This formula is effective properly for many vegetable gardens providing your soil is in good condition, to start with. For those who have an excessive amount of P or K inside your back garden based with your soil test, eliminate the bone meal (P) or feather meal (K) as required. https://npk-15-15-15-meaning59157.blogsidea.com/35849941/the-2-minute-rule-for-npk-15-15-15-vietnam-nhật-15-15-15