Sometimes a fertilizer ratio is specified on soil test reports or in fertilizer recommendation sheets. The fertilizer ratio indicates the proportion of nitrogen, phosphate, and potash in the fertilizer product, and is determined by dividing each of the three numbers in the fertilizer grade (listed on the container) by the lowest number in the grade. For example, when each number in a fertilizer grade of 18-6-6 is divided by 6 (the lowest number in the grade), the proportion is determined as: three parts nitrogen to one part phosphate, to one part potash. Thus, the fertilizer has a 3-1-1 ratio.
If your soil test report recommends applying 1.5 lb of nitrogen, 0.5 lb of phosphate, and 0.5 lb of potash per 1000 sq ft, you should apply a fertilizer with a ratio of 3-1-1 since you need three times as much nitrogen as phosphate and three times as much nitrogen as potash. The simplest method of determining a ratio is to divide the weights of nitrogen, phosphate, and potash listed on the soil test report by the lowest weight of the three.
To determine a fertilizer ratio for a soil test recommendation of 1.5 lb of nitrogen, 0.5 lb of phosphate, and 0.5 lb of potash, divide the weight of each of the three nutrients (1.5 lb, 0.5 lb, 0.5 lb) listed on the report by the lowest nutrient weight (0.5 lb in this case).
1.5 ÷ 0.5 = 3
0.5 ÷ 0.5 = 1
0.5 ÷ 0.5 = 1
Thus, the fertilizer ratio that best fits this recommendation is 3-1-1. As demonstrated in the first paragraph, you can match the fertilizer ratio for this recommendation with a fertilizer grade by dividing each number in the fertilizer grade by the lowest number in the grade.
As you can see from these three examples, fertilizer grades for certain products do not always match the exact fertilizer ratio you are searching for. Thus, the goal is to find a product with a grade that is as close as possible to the specified ratio.
Want more information on npk fertilizer, npk 15-15-15 fertilizer, NPK Fertilizer for sale? Click the link below to contact us.