Drip tomatoes require new thinking

By installing subsurface drip irrigation on 2,600 acres of California farmland, Gary Hughes and his son Jeremy were able to rotate cotton with this new tomato crop.
Photos by Allison Hughes.

It sounds so easy; install a drip irrigation system on a crop and stand back and watch it excel. That’s exactly what happened in Tranquility, Calif., when Jeremy Hughes and his father Gary tried subsurface drip tape in 2004. Their tomato crop excelled.

However, they couldn’t just stand back and watch from the front porch. They eventually found that the irrigation system would produce 30 percent more tomatoes than their old furrow irrigation system would, but they had to work at learning this new methodology and its idiosyncrasies. It was such a boon to their farms, however, that they went from that initial 320 acres to about 2,600 acres on drip this year. Some of that is in cotton, but the bulk of it is in processing tomatoes, which over a few years have become an extremely successful crop for them.

The Hughes family settled in this part of the Central Valley in 1910, and Jeremy is the fifth generation to farm this land. He and his father farm separate enterprises, known as Jeremy Hughes Farms and Gary Hughes Farms, respectively, and for years were mostly cotton farmers using furrow irrigation. They grew a few tomatoes for the canneries. It was in 2003 when they saw a neighbor growing tomatoes on drip tape and having outstanding uniformity and yields from the crop. They got interested very quickly.

“We had always grown some processing tomatoes, but it wasn’t a steady crop for us,” the younger Hughes says. They applied for and received some USDA Natural Resource Conservation Service funds to try out subsurface drip tape, and they decided to become better tomato growers in the process. They shopped around, talked to other growers and settled on Netafim 1 3/8-inch tape. That is wide tape, strong enough to use in the half-mile runs common on their Westside ranch.

Gary and Jeremy Hughes plant a successional crop using both direct seeding and transplants over subsurface tape under 66-inch tomato beds.

Hughes selected an irrigation company with a good reputation, Cal West Rain, to design the system and help them install the base stations and pipeline. The system was engineered to accommodate multiple crops during the summer heat in the Central Valley. The tape was installed about 16 inches deep to allow for aggressive tillage over it. The farm purchased an Andros Engineering three-row tape injection system, which was mounted on a tool bar the Hughes built themselves. Installation was off 2,700-foot rolls, and a sled was used on the tool bar to ensure the correct depth.

After installation, the real work started: learning to use the system. The first thing they learned was that different water qualities could create filtration issues. Hughes farms in several different irrigation districts. The water quality from each district varies. Districts with open canals require sand media filtration to remove algae, fine sediment and aquatic weeds. The water in closed pipeline systems, such as Westlands Water District, has fewer problems with algae and almost no aquatic weeds so disc filters are used.

The use of wells has increased over the past few years due to water allotment issues. This creates another problem, in that more sand is added to the water by some wells. Hughes has learned to solve this problem by trial and error. Some wells need to be pumped for a certain amount of time prior to running a drip system, and some had to have additional sand media filters added to each station to filter the higher sand loads. Wells drilled more recently have fewer sand issues since the drillers have improved their methods and have almost eliminated the sand issue. New wells are gravel-packed much better. This alone can solve the problems with sand in a well. Filter flushes are automatic and can be varied from 20 minutes to 6 hours depending on water quality.

One of the best moves he made was to install tensiometers in each field. Both 12 and 24-inch Irrometer Tensiometer soil moisture sensors were placed 100 to 200 feet inside the fields, and these, combined with flow meters at the drip stations, allow excellent readings for the purpose of irrigation timing, as well as verifying proper water application. Irrometer WaterGraph software reads the sensors and gives him excellent cues on the needs of the crop.

This whole process got easier when, in 2009, Hughes tried out radio telemetry on some tensiometers to see how that cut down on the time required to check each field in person. That was so successful it resulted in the installation of telemetry over the entire farm this year. Now, all soil sensors report to the central computer at ranch headquarters, saving a lot of time. Water is still turned on and off manually at each field, but the data he gets is now instantaneous and instrumental in modifying irrigation timing. That’s particularly important during crucial periods such as hot days when the tomato vines are mature and water consumption high.

Hughes aims to keep moisture levels at field capacity on each field, and this is much easier with the soil sensor system. Using this feedback, he is able to make adjustments that provide appropriate irrigation timing. That results in a uniform crop and increased yields. It helps that the fields were all engineered to apply the same amount of water per acre per day, enabling him to do a simple calculation and determine whether the system is running smoothly. He uses Excel spreadsheets to get visual representations of what each field is doing, as well as to predict to some degree what water usage will be the next day.

