Evidence that soil compaction may be limiting high rainfall pasture production is being supported by observations from local livestock producers who are seeing a response from management actions.
One producer seeing results is Karridale merino farmer Matt Nield, who usually needs a crowbar to break through his topsoil.
“The sandy loam just seems to harden up and compact in the top 10 cm with livestock,” Matt says.
However, the use of knife-points’ on his pasture seeder is helping break up his compacted soil.
“It was noticeable a couple of years ago when I saw a germination line in the knife point rows from the previous year’s seeding. I’m getting better starts because I think the knife points are improving infiltration, germination and root establishment.
“My machine is on 6-inch spacing and if I’m running at full depth, I should be running at 4-5 inches. But I was only able to get down to two inches (carrying 180-200 pound of break-out). When I come back with a second run the machine digs in a lot better.
“Where I have found a hard layer at 10 cm I’ve seen roots go sideways, so that may need deep ripping. But deep ripping might bring up more issues in this country even if you only went to 300 mm. I think with the very high rainfall you could get major issues in the winter.
“So I think freeing up the top 10 cm first and seeing if that helps any compaction in the lower layers before trying to deep rip is the safer approach.”
Matt was battling to run 100 ewes on a 20-hectare paddock at lambing and into spring. That changed in 2019 when it ran 250 ewes that came off “as fat as fools” with some of the heaviest lambs he had ever had.
“For the time being I will only seed with knife points and will tickle each paddock up with them every three to four years.”