10, 20, 30, 32, 36, 38, 42, and 60 are not the winning numbers for this week’s lotto.
They are a partial listing of row spacings California and Arizona cotton growers have used to try coaxing more cotton out of fields without increasing costs. The goal was basically to crowd together as many plants as practical to get more yield.
For decades spindle cotton has been grown spaced apart in 38- to 42-inch rows. The late and legendary San Joaquin Valley cotton breeder H.B. Cooper once responded, “Because that is the width of a mule’s butt,” when asked why cotton had been grown since the Civil War in that space range.
He was not joking. It was the truth. Spindle picker heads were designed to gather cotton rows spaced that far apart because that was how cotton was farmed before the industrial revolution.
It was not until the 1980s that the idea of narrow-row or 30-inch cotton became a logical closer spacing, when a pair of San Joaquin Valley cotton farmers shop-modified a couple of straddle two-row pickers that would gather two rows of 30 inch cotton while straddling a single row. It was not very practical, but it made enough sense that major picker manufacturers redesigned picker heads to gather 30-inch cotton because of grower interest.
The reason 30 became popular over other configurations was because that was the row spacing of many other crops, particularly corn and bean crops. It also fit 60-inch processing tomato beds. It meant that farmers would not have to adjust tillage equipment between operations. The same cultivator would work in all 30-inch crops.
Narrow-row cotton also became popular because the rows closed earlier and shaded out weeds.
Not everyone converted to narrow-row cotton, but it is a good fit where soil types limit plant growth.
In other parts of the Cotton Belt, growers plant far narrower than 30 inches. However, that cotton is harvested with non-spindle or brush harvesters, which never caught on in irrigated areas like California and Arizona because brush harvesters gathered too much trash along with the seed cotton. Western cotton ginners despised ‘stripper’ cotton because of the trash it generated. Spindle pickers gather only seed cotton and minimal trash.
60-inch cotton doesn’t seem to fit with the other numbers because it flies in the face of the narrow-row theory. Nevertheless, Worth Farms of Coalinga, Calif., has grown cotton with rows that far apart without sacrificing yield and reducing cost.
Actually, it makes sense because of what growers have learned from the old skip-row cotton and from outside rows in solid planted fields. Although crowding does tend to encourage fruiting, growers like Rick Worth know ‘outside rows’ tend to yield more. Therefore, why not have a well managed field of outside row cotton?
Cotton and processing tomatoes are a common rotation on the West Side of the San Joaquin Valley, and growers have long planted 30-inch cotton on 60-inch cotton beds by ‘splitting the beds.’ Worth Farms partners Worth and Chuck Herrin Jr. have done that. They plant cotton rows on the edge of the permanent tomato beds. These beds are 40 inches wide beside a 20-inch furrow, thus 60 inches. Twin 30s on a 60-inch bed work, but some are concerned about possible drawbacks where there is only one drip line down the center of the tomato bed like at Worth Farms.
Cotton cannot be irrigated up that far from the drip lines. Some growers have also discovered that irrigating from the center to the outside of the beds drives salts into the cotton root zones, limiting production.
However, the biggest reason Worth and Herrin wanted to get away from twin 30s is that tomato cultivation equipment must be modified on the tool bar to work the 30-inch cotton.
Worth and Herrin decided to try planting one row of cotton down the center of the 60-inch tomato bed. Surprisingly, it has worked.
University of California Cooperative Extension Farm Advisor Dan Munk confirmed it in a one-year trial last season, where yields were not significantly different between one-row 60-inch cotton and twin 30-inch rows on the same tomato beds.
This is the third year for Worth Farms to try the 60-inch cotton. About 250 of Worth Farms’ 1,500 acres of cotton are single row 60. They expect that number will grow as they become more comfortable with the configuration.
Drip irrigation is one of the keys to this. Row crop drip irrigation has exploded in the valley. Munk estimates 95 percent of processing tomatoes are grown on drip irrigation in his county. “Growers are putting in all kinds of drip from buried tape to above ground drip they put in and pull out of fields,” said Worth. Mobile filtration systems are on every field corner, it seems.
“We were forced into drip because of our reduced water supply,” said Worth. The farm is in Westlands Water District where its 100 percent federal water allocation is now only 2.6 acre feet. The possibility of receiving the full water allocation is tenuous at best as Worth stressed, “If we get 100 percent of that entitlement, and we never do.” Environmental laws have severely curtailed water deliveries to the sprawling water district over the past couple of decades.
Worth Farms is almost 100 percent drip irrigated on its 6,000 acres after just three years at a cost of roughly $1,000 per acre for a semi-permanent drip installation.
