Soil Improvement

.Knowledge Nuggets

• Soil is a non-renewable natural resource. A single gram of coarse sand has approximately 1,000 particles. A gram of clay has approximately 90 billion particles.

• Soil is made from the weathering of rocks taking between 100 to 1,000 years to form one centimeter of soil. Many soil properties are determined by the original type of rock or parent material.

• A single spade full of rich soil contains more species of organisms than can be found above ground in the entire Amazon rain forest. A teaspoonful of soil contains more than two billion microorganisms, more than the number of people on earth.

• A healthy soil supports plant growth, protects air and water quality and ensures human and animal health.

• Soil erosion causes redistribution of soil in the landscape due to the action of wind, water and tillage. The loss of one inch of topsoil is equivalent to 150 tonnes of soil per acre. Approximately 7 tonnes of organic matter, 400 kilograms of nitrogen, 300 kilograms of phosphorus and 3 tonnes of potassium are also lost.

• Management practices to reduce carbon loss and increase organic matter include reduced tillage systems, continuous cropping, manure appliation and converting land to permanent cover. Plants protect soil from erosion by forming a blanket of vegetation that shelters soil from wind, rain, running water and sunlight.

• Organic matter consists of decomposed plant and animal parts as well as millions of microscopic soil organisms that hold individual soil particles together in soil aggregates, thereby improving soil structure, workability, aeration, water penetration and water holding capacity and reducing the risk of erosion.

• Organic matter reduces the risk of crusting on the soil surface which can reduces seedling emergence. Crop rotations with forages and application of manure result in higher organic matter levels because these strategies net more residues.

• Soil compaction can develop in any type of soil and causes poor soil structure and unstable aggregates. Medium and fine textured soils are most susceptible to compaction.

• Addition of organic matter can improve virtually all soil properties resulting in more porous soil, lower bulk density, higher water-holding capacity, greater aggregation, increased aggregate stability, lower erosion problems, greater soil fertility and increased electrical conductivity.

• Erosion of one inch (2.5 cm) of topsoil per acre removes as much total nitrogen and phosphorus as 485 bushels of wheat. Blowing soil looses at least five tons of topsoil per acre. Soil losses of 50 tons per acre or more can occur in more severe storms. Wind erosion carries off the most nutrient-rich fraction of the soil.