Manure incorporation equipment effects on odor, residue cover, and crop yield

Land application of manure may produce unacceptable odors. Field experiment s in undisturbed (no-till) soybean and corn residue were conducted to evalu ate six liquid swine manure application/incorporation methods. The methods were injection with a commercial(1) chisel or (2) sweep, (3) incorporation with tandem disk harrow after broadcast application, (4) broadcast applicat ion with no incorporation, (5) injection with a narrow-profile knife, and ( 6) surface application behind row cleaners. The row cleaner and all injecti on treatments used spoke-covering wheels. Air samples over the soil surface were obtained immediately following and one day after manure application, and odor level was measured by olfactometry (i.e., the amount of air diluti ons to reach odor threshold). Residue cover and yield were also measured. I ncorporation techniques typically reduced odor level by a factor of three t o ten as compared with a broadcast application. One day after application, odor was greatly reduced and often indistinguishable from that of untreated soil (no manure application). Residue cover differences among application methods were more pronounced in soybean residue. Application by the narrow- profile knife, row cleaner and chisel maintained soybean residue cover bett er than other incorporation methods yet limited odor similar To these metho ds. Although cover was reduced over winter, greater soybean residue cover r emained after planting with fall than with spring manure applications. Diff erences in odor level and residue cover among methods were less in corn tha n soybean residue. All incorporation techniques reduced odor levels, and ch isel incorporation maintained corn residue cover after planting similar to broadcast application. For both crops, broadcast application maintained the greatest residue cover but had the highest odor level. Incorporation of ma nure generally reduced odor reduced residue cover increased corn yield, and did not affect soybean yield.