Microbial responses and nitrous oxide emissions during wetting and drying of organically and conventionally managed soil under tomatoes

• Published in: Biology and fertility of soils 2005-11, Vol.42 (2), p.109-118
• Main Authors: Burger, M, Jackson, L.E, Lundquist, E.J, Louie, D.T, Miller, R.L, Rolston, D.E, Scow, K.M
• Format: Article
• Language: English
• Subjects: acetylene; Agricultural land; Agricultural practices; agricultural soils; Agrochemicals; Agronomy. Soil science and plant productions; Biochemistry and biology; Biological and medical sciences; Carbon dioxide; Chemical, physicochemical, biochemical and biological properties; community structure; Cover crops; crop rotation; Cropping systems; denitrification; Drying; Emissions; fertilizer application; Fundamental and applied biological sciences. Psychology; gas emissions; irrigation; Irrigation systems; Loam soils; Lycopersicon esculentum; Microbial activity; microbial biomass; Microbiology; Mineral fertilizers; Nitrous oxide; Nutrient availability; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; rainfall simulation; Silt loam; Simulated rainfall; soil chemical properties; Soil management; soil microorganisms; Soil moisture; soil respiration; Soil science; Soil sciences; soil water content; Solanum lycopersicum var. lycopersicum; Tomatoes; Water management; wet-dry cycles
• ISSN: 0178-2762; 1432-0789
• DOI: 10.1007/s00374-005-0007-z

The types and amounts of carbon (C) and nitrogen (N) inputs, as well as irrigation management are likely to influence gaseous emissions and microbial ecology of agricultural soil. Carbon dioxide (CO^sub 2^) and nitrous oxide (N^sub 2^O) efflux, with and without acetylene inhibition, inorganic N, and microbial biomass C were measured after irrigation or simulated rainfall in two agricultural fields under tomatoes (Lycopersicon esculentum). The two fields, located in the California Central Valley, had either a history of high organic matter (OM) inputs ("organic" management) or one of low OM and inorganic fertilizer inputs ("conventional" management). In microcosms, where short-term microbial responses to wetting and drying were studied, the highest CO^sub 2^ efflux took place at about 60% water-filled pore space (WFPS). At this moisture level, phospholipid fatty acids (PLFA) indicative of microbial nutrient availability were elevated and a PLFA stress indicator was depressed, suggesting peak microbial activity. The highest N^sub 2^O efflux in the organically managed soil (0.94 mg N^sub 2^O-N m^sup -2^ h^sup -1^) occurred after manure and legume cover crop incorporation, and in the conventionally managed soil (2.12 mg N^sub 2^O-N m^sup -2^ h^sup -1^) after inorganic N fertilizer inputs. Elevated N^sub 2^O emissions occurred at a WFPS >60% and lasted