Does Liquid Swine Manure Application Timing and Nitrapyrin Affect Corn Yield and Inorganic Soil Nitrogen?

Core Ideas Nitrapyrin (Instinct) effectively slowed nitrification of swine manure. Delaying fall application of swine manure increased corn yields and N availability. Instinct enhanced corn production in years with greater than normal precipitation.Fall application of liquid swine ( Sus scrofa ) manure (LSM) is preferred but it can increase N loss potential. Delaying application of LSM or adding a nitrification inhibitor could reduce N losses. This study measured the effects of LSM application timing and nitrapyrin [2‐chloro‐6‐(trichloromethyl) pyridine] as Instinct on soil inorganic N and corn ( Zea mays L.) production. Field experiments were conducted from 2010 through 2014 on clay loam soils (Aquic Hapludolls). Treatments consisted of two fall application timings (early and late) and three rates (0, 2.56, and 5.11 L ha −1 ) of Instinct. Manure was injected 10‐cm deep at 134 kg of available N ha −1 . Additional treatments included a control and 134 kg ha −1 of N as anhydrous ammonia (AA) with and without nitrapyrin as N‐Serve. Treatments were arranged in a randomized‐complete block design with four replicates. Late fall application of LSM and Instinct use resulted in greater fall and early spring NH 4 –N concentrations in manure bands. When averaged across years, LSM applied late increased corn grain yields 0.5 Mg ha −1 compared with early application and yields were 0.5 to 0.7 Mg ha −1 greater with Instinct than without. An interaction between main effects showed the yield response to Instinct was greatest when LSM was applied early. Total N uptake and removal were greater with Instinct than without Instinct. In this study, delaying LSM application until late fall (November) and using nitrapyrin (Instinct) increased corn yields and N uptake in years with greater than normal spring precipitation.