Soil carbon fluxes and balances and soil properties of organically amended no-till corn production systems.

摘要

The addition of organic amendments is essential for sustainable soil fertility management and crop production, but can also increase greenhouse gas (GHG) emissions. Thus, understanding the impacts of organic soil amendments on gaseous emissions is pertinent to minimizing agricultural impacts on the net emissions of GHGs. A long-term field experiment was conducted to assess the impacts of continuous application of organic amendments (i.e. compost and farmyard manure) and cover crop [mixture of rye (Secale cereal), red fescue (Festuca rubra), and blue grass (Poa pratensis L.)] on selected soil properties, apparent carbon (C) budget (calculated from the difference of sum of all sources of C inputs and outputs), gaseous flux (i.e. carbon dioxide, CO_2, and methane, CH₄), and relationship with weather parameters under no-till (NT) corn (Zea mays L.) cultivation in an Alfisol of central Ohio, USA. Soil properties and gaseous fluxes were measured continuously for 2 years. Ten years of continuous application of soil amendments increased soil pH and electrical conductivity, enhanced soil C pool, and decreased bulk density especially in 0-5 cm depth than that with cover crop and control plots. Two years average, cattle manure, compost, fallow, and cover crop emitted 14.1, 10.2, 7.5, and 7.2 Mg CO₂-C ha-1 yr-1, respectively. Methane emission was 10.7 kg CH₄-C ha-1 yr-1 from cattle manure and 4.0 kg CH₄-C ha-1 yr-1 from compost. However, fallow consumed 3.3 and cover crop 5.0 kg CH₄-C ha-1 yr-1. These data suggest that long-term application of compost in NT corn decreased emissions of CO₂ by 38% and of CH₄ by 167% compared to application of manuring. In general, soil temperature, air temperature, and precipitation were positively correlated with CO₂ emissions. Estimation of C budget indicated that amended soil under NT is a C-sink while a non-amended system is a C-source. The application of composted soil amendments in NT corn enhances soil quality and reduces net GHG emissions.