Title page for ETD etd-11122012-221157

Type of Document Master's Thesis
Author Dalen, Marilyn Sebial
Author's Email Address mdalen1@tigers.lsu.edu
URN etd-11122012-221157
Title Understanding Phosphorus Dynamics of Two Alluvial Soils Grown with Corn at Different Phosphorus Rates
Degree Master of Science (M.S.)
Department Agronomy & Environmental Management
Advisory Committee
Advisor Name Title
Tubana, Brenda Committee Chair
Mascagni, Henry Jr. Committee Member
Wang, Jim Jian Committee Member
  • commerce siltloam
  • perry clay
Date of Defense 2012-10-31
Availability unrestricted
There is little information documented on the influence of soil properties on P availability of Louisiana alluvial soils thus this pot experiment was conducted in 2011 to: 1) evaluate the effect of P fertilizer rate on growth and development of corn grown on Perry clay and Commerce sl soils, 2) relate soil test P values using Mehlich-3 and Bray-2 procedures with yield, total biomass, and P uptake of corn, and 3) identify the soil properties that influence P partitioning into functional fractions of two alluvial soils. Different P fertilizer rates (0, 34, 67, 101 and 134 kg P2O5 ha-1) were applied, replicated four times and arranged in a randomized complete block design. After 30 days, corn was planted and grown until maturity. Mehlich-3 extractable-P, Bray-2, total-P and Pi fractions (labile-P, Al-P, Fe-P, reductant-P, and Ca-P) of soil samples collected at 30 DAP and at harvest were quantified.

The Bray-2 P values were about six times higher than Mehlich-3 P values for Commerce sl while for Perry clay, the amounts of P extracted by these two procedures were very similar (1:1 ratio). Both Bray-2 and Mehlich-3 extractable-P of both soils increased with increasing P rate. Commerce sl and Perry clay soils tested low to medium for Mehlich-3 extractable-P but responded differently with the application of P fertilizer. Grain yield of corn grown on Perry clay significantly responded to P rate but not in Commerce sl which was testing very high for Bray-2 extractable-P. The applied P fertilizer was transformed into Ca-P for Commerce sl while Perry cl transformed into Fe- and reductant-P. Overall, the labile- and Al-P at 30 DAP increased with increasing P rate. With time across P rates, both soils showed build-up of less readily-available reductant-P. For total-P, residual-P and total-Pi components, Commerce sl and Perry clay differed significantly (P<0.05) at both 30 DAP and harvest; while total-P and residual-P of both soils were not affected. Refinement of soil test P prediction should be pursued such that P fertilizer recommendations will not be based solely on P soil test.

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