Residual Effect of Ammonium Sulfate Substitution on Soil Properties and Productivity of Plant and Ratoon Cane

Overuse of the Ammonium Sulfate (AS) fertilizer in the long-term sugarcane cultivation has a negative impact on the soil properties which in turn can decrease soil and crop productivity. The study to describe the residual effect of AS substitute fertilizers on soil physico-chemical properties and cane productivity compared with AS fertilizer, was conducted at up-land in East Java during two cycles of the sugarcane growth (plant cane and ratoon cane). There were ten treatments which were tested consisting of three treatments using AS fertilizer, six treatments using the AS substitute fertilizer, and one control (without the use of the fertilizers). The measured variables were soil bulk density, total N, SO42- content, soil pH, and yield variables. The use of the AS fertilizer substitute decreased the soil bulk density and increased the total N, SO42- content, and soil pH at the post-harvest of plant and ratoon cane. It confirmed a better condition in the soil with the AS fertilizer substitute rather than the AS fertilizer by itself. The residual effect of the AS fertilizer substitute on the soil properties at the post-harvest of plant cane significantly provided a positive impact on cane and sugar yield at the ratoon cane. The soil SO42- and total soil N content were the most important soil properties that influenced cane and sugar yield of ratoon cane. It suggests that the use of the AS fertilizer substitute is recommended on sugarcane cultivation for minimizing adverse residual effect and maintaining the soil quality.