Long Term Nitrogen Fertilization Effects on Lint Yields and Certain Soil Properties in the Texas Coastal Bend

J. E. Matocha, Dennis L. Coker, Fred L. Hopper


A long-term field study was conducted to determine response of short-season cotton to nitrogen (N) fertilization under non-irrigated conditions. Precipitation records show annual rainfall varied up to 400 percent while growing season subtotals fluctuated 1800 percent during the study. An Orelia sandy clay loam, typical of soils used in cotton production, was used in the 14 year study. Acid-base urea phosphate fertilizers were the primary sources of N and phosphorus (P). Ammonium nitrate and urea were used as additional sources of N. Nitrogen was compared at 0, 20, 40 and 80 lb N/Ac with P varying at the same rates. Treatments were arranged as an incomplete factorial. Lint yields ranged from 200 to 1000 lb/Ac during the term of the study, largely reflecting wide fluctuations in seasonal precipitation. In seasons with ample rainfall, N response usually followed strong quadratic functions. In seasons when plants stressed for soil moisture, only slight yield increases and in extremely dry seasons decreases in lint yields were recorded due to N fertilization. Soil pH in the highly buffered calcareous soil was reduced after 14 years of fertilization with 80 lb N/Ac and 20 lb P2O5/Ac. This pH depression appeared to enhance P availability. Soil nitrate distribution in the profile was highly variable with fluctuations in seasonal precipitation. However, no substantial buildup of nitrate in the soil profile was evident regardless of N rate.

Reprinted from Proceedings of the 1994 Beltwide Cotton Conferences pp. 1549 - 1551
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998