Effects of Foliar Fertilization on Texas Southern High Plains Cotton

C.W. Bednarz, M.G. Hickey, and N.W. Hopper


 
ABSTRACT

Field studies were conducted at Petersburg, Texas, in 1991 on Pullman clay loam. Paymaster 145 was planted on May 12 at the rate of 30 seeds per meter of row on 102 cm rows. Prior to planting, N and P were applied at rates of 120 kg N ha-1 and 49 kg P2O5 ha-1. Six treatments were established: three commercial products and two rates of soluble urea. The commercial products were applied following label rates and timing. Urea was applied at 2.8 L ha-1 at 2,4, 6, and 8 weeks after match-head square. Another urea treatment was applied at 5.6 L ha-1 at 4, and 6 weeks after match-head square and 11. 2 L ha-1 at 8 weeks after match-head square.

Ten plants were collected from each plot at 82, and 124 days after planting (DAP), and mapped to determine fruit numbers. Additional samples were collected at 93 DAP. Leaves were removed from the plant after all collection dates by nodal horizon: (1) nodes 6-9, (2) nodes 10-13, and (3) nodes 14 and above. Leaf area was determined. Plants were then dried for dry weight determination, and leaf nutrient contents and fruit numbers were analyzed.

Leaf areas ranged from a low of 573 cm2 plant-1 at 82 DAP to a high of 994 cm2 plant-1 at 124 DAP. Dry weights at 124 DAP were approximately 34.59 g plant-1. No statistical differences were observed in leaf area or dry weight. Leaf N levels within nodal horizon 6-9 were below the sufficiency range (35 to 45 q kg-1) at 82 DAP, and then increased slightly at 124 DAP. Total N levels across all treatments in nodal horizon 10-13 were 28% greater at 124 DAP than at 82 DAP, well below the sufficiency range. Nodal horizon 14 and above contained total N means that were 70% greater at 124 DAP than at 82 DAP. Phosphorous concentrations were never below the adequate range that has been reported for cotton in late bloom (0. 0 3 to 0. 0 6 5 g kg-1). Potassium concentrations were also never below the sufficiency level of 15 g kg-1. Leaf total Zn levels also never declined to less than the 0.02 g kg-1 sufficiency level. Treatment 2 improved the plants total Zn status. No differences in fruit numbers or yields were observed.



Reprinted from 1992 Proceedings Beltwide Cotton Conferences pp. 1154 - 1157
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998