RESPONSE OF CORN TO NITROGEN IN PREPLANT AND SIDEDRESS APPLICATIONS OF LIQUID DAIRY CATTLE MANURE

Abstract

Two field experiments were conducted, each over a 3-yr period, to compare the availability of N from liquid cattle manure (LCM) with that from urea and anhydrous ammonia to corn. Two times of application (preplant vs. sidedress) and two methods of application (surface vs. injection) of LCM were compared with respect to corn grain yield and soil NO3− concentration during two periods of the growing season. The availability of LCM N was approximately one-half that of fertilizer N. Injection of LCM either before planting or as a sidedressing between the corn plant rows resulted in LCM N being approximately 60% as available as fertilizer N. Application of LCM to the soil surface, as a side dressing resulted in LCM N being approximately one-third as available as anhydrous ammonia N. The data were discussed and interpreted on the basis that manure N is made up of two principal fractions, "organic" and ammoniacal N. The organic N fraction, consisting of all the N other than ammonia, becomes only partly available to the crop through mineralization whereas the ammoniacal N fraction is subject to volatilization if not incorporated into the soil immediately. Soil NO3− concentrations in the June-July period showed the surface preplant LCM N availability to be approximately one-half that of preplant applications of urea. Nitrate concentrations during the September-October period suggested that LCM showed no greater levels of NO3− than urea even at twice the rate of N application. Key words: Corn, nitrogen, preplant and sidedress applications, liquid dairy cattle manure