Maintaining productivity from grassland long-term

Grassland productivity on organic farms varies widely. This workshop drew on the experiences of farmers to identify some of the causes of low performance and how to remedy them: phosphate and potassium levels, biological activity, soil structure, forage species, manuring and grazing systems. This session was sponsored by OMSCO/IOTA
Mark Measures (IOTA): chair.

Session summary

Grassland productivity on organic farms varies widely; some farms report excellent production and stocking rates while others are finding it difficult to maintain forage production. The session drew on the experiences of farmers to identify some of the causes of low performance and how to remedy them. Tim Downes has been an organic farmer since 1998 and his farm with 250 cows runs on a New Zealand grazing system. They use soil analysis to facilitate decisions on recycling of nutrients and over the past 7 years have used plate meters to estimate forage production. He pointed out that calculations to estimate forage Metabolizable Energy (ME) are not adjusted for farms, which creates some uncertainties. Over recent years forage yields have declined, but it is likely that poor weather conditions have contributed to this.

Tom Willoughby’s 108 cow dairy farm has been organic since 1999 and in the early years forage production and stocking rates were satisfactory. Over the last 5 to 6 years the farm has experienced a decline in forage production of 30% and a 45% reduction in arable crop yields. To address the problem leys have been re-seeded, routine soil aeration has been carried out, targeted manure applications as well as organic fertilisers have been used, but, soil K and P levels still remain low. Low milk prices are also a disincentive for the farmer to invest in solutions.

Edward Goff started conversion of his 150 acre dairy farm in 1983. With regular re-seeding of white and red clover leys, soil analysis and occasional use of rock fertilisers, he has successfully maintained pasture yields over 3 decades and is still stocking at 1.8 LU/ha. However, all the speakers agreed that low forage yields, despite the severe weather conditions, are likely associated with soil nutrient levels.

Discussion focused on soils and minerals, forage mixtures and forage quality. Comments about the limitations of standard forage analysis, pointed out the importance of wet chemistry to get reliable indications of forage quality. The associations between soil nutrient levels (particularly trace elements) and the serious trace element deficiencies recently found in organic milk was highlighted, indicating also the need for farms to monitor more closely. With regards to forage quality, the importance of specifying better varieties and the great value of herbs and alternative grasses were emphasised as a means of minimising the effect of drought.

Tom Willoughby

Key conclusions

The discussion that followed the presentations brought out the following points:

  • Wet chemistry to get reliable indications of forage quality
  • Monitor trace elements in the soil
  • Soil fertility and surface compaction are important elements of productivity

Action points

  • Soil should be analysed for major nutrients and trace elements every 3 to 4 years
  • Surface compaction can be dealt with by grass slitter
  • Assess the clover percentage for each field every 6 months for a target of 20- 30%
  • Ensure that grazing rotation allows sufficient time (at least 3 weeks) for recovery of the sward.

Individual speaker presentations and abstracts

Tim Downes (JR & MC Downes & Son): Growing forage in the ‘Orange Triangle’!

We converted to Organic in 2000 and have since moved to an all grass system this season, 250 Cows and finish beef from red clover silage. All loose-yarded, so making use of compost and recycling of nutrients according to soil analysis. We plate meter measure the grazing block weekly and have done for over 7 years giving a good idea which paddocks are under or over performing. Recently forage yields have declined; we will discuss if that is due to the difficult weather conditions or if there is some other factor after 13 year of organic farming.

Edward Goff (Hindford Grange): Forage production at Hindford Grange (no powerpoint)

I started organic conversion of the 150 acre dairy farm 30 years ago, since which successful forage production has been central to the business. Through regular re-seeding with white and red clover leys, soil analysis and occasional use of rock fertilisers, use of composted FYM and paddock grazing acceptable stocking rates have been maintained throughout the period.

Tom Willoughby: Experiences of declining forage production (no powerpoint)

Organic conversion of our 108 cow dairy farm started in 1999. In the early years forage production and stocking rates were good but we have experienced declining forage yields during the last 5 or 6 years, associated with declining P and K levels, despite routine soil aeration, targeted manure use, reseeding and some use of fertilisers. The presentation will provide and overview of the current situation, what we have done to address the problem and hopefully stimulate some discussion on the way forward.


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