Soybean is grown in rotation with corn or winter wheat, which is an essential management practice to maintain soil health and maximize crop yields. Though herbicides are critical for weed management, there is potential for damage to soybean from herbicide carryover in a rotation system. Soybean has a high value of production in NC; therefore, it is critical to identify problems that soybean production could encounter in the near future and find ways to minimize
them.

Factors such as soil clay and organic matter contents, and temperature of field soil should be considered while selecting herbicides for use in a rotational cropping system to prevent carryover injury to the succeeding crop. Carryover from persistent atrazine and topramezone soil residue may be higher in soils with greater organic matter and clay contents, such as Portsmouth or Creedmoor sandy loam, and lower in coarse textured soils, such as Candor sand. Carryover risk of mesosulfuron-methyl can be greater when it is applied to winter wheat at cooler soil temperatures.

The influence of edaphic and environmental conditions on soil herbicide persistence may cause regional differences in carryover residue concentrations, but it is important to keep in mind that carryover crop damage can also depend on herbicide bioavailability differences among soils. Similar soil properties that are attributed to longer herbicide persistence, such as organic matter and clay content, may also result in reduced bioavailability of herbicide residue due to sorption and binding of herbicides to these soil fractions. Therefore, growers should make herbicide selections considering soil properties and rotational crop plan, giving significance to organic matter content, clay content, and cation exchange capacity, along with the sensitivity of rotational crop species to specific herbicides, as canola and radish were found to be more sensitive than soybean.

Evaluations of genotypic variation in carryover sensitivity may be useful in prevent damage to rotational crops such as soybean by aiding growers in appropriate variety selection. Soybean genotypes that exhibit recovery from atrazine injury maybe recommended for planting under atrazine carryover conditions since recovery signifies resumed productivity. Recovery in photosynthesis can prevent early-season defoliation caused by atrazine-induced leaf necrosis, which is pertinent since greater canopy cover in soybean can enhance weed suppression and yield potential. Growers practicing soybean crop rotation should be cognizant of soybean genotypic differences in sensitivity to atrazine while making soybean seed selections to avoid carryover damage.