared with 2010-2013. For the 12 weeks ME content averaged 12.3MJ/kg DM but from the middle of May onwards ME contents averaged 11.5 MJ/kg DM.

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Figure 4: Grass metabolisable energy, content from the FfK farms during the 2010-2013 and 2014 growing season

This was largely an effect of winter 2013-2014, which saw average air temperatures 1.5oC higher than the 30 year average, and notable lack of frost, with 20 days less air frost than average across the UK (Figure 5, Met Office, 2014). The higher air temperatures resulted in delayed dormancy on many grass plants, meaning that through the winter grass kept respiring, photosynthesis was curbed by the lack of sunlight typical at this time of year. As a result, continued respiration through the winter months meant that grass plants used up a significant portion of their internal energy store which is replenished during the growing season by photosynthesis. This most likely resulted in a loss of quality earlier in the season than we typically would expect.

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Figure 5: Mean temperature anomaly (difference from long-term average) map for Winter 2013/2014.

Forage for Knowledge grass growth monitoring will be starting again in February 2014. We would like to thank all the FfK farmers for their contributions to the newsletter over the last 11 months and wish all our contributors and readers a Merry Christmas and a Peaceful New Year.