def compute_field_capacity(clay_val, oc_val, sand_val):
    """
    Calculate Field Capacity based on Clay, Organic Matter and sand value
    :param clay_val: percentage of clay
    :param oc_val: percentage of organic carbon
    :param sand_val: percentage of sand
    :return: a float value representing FC
    """
    om_val = 2 * oc_val
    om_val /= 1000
    clay_val /= 100
    sand_val /= 100
    theta_33_t = (0.299 - 0.251 * sand_val + 0.195 * clay_val + 0.011 *
        om_val + 0.006 * sand_val * om_val - 0.027 * clay_val * om_val + 
        0.452 * sand_val * clay_val)
    theta_33 = theta_33_t + (1.283 * theta_33_t * theta_33_t - 0.374 *
        theta_33_t - 0.015)
    return round(theta_33, 2)
