Nitrate Monitoring for Cotton Lint Production on a Typic Paleudult1
- M. C. Lutrick,
- H. A. Peacock and
- J. A. Cornell2
Diagnostic criteria for monitoring the N status of both soil and cotton plant are needed to aid in adjusting N fertilization to compensate for seasonal variations. A 3-yr study was initiated in 1981 to determine the feasibility of using soil and petiole NO−3-N testing as an aid in cotton (Gossypium hirsutum L.) lint production along the Gulf Coast. A factorial experiment with four rates of N, three rates of K, and four replications was established on an Orangeburg fine sandy loam (fine-loamy, siliceous, thermic Typic Paleudult). Soil samples were taken each year just prior to the addition of N and K fertilizer treatments. Response to K fertilization was not significant. Cotton petiole samples were taken on selected plots for 9 weeks beginning 1 week prior to first bloom. The response to N resulted in a 3-yr average maximum yield of 1294 kg ha−1 of lint cotton from 114 kg ha−1 of applied N. Petiole analyses for NO−3-N indicated that additional N should be applied to all treatments after the second week of petiole sampling, even though lint yields were above average in this study (average yield for this soil is 1008 kg ha−1). This suggests that the sufficient-N zone established for petiole analyses of NO−3-N in Arkansas and accepted in Georgia is higher than is desirable for thermic Typic Paleudults. Repeated applications of N to the soil over the 3 yr of the experiment did increase the amount of NO−3-N extracted from the soil indicating that some of the applied N was not used by the cotton plant. A revised NO−3-N sufficient-N zone, developed by Georgia researchers and first used in 1985, conforms with the data presented in this paper and could be used satisfactorily to determine N recommendations from petiole analyses for cotton lint production on thermic Typic Paleudults of the Gulf Coast of Florida.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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