Fate of nitrogen-15 applied to spring wheat grown for three consecutive years in a semiarid region [Israel]

• Published in: Soil Science Society of America journal Vol. 48; no. 4; pp. 838 - 843
• Main Authors: Feigenbaum, S, Seligman, N.G, Benjamin, R.W
• Format: Journal Article
• Language: English
• Published: Madison, WI Soil Science Society of America 01-07-1984
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Nitrogen fertilization; Nitrogen, phosphorus, potassium fertilizations; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Nitrogen fertilization; Semiarid zone; Monocotyledones; Gramineae; Dynamics; Angiospermae; Soil; Spermatophyta; Nitrogen; Cereal crop; Triticum aestivum
• ISSN: 0361-5995; 1435-0661
• DOI: 10.2136/sssaj1984.03615995004800040028x

Uptake and recovery of fertilizer N applied to spring wheat was monitored over a 3‐yr period in a semiarid region. Tagged fertilizer with enrichment from 8.9 to 28.5 atom % 15N was applied as KNO3 at rates equivalent to 180 kg N ha−1 as a single application or split equally over 3 yr. The wheat was grown in 1.25‐ × 1.25‐m open plots and in 0.3‐m diam microplots enclosed by hard plastic tubes that were inserted 0.6 m into the ground. The 15N enrichments in plant and soil were determined by emission spectrometry. In open plots fertilizer N recovery in plant and soil was 976 g kg−1 in the first year and 697 to 721 g kg−1 in subsequent years. In the tubes, equivalent recoveries were 755 to 841 g kg−1 and 377 to 560 g kg−1. The greater loss in the tubes is attributed to denitrification that could have occurred under excess waterlogging caused by the rim of the tubes that protruded about 0.05 m above the soil surface. In a dry year, 338 to 558 g kg−1 of the applied fertilizer N was found as mineral N in the soil and, especially in the open plots, was utilized in the second growing season, after which only negligible amounts remained in the mineral N fraction. At the end of the third year, 69 to 84 g kg−1 of the applied fertilizer N was found in the soil as organic N. At the end of 3 yr, recovery of fertilizer N was lower when determined directly with 15N than when determined by difference between treatments and control. The additional N could result from the controversial “priming effect” of fertilizer N application on release of soil N, although the evidence is not conclusive. It is concluded that when fertilizer N is applied in a dry season, a large amount of residual mineral N in soil remains at the end of the growing period. This N can be utilized in subsequent years and should be taken into account when determining fertilizer requirements. In a wet years, losses can be significant and residual fertilizer N in the soil is negligible.