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In-Season Nitrogen Status Sensing in Irrigated Cotton: I. Yields and Nitrogen-15 Recovery.
- Source :
- Soil Science Society of America Journal; Sep/Oct2003, Vol. 67 Issue 5, p1428-1438, 11p, 8 Charts, 2 Graphs
- Publication Year :
- 2003
-
Abstract
- Nitrogen recommendations for Upland cotton (Gossypium hirsuturn L.) in the western USA are based on spring soil NO[sup -, sub 3]-N tests. In-season monitoring of plant N status is another approach. Our primary objective was to test spectral reflectance and chlorophyll meter measurements as in-season N decision aids for irrigated cotton, and to compare these with soil test-based N management. The secondary objective was to determine the fate of [sup 15]N as affected by N management and irrigation modes. Urea ammonium nitrate was applied with low energy precision (LEPA) center-pivot, surface drip, and subsurface drip irrigation. Microplots received 3 atom% [sup 15]N. Soil test N application was based on 0- to 60-cm soil NO[sup -, sub 3]-N and 1400 kg lint ha[sup -1] expected yield. Thirty-four kilograms of N per hectare was applied when green vegetative index (GVI) or chlorophyll meter readings relative to well-fertilized plots were <0.95. Lint yield responded to N at Lubbock in 2000 and 2001, but not at Ropesville. Nitrogen applied with in-season monitoring in 2000 at both sites was 34 to 101 kg N ha[sup -1] less than soil test N application of 134 kg ha[sup -1], with similar yields. In Lubbock, 2001 lint yields were near the expected yield, and in three of four cases, N applications with in-season monitoring equaled soil test N applications of 101 kg ha[sup -1]. Nitrogen-15 recovery in plants ranged from 19 to 38%, and was affected by N management in two of three site-years, but not by irrigation. This study indicates that basing N applications on in-season monitoring can reduce N applications in low yielding seasons and match the yield potential in high-yielding seasons. [ABSTRACT FROM AUTHOR]
- Subjects :
- COTTON
NITROGEN
SOIL mineralogy
SOILS
IRRIGATION
Subjects
Details
- Language :
- English
- ISSN :
- 03615995
- Volume :
- 67
- Issue :
- 5
- Database :
- Complementary Index
- Journal :
- Soil Science Society of America Journal
- Publication Type :
- Academic Journal
- Accession number :
- 10962261
- Full Text :
- https://doi.org/10.2136/sssaj2003.1428