MANURE INCORPORATION EQUIPMENT EFFECTS ON ODOR, RESIDUE COVER, AND CROP YIELD

Abstract

Land application of manure may produce unacceptable odors. Field experiments in undisturbed (no-till)soybean and corn residue were conducted to evaluate six liquid swine manure application/incorporation methods. Themethods were injection with a commercial (1) chisel or (2) sweep, (3) incorporation with tandem disk harrow afterbroadcast application, (4) broadcast application with no incorporation, (5) injection with a narrow-profile knife, and(6) surface application behind row cleaners. The row cleaner and all injection treatments used spoke-covering wheels. Airsamples over the soil surface were obtained immediately following and one day after manure application, and odor levelwas measured by olfactometry (i.e., the amount of air dilutions to reach odor threshold). Residue cover and yield werealso measured. Incorporation techniques typically reduced odor level by a factor of three to ten as compared with abroadcast application. One day after application, odor was greatly reduced and often indistinguishable from that ofuntreated soil (no manure application). Residue cover differences among application methods were more pronounced insoybean residue. Application by the narrow-profile knife, row cleaner, and chisel maintained soybean residue cover betterthan other incorporation methods yet limited odor similar to these methods. Although cover was reduced over winter,greater soybean residue cover remained after planting with fall than with spring manure applications. Differences in odorlevel and residue cover among methods were less in corn than soybean residue. All incorporation techniques reducedodor levels, and chisel incorporation maintained corn residue cover after planting similar to broadcast application. Forboth crops, broadcast application maintained the greatest residue cover but had the highest odor level. Incorporation ofmanure generally reduced odor, reduced residue cover, increased corn yield, and did not affect soybean yield.