Mitigating Soil Sodicity in Irrigated Sugarcane Plantations with Canavalia Rosea: A Pot Experiment

Abstract To promote the use of legumes for the alleviation of sodicity in small-scale irrigated sugarcane plantations to reduce the cost of soil amendments for small-scale sugarcane farmers. A greenhouse pot experiment was conducted by growing Canavalia rosea (Sw.) DC. in high sodium (Na + ) concentration/sodic sugarcane plantation soils over a period of seven months. Plant material and soil characteristics, including salinity indicators, were analysed pre– and post- C. rosea harvest. Canavalia rosea hyperaccumulated more sodium (Na + ) with age significantly decreasing soil Na + concentrations from 271.870 to 51.573 µmol Na g -1 post- C. rosea harvesting. The electrical conductivity (EC), sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP) were significantly reduced after three months and remained statistically similar over the period to the seventh month. Pseudomonas putida and various species in the Bacillus genus including B. amyloliquefaciens , B. safensis , B. pumulis , B. subtilis , and B. zhangzhouensis were isolated from C. rosea plants, revealing associations that likely assisted C. rosea in Na + tolerance and improved nutrient availability. The increased abundance of Flavobacterium species in rhizosphere soils was attributed to the ability of C. rosea to reduce soil Na⁺ concentrations, creating favourable conditions for microbial proliferation. Consecutive cultivation of C. rosea reduced Na + concentration by five-folds and improved soil characteristics in sugarcane plantation soils from Sikhwahlane, Mpumalanga. However, field studies are recommended to study the soil Na + / sodicity reduction, microbial interactions and growth of C. rosea at irrigated sugarcane plantations. Pot size and irrigation protocols in controlled experiments may lead to pot binding, potentially influencing the response of C. rosea in sodic soils. Graphical Abstract