Still in Rotation

A 44-year-old cropping study offers a window on sustainability.

It’s said that with age comes wisdom. And for CALS’ long-running field trials at Lancaster Agricultural Research Station, wisdom means data.

Established in 1966 to test the advantages of various crop rotations, the Lancaster trials have produced reams of feedback for producers as they weigh their planting decisions. One of the study’s key findings, for example, has been to show the profitability of a corn-soybean crop rotation, says Joe Lauer, an agronomy professor who has compiled 39 years of data from the trials.

But as the study enters its 44th season, its longevity is paying off in other ways. Its four-decade history is giving agronomists a rare tool to study the sustainability of cropping systems over multiple decades.

“To truly answer questions about sustainability, you need longitudinal data across generations of farmers,” Lauer says. “These trials have been in place long enough and are well-designed to address questions we never thought about when the experiments were conceived.” That is why institutional support for this kind of work is critical, Lauer says.

Lauer notes that the Lancaster studies are among the longest-running replicated cropping studies in the country. Another trial at CALS’ Arlington research station has been going on for 26 years. By contrast, most cropping studies focus on three- to five-year projects.

While that time frame may be fine for studying yield or profitability, Lauer says the new questions being asked about cropping systems require a longer view. Farmers and agronomists are increasingly concerned with how soil characteristics change after decades of agricultural use, as well as the long-term effects of tillage and pesticide use. Studies such as those at Lancaster “are our best chance to address whether a cropping system is going to be sustainable,” says Lauer. “Every five years, as a rotation cycle is completed, we can go back to the same piece of ground and get hard data and predict the direction the rotation is taking us.”

For instance, the study’s data show that it’s necessary to add nitrogen to make the corn-soybean rotation effective. But without nitrogen, forage crops may offer a better option for maximizing grain yield because they leave more residue on the fields, says Lauer. In fact, if governments enacted policies based on carbon credits, he predicts that soybeans might disappear from the rotation mix because they don’t create much organic material.

“These are some of the questions that society is asking,” says Lauer. “Data can get at the crux of these issues.”