Aneeza Soobadar, Suman Seeruttun and Arouna Seechurn
Mauritius Sugarcane Industry Research Institute, Réduit, Mauritius; aneeza.soobadar@msiri.mu
Mauritius has been experiencing a yield decline in its sugarcane productivity since late 1980s; a gradual loss in soil health was reported as one of the major causes in 2008. Despite some positive results obtained from remedial actions through the development of new cropping systems, yield decline has not been fully mitigated. Restoring soil health calls for a review of the current fertilizer strategies that would integrate all chemical, biological and physical properties of the soil. In a study initiated in 2023 to assess the soil-health status of sugarcane lands, soil samples were collected from the major agroclimatic zones before being analyzed for their chemical, physical and biological indicators; a soil microbiome assessment was also conducted. In parallel, field trials were conducted to assess the impact of soil-health promoters on soil quality and sugarcane yield. Irrespective of soil types and management practices, yields of older ratoon crops correlate well with water-extractable organic C (R=0.95). For Humic Acrosol soils, yield was significantly correlated to Mehlich III extractable Boron (r=0.70) and to soil bulk density (r=0.63). The results suggest that these indicators could be considered before fertilization strategies are developed for the respective soil groups. CO2 bursts correlated well with soil-health score (r=0.97). No significant difference has been observed in cane yield between conventional fertilization practices and soil-health promoters despite the latter showing an increase in soil nitrates and Water Extractable Organic N, indicating that such products may take longer to impact on yield. More soil samples currently under analysis will provide a better insight of the soil-health status in Mauritius and lead to new fertilization strategies.