Mulched and soil-incorporated sugarcane greenchop residue effects on soil nutrient levels, sugarcane physiochemical and yield parameters, and injury caused by the Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae)

Burning of sugarcane, Saccharum spp., fields to remove leaves before harvest can have deleterious effects on soil and air, and in some parts of the world the practice has been discontinued.  This study, conducted in the Lower Rio Grande Valley of Texas, examined effects of the leaf residue, or “greenchop”, remaining in the field after harvest as a mulch, as soil-incorporated organic matter, and sprayed with compost extract then soil incorporated compared against a nontreated control and soil-incorporated compost, on levels of soil and sugarcane plant nutrients, injury by the Mexican rice borer, Eoreuma loftini (Dyar), and crop yield parameters.  Although the compost amended soil had greater concentrations of many nutrients, particularly P, Ca, Mg, and Zn, in leaf tissue those elements, sugars, and, during the first growing season, free amino acids were not affected by any of the treatments.  Levels of Mexican rice borer injury to sugarcane stalks during the first season, however, were generally greater in the greenchop and compost treatments than in the control.  In the second growing season, free histidine and lysine, both essential for insect growth and development, were elevated in the compost treatment, which was the only treatment associated that year with heightened Mexican rice borer infestations.  Greenchop had no positive or negative effects on soil and the measured nutrients in sugarcane leaf tissues, but it can increase the risk of greater Mexican rice borer injury.  Possible mechanisms explaining the associations between the treatments and Mexican rice borer injury to the crop are discussed.