Very interesting scientific article, note the root development following an application of compost on the surface for 5 years

http://www.globalsciencebooks.info/JournalsSup/images/0812/DSDP_2%28SI1%2967-71o.pdf

Thanks for the link Ivannn, very interesting study.

I read only the abstract, but have book marked the entire article for further study. I have a in ground Cara Cara navel, currently about 9-10 feet tall and 7 feet wide, that I have been mulching with a constant layer of just about anything organic that I find laying around. The mulch layer seems to constantly remain about 2 inches thick. It has been about 6 months since I began adding the mulch. I am not an organic grower, so I also fertilize tree with 25-5-15 W/TM fertilizer. Time will tell how well the tree does compared to the conventional growing method of keeping the ground beneath a citrus tree completely bear. Thanks for the article. I am going to study the complete article in the coming week. - Millet (668-)

Looks like an interesting article. I copied off, and will read. The abstract points to positive benefits, except for nitrogen. I have property in California's citrus district that I had been considering these ideas. I want to stay organic, but how can I get enough nitrogen?

Actually, the article says that the best fruit production was from the trees that were given both fertilizer and "compost", not what Americans normally call compost, but rather ordinary bark chips, annually for 5 years.

The use of urea is prohibited for certified organic growing in the USA.

www.soils.wisc.edu/extension/materials/Organic_NM.pdf

Millet (658-)

Yes you're right, and thanks for the link!

Can anyone tell me why you would not get similiar if not better results in sandy soil? I have never had anything grow better in unimproved soil. I'm seriously considering using leaf mulch around my citrus leaving a one foot circle clear around the trunk. It would virtually stop the use of herbicides and manual eradication of weeds and such. I really do not want to use chemical controls and this would surely help.

On a side note what would be the diffeence between pine bark mulch (large chunks), small live oak tree leaves and shredded live oak tree leaves?

I've always heard that mulch in general is the gardener's best friend.
Conservation of moisture, addition of organic material to the soil, prevention of weeds,etc. all tend to be good things for plants.

I plan to mulch my citrus this year.

One thing though:

I have also heard that bare soil is best for citrus in winter. This allows the sun to "charge" the soil during the day. The escape of heat from the soil in the night helps protect against frost.
However, if there is a long, dark, freeze spell, wouldn't bare soil freeze faster than mulched soil?

I'm not sure if I should take the mulch back off for winter...

One thing that separates us zone pushers from the citrus belt growers is the number of cold days and nights that we experience. In central Florida having the warm bare ground to radiate heat is a benefit as it would be for us the first few times a chilly cold evening arrives however where the citrus belt will have numerous days to recharge the ground we may not. So in the early Winter it may benefit us to uncover the ground but I think the benefit will be short lived and rapidly turn to a deficit as the uncovered ground looses valuable stored warmth we may need before Spring arrives. I think I am leaning to permanent mulch but not within one foot of the trunk.

The best organic fertilizer is GUANO, but also chicken manure, cow manure and horse manure is very well.

http://en.wikipedia.org/wiki/Guano