JAMES SUA, CGCS,CCPC,CTP, CGIA
如何建立新草坪 Turf Establishment
The successful establishment of turfgrass areas is fundamental to turfgrass management. Often the success or failure of turfs can be traces back to procedures that were performed during establishment. Every turfgrass manager or gardener should familiar with the various methods of establishment.
SITE AND SOIL PREPARATION 鋪設地點及土壤的準備
Debris and Persistent Weed Removal殘礫及雜草的移除
The following discussion of site and soil preparation applies to all methods of establishment – plugging, sprigging, or sodding. Preparation is one of the most important steps in creating a healthy, high-quality turfgrass area.
One of your steps in installing new turf may be the removal of woody vegetation such as trees, shrubs, logs, and stumps. Buried tree stumps are often associated with mushrooms in established turf. By removing stumps, you can also avoid the soil depressions resulting from their decay, which can break up the smooth grade desirable for turf. Rocks should also be removed rather than buried in the site, since buried debris will eventually interfere with turfgrass root growth. If small rocks and stones are too numerous to remove by hand, you may want to use a stone-picking machine for this purpose.
Persistent weeds such as sedges should be controlled before planting. These weeds cannot be selectively removed after planting, and normal grading will not eliminate them since many have underground rhizomes or tubers. You can remove these weeds from the site through soil fumigation or the use of a non-selective herbicide.
Depending on the quality of the topsoil, it may be advantageous to remove it and stockpile it in an undisturbed area near the site. This is particularly important during construction of a new building or when significant grading is necessary. If the topsoil is not removed from a construction site, it is often buried under subsoil from the footer or basement excavation, lowering fertility can creating a poor soil structure. After construction is completed, topsoil that has been removed can be redistributed over the area.
Grading and Tillage整地與耕耘
After the removal of the topsoil, the area should be graded to establish a sub-grade. This may involve leveling high areas and filling in depressions. The goal is to ensure adequate surface drainage of the turfgrass area. The minimum grade should be 1 to 2 percent, sloping away from buildings.
Steep slopes or contours should be avoided; they will result in areas difficult to mow as well as increased erosion potential during establishment. Also, turfgrasses established on steep slopes, are more prone to heat and drought stress than turfs established on level ground. When steep grades cannot be avoided, consider a retaining wall or the use of a ground cover instead of turfgrass.
Following the creation of the subgrade, the topsoil should be replaced and a final grade completed. Fine grading involves smoothing the soil surface in preparation for planting. It may be advisable to mix the topsoil into the top 2 inches of subsoil to avoid layering and to create a more even transition between the topsoil and subsoil zones. Tilling the soil with implements such as plows, disks, harrows, or rototillers will help ensure rapid infiltration of water, improved aeration, and improved turfgrass rooting. Tillage is particularly important on those sites where heavy equipment has been in use, in order to loosen soil that has been compacted.
Soil modification may be necessary if the existing topsoil is of poor quality. The addition of various soil amendments to improve the physical properties of the soil will help speed the rate of establishment and ensure a healthy, high-quality turf area. A sandy loam to loamy sand topsoil of 8 to 12 inches in depth is ideal. Often sand is added to the site to improve aeration and drainage. This practice can be effective if done correctly. However, adding small quantities of sand to a fine-texture or clay soil can create a cement-like mixture. It is necessary to add large amounts of sand to a clay soil to realize any significant benefits.
Often contractors add a 1 or 2-inch layer of sand, organic matter, or loam to the existing soil in an effort to improve the rootzone of their turf areas. This practice rarely succeeds, and it may cause a layering effect that impedes water and fertilizer movement into the soil and restricts turfgrass rooting.
Similarly, there is no advantage to adding 0.25 to 0.5 inch of a soil amendment to the soil surface and incorporating it into the top several inches of soil. This is a waste of time and money. At least 4 to 6 inches of a soil amendment or soil mix should be incorporated into the surface to improve soil characteristic.
*For NEW turf areas, incorporate into soil to a depth of 6 inches before planting. Do not apply more than 50 pounds/1,000 square feet at one time. If using calcium oxide (CaO) or calcium hydroxide (Ca(OH)2) do not apply more than 25 poinds/1,000 square feet at one time.
Application of Fertilizer施肥
The topsoil should be tested to determine its pH, phosphorus, and potassium levels. If the pH is lower than desired, lime should be incorporated into the rootzone. The soil test will also indicate the amounts of phosphorus and potassium needed. The recommended amounts should be applied and incorporated into the top 3 to 4 inches of soil. It is particularly important to use a high phosphorus fertilizer at time of establishment, since phosphorus enhances the rate of establishment.
