Measuring annual pasture yield: it can be done

Measuring annual pasture yield: it can be done

13 April 2015

For years arable farmers have mapped variation in crop yields. Now, new research shows farmers can also measure variation in pasture yields, using readily available tools.

Mike Manning, Ravensdown General Manager of Strategy and Innovation, says the research takes precision farming to the next level, with immediate practical applications. “This work is in the early stages but already we can see how it will benefit farmers, particularly around identifying areas of pasture that are underperforming and places where avoidable problems are emerging.”

How do you measure yield when paddocks are frequently grazed?

Measuring pasture yield is complex. They are harvested multiple times during the year and frequently grazed. However, it is possible.

Using six paddocks at the Lincoln University Demonstration Farm (LUDF), managed by the South Island Dairying Development Centre (SIDDC), AgResearch researchers mapped pasture cover pre and post-grazing, every grazing, for two seasons using the latest C-Dax Pasture Meter.
They subtracted the post-grazing map from the pre-grazing map, to create an intake map. Adding up all paddock intake maps, they determined a total annual yield variation map for the six paddocks.

Collecting pasture yield maps from eight commercial dairy farms in Canterbury and the West Coast, with a variety of soil types and irrigation systems, researchers assessed whether the results measured at LUDF were applicable to other farms in the region and found that they were.

How can the data be used?

The LUDF results revealed substantial pasture yield variation in individual paddocks, even though the experienced LUDF management team believed them to be reasonably uniform. One option identified to tackle significant variation, which could not be attributed to known factors such as effluent areas or irrigation equipment, could be targeted fertiliser application on areas of low yield.

Mike Manning says: “from here work will continue to look more closely at the causes of variability and what can sensibly be done about it.”

SIDDC is a partnership between Lincoln University, DairyNZ, Ravensdown, LIC, Plant & Food, AgResearch and SIDE. Its partners network to advance South Island Dairying.