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United States Department of Agriculture

Agricultural Research Service

Title: Nitrogen Response in Cotton As Affected by Tillage System and Irrigation Level

Authors
item Bronson, K - TEXAS A&M UNIV
item Onken, A - TEXAS A&M UNIV
item Keeling, J - TEXAS A&M UNIV
item Booker, J - TEXAS A&M UNIV
item Torbert, Henry

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 12, 2001
Publication Date: July 20, 2001
Citation: Bronson, K.F., Onken, A.B., Keeling, J.W., Booker, J.D., Torbert, H.A. Nitrogen response in cotton as affected by tillage system and irrigation level. Soil Science Society of America Journal. 2001. v. 65. p. 1153-1163.

Interpretive Summary: More than 10 million hectares of cotton, half of which are irrigated, are grown in the Southern High Plains of Texas. Using conservation tillage systems with cotton following wheat has been shown to improve water use-efficiency as well as reduce wind erosion. But very little research has been conducted on N fertilizer response in this system. The objective of this 3-yr field study at Lubbock, TX was to characterize the response to N fertilizer at varying irrigation levels for conventional and conservation tillage systems. Additionally, we tested a meter that measured chlorophyll levels in leaves as an indicator of N status of cotton while it was growing. Tillage system on average did not affect lint yields, but tillage system did affect the N rate needed. Results indicated that 20 to 40 more kg N fertilizer ha**-1 was needed to produce economically optimum lint yields near 1100 kg N ha**-1 with conservation tillage than with conventional tillage. Chlorophyll meter readings did indicate the N fertilizer rate but were not affected by tillage system.

Technical Abstract: More than 1 million ha of cotton (Gossypium hirsutum L.), half of which are irrigated, are grown in the Southern High Plains of Texas. Conservation tillage cotton in terminated wheat has been shown to improve water use-efficiency as well as reduce wind erosion. Limited work regarding N fertilizer response has been done in this system. The objective of this 3-yr field study at Lubbock, TX was to characterize the response to N fertilizer (0, 28, 56, 84, or 112 kg N ha**-1) at varying irrigation levels (0, 25, 50, or 75 % ET replacement) for conventional and conservation tillage cotton in an Acuff loam (fine- loamy, mixed, superactive, thermic, Aridic Paleustoll). Additionally, we tested the chlorophyll meter as an indicator of in-season N status of cotton and compared it to petiole-NO3-analysis. Cotton lint yields showed a quadratic response to irrigation level in all years. Maximum lint yield was calculated at 75, 94, and 125% ET replacement for 1996, 1997, and 1998 (a drought year), respectively. Tillage system on average did not affect lint yields, but tillage system x N rate interaction was observed in 1997 and 1998. In these 2 yr, cotton lint yields responded to N at the 50 and 75% estimated Evapotranspiration (ET) replacement irrigation levels, but not at the 0 or 25% ET levels. Quadratic-plateau models indicated that 19 to 38 more kg N fertilizer ha**-1 was needed to produce economically optimum lint yields near 1100 kg N ha**-1 with conservation tillage than with conventional tillage. Chlorophyll meter and petiole-NO3 readings were positively related to N fertilizer rate but were not affected by tillage system.

Last Modified: 10/1/2014
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