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Irrigation JAMES SUA, CGCS,CCPC,CTP, CGIA 草坪草的灌溉 Irrigation INTRODUCTION前言 Proper irrigation is one of the most challenging aspects of turfgrass management. It is important for supplementing rainfall, washing in certain fertilizers and pesticides, keeping the soil moist for seed germination, and cooling the turf on hot days. Proper irrigation practices have taken on even more significance in recent years with the increased important of water conservation. Improper irrigation practices may be more harmful to turf than no irrigation at all. For example, light or occasional irrigation during extreme drought may cause the depletion of stored carbohydrates, reducing the vigour and drought tolerance of the turf. In such a situation, if irrigation cannot be maintained correctly, it may be advisable to allow the turf to go dormant. This is the natural defence mechanism of the plant. Following the drought, the turf will usually return to normal growth. The decision whether or not to irrigate depends on the use of the area, the turf quality desired, the severity of the drought, the availability of water, and budget. Under less server situations, improper-irrigation can increase both disease and weeds and can produce a meagre, shallow root system. 適當的灌溉是草皮管理的最重要挑戰之一。灌溉的作用可補充雨水的不足，沖掉特定的肥料和殺蟲劑，維持土壤的濕度以供種子發芽並且在炎熱的氣候中保持草皮的涼爽。近年來大家對水資源的保護愈來愈重視的結果，對於正確的灌溉方法也更顯得的重要。 不正確的灌溉對草皮的傷害反而比不灌溉要嚴重。例如在極度乾4的情況下少量的或偶爾澆灌後果會使植物儲存的碳水化合物流失，造成草皮的活力下降且對乾旱的耐力也減少。在這種情況下，如果無法保持正確的灌溉，最好是能讓草皮進入休眠期。這也是植物自我防衛的自然機制之一。在乾旱季節過後，通常草皮又會恢復生機。在作是否要繼續灌溉的決策時，條件取決於該地區的使用情況，預期的草皮品質，乾旱的嚴重度，現有的水資源，以及預算等。在較不嚴苛的環境下，不正確的灌溉不只會增加病蟲害和雜草，也會造成乏且無法深入的根部系統。 WHEN TO BEGIN IRRIGATION何時開始灌溉 As plant undergoes moisture stress, it suffers an overall reduction in growth rate and rigidity. The first visual symptom is often a loss of rigidity that is evident by “footprinting”, the appearance of footprints on the turf after walking over it. If the turf is under water stress, footprints will be highly visible because of the shoots’ inability to spring back. Turf that is wee-watered will barely show the footprinting effect, springing back almost immediately. The next symptoms of water stress are a blue-green or grey leaf colour. Large, patchy areas of the turf will show this colour change first; if the turf is left unwatered, the size of the areas will increase and the symptoms will progress. Following the colour change, the grass will begin to show obvious signs of wilting. Depending on the species, these include drooping, folding, or rolling of the leaves. Finally, if stress continues, the top begins to turn brown and die. The turf will enter a protective state of dormancy. Storage of water in the roots and crowns will keep the plant alive long after the shoots die. 當植物受到缺水的壓力時，整體的挺拔度及生長力都會降低。通常首先會看到的就是挺拔度下降，從“足印”痕跡可以判斷這點，也就是當人走過草皮後留下的足印。當草皮缺水的時候，因為葉片沒有足夠的彈力，足印的痕跡就非常明顯了。有足夠水份的草皮幾乎不會有足印的現象，因為草皮幾乎是立刻彈回原位。 接下來的缺水症候是藍綠色或灰色的葉片。一開始會看到一塊塊大片的草皮呈現這種顏色的變化，如果草皮繼續缺水時，變顏色的面積會更擴大。顏色改變之後草皮就會開始明顯的枯萎。不同的草種會出現包括落葉，葉片合攏及葉片捲曲等症狀。 最後，如果仍然持續缺水，葉片上方會開始變成棕色然後就枯死了。草皮會進入自我保護的休眠期。在幼芽死亡很久以後植物仍然可以靠儲存在根部及冠部的水份存活。