Drainage and Irrigation排水與灌溉
Drainage and irrigation systems maybe installed either before or after the replacement of the topsoil. Installing them before replacement will reduce settling in the trenches that might disrupt the uniformity of the final grade. Installation after the topsoil has been replaced or following soil with heavy or cumbersome tillage equipment. There are many types and designs of underground irrigation systems. Depending on your knowledge and experience, it may be advisable to work with an irrigation specialist on such a project.
Final Seedbed Preparation苗圃的最後準備工作
Final soil preparation should include lightly tilling, raking, and levelling the area. A firm, granular, and slightly moist soil is ideal for planting. Rolling with a hand- or tractor-drawn water ballast roller can firm the soil. Final seedbed preparations should take place within 24 hours of actual planting if possible.
Depending on the species, selected turfgrasses can be established from seed or through vegetative propagation. The four methods of vegetative propagation are sodding, sprigging, stolonizing, and plugging. Each method will be discussed in more detail below.
Sodding involves transplanting large sections of mature turf. Although sodding is expensive, usually several times more costly than any other method of establishment, it does offer the distinct advantage of providing almost “instant” turf.
Site preparation should be completed before the delivery of the sod. After delivery, the sod should be placed within 24 to 48 hours if possible. This will reduce the chance of damage to the sod due to heat buildup while stacked on the pallets. Ideally, the soil should be slightly moist at the time of transplanting. Laying sod involves placing the sod pieces in a staggered checkerboard pattern so that the ends of adjacent pieces are not in line. The edges of adjacent pieces should be fitted together tightly but without overlapping. Gaps between sod pieces should be avoided since this will cause a rough surface and will allow weeds to come up in the voids. Also, sod pieces should not be stretched because they will shrink upon drying, leaving gaps between the pieces. On steep slopes, it may be necessary to anchor the sod with wooden pegs. Slopes are usually sodded from the bottom up. Immediately after installation, the sod should be tamped or rolled to help ensure good contact between the sod and underlying soil.
Finally, irrigate the sod as soon as possible after installation. It may be necessary to irrigate a section already installed while the remainder of the job is being completed. Usually, sod will take about one to two weeks to root into underlying soil. Once sod is well established, the frequency of irrigation can be reduced.
Plugging involves the transplanting of plugs or smaller pieces of mature sod into soil. Sod plugs may be obtained from commercial establishment such as garden stores, nurseries, or sod farms. You can make inexpensive plugs from purchased sod strips or pieces. Usually, plug sizes range from 0.75 to 4 inches in diameter.
One of the first step when establishing a site with plugs is to determine the rate or density of plugs to use. The closer the plugs are placed, the faster the site will establish a mature turf.
After determining the amount of vegetative material needed, use a plugging tool to remove a 2- or 3-inch soil plug (Figure 1). Then insert a plug of the desire turfgrass species into the hole and slightly tamp or roll the plug and adjacent soil area to ensure good plug and soil contact. It is important for the plug to fit properly into the hole, because a recessed or elevated plug will result in an uneven surface that may require future topdressing procedures to level the area. Following the plugging operation, irrigate the site as soon as possible and as needed thereafter until the plugs are well rooted.
Figure圖1: Turfgrass plugging tool 草皮栓塞工具
This vegetative method of establishment involves the planting of stolons or rhizomes in furrows or small holes. These pieces of stolons or rhizomes have little or no adhering soil and are referred as sprigs. Sprigs are obtained from sod fields where the sod was allowed to grow high enough to produce large stolons. A machine then harvests the plant material, chopping and shredding the stolons into 3 to 6 inches long.
Insert sprigs in the furrows to a depth of 1 to 2 inches and about 4 to 6 inches apart. The closer the furrows and placement of the sprigs, the faster the rate establishment will be. Immediately following sprig placement, irrigate the site thoroughly. Frequent irrigation will be necessary until the sprigs develop an adequate root system. Once stolon growth is visible, light, frequent topdressing will encourage stolon spreading by providing a more favourable moisture condition.
This vegetative method of establishment is similar to sprigging except the plant material or sprigs are broadcast over the soil surface rather than planted in furrows or holes. The sprigs are then either lightly topdress (cover with a thin layer of soil), rolled or pressed into the soil, or disked into the soil. The rate of establishment for stolonizing is faster than sprigging. However, because the plant material is spread over the surface of the soil and not buried as in sprigging, the death of plant material due to drying out can be much greater. It is essential that the site be well irrigate until the stolons develop a sufficient root system to support plant growth.
Figure圖2 : Various types of turf plugs used for vegetative propagation. 提供植物生長的各種草皮栓塞。