化学灌溉，灌溉施药（chemigation）

　　 在灌溉农业中,避免化肥和农药的深层淋失以减少对地下水质量的影响,并使化肥和农药保留在使其最有效的根区是生产者所关注的。滴灌作为世界上公认的节水高效的灌溉方法,若与农药施用结合起来,其突出的优点之一是可以按照植物生长的需要和植物保护的要求精确供给水分和农药,从而达到省水、化学除防和增产之目的。

　　 在有滴灌的条件下，采用化学灌溉技术可取得良好的效果。该法使用简单，由于将熏蒸剂如威百亩、1,3-二氯丙烯和氯化苦可均匀施于土壤中，因而效果非常理想，并受到广泛的关注。该法需要将熏蒸剂制成乳剂，以便与水能混合均匀并施于土壤中，由于熏蒸剂在施用中是与水充分混合，并且浓度较低，因而散发性较少。与注射法比较，化学灌溉法效果更好。


　
　 　　 Chemigation is injecting a chemical into irrigation water and applying it (chemical) through the system to the crop or field. Applying chemicals with irrigation water is not new but has been used for years with furrow irrigation and anhydrous ammonia or with flood irrigation on rice and different chemicals. Chemigation is used mostly in conjunction with sprinkler or drip irrigation systems. When using irrigation to apply chemicals, a quarter-inch application of water per acre is equivalent to applying 6,790 gallons of water (with the chemical) on each acre.
　　The earliest work using chemicals through sprinklers was injecting a fertilizer into the system and applying it with irrigation water (fertigation). Herbigation followed when herbicides were applied through a sprinkler system, generally center pivots. The system was used as a long spray boom. Reduced amounts of water are used with herbicides. Other chemicals then started to be used -- insecticides for insectigation, fungicides for fungigation, and nematicides for nematigation. All the terminology was combined and the term chemigation evolved.
　　 Chemical injection is not just putting chemicals into an operating irrigation system and applying it to a field. When chemicals are injected into a closed pressurized system (center pivot, linear, drip, or other type sprinkler or irrigation system) there are precautions that must be taken. Most safety equipment used on a chemigation unit is to prevent chemical contamination of water sources and loss or dilution of the chemical itself.
　　 Water-application rate should not exceed the soil's infiltration rate.
　　 There are advantages and disadvantages of applying chemicals through an irrigation system. Consider these pros and cons carefully before using chemical injection methods.
The following discussion concerns center pivots, but the chemigation method can be adapted to other types of systems.

参考文献：
1.http://msucares.com/pubs/publications/p1551.htm