Division S-4-soil fertility and plant nutrition. [Lolium multiflorum]

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

OSTI ID:6065431

Norman, R J; Gilmour, J T

A portion of anhydrous NH/sub 3/ fertilizer applied to soil can be rendered nonexchangeable through fixation by clay minerals and soil organic matter. The plant availability of anhydrous NH/sub 3/ fixed by these two soil fractions can be important agronomically if such fixation limits plant uptake of the fertilizer N. In this study, three soils with clay and organic C contents ranging from 120 to 310 and 7.8 to 30.1 g kg/sup -1/, respectively, were injected with /sup 15/N-labeled (2 atom % /sup 15/N) liquid anhydrous NH/sub 3/ at a rate equivalent to 245 kg N ha/sup -1/. Soluble and exchangeable N were removed by leaching and the soil was cropped to rye grass (Lolium multiflorum Lam.) in pots. Soils were analyzed before and after cropping for clay fixed N and organic matter fixed N. Four cuttings (harvests) were made at 3- to 4-week intervals and roots were collected at the termination of the experiment. Above ground dry matter, total N uptake, and fertilizer-derived fixed N uptake (mg N pot/sup -1/) increased from the first to the second harvest and declined thereafter. Nitrogen recovered in the roots accounted for <11% of the total N and <7% of the fixed N utilized, and root dry matter accounted for 13 to 14% of the total dry matter produced. The ratio of fertilizer-derived fixed N uptake to total N uptake declined with harvest suggesting that the fixed N became less available to the rye grass with time. Fertilizer-derived fixed N recovered in the rye grass ranged from 19 to 26% of that originally fixed by the soil. The percentages of fertilizer-derived clay fixed N removed from the soils during cropping (35-72%) were much larger than those of the fertilizer-derived organic matter fixed N (<12%) suggesting that a majority of the plant uptake of fixed N originated in the clay fraction. Overall, fertilizer-derived fixed N removal from the soils (21-30%) agreed well with plant uptake data.

• Research Organization: Univ. of Arkansas Rice Research and Extension Center, Stuttgart
• OSTI ID: 6065431
• Journal Information: Soil Sci. Soc. Am. J.; (United States), Journal Name: Soil Sci. Soc. Am. J.; (United States) Vol. 51:4; ISSN SSSJD
• Country of Publication: United States
• Language: English

Related Subjects

510101 -- Environment
Terrestrial-- Basic Studies-- Radiometric Techniques-- (-1989)
54 ENVIRONMENTAL SCIENCES
553002* -- Agriculture &amp; Food Technology-- Horticulture-- (1987-)
60 APPLIED LIFE SCIENCES
ABSORPTION
AMMONIA
BIOLOGICAL AVAILABILITY
BIOMASS
CEREALS
CHEMISTRY
CLAYS
ELEMENTS
ENERGY SOURCES
FERTILIZERS
GRASS
HUMUS
HYDRIDES
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
MINERALS
NITROGEN
NITROGEN 15
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN ISOTOPES
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
PLANTS
RENEWABLE ENERGY SOURCES
ROOT ABSORPTION
ROOTS
RYE
SOIL CHEMISTRY
STABLE ISOTOPES
TIME DEPENDENCE
TRACER TECHNIQUES
UPTAKE