Thirsty Fields: by Tom Butzler

It was not too long ago that Pennsylvania newspapers’ had reports such as “Wet spring seriously delays planting and harvesting for Pa. farmers”. In fact, the National Oceanic and Atmospheric Administration stated that Pennsylvania experienced its wettest April since 1895. How quickly the pendulum can swing from one extreme to another.

Drive around Clinton County and the surrounding area and you could see the effect of the hot, dry days on summer crops. Corn fields have that ‘pineapple’ look as leaves stand straight up instead of arching or ending over and water is being applied to crops to compensate for the absence of the occasional summer shower.

Water requirements vary depending on crop being grown but it is safe to say that vegetable crops require large amounts of water, anywhere from 6 inches of water per season for radishes to 24 inches for tomatoes and watermelons. In addition, there are certain periods during crop growth where water is critical to ensure a good yield. For example, research has shown that the critical time period for sweet corn is when the plant is silking and tasseling. With cucumbers, watering is important during flowering and fruit development.

Here in Pennsylvania, growers use two methods of applying water to their crops, overhead and drip irrigation. They both have their advantages and disadvantages

Potatoes along Bald Eagle
Creek are irrigated with
overhead irrigation.  Click on picture
 to enlarge

Overhead irrigation, as the name implies, is where water is applied to plants from above the plant canopy. The nice aspect of this type of irrigation is that it provides a uniform distribution of water over the entire field and is typically used in large acreage situations like potatoes, snap beans, and sweet corn. It is also the most economical way to get water to thirsty crops.

There are several disadvantages to using overhead irrigation. Large amounts of water are used in this system; as a result, a grower must have easy access to a stream or river. Foliar diseases love wet leaves. Overhead irrigation keeps those leaves wet enough that fungi can get a good start on causing havoc in a field.

Drip solves some of those problems of overhead irrigation simply the way it is applied. Drip irrigation is where water is supplied directly to or near the plant’s root zone by moving water through plastic tubing which is emitted through small openings.



Drip irrigation is supplying
 water to tomatoes on Great Island.
Click on picture to enlarge

 Compared to overhead irrigation, drip can reduce water use by 50 percent. In addition, since the water doesn’t touch the leaves, foliar diseases are greatly reduced. One of the big disadvantages is costs as the investment of a drip system will be more than overhead. Cost is the main reason that drip is more suited for high value crops such as tomatoes, peppers, and strawberries.

Looking at the weather forecasts, it appears we have a chance of some rain next week. I’m hoping as I don’t have good access for water to my vegetable garden.

Table from North Carolina Cooperative Extension Service
Click on picture to enlarge