Table 1.

Changes in management practices between 2005 and 2018 based on survey data collected from a subset of 268 farmers across the three regions

Management practice	Average		Change	Yield gain
	2005	2018		kg ha−1 y−1
Sowing date (DOY)	120	121	+1
Seeding rate (seed m−2)	7.4	8.0	+0.6*	+28
Cultivar relative maturity (d)	112	112	nil
Conservation tillage (% fields)	33	83	+50*	−13
Rotation with soybean (% fields)	48	54	+6*	+2
Foliar fungicide and/or insecticide (% fields)	27	61	+34*	+7
Grazing prior crop stover (% fields)	43	43	nil
Applied N fertilizer (kg N ha−1)	187	220	+33*	+50

Averages for each year and the difference between 2018 and 2005 values are shown. Estimated annual yield gain associated with changes in individual management practices are also shown (SI Appendix, Table S4). Changes in management practices are shown separately for each of the three regions in SI Appendix, Table S3. Asterisks indicate statistically significant difference (P < 0.05) using t test or χ² test (for variables with normal or binomial distribution, respectively).