Effect of biostimulants on the nutrition of maize and soybean plants

The presence of humic substances in biostimulants composition affect positively plantgrowth by the improvement of the cation exchange capacity of the soils (CEC) and also by theformation of water soluble complexes with ions which can be uptaken by roots. Biostimulantsimprove plant growth due to the cytokinin and humic acids present in their composition. Over theyears the use of these products has been increasing and it is necessary to conduct more studies toevaluate their efficiency in promoting plant growth. The aim of this research was to evaluate theeffect of biostimulants (Brotax Solo®, Naturvital®, PT4-O® and Brotax-5®), applied with andwithout mineral fertilization, on nutrient uptake by maize and soybean plants. A greenhouseexperiment was conducted in Piracicaba, State of São Paulo, Brazil. Three-liter pots were filledwith 0-20 cm depth samples of Quartzipsamment soil. Base saturation was increased to 60% byapplying lime in the samples following incubation for 20 days at 80% the water retentioncapacity. After this period, mineral fertilizers were added to pots of specific treatments. Theapplied doses in L ha-1 were:Brotax Solo®: 0; 150 and 300; Brotax-5®: 0; 8 and 16; Naturvital®:0, 25 and 50; PT4-O®: 0; 0.5 and 1; referring to control, recommended dose by manufacturer and100% higher than this one, respectively. The products were diluted in water and they wereapplied in the pots 21 days after planting. Two months after planting, plant tops were collected,dried, weighted and nutrient contents in plants were determined. Data were subjected to analysisof variance (ANOVA) and means were compared by the LSD test (α = 0.05). Nutrient content inplants was higher in fertilized than in non-fertilized pots, for all products and crops. Ca and B;Zn; K; Ca and Mg contents were higher in maize plants treated with Brotax Solo®, Naturvital25®, PT4-O® and Brotax-5®, respectively. In soybean plants only the product PT4-O® showedincrement in Fe content. The amount of nutrients and humic acids in the studied products was notsufficient to increase significantly the amount of nutrients in the maize and soybean plants.