Plants grow best in moist, fertile, well-drained soil with plenty of organic matter. Soil conditioners are mixed with the soil to hold water in sandy soils, loosen clay soil and increase nutrient availability and organic matter. Mulch is put on top of the soil to retain moisture, reduce weeds and help moderate soil temperature. If the mulch is organic, it can also improve the soil over time.
Manure, compost, peat moss, sawdust, wood chips and leaves are all soil conditioners. They increase the organic matter content of the soil. Spread any of these soil conditioners on top of the soil, then till or dig them into the top 6 to 10 inches. The particles of organic matter between the soil particles allow more air space in the soil and act as a sponge to hold water. Peat moss should be soaked in water before using.
Wood chips, straw, pine needles, shredded leaves, pecan shells and other organic material can be spread on the top of the soil as mulch. A 4- to 6-inch layer will be necessary for effective weed control. Weed and water the area if necessary before putting down the mulch. A thick mulch layer on sandy soil will keep the soil up to 10 degrees cooler on hot days and hold moisture that would otherwise evaporate. As these materials decompose they, add organic matter and nutrients to the soil.
Inorganic mulches can be used to warm the soil in the spring, retain soil moisture and prevent weeds. Inorganic mulches include plastic, rubber, rocks and gravel, tumbled glass and other materials that do not decompose. Plastic mulches can prevent water penetration and overheat soil. They are generally used only temporarily to kill weeds or warm soil or as an underlayment to rocks where no plants will be grown. Rocks also warm the soil during the day and radiate heat at night. They ran be used as a mulch around heat-loving plants.
Avoiding Nitrogen Deficiency
High-fiber soil conditioners and mulches like wood chips, sawdust and straw do not provide much nitrogen. The microorganisms that break them down require nitrogen, which they will get from the soil. This limits the nitrogen available to plants. When using wood-based or straw mulch or soil conditioners, add nitrogen, either as ammonium nitrate fertilizer or manure, to compensate for what the microorganisms will take out of the soil.
- Photo Credit Jupiterimages/Photos.com/Getty Images