Question
Hi,
Could you please tell me the advantages and disadvantages for using organic and inorganic fertilizers?

Also if you can, could you help me to see how much fertilizer i put on a hectare of apples trees and which fertilizer to use?
Also could you give me the equation for it.
thanks any help appreciated
pat

Answer
I dont recommend organic nitrogen, especially manure which is typically used in orchards, because the nitrogen is released over a prolonged period of time. This slow release means this perennial crop continues to receive nitrogen throughout the year, resulting in poor fruit colour, excessive terminal growth and delayed hardening of the woody tissue. This makes trees more susceptible to winter injury. The practice of putting manure around newly planted trees is not recommended because of potential winter injury problems. If manure is used, it should be broadcast at moderate rates and worked into the soil in late fall or early spring before planting.

No more than 3 m.ton/acre poultry manure, 14 m.ton/acre of cattle or pig manure should be applied. Since manure is extremely variable in nutrient content, make sure you analyze it for nutrient content before application. When manure is used, reduce the rate of fertilizer.

The fertilizer of choice in my opinion would be a synthetic fertilizer high in nitrogen and potassium should be applied and the advantage of using synthetic fertilizer is that it release quickly when it is needed, and that you can time the release and the mix of nutrients.

When choosing between the many synthetic sources, try to get one which has a ratio of 2-1-2 or close. e.g. 20-10-20, 10-5-10 etc. You can go with 10-10-10 if you can not find the above, but dont go with 10-60-10 or 29-3-4 for example. Make sure the ratio (the internal relationship between the 3 numbers) are 2-1-2: 10-5-10, 20-10-20, 5-2-5, etc

Apply maximum 180 lbs per acre of actual Nitrogen. to find ACTUAL nitrogen, divide 18000 by the first number on the bag:

ex1: 18,000 / 10 (10-5-10) = 1,800 lbs/acre.
ex2: 18,000 / 20 (20-10-20) = 900 lbs /acre.
ex3: 18,000 / 10 (10-10-10) = 1,800 lbs/acre.

Apply one single application in June.

I also recommend that you have a soil test done to determine pH, iron, magnesium and calcium levels.

Generally, phosphorous is not required in high quantities by apple trees (since the smaller second number). If phosphorous is required, you could change to a 10-20-20 fertilizer for a single application one spring for example.

Potassium (the 3rd number) is generally required in same amounts as nitrogen.

Magnesium deficiency is sometimes a problem in orchards due to the high potassium rates. Dissolve 2 ouces of Epsom Salt (magnesium sulfate) per gallon of water and water into the root zone of the trees once if soil test show magnesium deficiency.

Soil pH/Calcium
if soil pH is too low (if it falls below 5.5) apply lime which will also add calcium. soil pH target should be 6.0-6.5. If magnesium also is needed choose dolimitic limestone rather than caltric limestone. Since calcium is beneficial to fruit trees, use a single application of Gypsum every 2 years if you do not need to to lime (do not lime if you do not need to, and do not double up on gypsum/lime).


In any event, I recommend that you contact your local county extension office and get a soil test done. A lot of issues can happen if the soil pH is off, or if you lack micro nutrients (boron in particular) so first step is a soil test.

I hope above helped you part of the way...