The majority of drip systems go in on high value crops like processing tomatoes. Lower value crops like cotton benefit from drip when growers rotate out of high-value crops.
Drip a no-brainer
Worth Farms contains some of the most productive farm ground in the state and people told Worth not to expect much of an advantage in converting from sprinklers and furrow to buried drip tape.
“When I first started looking at drip, people told me if you have good ground you would not see much yield increase. That is not true. It is also not true that you will not save water — you will,” Worth said.
“We have doubled our tomato yields and use one less acre foot of water. It far exceeded our expectations. Drip is a no-brainer.”
That is a goal for the 60-inch cotton. While they have not achieved quite as dramatic a payback, Herrin said they have saved costs by using the same tillage equipment on tomatoes and cotton and drip will save water on just about any row crop.
“You do not necessarily save water with drip on trees, but you definitely do on row crops,” Worth said.
“We do not pre-irrigate the 60-inch cotton on tomato beds and that is a water savings. We plant to moisture from the drip tape; cap and then de-cap it and we can get a stand.” With twin 30-inch cotton, they have to pre-irrigate with sprinklers to plant to moisture.
Worth planted all his cotton to rainfall moisture this rare, above normal rainfall year, but he also had to replant some cotton due to stand loss from the cool spring.
The nice thing about being able to plant either 60-inch cotton or twin 30s on a bed, Worth said, is an easy replant. “If the twin 30s fail on the bed, all you have to do is seed a single 60 and vice versa. We did that this year.”
The precision of drip irrigation is also paying off through in-season water savings. Munk’s trial last year also determined that there was no yield difference between cotton irrigation based on 100 percent evapotranspiration and 80 percent evapotranspiration. That represents a huge water saving factor for growers in Westlands Water District like Worth Farms, which loses federal water allocations annually.
Worth Farms’ drip system is buried 12 inches, all on 60-inch centers. It is designed to deliver .05 inches of water per hour. During the height of the irrigation it runs virtually 24 hours per day.
While drip is very efficient, it is not foolproof. Worth explains that with other irrigation systems, dry soil spots are evident. There are no wet spots with drip, so a grower must monitor the drip system to make sure it is working. “The only way you can tell in the field if the system is not working is when the plants start showing stress. By then it may be too late to recover.”
Seeding rates differ between the two row cotton spacings. “We increase the seeding rate to get 62,000 plants per acre with 30-inch rows and 40,000 to 45,000 with the single row 60,” he explained. 30-inch cotton closes two to three weeks earlier than narrow-row cotton.
Worth Farms has been a 100 percent Pima grower. Pima, said Worth, can develop a large plant loaded with bolls. Pima bolls are roughly half the size of an Acala cotton boll.
“We have had some lodging issues with the Pima, but we can pick it up without any problems,” Worth said.
The 60-inch cotton is picked three rows at a time.
Their Pima variety is Phytogen 805RR.
With a more open plant, Munk said the cotton plant tends to fill in more positions down below because the high light environment allows additional fruit to be produced on vegetative branches and fruiting branches shed less late season fruit. In this way the cotton plant compensates by expanding it’s vegetative canopy and producing more fruit per plant. There was a difference in height between the two row spacings, but there was no yield difference. With more room, there are more vegetative branches on the 60-inch cotton and more positions coming off those branches.
The large plants on the 60-inch rows were robust with large, deep roots. “Roots were huge and deep,” Worth noted. He was concerned about turning around beds in time for transplanting tomatoes in the early spring.
Worth called in silage choppers to shred the standing stalks. At first they put the stalks into silage trucks to haul away, but it was a hassle finding a place to dump the shredded stalks. Then Worth asked the custom choppers to simply blow the shredded residue across the field.
“It worked great. They absolutely shredded it — better than mowers and stalk cutters.
“We came in behind the silage choppers with a flail mower and root cutter to get the rest of the plant out of the ground. Then we worked the beds with regular tillage equipment. The fields were ready in time for planting. The tomatoes after cotton look great — better than tomatoes after tomatoes. Rotation with different crops is a good thing when you can do it,” he said.
Pima cotton priced at more than $2 per pound makes it easier to put cotton back in the rotation.
Worth and Herrin said several cotton growers have talked with them about the 60-inch cotton. One neighbor converted all his cotton to the wide rows on tomato beds.
“The results we have thus far in comparing the two row configurations are encouraging,” said Munk. “However, I’m not rushing to make a 60-inch bed recommendation yet, as a larger number of tests and additional years will be needed to understand the range of crop and yield conditions. This is still very experimental, but I agree there are potential advantages with what I have seen that Rick and Chuck are doing at Worth Farms.”