Soil Alkaline 7.5
I have several citrus trees in my backyard: Minneloa Tangelo (darwf - planted 8 yrs ago), Washington Navel Orange (darwf - planted 8 years ago), Nagami Kumpuat (planted 8 years ago), Lisbon Lemon Tree (three years old)and two Black Mission Fig trees (planted two years ago). All these trees in the back yard are not over 4 feet tall. I have been following the prescribe water schedules accordingly. Recently I tested the soil with a meter and its reading was 7.5+ Alkaline. I have a desert landscape in my front yard and my mesquite tree (planted it when it was a twig now 40+ft tall - planted 8 years ago), cactus, ocotillo, agaves grow beautifully and rapidly with new growth every where but in my backyard my fruit trees are struggling to grow more than an inch or two with proper watering and quarterly food delivery. New growth and leaves take place at a very very slow rate with many 0-7 fruit per year. Every spring the trees start with tons of fruit but they all fall off within 30 to 60 days afterwards. In the passed I have used a product sold by Garderner's World call Dispursel (qtrly application)(it is similar to gypsum) and it helped my citurs trees in my other homes to yeild boxes full of citrus fruit when my trees were not yeilding any fruit but in this home's backyard the citcus trees are not doing too well.
I called several nurseries in town and they advsied me that the soil is too alkalinized for citrus which like it around 6.5. They told me to add soil sulfur or if I drank coffee to add the used coffee grinds around the trees. Does coffee grinds really work to lower the alkaline from 7.5 to 6.5?
How much soil sulfur should be added to lower the 7.5 level to 6.5 and how frequently should this be applied?
Could you share with me how to help my trees grow at a better rate than an inch or two per year for the past 4-5 years. I have had cirtus trees before and planted them before in my other houses and they have taken off to grow 20 feet tall. I live right next to South Mountain (Phx AZ) and so the soil needs some conditioning compared to my other houses which were cirtus orchards before the houses came in.