title: Soil carbon dioxide emission and carbon content as affected by irrigation, tillage, cropping system, and nitrogen fertilization.
abstract: Management practices can influence soil CO(2) emission and C content in cropland, which can effect global warming. We examined the effects of combinations of irrigation, tillage, cropping systems, and N fertilization on soil CO(2) flux, temperature, water, and C content at the 0- to 20-cm depth from May to November 2005 at two sites in the northern Great Plains. Treatments were two irrigation systems (irrigated vs. non-irrigated) and six management practices that contained tilled and no-tilled malt barley (Hordeum vulgaris L.) with 0 to 134 kg N ha(-1), no-tilled pea (Pisum sativum L.), and a conservation reserve program (CRP) planting applied in Lihen sandy loam (sandy, mixed, frigid, Entic Haplustolls) in western North Dakota. In eastern Montana, treatments were no-tilled malt barley with 78 kg N ha(-1), no-tilled rye (Secale cereale L.), no-tilled Austrian winter pea, no-tilled fallow, and tilled fallow applied in dryland Williams loam (fine-loamy, mixed Typic Argiborolls). Irrigation increased CO(2) flux by 13% compared with non-irrigation by increasing soil water content in North Dakota. Tillage increased CO(2) flux by 62 to 118% compared with no-tillage at both places. The flux was 1.5- to 2.5-fold greater with tilled than with non-tilled treatments following heavy rain or irrigation in North Dakota and 1.5- to 2.0-fold greater with crops than with fallow following substantial rain in Montana. Nitrogen fertilization increased CO(2) flux by 14% compared with no N fertilization in North Dakota and cropping increased the flux by 79% compared with fallow in no-till and 0 kg N ha(-1) in Montana. The CO(2) flux in undisturbed CRP was similar to that in no-tilled crops. Although soil C content was not altered, management practices influenced CO(2) flux within a short period due to changes in soil temperature, water, and nutrient contents. Regardless of irrigation, CO(2) flux can be reduced from croplands to a level similar to that in CRP planting using no-tilled crops with or without N fertilization compared with other management practices.
authors.affiliation: USDA-ARS, Northern Plains Agricultural Research Lab., 1500 North Central Ave., Sidney, MT 59270, USA. usainju@sidney.ars.usda.gov
authors.forename: Upendra M
authors.initials: UM
authors.lastname: Sainju
authors.forename: Jalal D
authors.initials: JD
authors.lastname: Jabro
authors.forename: William B
authors.initials: WB
authors.lastname: Stevens
mesh_terms: D000383:Agriculture / Q000379:methods*; D000393:Air Pollutants / Q000032:analysis*; D002244:Carbon / Q000032:analysis*; D002245:Carbon Dioxide / Q000032:analysis*; D018556:Crops, Agricultural; D004784:Environmental Monitoring; D005308:Fertilizers; D009009:Montana; D009584:Nitrogen; D009658:North Dakota; D011891:Rain; D012987:Soil / Q000032:analysis*; D013696:Temperature; D014867:Water / Q000032:analysis
chemical_list: D000393:Air Pollutants; D005308:Fertilizers; D012987:Soil; D014867:Water; D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen