Jeff Dahlberg director University of California Kearney Agricultural Research and Extension Center in Parlier stands between grain sorghum on left and far right and a forage sorghum line illustrating the height difference between the types of sorghum

Jeff Dahlberg, director, University of California Kearney Agricultural Research and Extension Center in Parlier, stands between grain sorghum (on left and far right) and a forage sorghum line, illustrating the height difference between the types of sorghum. He was a featured speaker at Kearney's Open Farm event.

Drought-tolerant sorghum solid option as livestock forage

Sorghum is gaining more attention in California as a multi-purpose, low-input forage crop option for growers.  Sorghum is a possible replacement crop for corn grown for grain and silage, in part due to sorghum’s lower input requirements and costs, and drought tolerance.

Grain sorghum is a multi-purpose crop which, perhaps similar to the late comedian Rodney Dangerfield, has never received the respect and deserved accolades in California until now.

Sorghum is gaining more attention in the Golden State as a multi-purpose, low-input forage crop option for growers. Its primary use is for livestock feed, primarily in dairy cow rations, but also for beef, poultry, and the pet food market.

Sorghum is viewed as a possible replacement crop for corn grown for grain and silage, in part due to sorghum’s lower input requirements and costs, and its drought tolerance.

“Over the last several years, there have been more acres planted in forage sorghum in California driven by the drought,” says Jeff Dahlberg, director of the University of California Agriculture and Natural Resources (UC-ANR) Kearney Agricultural Research and Extension Center (KARE) in Parlier (Fresno County).

Sorghum’s drought tolerance and high quality nutritional forage components – the latter which Dahlberg calls “almost as good as corn” – makes it a good crop alternative to corn.

Dahlberg says forage sorghum production in California requires about 1.5 acre feet to 2 acre feet of water, compared to two-to-three times the amount for corn. Nitrogen requirements for forage sorghum are about 125 units per acre, compared to 200-plus units for corn silage per acre. He questions the use of any amounts over this.

Comparing actual yields between the two is difficult since forage sorghums are typically not treated the same as corn, the forage specialist says. Yet, research conducted in the panhandle of Texas suggests forage sorghum is more productive than corn silage, based on a per-inch equivalent.

While USDA grain sorghum acreage statistics are no longer available in California, Dahlberg estimated that farmers planted more than 90,000 acres of all types of sorghums last year. Other sorghum types include grain, energy, hay, sudangrass, and sweet sorghums.

Sorghum History 101

Sorghum was first domesticated in Sudan-Ethiopia in eastern Africa about 8,000 years ago, and then spread to the rest of the world. The first plantings in California date back to the late 1800s when farmers sought drought tolerant forage for animals. In the 1960s, California grain sorghum acreage topped 400,000 acres.

While Dahlberg doubts acreage will again reach the 400,000 plateau anytime soon, he expects acreage to continue to increase – largely due to its water stinginess.

As meteorologists predict more frequent and longer droughts in the West, he believes sorghum could be a better forage crop option for growers. Dahlberg calls sorghum an excellent crop in no till conservation systems, and in crop rotations with cotton, wheat, processing tomatoes, and other row crops.

Research conducted over the last five years by Dahlberg, other UC specialists, and partner organizations clearly point to sorghum as a worthwhile crop in California’s future.

Right man, right time

One might say sorghum is in Dahlberg’s genes. The San Francisco native grew up spending many summers in the Sacramento Delta visiting uncles who farmed a variety of crops. He graduated from Occidental College, joined the Peace Corps, and then served as an Extension agent in Niger (Africa) where he launched his 30-year career in sorghum.

Dahlberg earned his PhD at Texas A&M in sorghum plant breeding and genetics. He became the sorghum curator for the USDA’s Agricultural Research Service (ARS) in Puerto Rico. Later, he joined the National Sorghum Producers organization as research director where he helped craft the United Sorghum Checkoff program to help expand funding for sorghum research.

Dahlberg’s arrival at UC-ANR KARE five years ago launched a new university emphasis on sorghum and its intrinsic value as a quality forage crop. Coincidentally, the current four-year California drought began after his arrival – perfect timing for Dahlberg and others to closely study sorghum’s water-saving characteristics.

