Isotopic and Nonisotopic Estimations of Fertilizer Nitrogen Uptake by Sudangrass in Field Experiments1
Recoveries of fertilizer N in above-ground portions of crops grown in field experiments were estimated by: the difference method; linear regression of total N in crops on rates of applied N; /sup 15/N isotopic tracer method; and linear regression of labeled fertilizer N uptake on rates of labeled fertilizer N. In order to evaluate the use of the isotope, these four methods were applied to data from prsviously reported experiments that involved two /sup 15/N-labeled fertllizers (urea and oxamide) at rates of 0, 56, 112, and 188 kg N/ha. The test crop was Sudax (SX11) sorghumsudangrass hybrid (Sorghum sudanense) and harvests were made at approximately 30-day intervals during the cropping seasons. The difference method overestimated recovery of urea and oxamide nitrogen in sudangrass 35 and 31%, respectively, in 1986 and 23 and 35% in 1987 when compared to the isotopic tracer methed. Similarly, linear regression of total N in crops on rates of N overestimated recoveries of urea and oxamide nitrogen 32 and 17%, respectively, in 1988 and 17 and 21% in 1987 when compared to linear regressions of fertilizer N in crops on rates of /sup 15/N labeled nitrogen. Isotopically- labeled fertilizers are almost a necessity for estimating N recovery in many dgronomic experiments.
- Research Organization:
- Univ. of Illinois, Urbana
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-29-024561
- OSTI ID:
- 4335540
- Journal Information:
- Soil Science Society of America Journal, Vol. 38, Issue 1; Other Information: Orig. Receipt Date: 30-JUN-74; ISSN 0361-5995
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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