Stinky manure has resulted in a dozen complaints to Hawke's Bay Regional Council from Havelock North residents.
The odour was tracked to a paddock west of Te Aute Rd.
Environmental officer Ian Lilburn said a mix of wool dust and compost was spread on Tuesday and Wednesday mornings as a fertiliser/soil conditioner and dug in on Wednesday afternoon.
"Normally this product is okay but in this case the wool dust/compost mix was wet from recent rain, which really brings the odour out of the wool dust when it is disturbed in the spreading process," Mr Lilburn said.
"Generally there is little or no odour with just mature compost, or if this mix is dry and disked or hoed in straight away."
Nearby resident Graham Dawson said the smell had been particularly bad on Wednesday and was noticeable at the Havelock North library, at the far side of the shopping precinct.
"It smelled like the Clive sewer works had been brought to Havelock North," he said.
Neighbour Victoria McIntosh said she was in the Havelock North domain on Thursday and the smell was "quite noticeable".
"Everyone was picking up their shoes thinking they had stepped in something. Everyone was commenting on it," she said.
Mr Lilburn said a council officer was monitoring the situation "by his/her nose" against the FIDOL factors of the Resource Management Act.
"FIDOL factors are: frequency, intensity, duration, offensiveness and location.
"For example, a strong odour for a short duration in a certain area may be permitted, but if that odour is present for a long time or happens frequently, then it maybe a breach of the RMA and we would act accordingly."
Mr Dawson, a Havelock North resident for 25 years, said he accepted the occasional odour was to be expected when living near farms. "A bit of manure yes, but a bad stink that takes out a couple of square miles? I don't think so."