FREQUENCY OF IRRIGATION灌溉的頻率 As mentioned above, to maintain maximum turf vigour and quality, it is ideal to initiate irrigation before visual symptoms are apparent. As irrigation frequency exceeds the optimum level needed to maintain the proper water balance in the plant, several negative effects will occur. For example, if turf becomes adapted to using excessive amounts of water, shoot and root growth will decline, resulting in reduced vigour and quality. The turf will become susceptible to disease, insects, and weed invasion and more vulnerable to traffic, environmental, and management stresses. The recuperative rate from all injury will be greatly reduced. As a rule, daily irrigation is not recommended for mature stands of turfgrass. Such a practice keeps the soil surface constantly wet and encourage shallow rooting. To help encourage the development of a deep, extensive root system, irrigate deeply but infrequently. Deep, infrequent irrigation will allow the surface to dry out, forcing roots to grow into lower depths of soil that contain water. Frequency of irrigation depends on soil type, species, management practices, and climatic conditions. Generally, about half the amount of the water needed each week should be applied every 3 to 4 days. 如同先前所強調的，若要維持草皮最佳的生命力和品質，一定要在目視的症狀發生前開始灌溉。當灌溉的頻率超過了植物所需的最佳平衡時，反而會產生一些副作用。例如葉片適應了過量的水份之後就會減少幼芽及根部的生長，使其生命力和品質同時降低。草皮較易受病蟲害和雜草的侵襲，而且也不耐踐踏與環境和管理所帶來的各種壓力。對受傷後的復原力也大幅的降低。 一般來說，對於成熟的草皮是不需要每日灌溉的。若是每天澆水會使土壤表面永遠是溼的而會造成根部無法深入。 為了要促進有較深入及廣泛的根部發育，灌溉要較深層但不規則。深層及不規則的灌溉可以使表面乾燥，迫使根部更深入土壤的含水區。灌溉的頻率取決於土壤的類型，草的種類，以及保養的方式和氣候的狀況。通常每三到四天澆灌每週所需灌溉量的一半就足夠了。 Frequency of Irrigation 灌溉頻率 Paspalumgrass雀稗草 Least frequent 頻率最低 Bermudagrass百慕達草 Zoysiagrass韓國草 Carpetgrass地毯草 Most frequent 頻率最高
QUANTITY OF WATER APPLIED澆水量 Since most of the root system of many turfgrasses grows in the upper 6 inches of soil, it is important to apply enough water to moisten the top 4 to 6 inches of soil. The degree of moisture can be determined with the use o a knife, spade, or soil probe. In some situations, we can determine how much water to apply by using an evaporation pan placed in the turf area during watering. There is a close correlation between water lost or evaporated from the pan. 因為大部份的草皮根部系統都是生長於土壤表層6英吋處，所以在表土上方4到6英吋處一定要提供足夠的水份以保持潮濕。土壤的濕度可用小刀，鏟子或土壤探針來測量。 在有些情況下，我們可以在澆水時在草皮上放置蒸發盤來測量所需的澆水量。蒸發盤裡所減少或蒸發的水份與此有直接的關係。 RATE OF WATER APPLICATION灌溉的速度 The slope of the turf area, soil type, degree of compaction, and presence of thatch will determine the rate of water application. Application should not excess the infiltration rate, runoff occurs, which significantly increases water wastage as well as increasing the potential for fertilizers and pesticides to move off the turf area and into the groundwater. Water must be applied slowly to fine-textured soil, sloping turf areas, and thatched or compacted soil. Coarse, sandy soils will usually take relatively large volumes of water in very short periods of time. Depending on the soil type, the rate may range from 0.1 to 1 inch per hour.
