Grazing in Michiana
There is a lot of talk these days about "Climate Change." I recently sat in on a day-long training session that featured one speaker representing the Purdue University Climate Change Research Center. Her topic was "Building Resilience for Tomorrow's Climate," and she specifically addressed how Indiana farmers are going to have to change their operations to stay productive with later spring season warm-ups and increased moisture levels. She cited some very convincing long-term statistics that seemed to prove that average temperatures are warming, and that average precipitation is increasing in northern Indiana. This was a very interesting presentation.
I do not intend to address the political aspects of this issue. I personally don't know whether the climate really is changing long term, nor will I commit to the idea that if weather norms are different than they used to be, that those changes are originated by human activity. Anything is possible, and there are people a lot smarter than I who don't fully understand the answers to some of these questions.
It does seem to me that weather is not like it used to be, and in the last 10 years, I have often yearned for conditions that I remember as "normal" as I was trying to manage our family produce and fruit operation. In answer to the theory that weather is getting warmer and wetter, proven by long-term records, I am old enough to remember the early 1980s, when several successive severe winters between 1977 and 1982 had scientists seriously predicting the onset of a new ice age! That idea was supposed to be based on long-term records too.
At any rate, I think we can all agree that this year has been one like few of us remember. Driving the roads in LaGrange and surrounding Indiana counties, I cannot remember seeing so many fallow fields that were just simply too wet this year to plant. These conditions have not only affected the grain and row crop farmers, but the livestock farmers and rotational graziers that met for July's Pasture Walk at the Allen Yoder farm west of Shipshewana. They had their own concerns to relate as well.
One would think that the cool, wet weather that we experienced this year until mid-June would be ideal for the growth of the kind of grasses and forage plants that are commonly grown in northern Indiana. Many of our grasses, like orchard grass, the various kinds of fescue, brome, timothy and ryegrass, as well as legumes like white and red clovers, are, of course, cool-season species that were brought by our European ancestors to the New World to feed their domesticated livestock. These forages thrive on lots of moisture and temperatures between 40 and 72 degree F. (I don't know about the moisture, but maybe it's no mystery why that temperature range suits me pretty good too!)
The farmers at July's Pasture Walk had a different story to tell, however. Forage did come on with rapid growth this spring, but the consistently cool temperatures didn't quite let things explode like they often do in spring. Of course, the continually wet weather made hay harvest a real challenge. Dry hay was near impossible to achieve, and in many fields, even those planning to wet-wrap bales found the ground too soft and saturated to get into with equipment and effectively manage harvest and transport operations. Graziers with cattle to feed found themselves running out of stored feed from the year before, and were forced to open muddy, saturated and even grazing paddocks containing standing water.
Now, by mid-summer, we have finally gotten some of more "normal" weather conditions, with temperatures in the 80s and 90s, high humidity and sunshine. I've seen cracks in the ground, and corn end rows with curled and spikey leaves. The producers at July's Pasture Walk had some concerns. Several in attendance were worried about fields that had been left fallow, and how best to manage them later this season so as not to admit a total loss this year. Warm-season annuals that normally fill a mid-season gap in the grazing season in many cases were not able to be planted. And perhaps the largest concern discussed that day was the apparent lack of vigorous regrowth in grazing paddocks.
First grazings or hay makings had been done on over-ripe forages due to wet conditions. Hay quality was almost universally agreed to as being only mediocre at best. Most of the graziers there observed that second cutting or grazing was just not recovering growth as usual. Most graziers time their rotations to give grazing paddocks 21-40 days worth of recovery time before bringing the livestock in again. This year, this time interval is apparently just minimally adequate.
There were several theories advanced as to the reason for this. Some thought that perhaps excess moisture in the soil somehow interfered with vital nutrient or micronutrient uptake in plants. The greatest consensus for slow regrowth, however, seemed to be that soil compaction was the main culprit. According to Purdue University in their "Handbook of Agronomy," compaction is "the moving of soil particles closer together by external forces such as falling rain, livestock traffic and the weight of farm equipment."
Compaction increases soil density, breaks down soil structure and decreases the pore space normally found between individual soil particles. This makes the soil hard, less able to absorb moisture, increases water runoff, and makes the soil less open to root growth, penetration and development. This, in turn, makes soil nutrients located deeper down inaccessible to plant life. Compaction, in extreme cases, can become so severe as to "sterilize" areas of soil. Take, for example, an area commonly used as a farm access lane—often identified by two tire tracks devoid of growth—even of the toughest weeds!
Some graziers think of compaction as a problem for large grain operations, and tied to big tractors, combines, grain carts and limited crop species rotation. Experienced graziers know, however, that livestock hoof traffic, especially on wet, saturated soils, can cause significant soil compaction as well. In a study done by Iowa State University, it was found that while a tractor tire exerts around 11.6 psi on the ground over which it travels, an average-sized, market-weight beef cow exerts around 18 psi where her hoof contacts the ground. Because of the construction of a cow's foot, the cow concentrates more weight on a smaller area than the tractor does.
Also, given the nature of grazing, that same area of soil is going to be repeatedly subjected to hoof traffic as the grazing herd travels back and forth over the same area as it is grazed before wires are moved and the herd moves on to fresh territory. Just as in a row-crop field, it is proven that soil compaction will adversely affect the quantity and quality of plant growth in a grazing paddock or hayfield just as much.