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  • Author or Editor: William S. McElhannon x
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Abstract

In a laboratory incubation study with soil inoculum, terrazole [5-ethoxy-3(trichloromethyl)1,2,4 thiadiazole] at 0.02 to 200 ppm in liquid culture suppressed N2 and N2O evolution and increased NO3-N retention. A Cecil clay soil, treated with terrazole at concentrations of 0.5 and 2.0 ppm, retained more NO3-N than the control in a greenhouse study.

Open Access

Abstract

Inhibition of N2 and N2O evolution from a liquid medium inoculated with soil was obtained with low levels (0.2, 2, and 20 ppm) of 2-chloro-6-(trichloromethyl)pyridine. Concurrent with the reductions in N2 and N2O evolution was increased NO3 retention in the medium. Results from this study confirm that nitrapyrin effectively inhibits denitrification in vitro at rates comparable to that applied in the field.

Open Access

Abstract

N-demand periods and the form and quantity of N absorbed during the growth cycle of sweet corn (Zea Mays L.) was determined for ‘Silver Queen’ grown in solution culture with a N ratio of 50% NO3–50% NH4. Absorption of NO3 and NH4 were similar up to the tasseling stage. During the tasseling stage, NO3 was absorbed at rates greater than NH4, while during the ear development stage NH4 was absorbed at rates higher than NO3. Evaluation of N demand during the growth cycle shows that 60% of the total N absorbed occurred during the tasseling-ear development stage. These results indicate that with ‘Silver Queen’, greater efficiency of applied N fertilizer can be obtained by correlating rate of N and form of N to a specific growth stage.

Open Access

Abstract

A commercial formulation of 2-chloro-6-(trichloromethyl)-pyridine (nitrapyrin) was incorporated within the N-fertilizer band in 2 consecutive years under widely different environmental conditions to evaluate the effect of nitrapyrin on denitrification occurring with field-grown sweet corn (Zea mays L.). Nitrapyrin significantly increased soil NO 3–N levels, total plant N, and yield; decreased rates of N2O evolved from the soil with both NH+ 4 and NO 3 forms of N-fertilizer. Denitrification appears to be a significant factor influencing the growth of sweet corn under field conditions, and nitrapyrin effectively inhibits the denitrification process.

Open Access

Abstract

The effectiveness of the s-triazines simazine [2-chloro-6-bis (ethylamino)-s-triazine] and atrazine [2-chloro-6-(ethylamino)-6-(isopropylamino)-s-triazine and nitrapyrin [2-chloro-6-(trichloromethyl)pyridine] in suppressing denitrification was evaluated in laboratory and greenhouse studies. Parameters used to measure suppression of denitrification were N2 and N2O evolution, soil NO3-N, and plant N (% N × dry weight). Simazine and atrazine significantly reduced N2O evolution in laboratory incubation studies, but had no effect on N2 evolution, while nitrapyrin reduced both N2 and N2O evolution. In greenhouse studies, 0.5 mg kg-1 soil of simazine and atrazine, and 2.0 mg kg-1 soil of nitrapyrin increased soil NO3-N and plant N as compared to the control. It is concluded that simazine and atrazine inhibited denitrification under greenhouse and laboratory conditions and, therefore, that increased media NO3-N availability is the most likely explanation why N concentration in the plant tissue was higher.

Open Access