澆水的速度取決於草皮區的坡度，土壤的類型，緊實的程度和是否有枯草層存在等因素。灌漑的速度不可大於滲透的速度，也不能有水份流出草皮區外的情形，否則不但浪費水資源，也會將肥料和殺蟲劑沖離草皮區而進入地下水。在細質的土壤，草皮斜坡和有枯草層或緊實的地區需緩慢的澆水，對於較粗質的砂地通常需要在較短的時間內灌溉較多的水份。依據不同的土壤種類，澆水速度的範圍在每小時0.1到1英吋左右。 Amount of water soils absorb in an hour without runoff 在沒有流失的情況下土壤每小時可吸收的水量 Soil Type土壤種類 Under Healthy Sod 健康的生草土 Coarse sandy loam粗糙的砂質壤土 1.3 inch per hour 每小時1.3英吋 Sandy loam砂質壤土 1.0 inch per hour每小時1.0英吋 Silt loam泥質壤土 0.6 inch per hour每小時0.6英吋 Silty clay loam泥質黏壤土 0.5 inch per hour每小時0.5英吋 Compacted clay緊實的黏土 0.2 inch per hour每小時0.2英吋
TIME OF DAY TO IRRIGATE灌溉的時間 Water according to the Weather 根據天候澆水 Water Less澆水量較少 Water More澆水量較多 Cooler temperature涼爽的氣溫 High temperature高溫 Cloudy or overcast有雲遮蓋 Bright sunlight大太陽 Low wind微風 High wind大風 High humidity濕度高 Low humidity濕度低 Rain or showers下雨或陣雨 No rain沒有下雨 Technically, turfgrasses can be irrigated any time of day or night. However, depending on the situation, certain times of the day may be more advantageous than others. 從技術面來說，草皮可以在白天或晚上任何時間澆水。但是依情況的不同，有些時間會更適合澆水。
Night晚上 The amount of water lost as a result of evaporation is lower at night because of reduced wind movement, cooler temperatures, and higher humidity. Reduced wind also allows for a better water distribution pattern. Night may be a more convenient time in some situations, particularly if an automatic irrigation system is used. Evening or night irrigation has less chance of interfering with the use of the turf area and disrupting scheduled management practices. Irrigating at night also allows adequate time for internal soil drainage. Since wet soil is more prone to compaction than dryer soil, this additional drainage time can be particularly important on highly trafficked turf. One serious drawback of night irrigation is that disease activity may increase on turf watered at night. Fungal spore germination and fungal penetration into plant tissue requires several hours of free water on the leaves of the turf, so reducing evaporation can make turf more susceptible to disease. 晚上的風速和氣溫較低同時濕度較高，所以因蒸發而散失的水份較少。較低的風速也可讓水份分佈的更均勻。在某些狀況下晚上的條件更好，特別是使用自動澆水系統的時候。在傍晚或晚上灌溉較不會幹擾到草皮區的使用及定期的保養。晚上澆水也能夠提供土壤內部足夠的時間來排水，因為潮溼的土壤比乾燥的土壤更容易變得緊實，而這額外的排水時間對於高使用量的草皮來說特別的重要。 晚上澆水最大的壞處是病蟲害在夜間灌溉的草皮上的活動會增加。因為黴菌的孢子發芽和菌絲的滲透到植物組織內都需要在草皮葉面提供數小時的水份，所以蒸發速度降低後會造成草皮更容易得病。 Midday中午 Midday or mid-afternoon irrigation has its own advantages and disadvantages. First, as much as 50 percent of the applied water may evaporate before it even hits the ground. Disease activity resulting from freestanding water is greatly reduced, but if the water application rate exceeds the infiltration rate or if a drainage problem exists, the turf may be subject to scald. Scald is the scorched appearance of turf that has been submerged or partially submerged on bright, sunny days, when water temperature increases to a point that injures plant tissue. In addition, because of more wind, sprinkler water distribution patterns may be disrupted. Midday watering may also interfere with the intended use of the site. 