Nitrogen cycling associated with the decomposition of sunflower stalks and wheat straw in a Vertisol.

摘要: The C mineralization and N transformations during the decomposition of sunflower stalks (Helianthus annuus L.) wheat straw (Triticum aestivum with without addition (NH4)2SO4 (27.53 atom% 15N) were studied in a Vertisol. Soil samples incubated under aerobic conditions for 224 days at 22 °C. plant residues added rate 5.2 g kg-1 soil. Nitrogen was applied 50.7 mg Carbon dioxide emission inorganic content soil periodically determined. Gross immobilization remineralization calculated on basis isotopic dilution technique. At end incubation period 15N balance established. Respectively, 68 45% residue-C mineralized from after days. Both crop caused losses up to 25% incubation. These about three times larger than control soil, probably due denitrification. net derived following residue incorporation largest case straw, depleting all N. In treatment remained available, resulting an enhanced initial compared stalks, high suppressed effects immobilization/mineralization. amounted 31.9 28.2 g-1 14 respectively. incubation, 35% newly immobilized remineralized both treatments. plotted against decomposed suggests that fairly uniform C-N relationships exist divers substrates. results demonstrate low fertilizer use efficiencies may be expected wheat-sunflower cropping system residues, as becomes largely organic fraction.