Efficiency is gained, Jeremy Hughes says, by adding extra filtration where needed and by the use of radio telemetry to transfer tensio-meter readings.

“We do the same with fertilizers,” Hughes points out. The nurse tanks at each drip station, where UN 32 is injected into the water, are made more efficient by the use of petiole tests to determine plant needs. Early in the drip game, a company was hired to do this sampling, and some money was saved in the process. It was discovered that too much nitrogen was being applied at projected rates. Another benefit of finding the precise amount of fertilizer to apply—the plants occasionally also need some phosphate but don’t need extra potassium in these soils—was that smaller but higher-quality tomatoes were produced.

The upshot of all this precision was that his crops of tomatoes, which are more sensitive to water pressures than cotton, have onsistently yielded over 50 tons per acre. That’s about 15 tons more than the farm got from its previous furrow-irrigated tomatoes. Furthermore, that yield increase held firm even as they added hundreds of acres of production each subsequent year. Last year, for example, their 2,000 acres of tomatoes yielded an average of 52 paid tons.

That is somewhat surprising to Hughes, given that his and his father’s cropped ground is spread widely and has a variety of clay-loam soils. In addition, some of the ground is salty and highly alkaline. “When you go to drip irrigation you push the salts out of those rootzones,” Hughes says, and it provides a crop that looks and tests uniformly over most types of soils.

A great benefit is that those last 30 days of tomato growth, which can be troublesome if too much or too little water is applied, can be precisely controlled with the drip/tensiometer system. This allows the proper application of fertilizer and water to get a crop that’s highly desired by the canneries—properly sized and with the correct percentage of solids. Processing plants prefer tomatoes with high soluble solids, color and other attributes, so much so that incentive programs are sometimes used to encourage farmers to deliver this desired fruit.

“The processors have told me that the uniformity is spectacular,” he says. Uniformity allows the processor to run more efficiently and produce a high-quality product. Sizing is particularly important for diced fruit, and the processors he works with were leery at first about drip irrigation as a water source because of a perceived danger of overwatering and causing the fruit to gain size with an increase in water and not in soluble solids. They have since become convinced of the precision of the system. Along with water management, varietal genetics and proper fertilization, Hughes has been able to deliver a high-quality product, resulting in premium prices.

Jeremy and Gary Hughes say the steep learning curve includes the filtration and timing of water by use of drip stations and water sensors.

Hughes plants several varieties of tomatoes, with most of his crop going for dicing. Successional planting, starts with direct seeding in February and continues with transplants in March and April, so harvesting spans a period of six to eight weeks. He and his father were able to set their fields up to accommodate much of their existing cotton cultivation equipment; they use 66-inch beds for the tomatoes and 33-inch rows for the cotton. This allows them to rotate the two crops, and using projected crop pricing as a guide, they can determine in the fall what their acreage will be for each crop the following year. They use Trimble GPS guidance systems on their tractors to assure accurate tillage over the buried drip tape.

One of the biggest gains from the drip installation was the ability to compensate for the drop-off in water availability in the Central Valley in drought years when water cutbacks are common and severe. Because they can better manage water, and make a little water go a long way, they were able to farm 92 percent of these acres on a 10 percent water allotment, while other neighbors were fallowing 50 percent of their acreage. With almost no water lost to evaporation or deep percolation, the system is extremely efficient, and labor costs have dropped. Where he once had to have one irrigator per field, now he has about one for every eight fields.

The subsurface drip system cost about $1,000 per acre when he first started installing it in 2004, but has since risen to about $1,300. That can vary a lot, because small fields cost more per acre, and fields with high algae loads and PPM sand require more filtration.

The Hughes family is satisfied with their venture into high-tech irrigation because it yields profits along with flexibility. They have looked into the potential of growing other vegetable crops, but with this system working so well on tomato and cotton crops that are currently enjoying good pricing, they are content where they are. An unexpected benefit is that the drip tape they first installed is still working fine and should be for several more years.

Now they’re not only tomato growers, they’re extremely efficient tomato growers. “Drip irrigating tomatoes is like putting tomatoes on steroids,” Hughes says, and they will continue to ride that high all the way to the market.

Don Dale is a freelance writer and a frequent contributor. He resides in Altadena, Calif.