中午或下午灌溉有優點也有缺點。首先，大約有百分之五十的灌溉水份還沒進入地下前就已蒸發了。因為停留在葉片上的水份所造成的疾病發生率也大幅降低了。但是如果澆水的速度超過滲透的速度或是有排水的問題發生時，草皮就容易灼枯。灼枯就是草皮被曬焦的現象，因為全部或一部份暴露在大太陽下使水溫升高而造成的植物組織受傷。除此之外，因為風更大，自動澆水系統的範圍也會受到幹擾。在中午澆水也有可能會影響到該區域的正常使用。 Morning早晨 Early morning irrigation combines several of the advantages of night and midday watering. For example, winds are reduced, humidity is high, and solar radiation is low. Theses factors help to reduce evaporation. Early or mid-morning irrigation also avoids prolonged free water on the turfgrass leaves, discouraging disease development. Reduced wind movement allows proper water distribution from sprinkler. There is also less chance of interfering with the use of the area. Finally, the application of water in the morning removes guttation water from the surface of the plant tissue. Fluid excluded from the plant leaf tissue that is rich in organic and inorganic substances is called guttation water, and it provides a medium for pathogens that cause turf disease. 清晨灌溉具有晚上澆水及中午澆水的幾個優點。例如風速較小，濕度較高，和日照較低。這些因素都會降低蒸發量。清晨或早晨澆水也可避免葉片上長期的積水，減少疾病的發生。降低的風速也可使自動澆水系統發揮均勻的功效。 同時對草皮區的使用上也會有較少的干擾。最後，早晨澆水可沖掉葉片上因泌液作用所產生的水滴。泌液是由植物葉部組織所分泌出來的液體，內含豐富的有機及無機物，能夠提供病原菌養份而造成草皮病害。
TURFGRASS WATER USE AND MANAGING DROUGHT 草皮澆水及乾旱管理 Water Use Rate水的使用速度 Water use rate reflects the total amount of water required for turfgrass growth plus the quantity of water transpired from the grass and evaporated from the soil. The water use rate of most turfgrasses ranges from 2.5 ml to 7.5 ml per day, with maximum values as high as 12 ml per day. Species or cultivars vary in the amount of water they use. Cultural practices can have a significant effect on the amount of water used by turfgrass. For example, turfgrasses mowed excessively high will use more water because they have more leaf area available for transpiration. However, the higher cut promotes deeper rooting, which offsets the increased water usage. A higher cut will also insulate the soil from high temperature and excessive evaporation. Therefore, from a water-use standpoint, turfgrasses should be mowed from the mid-to-high range of the recommended height for that particular species. A sharp, well-adjusted mower should always be used. The tearing and shredding of leaves caused by a dull mower blade will increase water use. Any cultural practice that results in increased leaf surface area will also increase water use. Nitrogen fertilization should be carefully managed; generally, increasing it beyond a minimum-to-adequate level will increase water use significantly. Turfgrasses irrigated infrequently but deeply tend to use less water. Finally, the total amount of water used on compacted turf sites tends to increase as a result of reduced infiltration rates and increased runoff. 水的使用量可反應出草皮生長所需的全部水量加上草皮散發掉的水份及土壤裡蒸發的水份。大部份的草皮區的每日需水速度是從2.5毫升到7.5毫升，每日最大的速度為12毫升。使用量是因草皮的品種及培養方法而不同。 培養方法對草皮需水量有很大的影響。例如割草的長度較高時會需較多的澆水量，因為葉片有更多的面積來進行蒸散作用。但是割草長度較高時也會促使根部更深入土壤，也會降低澆水的需求量。割草長度較高時也會在日曬時保護土壤不致溫度過高與水份蒸發過度。