Total Salts  Water that contains heavy ions or salts are toxic to plants. Salinity is most important measure of water quality for landscape plants. It is expressed as total dissolved solids and electrical conductivity. When water is applied to soils, some of the salts, notably sodium, chloride, and boron accumulate in the soil creating plant toxicity.  The degree of the problem depends on the sensitivity of the plant to salts and the accumulated concentration in the soil. Salt toxicity is expressed as stunting of growth, yellowing of foliage, burning of the edge of the leaves and defoliation. Ion toxicity is difficult to distinguish specific symptoms from each other. Ion toxicity through foliar absorption occurs at much lower concentrations than soil absorption. Toxic symptoms of specific ions are difficult to distinguish, as some plants have a high tolerance, as others are highly sensitive. There is little information is available on plant sensitivity to specific ions and one must rely on experience and observation. (See Essential Nutrients)

Bicarbonate   Hill Country soils typically have high bicarbonate levels which, can cause iron chlorosis (See Iron Chlorosis) and also affect plants through its influence on pH (See Soil pH) and interaction with sodium. Water, high in bicarbonate, carbonate, calcium, or magnesium, or a combination of these elements, can cause white precipitate of foliage under irrigation and can cause harm not only to the equipment, but create residual problems in the soil as well as water absorption.

Heavy Metals   Are rarely present in water in sufficient quantities to be directly toxic to plants. Most metals, however, become tied up in the soils and their concentrations increase over time. It is this accumulation of these elements which become toxic to plants. This is where biological and microbial activity become essential.

Soils Urban  Natural conditions create forest soils, whereas, urban soils lack the natural characteristics that benefit trees. Urban soils rarely have an organic layer. They may be compacted, crusted, have poor water absorption, elevated pH, asphalt hardscape (parking lots) and, surface barriers (buildings). All these factors harm "soil life" .... root growth and tree health.  (See Soil of Life)

Trees, Soil, Boilogical and Microbal Life  The loss or reduction of organic matter decreases biological and microbial activity, hampers soil structure development and interrupts element cycling. (See Cation Exchange) Soil compaction is often caused by construction, foot or vehicular traffic, and recovery from structural damage can take a long time. Urban soils may be contaminated with construction debris, such as asphalt, concrete, plaster, paper, paint etc. and other waste materials. These conditions for trees range from unfavorable to antagonistic. To best describe the micro eco-system or rhizophere under a tree, it is like a piece of thick fresh baked bread, spongy soft and porous. All the capillaries contain all the gasses,nutrients, and moisture for the health of the tree and roots. Compact or flatten this rhizophere like a tortilla and the nutrients, water,oxygen and elements are present but no longer available to the tree roots which can in turn forfeit the overall tree health.

Trees blend with, rather than grow on, the soil. Fallen leaves and twigs accumulate as a distinctive organic layer on top of, and incorporates into, soil. The chemical makeup of organic matter brings about species, and these effects positively impact growth, vitality, disease resistance, and longevity. Trees and soils are so ecologically interdependent. (See Trees are Vital)   (See Bio-Stimulants)

Trees are living systems driven by energy for their metabolism growth, reproduction and resistance to disease. Trees must obtain sufficient oxygen, water, essential elements and nutrients from the soil to meet their energy requirement. Organic, and nutrient rich soils contribute to biological and microbial activity, particularly mycorrhizal which are essential to tree health. (See Nitrogen Article)