WHAT KIND OF SOIL DO YOU WANT?

WHAT KIND OF SOIL DO YOU WANT? Soil consists of four important parts: mineral solids, water, air, and organic matter. Mineral solids are sand, silt, and clay and mainly consist of silicon, oxygen, alu-minum, potassium, calcium, and magnesium. The soil water, also c nutrients and is the main source of water for plants. Essential nutrients are made available to the roots of plants through the soil solution. The air in the soil, which is in contact with the air above ground, provides roots with oxygen and helps remove excess carbon dioxide from respiring root cells. When mineral and organic particles clump together, aggregates are formed. They create a soil that contains more spaces, or pores, for storing water and allowing gas exchange as oxygen enters for use by plant roots and soil organisms and the carbon dioxide (CO2) produced by organisms leaves the soil. Farmers sometimes use the term soil health to describe the condition of the soil. Scientists usually use the term soil quality, but both refer to the same idea— how good is the soil in its role of supporting the growth of high-yielding, high-quality, and healthy crops? How would you know a high-quality soil from a lower-quality soil? Most farmers and gardeners would say that they know one when they see one. Farmers can certainly tell you which of the soils on their farms are of low, medium, or high quality. They know high-quality soil because it generates higher yields with less effort. Less rainwater runs off, and fewer signs of erosion are seen on the better-quality soils. Less power is needed to operate machinery on a healthy soil than on poor, compacted soils. The first thing many might think of is that the soil should have a sufficient supply of nutrients throughout the growing season. But don’t forget, at the end of the alled theseason there shouldn’t be too much nitrogen and phos-phorus left in highly soluble forms or enriching the soil’s surface. Leaching and runoff of nutrients are most likely to occur after crops are harvested and before the follow-ing year’s crops are well established. A high-quality soil is free of chemicals that might harm the plant. These can occur naturally, such as soluble aluminum in very acid soils or excess salts and sodium in arid soils. Potentially harmful chemicals also are introduced by human activity, such as fuel oil spills or application of sewage sludge with high concentrations of toxic elements. A high-quality soil should resist being degraded. It also should be resilient, recovering quickly after unfa-vorable changes like compaction. We also want the soil to have good tilth so that plant roots can fully develop with the least amount of effort. A soil with good tilth is more spongy and less compact than one with poor tilth. A soil that has a favorable and stable soil structure also promotes rainfall infiltration and water storage for plants to use later. For good root growth and drainage, we want a soil with sufficient depth before a compact soil layer or bedrock is reached. We want a soil to be well drained, so it dries enough in the spring and during the following rains to permit timely field operations. Also, it’s essential that oxygen is able to reach the root zone to promote optimal root health—and that happens best in a soil without a drainage problem. (Keep in mind that these general characteristics do not hold for all crops. For example, flooded soils are desirable for cranberry and paddy rice production.) We want the soil to have low populations of plant disease and parasitic organisms so plants grow bet-ter. Certainly, there should also be low weed pressure, especially of aggressive and hard-to-control weeds. Most soil organisms are beneficial, and we certainly want high amounts of organisms that help plant growth, such as earthworms and many bacteria and fungi. soil solution contains dissolved