所以，從用水量的角度來看，割草的高度最好能維持在草皮的中高範圍，並且一定要使用銳利且適當調整的割草機。太鈍的刀片所造成的葉片撕裂和碎屑會造成用水量的增加。任何造成葉片表面積增加的培養方法也都會增加水的使用量。 氮肥的使用一定要特別小心，一般來說，過多的氮肥會大幅的增加用水的需求。深層及不規則的草皮灌溉所使用的水量較少。最後，密實的草皮區所需的灌溉量較高，因為滲透率的降低及溢流的增加。 Amount of water needed to soak soil 6 to 8 inches deep and time required for the soil to absorb water 浸潤6到8英吋土壤所需的水份及土壤吸收所需的時間 Amount of water Absorption time 所需水份 吸收時間 Sandy loam砂質壤士 0.5英吋inch 30分鐘minutes Loam soil壤土 1.0英吋inch 2小時hours Compacted clay soil緊實黏土 1 to到 1.3英吋inches 5小時hours
MANAGING DROUGHT乾旱管理 Sooner or later, every gardener will be faced with varying degrees of drought. Several cultural practices can alleviate drought stress and help ensure a full and speedy recovery of the turf when favourable conditions return. Mowing, fertilization, irrigation, cultivation, and thatch and weed control can all influence the turf’s response to drought stress conditions. Proper irrigation practices are critical during a drought. Turfgrass should be irrigated deeply but infrequently. To avoid runoff, it may be necessary to apply the required amount of water in several short intervals, a few hours at a time. In addition, thatch should be removed or reduced and compacted soil aerified to ensure maximum water movement into the soil. To minimize evaporation, irrigation should be done from night to early morning. As a general rule, turfgrasses grown under limited soil moisture have better drought tolerance than those grown under adequate soil moisture conditions, as a result of a hardening of the plant. Therefore, light, frequent irrigations should be avoided; such a practice encourages multiple growth spurts of the shoots that may exhaust stored carbohydrates, reduce root growth, increase succulence, and prevent the hardening of tissue. Turfgrasses in this condition are more prone to serious drought injury and are slower to recover when the drought has ended. Finally, if a minimal water supply is not available or the cultural practices described above cannot be carried out, it may be advisable to allow the turf to enter dormancy. Dormancy will allow a more rapid recovery from drought than a physiological state that vacillates between semi-active growth and dormancy. Turfgrasses that go into dormancy lose all green colour. The resulting brown cover can be sprayed green with a variety of dyes formulated for such purposes. 每一位園藝人員遲早都會遇上不同程度的乾旱。不同的培養方法可以減少乾旱所造成的影響，同時在情況好轉後也可幫助草皮快速及完整的草皮復原。割草，施肥，灌溉，培養及枯草層和雜草的控制都會影響到草皮對乾旱的反應。 在乾旱期的灌溉是非常重要的關鍵。草皮必需作深層但不定期的灌溉。為了避免溢流，可能需要將所需的水份分批澆灌，每次間隔數小時。另外，枯草層必需減少或移除，緊實的土壤必需通氣以確保水份滲入土壤的最佳狀況。為了將蒸發量減少到最低，灌溉的時間最好是從晚上到清晨的時段。一般來說，在土壤濕度有限的條件下所生長的草皮較佳的乾旱耐受度，反而比起在有適當土壤濕度的環境下所生長的草皮有更好的硬度。所以要避免少量且頻繁的灌溉，因為這樣會造成植物多重的發芽而消耗儲存的碳水化合物，降低根部的發育，及增加多汁性而阻撓了組織硬度的發育。在此種生長環境下的草皮較易受到乾旱所造成的傷害，並且在乾旱後的復原也較慢。 最後，如果水量不足時或是上面所提到的培養方法都無法實施的時候，最好讓草皮進入休眠期。完全休眠時的生理狀況比起在休眠及半活性來回不定的狀況下會有更好的烣復能力。進入休眠期的草皮會喪失所有的綠色。這時可以用綠色的染劑來遮掩棕色的部份。 