Hog manure lethal to nematodes -
Add manure to areas with acidic soil and it can improve nematode control in potato fields

By Peter Reschke, ONTARIO FARMER

Research at the University of Manitoba has shown that potato growers can use liquid hog manure to help control harmful nematodes in the soil.

But it's not as easy as simply making an application. Other factors, like soil pH and volatile fatty acids in the manure, will determine how successful the strategy will be, says the university's soil ecologist Mario Tenuta.

Tenuta gave a presentation at a recent potato conference in Guelph where he described small plot and field-scale trials done in the past five years. He stressed the importance nematode control in potato production, saying that 15 different species of lesion nematodes can affect the crop, with some capable of causing yield reductions of up to 50 per cent. Others open up pathways for disease, like early dying syndrome, to enter the tubers.

Tenuta ran two small plot studies in 2004 and 2005, using four different treatments. One series of plots was acidified with sulphuric acid, another got a 5,000 gallon/ acre application of liquid hog manure, a third received hog manure and acid, while the last one was an unaltered control plot. Applications were made in early May, with planting one week later.

The researchers took soil samples for nematodes when the plots were harvested in September.

In all cases, the acidified liquid manure did the best job of reducing nematode numbers, while the liquid manure-only plots ranked second.

Tenuta also described a field-scale trial done on a sandy loam Alliston-area farm in 2005 where soils were treated with acidified liquid hog manure.

He now believes that liquid hog manure can kill nematodes but its composition is important. If volatile fatty acids in the manure are high, manure alone will be able to do the job. If the acids are in low concentration, acidifying the soil greatly improves the manure's effectiveness, he says.

A couple of obstacles still need to be overcome to make this management strategy feasible for growers. Firstly, a reliable test to estimate volatile fatty acids in manure, he says. Growers would also benefit from a more economical source of acid to lower the soil pH if concentrations are found to be low.

See scientific abstract "Mortality of Pratylenchus penetrans by Volatile Fatty Acids from Liquid Hog Manure"

OACC gratefully acknowledges Ontario Farmer for permission to post this article.

Posted June 2009