Do phosphogypsum combined with Organic Amendments improve Rice Growth in a Saline Environment?

Aims: The aim of this study was to investigate the effects of organo-mineral amendments on rice growth under saline stress conditions.

Study Design: A 3x8 factorial block design was adopted, with 3 concentration levels: 0, 1.94 and 3.88 g/l NaCl and 8 different amendments: control, phosphogypsum (Phos), compost (C), biochar (B), Phos+C, Phos+B, B+C and Phos+B+C. This system was repeated 3 times in 3 blocks. Organics amendments were applied at a rate of 5 kg/m² and 0,2 kg/m² for phosphogypsum.

Place and Duration of Study: The trial was conducted from April to June 2021 on the farm of the Agroforestry Department of the Assane SECK University of Ziguinchor, located at 12°32 - 88' N, 16°17 - 23' W, in the Ziguinchor region.

Methodology: After two months of cultivation under semi-controlled conditions, growth parameters were measured. In fact, the survival rate is obtained by counting the number of plants that have survived, and the height of the plants is determined using a graduated ruler. The number of tillers was obtained by counting the number of branches and the diameter using a caliper at the base of the crown. Root and above-ground biomass were determined by weighing the plants after 72 hours of oven-drying at 70°C.

Results: For the amended treatments, plant survival rate was 100% compared with unamended controls, where plant survival decreased with increasing salinity, with rate of 96, 80 and 70% corresponding to 0; 1,94 and 3,88 g/l NaCl respectively. The number of tillers, crown diameter and above-ground and root biomass of the plants were significantly higher (pr < 0,001) for compost amendments alone (C) and those combined with compost: B+C, Phos+C, Phos+B+C, regardless of the salinity level.

Conclusion: The combined use of organic and chemical amendments could enable farmers to restore salinity-affected soils and improve rice growth.