TYPES OF IRRIGATION SYSTEMS灌溉系統的類型 Aboveground irrigation system. It is important to have the right sprinkler to water the turf correctly and to avoid wasting water. Types of sprinklers include oscillating, traveling, pulsating and turrent. The traveling sprinkler works best in odd-shaped areas. For a more restricted area, use the oscillating, pulsating or turrent sprinkler 地面灌溉系統。正確的噴水龍頭適當的澆水是省水最重要的關鍵。各類的龍頭包括了振盪式，可移動式，脈衝式，和連續流水式。移動式的龍頭較適合崎嶇不平的地形。在特定的環境下，可使用振盪式，脈衝式，或連續流水式的龍頭。 Underground irrigation system. The underground irrigation system with an automatic timer is popular because of the convenience of not having to move hoses, sprinklers, and turn water on and off. Because automatic timers do not account for the changing water requirements of the turf unless a moisture sensor is attached. 地下灌溉系統。地下灌溉系統最好是使用自動定時器來控制，不需移動水管，水龍頭和開水及關水的動作。除非另外加裝濕度感應器來感應草皮的需水量，否則自動定時器不會感應到不同水量的需求。 A moisture sensor measures the amount of moisture in the soil and regulates the sprinkler system accordingly. It will automatically turn the water on and off when needed. A moisture sensor saves money by reducing unnecessary water applications. Additionally, leaching of fertilizers past the root zone is likely to occur. Rainout devices also can be installed to avoid irrigating when it’s raining. 濕度感應器可測量出土壤內部的濕度且適度的控制噴水系統的出水量。在有需求的時候會自動的開水及關水。濕度感應器因為減少了不必要的灌溉而可以節省成本。除此之外，肥料也會較容易溶入根部的範圍內。另外還可加裝下雨感應器以避免在雨天澆水。
Oscillating sprinkler振盪式龍頭 Traveling sprinkler可移動式龍頭
Pulsating sprinkler脈衝式龍頭 Turrent spinkler連續流水式龍頭
Water Conversion Table省水比照表 1 inch of water per 1,000 square feet = 623.37 gallons or 83.33 cubic feet 每1000平方英呎1英吋的水 =623.37加侖或83.33立方英呎
1 inch of water per acre = 27,154 gallons or 3,630 cubic feet 每英畝1英吋的水 =27.154加侖或3,630立方英呎
1 cubic foot of water = 7.48 gallons or 62.37 pounds 1立方英呎的水 =7.48加侖或62.37磅
1 gallon of water = 0.1337 cubic foot or 8.34 pounds 1加侖的水 =0.1337立方英呎或8.34磅
WETTING AGENTS潮溼劑 Wetting agents reduce the surface tension of water, allowing it to wet a resistant surface. Said to “make water wetter”, these agents are very effective in the rewetting of water-repelling soils. They have also been said to increase water infiltration and drainage and reduce evaporation, soil compaction, wilting, disease, dew formation, and thatch accumulation. They can aid the movement of pesticides through thatch and into the soil. 潮溼劑能夠降低水份的表面張力，充份溼潤表土。除了 “讓水更溼” 之外，潮溼劑對於親水性較差的土壤有很好的溼潤力。同時也可以加強水份的滲透及排水能力，減少水份蒸發及土壤的緊實，降低枯萎，疾病及露水的形成，還有枯草層的累積。另外也可幫助殺蟲劑透過枯草層進入土壤。
WATER CONSERVATION TIPS省水的小偏方 1. Mow as infrequently as possible, but follow the one-third rule. 2. Mow with sharp blade. 3. Water deeply and infrequently. 4. Water at night or early morning. 5. Hand-water areas prone to runoff. 6. Core or aerify compacted soil. 7. Remove or reduce thatch. 8. Avoid excessive nitrogen fertilization. 9. Use pesticides judiciously to avoid injury to turf. 10. Use a soil probe to determine soil moisture content.
1. 割草頻率越不規則越好，但是要尊求1/3的法則 2. 使用銳利的割草刀片 3. 不規則的深層澆水 4. 夜間或清晨澆水 5. 人工澆灌容易溢流的區域 6. 將緊實的土壤鑽孔或通氣 7. 移除或減少枯草層 8. 避免過量的氮肥 9. 正確的使用除蟲劑以避免傷害草皮 10. 使用土壤檢測器來判斷土壤的濕度
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