Dahlberg told Western Farm Press, “Don’t blame me for the drought.” During his first year on the job, California received 150-plus percent above normal rainfall and snow.

Today, Dahlberg supervises UC research in 44 crops at the center.

First sorghum trials

A wide variety of sorghum trials have been conducted simultaneously at KARE and the UC-ANR Westside Research and Extension Center (WREC) at Five Points, the latter under Director Robert Hutmacher.

Dahlberg’s and Hutmacher’s first trials studied 80 different commercial forage sorghum hybrids to help determine which varieties were best adapted (or not) for California. Dahlberg was shocked at how fast sorghum grew in the Valley, and quickly determined that California farmers might grow sorghum differently than in the U.S. sorghum belt (South Dakota, Nebraska, Kansas, Colorado, Oklahoma, Missouri, and Texas).

Lodging issues were common in the early trials, possibly tied to higher than needed water and nitrogen applications. It was determined that sorghum should be managed carefully and differently than corn silage.

Among one of the more intriguing sorghum types grown in the UC trials are sudangrass sorghums shown to reduce nematode populations, especially in rice. Sudangrasses are used in California as green manure to help breakdown nematode life cycles in rice. Dahlberg and others will explore how this occurs.

“Sudangrasses make excellent hay and there is quite a bit grown in California for hay,” Dahlberg says. “Its ability to impact nematodes could offer unique opportunities for this type of sorghum.”

Current sorghum research

Current KARE-WREC sorghum research is funded in part by a three-year, $550,000 grant from UC-ANR to, in part, study grain and forage sorghum’s water use efficiency (WUE). The findings will soon be available for growers.

“We are also evaluating agronomic modeling to provide predictive models on how growers can estimate how sorghum might react under various environmental conditions,” says Dahlberg. The trials will be concluded soon with the findings to follow.

He notes that California is “the perfect place” to study sorghum drought tolerance in the field due to its Mediterranean climate.

“We really have a unique opportunity to develop field screening drought nurseries here where we can screen germplasm and identify drought-resistant genes.”

Benefits for other cereal crops

According to Dahlberg, gaining a better scientific understanding of sorghum’s water frugalness nature is important, given the need to feed a burgeoning global population, and since cereals and legumes are primary components of the human diet. He believes future sorghum research findings could be applicable to other cereal grain crops, perhaps saving more water in other cereal crops.

“This is important as agriculture will be required to grow more food on more marginal land, using less water in the future, especially as climate change impacts precipitation in more places,” Dahlberg said.

Soil microbes

Other UC sorghum research will examine pre-flowering and post-flowering drought tolerance in sorghum, and take a closer look at how soil microbial communities may impact the plant. UC-ANR, UC Berkeley, and the Pacific National Laboratory (PNL) have partnered to study how microbial populations in the soil influence the plant’s drought response.

“Research is generally conducted on the 50 percent of the plant above the ground,” Dahlberg says. “We really don’t understand what’s happening below ground.”

He adds, “There is some thought that soil-based microbial populations indeed help plants adjust to stress and we are looking to research to determine how these microbes interact with the sorghum plant.”

No such thing as ‘junk'

Through another research grant, the sorghum specialists will explore epigenetic control – in other words the impact that small genes have on people and how plants respond to the environment. There are 20,000 to 30,000 major genes in humans and plants which make up about 10 percent to 15 percent of all DNA. Up until recently, Dahlberg says the remaining 85 percent plus were viewed as “junk” genes.

He says research has uncovered that ‘junk DNA’ is actually extremely important in how major genes are expressed. Epigenetics explores how this happens. The research group will apply epigenetics to sorghum and its drought response.

Lessons learned

In the end, Dahlberg hopes sorghum research findings will provide growers with improved tools to more efficiently grow the crop with fewer inputs and costs. More importantly, he sees sorghum as a model crop which can help feed the world and grow cereal crops more efficiently with less water.

Dahlberg concludes, “Helping growers find better mechanisms to combat drought helps everyone.”

Sorghum is a highly adaptable crop which can grow on about 80 percent of the world’s arable land. The crop is grown in other parts of the world for human food consumption.

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