San Diego soils can be very interesting and do differ in composition and structural makeup depending upon their unique location. You can find a blend of beach cobble and clay throughout the Mira Mesa highlands, rich porous red brown sand in Leucadia and California Gumbo as we like to call the green compressed hardpan clay found in Escondido and the outlying areas around the coast.
This clay is perfect for digging and moving large specimen trees like the Canary Island Date Palm or an Oak tree. Usually the rootball will hold together nicely during transplant but more importantly, the roots of these large specimen trees do not penetrate past this extremely hard substrate into deeper ground making it relatively easy to break them loose with little transplant shock during harvesting.
Western soils, in our country, are relatively high in alkalinity. This means we have a higher soils ph number here in California. Since little rain falls here naturally, the leaching process that you will find in the East where the soils ph is low does not occur. Typically, desert soils are more porous and have greater levels of magnesium, calcium and iron.
The lower the ph in soils, the more readily plants can absorb the constituent metals of iron, copper, manganese, zinc and boron. Higher ph soils or alkaline soils help plants absorb phosphorus, potassium, sulfur and molybdenum at a greater rate than lower ph or neutral soils.
I find it so interesting that out of more than 100 constituent elements in the periodic table, there are only 16 elements absolutely necessary for plant growth and development. The top three of course being oxygen, hydrogen and carbon. These three are inextricably intertwined as they combine to make the foodstuffs of all living things: carbohydrates, sugars and water the mixer elixir that transports minerals and foodstuffs throughout the vascular systems of plants.
The other 13 elements are composed of iron, magnesium, manganese, sulfur, nitrogen, molybdenum, zinc, boron, potassium, phosphorus, calcium, copper and believe it or not chlorine, which can be found universally in nature.
All plants need and use nitrogen to grow. This element is found universally throughout the atmosphere where it contains 78 percent nitrogen over all. Plants cannot readily uptake nitrogen unless it combines with oxygen or hydrogen in a process called nitrogen fixation. Soils bacteria fix the nitrogen gas into nitrate or N03. Nitrogen can also be fixed into another usable source, known as ammonium or NH4.
This process makes the nitrate form of nitrogen able to pass clear through the soils where it is readily taken up by the root system. Nitrates or nitrogen are truly the building blocks of life. Nitrates form the backbone of all amino acids, which in turn create the building blocks of protein which all organic forms (including you and me) are made from.
Chlorophyll is the key protein resulting from nitrogen absorption that ultimately controls the production of sugars and carbohydrates during photosynthesis so necessary to the engines of plant growth.
Phosphorus, another constituent element, is very important in flower production and seed growth. It is an important building block in the production of nucleic acids found in RNA and DNA. These are the blueprints for cell growth and reproduction.
Interestingly, the more nitrogen available with phosphorus, it would be the better the absorption of both elements by the plants. This is due to the increased subsequent root growth and physiological changes (especially during the warmer months) that favor the uptake of these two important elements. (This is why you fertilize typically in the third, sixth and ninth months of the year when temperatures are warmer.) Not much growth or absorption happens when it is cold and your nutrients are washed away by the winter rains.
Potassium, the third most common constituent found on a triple 16 or triple 20 bag of chemical lawn fertilizer, is not converted into a plant structure or tissue. It is more of a facilitator of water or vascular operations element. Potassium also helps facilitate the movement of carbohydrates and sugars throughout the plant and is essential to the production of good fruits and grains.
When you know your soils and plants requirements, you will grow a beautiful landscape.