WATERLOO, N.Y. — Better plant nutrition means higher yields for soybean growers. Jodi Putman, a field crops specialist with the Northwest New York Dairy, Livestock and Field Crop Team, recently offered a presentation on the topic at the Soybeans & Small Grains Congress hosted by Cornell.
“We had a tough harvest season in 2018,” Putnam said.
She considers the history of soybean genetics a timeline of progression that shows improved protein content to benefit livestock and poultry, as well as plant traits and management techniques that help growers achieve better yields.
In 2017, farmers raised 120 million tons of soybeans in the U.S. — an incredible feat compared with early U.S. records— but Putnam said that recent decades of maximizing yields has also resulted in nutrient mining from the soil.
“The amount of sulfur deposited on the land is much less in 2015 than in 2001,” she said.
Putnam advocates for “intentional soybean management,” which includes careful variety selection, soil fertility, timely planting, and control of weeds, insects and disease through weekly scouting.
Putnam compared a photo of soybean plants from 1923 with 1943, 1964 and 2011. She said that the differences in color, leaf shape and biomass among the years indicate greater nutrient retention in plants in more recent years.
Putnam referenced findings of Dr. Shaun Casteel, associate professor of Agronomy at Purdue University. He said that new, more modern soybean varieties responded favorably to planting earlier, showing leaf nitrogen concentration and leaf nitrogen accumulation increased consistently throughout the entire growing season. Plants also showed better leaf retention and photosynthetic activity.
“Modern varieties are taking up more nitrogen and sulfur than previous variety releases,” Putnam said. “They have higher nitrogen and sulfur concentrations in the biomass and more biomass produced.”
She believes that greater allocation of nitrogen and sulfur to the leaves leads to improved pod and seed production and, ultimately, more nitrogen and sulfur removed in the grain because of the dry matter produced.
“Soybean planting date has a large effect on yield,” she said. “Yield reduction as a result of late panting ranges from 0.25 to 1 bushel per acre per day, depending on row width, date of planting and variety.”
In general, about 1-3 pounds of sulfur are released for every one percent of sulfur oxidizing microorganisms present in the soil.
Putnam researched sulfur treatments in 2016, 2017 and 2018, comparing different rates of sulfur application with a control group which did not receive treatment.
Each year, Putnam received higher yields with sulfur than without. However, farmers should only apply sulfur or any amendment as needed. Putnam said that soil analysis can help farmers know what to apply and how much.
“Late spring broadcast with soluble sources, for example, AMS, Gypsum, MES10, ATS, is proving to be a good management strategy for the addition of sulfur fertilizer, according to Dr. Casteel at Purdue University,” Putnam said.
The Cornell Cooperative Extension Northwest New York Dairy, Livestock and Field Crop team hosts the annual Soybean & Small Grains Congress in Batavia and Waterloo, New York.