OPTIMUM PLOT SIZE FOR RICE TRIALS UNDER THE IMPACT OF BIO-AGENTS WITH A SIGNIFICANT INFLUENCE ON SOIL VARIABILITY IN BAGACES, GUANACASTE, COSTA RICA

Abstract

This study was conducted in order to determine whether adding products based on microorganisms could increase, through their natural dynamics and their interaction with native microflora and microfauna populations, the variability of the soil and, therefore, the optimum plot size for rice trials in Bagaces, Guanacaste, Costa Rica.  This trial was conducted at the same farm where the optimum plot size was defined for rice trials in the area (Vargas & Navarro 2014). Four uniformity trials were planted, one for each product used: Trichoderma, Bioactivado, Nitrobacter, and Micro Plus. The data obtained was used to apply the maximum curvature method. The point of maximum curvature was determined using the partial derivative of the regression equation, which relates the plot size (X) with the corresponding variation coefficient (Y). None of the product’s point of maximum curvature exceeded the scope defined by Vargas & Navarro (2014) from 15 m² to 20 m². None of the indices of heterogeneity obtained exceeded the 0.83 value (the scope of the scale for this measure ranges from 0 to 1, where 0 indicates total homogeneity and 1 total heterogeneity) (Vargas & Navarro 2014), which shows that very diverse soils can be found in the same farm.  Finally, the variance analysis showed differences in the production obtained with each product. A 17tm/ha production was obtained with Bioactivado, which triples the normal production of the farm.