Boron Management for Sugarcane on Volcanic Ash-Derived Soils.

Sugarcane world production represents one of the greatest contributors to the consumption of plant calories in the human diet, and the efficiency to produce ethanol from its extracted juice places it as one of the most important crops for bioenergy production. While this crop expands rapidly in global agriculture, the average yields are as yet far from their estimated potential. An increased interest in microelement nutrition of sugarcane has led to several advances in fertilizer applications. However, response to Boron (B) has not been consistent for either soil or foliar applications to this crop in Central America. Boron rates are commonly applied without considering soil interactions that might limit its availability. Applications of 0.5 to 4.0 kg B ha^-1 have not solved B deficiency problems in volcanic soils. In a separate study on B adsorption, volcanic soils were shown to have low availability of applied B. Based on B adsorption capacity of a volcanic Mollisol from Guatemala B rates were calculated to evaluate yield responses of the variety CP-722086. Significant 5% yield increase was obtained at 7.6 and 15.2 kg B ha^-1 for this soil with an adsorption capacity of 53 kg B ha^-1, showing that the lack of previous response was due to an underestimated application rate, and that yield increases are achievable if B rates are estimated from B adsorption capacities. Because B is involved in the translocation of sugars, a set of independent experiments were performed to evaluate the effect of B on the ripening stage by foliar application 8 weeks prior harvest. Boron increased sucrose accumulation in the culm when applied at 0.2 kg B ha^-1 with comparable effects to those of glyphosate and trynexapac-ethyl. These results show that B management based on sound scientific principles can lead to substantial yield improvements on these soils.