Dairy: Three-day deluge was a shock to the system
Published 23/09/2015 | 02:30
A deluge of 111ml (almost seven inches) of rain fell on our farm the weekend before last. It was some shock to the system as the rainfall for the year until the end of August had been the lowest for four years.
The amount varied by parish and county, but I know that as the rain clouds headed east, many farmers in the west experienced similar downpours.
I'm sure this downpour was also a shock to the system for the cows, who often exhibit a dive in milk yield and become unsettled in these extreme conditions.
During the very wet years of 2009 and 2012, I found that offering or increasing the meal feeding by at least 1kg helped the cows, especially in prolonged rainy periods.
Back to this year, on the ground many ponds or wet areas remained several days later.
This meant farmers found themselves on a shorter than planned rotation as they had to return to drier paddocks while increasing the area on offer and foregoing residuals somewhat to minimise poaching risks.
Thankfully in most cases the ground has coped extremely well and has soaked the rains away, so normal grazing practices have resumed.
Experience has also shown me that, once rainfall breaches 100ml in a 30-day period on heavier soil types, ground conditions can become challenging with increased risks of poaching and sward damage.
It sets my alarm bells ringing about potential trouble ahead.
I've had all fingers crossed that last week would remain dry to let my fears subside as much as the water-table.
September is usually a mighty month for grazing and grass growth, but autumn rainfalls on heavier farms have a cumulative impact.
The shortening days and falling temperatures result in less drying than in the spring and summer months.
In these circumstances, repeated heavy rains will force the heavy farm to withdraw from grazing, and house prematurely. Again fingers crossed this doesn't happen too soon.
But I will always promote the importance of extended grazing on free-draining soils, and on heavy soils in lower rainfall areas.
And while I'd love to be one of these farmers, the reality is that on our farm in Kerry, with a heavy soil in a high rainfall area, this practice just doesn't work.
Ground conditions have always become saturated in the last eight years.
Therefore the key to autumn grazing management is to protect the cows' body condition score and to protect the sward for spring grass growth and grazing conditions.
From what I've seen, the damage done to a sward in the autumn is ten times worse than the same level of poaching in spring.
While poaching damage should be minimised in either season, autumn damage will be seen right into the next year reducing sward density and grass growth, yet spring damage is more likely to recover.
Therefore a heavy farm will extend rotation up to 35 days, and will avoid building heavy covers of greater than 1,800kgDM/ha. If the covers get any heavier, you risk not getting these grazed off before conditions potentially deteriorate.
Carrying over very heavy covers through the winter risks winter kill and does not promote grass growth in the following year.
I'm aware that I may risk encouraging a farmer who has free-draining ground not to maximise the potential of grazed grass.
However I feel it's important to recognise the skill set and the ability of the farmer who learns to manage wet ground.
Mary Kinston is a discussion group facilitator and consultant, farming with her husband in County Kerry