Part3Lecture9-11 - Fertilizer Management - Macronutrients...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
35 Fertilizer Management - Macronutrients There is a general ratio of macronutrients to maintain in the root medium. Inputs from the water, fertilizer and root medium must be considered. The macronutrients are Nitrogen (N as NO 3 and NH 4 ) Potassium (K) Magnesium (Mg) Phosphorous (P) Calcium (Ca) Sulfur (S) There are many fertilizer salts. There must be a system to decide which to use. On the following pages are a summary table of common macronutrient fertilizers and a listing of Peter’s commercially blended water soluble fertilizers. There are five things to consider in selecting a water soluble fertilizer: Balance of nutrients Nitrogen reaction and effect on media pH Nitrate versus ammonium nitrogen Solubility of salts and the mixture Effect on nutrient intensity or electroconductivity Balance of Nutrients The ratios on the fertilizer bag represent the amount of nitrogen, P 2 O 5 and K 2 O. P 2 O 5 is only 44 percent phosphorous and K 2 O is 83% potassium. So, for a 20-20-20 fertilizer, the nitrogen-phosphorous-potassium ratio is 20-8.8-16.8 or 2.3-1-1.9. The effect of fertilizer on soil test levels and analytical results are reported in parts per million or ppm and change more in relation to the applied ppm ratio. While there are many different commercially available blends of water soluble fertilizers recommended for a specific crop, the majority of crops in peat-based media can be grown with one nutrient ratio. Only a limited number of solutions should be necessary. In the majority of cases, the sum of the nutrients in the irrigation water and fertilization program for peat- or bark-based media amended with phosphorous, calcium and magnesium should approach the following ratio: Nutrient Ratios N : P : K : Ca : Mg : S 13 : 1 : 13 : 7 : 2 : 2 200 : 15 : 200 : 100 : 30 : 30 ppm ratios Example ppm
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
36 In these examples all the elements were either cut in half or doubled. This is what typically happens when fertilizer rates are reduced or increased. It is how changes have traditionally been made. It usually results in excess phosphorous, calcium, magnesium and sulfur being applied when high nitrogen and potassium are added under rapid growth conditions. In this example nitrogen and potassium are changed in concentration while the others are not. This example is what I recommend based on research at MSU and my experiences. Our research indicates that maintaining phosphorous, calcium, magnesium and sulfur at a similar level while changing nitrogen and potassium as the amount of growth desired changes provides for more efficient nutrient utilization and perhaps easier management. Following are some general rules to consider: The ratio of nitrogen to potassium in ppm is typically 1:1. This ratio may change depending on the plant species, but it will be in the range of 1N : 0.3K to 1N : 3K. The “K ratio” is the ratio of nitrogen to potassium with nitrogen as 1. A 20-10-20 fertilizer has a K ratio of 0.8 since the fertilizer is 20 percent K
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/25/2008 for the course HRT 221 taught by Professor Biernbaum during the Fall '04 term at Michigan State University.

Page1 / 18

Part3Lecture9-11 - Fertilizer Management - Macronutrients...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online