Evaluating pasture measurement results after the 2012 drought

I have been measuring my weekly pasture growth for the past seven years. My initial goal was to grow as much forage as economically as possible.

Dry matter target

I targeted 5.5 tons of dry matter per acre, per year. I utilized the county soil survey report and the Ohio Agronomy Guide as my guide to help set my yield goal. The soil survey is more than 30 years old. The corn yield for my soil type was only 115 bushels per acre back then.

We know the average corn yields have been more than that in the recent years. We should also be growing more forage per acre just as our corn yields have increased over the last thirty years.

The average state forage yields have been lower than the soil survey yields. Why we are not growing more forage per acre will be a topic for another article.

Pasture yield

The Agronomy Guide has 11,000 pounds of dry matter per acre per year as the highest grass-legume pasture yield for a deep soil with very good fertility. That was the yield I selected. I have grown more than 7 tons of dry matter per acre, per year my first two years I was measuring my pasture growth.

One of those years I was 90 pounds short of 8 tons per acre. That is like growing 300 bushel an acre corn for you corn farmers. That is a big yield from a pasture field.

I have also been through some very dry summers as well. Over the past seven years, two years were below average, two years were average, and three years were above average. Remember my average is 11,000 pound of dry matter per acre, per year.

This year will be another below average year. I have only grown about 2 tons of dry matter per acre so far this year. About 60 percent of the cool season pasture growth in Ohio comes before July 1. It takes the next six months to grow the remaining 40 percent.

Not a good year

The most I can hope for this growing season is another 2 tons of dry matter from my pasture fields utilizing stockpiling methods. The month of April in my pasture growth measurements has been higher than the long term average ever year for the month of April, including this year.

April 2012 was my second lowest April production in the last eight years. The lowest April production was in the dry spring of 2007. That year was my lowest total dry matter production year. The pasture yielded only 3.26 tons of dry matter per acre. That is still 50 percent higher than the state average yearly forage production on a per acre basis.

This year the total forage dry matter production in my pastures for May, June, and July is the lowest I have ever measured, including the dry year of 2007. May was 50 percent of the estimated yield, June was 25 percent and July was 30 percent of the estimated yield.

August looks to be similar to July at about 30 percent of the long term growth curve average for a highly productive mixed grass-legume pasture. The estimated growth curve for my pasture is 13 percent in April, 25 percent in May, 20 percent in June, 5 percent in both July and August, 15 percent in September, 10 percent in October, 5 percent in November and 2 percent in December.

Actual growth

What we have been seeing by measuring the actual growth the past seven years is a growth curve with the growth distributed 21 percent in April, 18 percent in May, 31 percent in June, 8 percent in July, 5 percent in August, 9 percent in September, 5 percent in October, 2 percent in November and 1 percent in December.

The fall growth of September through November has been less than half the long term average since I started weekly measurements. Even in those great production years of 2005 and 2006 when I average more than 7 tons of dry matter per acre, we had only 70 percent of the projected fall forage growth. I presented this data at an American Forage and Grassland Council Annual Meeting.

Raising the questions are we seeing a change in our long established forage growth curves? Is this a short term effect and will average out over the long term? Are the weather patterns affecting the growth curve?

Are the new and improved forage varieties growing differently than the older varieties? Do the Management intensive Grazing practices that I am implementing affect the growth curve?

Studies needed

It may take some long term studies to know for sure. What I do know is you cannot manage what you do not measure. Without measuring I could not compare year to year and we would not be able to challenge the researchers with these questions. I did know by measuring pasture growth weekly this year the April growth is far behind previous years and I should start managing for a drought.

By the end of May there was no doubt that forage production was going to be very low. I got extra hay in the barn as it came out of the field. I bought all my hay needs.

We started making grazing management adjustments as well. We started leaving more residual leaf area after each grazing event. We were leaving 1650 to 1850 pounds of dry matter (leaf area) after each grazing event instead of the typical 1200 to 1500 pounds per acre. That helped shade the soil from the hot sun, reduced evaporation of soil moisture.

Cooler soil

The cooler soil may have also kept the plant roots more active and absorbing more moisture. That extra residual also helped hold more dew and rain when it did rain. Very little of the rain ran off my pasture this summer even in the ”very short lasting” high intensity storms.

We also lengthened the rest periods by allowing smaller grazing areas which also increased the grazing utilization rate. The ewes and lambs wasted less forage and did less selecting.

My pastures have stayed active and have not gone dormant. We have had weeks with no growth, but the forage plants were active. The 90-plus-degree days and the warm nights have been more difficult to manage around. The grass plants burn more energy than they make on those days and do not leave much energy for the grazing animal.

Energy needed

We started feeding hay, not because are animals need feed, but because they need the energy. There was not enough energy in the grass they were grazing. I believe this is the year to plant fall and winter annuals, oats, annual rye grass, rye, turnips, triticale and wheat.

Annuals will produce more dry matter in a growing season than perennials; they may cost more with annual seed and planting costs. Those of us with tall fescue we also have the advantage of fertilizing and growing stockpile winter grazing forage.

I will be measuring my fall stockpiled grass in late November to help figure out my winter feeding program What about you?

About the Author

Bob Hendershot retired from the USDA NRCS as Ohio's first state grasslandc onservationist and GLCI coordinator after nearly 37 years of service. He and his wife live on a farm in Pickaway County. He is still active in grazing and sheep activities. He is a Certified Forage and Grassland Professional (AFGC) and a Certified Crop Consultant (ASA). He was named the nation's outstanding pasture conservationist in 1999 and was inducted into the Ohio State Conservationist's Hall of Fame in 1998. He is also a past president of the American Forage and Grassland Council, and recently received the Bob Evans Leadership Award for being a "champion" for forages. More Stories by Bob Hendershot

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