Effects of Application Timing and Soil Type on Optimal N Rate Requirement of Sugarcane (Saccharum spp.) and Changes in Soil Inorganic and Leaf N Concentrations
Semester of Graduation
Master of Science (MS)
School of Plant, Environmental and Soil Science
Research is limited on the effects of soil types and early nitrogen (N) fertilizer applications to N management strategies in sugarcane (Saccharum spp.) production in Louisiana. This study was established in 2015 at two locations in St. Gabriel, LA to 1) determine the effect of fertilizer application timing and soil type on the optimal N rate requirement and yield of sugarcane and 2) relate the relationship of soil and leaf N content to yield at different growth stages with sugarcane yield. Treatments were set in a randomized block design on a clay soil and in a complete randomized design on silt loam soil, using sugarcane variety L01-299. Granular (Agrocote Max®, 45%N) and solution (urea ammonium nitrate solution-UAN, 32%N) N sources were applied at rates of 45, 90 and 135 kg N ha-1 and at two application timings (March and April). All treatments including a control (0 kg N ha-1) were replicated four times. Sugarcane yield was recorded at harvest. Sequential sampling of soil were done at two depths (0-15 and 15-30 cm) and leaf below the top visible dewlap (TVD). The N application timing did not have a large effect on inorganic N release within the soil particularly outside the active N uptake growth period of sugarcane. The optimal N rates on the silt loam soil using UAN fertilizer applied in March were 39 and 43 kg N ha-1, yielding 14,102 kg sugar ha-1 and 117 Mg cane ha-1. Yield for sugarcane applied with CRF were maximized at lower N rates, but resulted in lower yields. The positive linear relationship between leaf N content and yield was highest in mid-May sampling with r = 0.85 for cane and sugar yield. Highest correlations between leaf N content and soil inorganic N were all within 8 WANF, with April-applied fertilizer showing high correlations between the two variables earlier than March-applied fertilizer. The dynamic nature of inorganic N in Louisiana can be better understood and more efficiently utilized for sugarcane production through further research on the effects of N management practices and site-specific factors.
Garrett, Joseph Martin, "Effects of Application Timing and Soil Type on Optimal N Rate Requirement of Sugarcane (Saccharum spp.) and Changes in Soil Inorganic and Leaf N Concentrations" (2018). LSU Master's Theses. 4703.