Floodwater properties, nitrogen utilization, and nitrogen-15 balance in a calcareous lowland rice soil

Conference · · Soil Sci. Soc. Am. J.; (United States)

OSTI ID:6739121

De Datta, S K; Fillery, I R.P.; Obcemea, W N; Evangelista, R C

Large areas of lowland rice (Oryza sativa L.) soils in South and Southeast Asia are calcareous. Field studies in the 1983 dry and wet seasons evaluated the effects of N source and application method on N loss and N utilization in a calcareous clay loam soil using the /sup 15/N-balance technique. In the 1983 wet season and the 1984 dry season, crop recovery of the residual /sup 15/N remaining after the first crop was determined. When urea supergranules (USG) were deep point-placed, the partial pressure of ammonia (pNH/sub 3/) in the flood-water was negligible. High flood-water pNH/sub 3/ was calculated with split application of fertilizer. Farmers' split of prilled urea (PU) gave the highest pNH/sub 3/ (0.44 Pa in the wet season). pNH/sub 3/ in the flood-water peaked on the third day and dropped to negligible thereafter. Deep placement (10 cm) of USG had the highest grain yield in the dry season. Ammonium sulfate produced a yield similar to that of urea. The highest /sup 15/N recovery by the crop was 78% in the dry season and 64% in the wet season with deep point placement of USG. Nitrogen-15-balance data showed that with point placement of USG, 3% N was not accounted for after harvest in the dry season and 10% in the wet season. In contrast, when urea or ammonium sulfate was split-applied using improved timing and water management, 26 to 28% of applied N was not recovered at harvest in the dry season and 36 to 41% in the wet season.

• Research Organization: International Rice Research Institute (IRRI), Manila, (Philippines)
• OSTI ID: 6739121
• Report Number(s): CONF-871180-; TRN: 88-035745
• Journal Information: Soil Sci. Soc. Am. J.; (United States), Vol. 51:5; Conference: 51. annual meeting of the Soil Science Society of America, Atlanta, GA, USA, 29 Nov 1987
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
NITROGEN
BIOLOGICAL AVAILABILITY
FRACTIONATION
RICE
PRODUCTIVITY
ASIA
FERTILIZERS
NITROGEN 15
NITROGEN FIXATION
SEASONAL VARIATIONS
SOILS
TRACER TECHNIQUES
UREA
AMIDES
CARBONIC ACID DERIVATIVES
CEREALS
ELEMENTS
GRASS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
NITROGEN ISOTOPES
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PLANTS
SEPARATION PROCESSES
STABLE ISOTOPES
VARIATIONS
510200* - Environment
Terrestrial- Chemicals Monitoring & Transport- (-1989)
560300 - Chemicals Metabolism & Toxicology
510101 - Environment
Terrestrial- Basic Studies- Radiometric Techniques- (-1989)