Why farmers spread manure when they do
By: Patricia Grotenhuis, sixth generation farmer
This summer, one of our neighbours asked us a favour, and we just couldn’t grant it.
One Saturday morning at approximately 9:30 a.m., we heard a knock at the door. Our neighbour had a request – could we please not spread manure that day, since he was having a family reunion and was afraid the smell would be too strong. We were left in an awkward position. The request seems simple enough to grant. There are always jobs to do on the farm, so simply switching a day of spreading manure for a day of doing other jobs is surely easy, right? Wrong.
There is a science behind spreading manure, and following it helps protect the environment and ensure the nutrients are available to the crops. The specific field we were spreading on was an alfalfa and timothy mix (a legume and grass mixture used to feed cattle), which had been harvested for haylage. This means the crop was chopped and put in the silo while it was still partially wet. It will ferment in the controlled conditions of the silo, creating a rich feed for our cows.
Growing hay and haylage crops takes nutrients out of the soil, and these nutrients have to be replenished. Since hay and haylage are grass crops, they begin growing again as soon as they have been harvested, making it essential to get fertilizer on the fields as soon as possible after cutting so the soil nutrients are not depleted.
We had just finished harvesting the night before, so it was a perfect time to apply.
What about the environmental conditions, though? Are there ideal times to spread manure? There are, and that day fit all of the requirements perfectly. The Ontario Ministry of Agriculture and Food (OMAF) website suggests farmers should spread manure on a cool, cloudy day with a light rain in the forecast to help work the nutrients into the soil.
The day in question was about 20 degrees with a breeze and a heavy cloud cover. There was a gentle rain in the forecast both for that night and the following day. We looked ahead in the weather forecast to see which other days might fit the environmental requirements. None did. After the two overcast days and the light drizzle, the weather was to turn hot, humid and sunny, with no rains.
Hot, sunny days are bad for spreading. A chart on the OMAF website shows how quickly nutrients are burned off by the sun on these days, and from looking at it, we realized if we waited to spread, the nutrients our soil needed would instead be lost in the air. We can all agree this is not a good way to help the environment. Nitrogen is much better in the soil than it is in the air we breathe.
On top of the fact we would be benefiting the environment by spreading that specific day, and would be harming the environment if we spread at the start of the following week like our neighbour suggested, there was the final determining factor. All of the equipment was out and set up, the manure pit had been agitated, and we were ready to begin when he drove in. Since the manure sits in the pit between applications, the top forms into a crust. Agitating the pit breaks up the crust and makes the manure in the pit uniform, so we know which application rate to use.
In the end, we went ahead and spread manure, like many other farmers in the area. We did not spread on fields that were directly upwind of the gathering to try and minimize the odour, and we only spread on one field and one pasture. The light drizzle that fell that evening during chores took away the odour and incorporated the nutrients into the soil, confirming we made the correct decision.
As farmers, we take pride in being good environmental stewards and good neighbours. We try to limit our impact on our neighbours so we can all live in this area comfortably. With advance notice given, we will try to fulfil requests made by neighbours. However, because the farm is a business, it does have to continue operating and we often cannot change plans at the last minute. In the end, our final decision will always be based on doing what is right for the environment and our animals.