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Nitrogen Utilization by Wheat from Residual Sugarbeet Fertilizer and Soil Incorporated Sugarbeet Tops 1
Author(s) -
Abshahi A.,
Hills F. J.,
Broadbent F. E.
Publication year - 1984
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1984.00021962007600060021x
Subject(s) - agronomy , fertilizer , loam , ammonium sulfate , chemistry , crop , nitrogen , environmental science , soil water , biology , organic chemistry , chromatography , soil science
Sugarbeet ( Beta vulgaris L.) crops usually receive N fertilizer and sugarbeet tops are often returned to the soil following the harvest of storage roots. Residual sugarbeet fertilizer N and N in tops may reduce the amount of fertilizer N required for a subsequent crop. Field experiments at Davis, CA in 1980 and 1981 were designed to assess the contribution of these factors to a following wheat ( Triticum aestivum L.) crop and to trace the partitioning of fertilizer N applied to sugarbeet, N in sugarbeet tops, and fertilizer N applied to the following wheat. The site was a Reiff loam, a deep alluvial coarse loamy soil with medium‐textured substratum (Typic xerothents, Entisols, mixed, nonacid thermic). Sugarbeet, with and without 157 kg fertilizer N ha −1 and each with and without beet tops returned to the soil, were followed by wheat receiving four rates of fertilizer N (0, 62, 124, and 186 kg ha −1 ). The fertilizer used for both crops was stable, isotopically labeled 15 N‐depleted ammonium sulfate. Nitrogen from sugarbeet tops was traced in the wheat crop by returning sugarbeet tops containing labeled N to plots where sugarbeet had been fertilized with nonlabeled N and tops and storage roots removed. Residual sugarbeet fertilizer N was traced by additional plots of sugarbeet fertilized with more strongly labeled 15 N‐enriched ammonium sulfate. Of the 157 kg N ha −1 applied to the sugarbeet crop, 43% was taken up by tops and storage roots, 45% remained in the soil, primarily as organic N, leaving 12% not accounted for. Of the 45% (71 kg N ha −1 ) remaining in the soil only about 10% was taken up by the wheat crop, 66% remained in the soil, mostly as organic N, and 24% was not accounted for. When beet tops were returned to the soil, wheat straw and grain yield were maximized for this site with about 62 kg fertilizer N ha −1 , but when tops were not returned, 124 kg fertilizer N ha −1 were required. From these applications, fertilizer N recovery by wheat was 82 and 61%, respectively. Sugarbeet tops contained, on average, 119 kg N ha −1 of which 27% was taken up by the wheat crop, 39% remained in the soil, mostly as organic N, leaving 34% not accounted for. Sugarbeet tops supplied the equivalent of 15 kg fertilizer N Mg −1 dry tops.