In early June we were visiting with family in Cross County Arkansas. One of the things I did for two days was riding with my brother-in law in a pickup truck while surveying levees for soybean irrigation. The levee system is used to contain the water for flood irrigation.. Flood irrigation involves pumping large volumes of water in the field to completely cover it to provide good irrigation. The first step in levee preparation is to survey where the levees will be placed in the field. The modern method of levee surveying is by use of a laser. A laser generator is placed at the edge or center of a large field. The laser beam that is generated is kept level by a spinning gyroscope. The photo below shows the laser generator.
Here is a close up of the generator head.
The laser generator is powered by a 12 volt battery. It generates a continuous rotating laser beam. A receiver mounted on the front of the truck picks up the beam.
This is the truck mounted receiver.
At the base of the receiver is a gauge that the operator watches for determining what the elevation is.
The operator drives around the field watching this readout and keeps the readout on the same meter number. A turn to the right would increase the number and would indicate that you are at a higher elevation, to the left would be a lower elevation. Each readout change is a increase or decrease of 0.1 foot elevation in the field. Typically a new levee is placed at every 0.2 foot change in elevation. At the the edge of the field, you drive along the edge until you get to another 0.2 foot change in elevation then start back across the field for marking another levee. To make steering easier and faster a steering wheel spinner knob is used.
Steering wheel spinners or suicide knobs as they were called were popular on cars in the '50 and '60s but is not legal today in many areas.They are still popular on farm vehicles - tractors and combines - to facilitate faster turning.
Staying at the same elevation requires a lot of twists and turns throughout the field (keeping on the same gauge readout). As the operator is driving around in the field he is marking the location of the levee by use of a plow that is mounted on the back of the truck. The plow can be raised at the field edge by use of a toggle switch that the operator uses to control a electrically operated hydraulic that raises or lowers the plow.
Here is the rear mounted plow.
Here are several photos of the leveling operation.
This a levee survey mark as seen from the edge of the field.
Here you can see three different levee survey marks that are very close to each other at the field edge. Thus the elevation of this field is changing 0.4 foot from the far right mark to the far left mark.
In soybean fields levee survey marking there may be several weeks between the time of the levee marking and the actual levee plowing so a small tractor may be used to follow the marks and plow a four foot wide mark that will not be destroyed by rain before the levee is plowed. Some operators use the laser equipment on the tractor that is making the wide mark as they survey. The use of the truck makes it more comfortable as you can do it from the comfort of an air conditioned cab. It can still be a bumpy ride over the field as there are drainage ditches (to keep down flooding of fields from excessive rain) to cross and a lot of uneven ground. Once I was trying to drink soda while we moving. We hit one of those ditches and I ended up wearing a lot of the soda.
Soybean levee surveying and levee plowing is typically done after the beans are up and growing as water is not needed right away. Rice field levee contruction is done immediately after the field has been planted as water is needed when the plants are 3-4 inches tall.
The finished levee is made by using a levee plow. The levee plow operator follows the previously made marks in the field. A levee is also plowed around the field edge to inclose all the interior levees.
The finished levee is a continuous dike (about 2 ft. high) that holds back water. It took about 4-4.5 hours to mark a 75 acre field. This is a lot of twisting and turning in the field. This field started out on a laser receiver gauge reading of 34 at the high edge of the field and dropped to 00 then to 96 (a 38X0.1 foot or 3.8 feet change in elevation from the high edge to the low edge). This meant about 19 levees in this field. At the rate of about 150 acres per day and 1500 acres of soybean land to survey, this meant 10 days of boring but necessary work. He had already surveyed about 1500 acres of rice land in April.
My brother-in-law tells me that when the wind is high during the day it can make it difficult for the laser generator to maintain a steady laser level in spite of the gyroscope. He says he will run sometimes at night when the wind is not as bad. Can you imagine watching this operation from a road and seeing someone driving circles in a field with headlights on. You would think a drunk driver has got into a farm field and creating a mess.
Here is some Google Earth view of fields in the area we were in. You
can see the levees in the fields and see their many twists. If you click
on an individual photo it will enlarge it and you can see the levees
easier.
Here are some photos of rice fields showing close up of the levees. The orange plastic is where gates (opening in a levee) are located. When flooding a field at the start of adding water the gates are down so water can flow freely from higher to lower levee areas. When the field is totally flooded at the desired depth, the gates are closed (a long 2X4 board is placed on top of the levee at the opening and the orange plastic tarp is draped over it and held down by dirt to close the gap). The flag is denoting a particular variety of rice or soybeans that is planted in the field. Different color flags for different varieties.
This photo shows a water riser where water is pouring into a field from an underground pipe. The underground pipe is coming from a electric submersible irrigation pump (8-10 inch flow) that may supply several different fields. Some may be rice and others soybeans. The fields rotate from rice to soybeans from year to year.
In this photo you can see a crop duster that is applying fertilizer or herbicide to a nearby field.
Here is a rice field where the water flooding has just been started. You can still see water free ground around the young plants.
Irrigation of rice is necessary but for soybeans it is used to provide good water for increased yield. Research has shown that irrigation of soybeans with proper level of water during the growing season can increase yields up to 10-20 bushels per acre. A good irrigated field should yield 50 bushels/acre. At today's current price of soybeans ($15.00/bushel) irrigation can increase a farmers return up to about $150 to 300 per acre. This is considerably below the cost of levee preparation labor cost and electricity cost for pumping the water (total combined cost of $2-5/acre). In many areas the crop is rotated from rice to soybeans from year to year. Since the irrigation equipment and facilities are already in place and it makes since to irrigate soybeans for the increased yield,
Here is a
video of a typical irrigation pumping system in Arkansas. This operation uses a diesel engine. My brother-in-law uses electric submersible irrigation pumps for all of his fields.
Here are two good websites from the University of Arkansas that discusses rice and soybean water management.
Soybeans
Rice
