Maintaining or improving the soil quality is crucial for agricultural productivity. This study was undertaken to evaluate the effect of zeolite and its combination with chemical fertilizer and organic fertilizers on soil quality and sugarcane yield in the north coast of Cuba, Villa Clara province. The organic fertilizer (sugarcane filter cake-SFC), and natural mineral (zeolite-Z) and chemical fertilization (nitrogen-phosphorus-potassium-NPK) were applied as treatments. The experiment was laid out in a randomised complete block design with nine treatments and four replicates. The soil samples were taken at a depth of 0-20 cm to determine soil properties such as degree of soil aggregation, water-stable aggregates, permeability, lower plastic limit, pH in water, pH in KCl, organic matter, assimilable P 2 O 5 and K 2 O. The sugarcane yield components such as cane yield (t ha -1 ) and sucrose yield (t ha -1 ) were evaluated. Principal components analysis (PCA) and simple regression analysis were also performed. The best results on cane yield were obtained with the treatment Z 7.5 t ha -1 + SFC 22.5 t ha -1 , which represent a relative increase of 200% vs control (without fertilization). Relations between soil properties and principal component analysis confirmed the good response of zeolite application on soil quality and sugarcane yield.

The Cr (VI) and Ni (II) ion biosorption process by natural sugarcane bagasse in a fixed bed column was investigated. The characteristic removal parameters such as retention capacity, removal percent and unused bed length were experimentally determined at different operating conditions. Overall mass transfer coefficient was investigated and reported for the studied biosorption system. The breakthrough curves were simulated using Matlab2010a software to check the validity of the obtained overall mass transfer coefficients. Experimental data fitted well with predicted data (R 2 = 0.94). A statistical analysis was performed using the software Statgraphics Centurion-X V 15.2.06 to compare the simulated and experimental data. No significant differences were observed between experimental and simulated data. The best operating conditions for Cr (VI) removal were 15 mg/L of inlet concentration and 1.5 g of biosorbent. For Ni (II) removal the best results were obtained with 25 mg/L of inlet concentration and 1.5 g of solid. The results obtained through the breakthrough curve showed high removal percentages (94.70 and 97.90% for chromium and nickel, respectively). Moreover, results indicated that sorption of these metals was irreversible and it was controlled by the mass transfer at the external film.