PUUNENE – Sorghum is a top contender to replace sugar cane in some of Hawaiian Commercial & Sugar Co.’s 36,000 acres after the plantation closes at the end of this year.

“We feel the most comfortable with it,” HC&S General Manager Rick Volner said of sorghum, the grass crop that can be used for cattle feed and biofuel.

Now, several different varieties of sorghum are being grown on 182 acres of HC&S land. Trials began around five years ago, said Mae Nakahata, a 30-year HC&S veteran and director of agricultural research and crop control.

Sorghum “seems to have a lot less pest problems than the other crops,” she said.

And, after it’s harvested, sorghum will regrow on its own, she said.

For now, the sorghum trial plantings are being given away for free as cattle feed to island ranches. Nakahata and Volner said sorghum could be sold to businesses and ranches. Ranchers have already offered to pay for sorghum to have an ample supply of feed, even after the sugar operations have ended, they said.

On Wednesday, a forage harvester was being driven through a field of sorghum – harvesting it with mechanical blades in a flat field off of Mokulele Highway near the Puunene Mill. Volner said sorghum is planted in flat, relatively rock-free fields to allow for equipment to easily harvest the crop. However, not all portions of the plantation are conducive to mechanical harvesting.

White cattle egrets flew by, landing and poking around in the green field in a search for bugs, a familiar sight after cane is burned and cane spiders and bugs scatter from the fields.

While birds can be seen as pests, especially when some species have been eating HC&S’ trial crops, Nakahata said the egrets are a good sign because they eat the pests.

“They are the good birds,” she said smiling.

Volner said another plus about sorghum is that it needs less irrigation than sugar cane.

Experts have said sorghum uses only about one-quarter as much water as cane. From afar, the sorghum plants look like sugar cane with their green, long, skinny shape and slender leaves. In the United States, some varieties are used as livestock feed or turned into ethanol.

Like the sorghum plantings, HC&S has a variety of other trial crops and diversified agriculture models under experimentation as the plantation’s closure approaches.

Other experiments include energy crops, such as a sorghum plants and corn – both of which can be used for anaerobic conversion to biogas. HC&S is working with oil seed crops, such as soybeans and sunflowers for biodiesel production by crushing the seeds to extract oil. And trials are being conducted with grass-finished livestock on old sugar cane fields in Hamakuapoko.

Other planting trials are being done on plots smaller than an acre. Hemp could be a crop as well, company officials said.

Shyloh Stafford-Jones, a project manager for diversified crop operations, said that in addition to the sorghum crops, HC&S’ larger experiments include different varieties of sunflowers on 2 acres, soybeans on 3 acres, corn on 3 acres and purple bana grasses on 2 acres.

He added that along with those crops, other types of crop cover and plants that help condition the soil are being planted in between crop rotations. These include large radishes, known to longtime residents as “daikon,” which have roots that dig into the ground to help with soil compaction. A crop of legumes helps fertilize the soil with nitrogen.

Nakahata said the plantation is having trouble with birds eating soybean and sunflower plants and seeds.

She picked up a sunflower in a dusty field, which had nearly a quarter of its seeds eaten by birds. The seeds are what would be used to provide oil for biodiesel.

The sunflowers are not typical ornamental sunflowers one would see sold in flower shops, Volner said. The ones the plantation is growing are for oil seed crops and are close to 3 feet high, with a smaller flower diameter than the larger ornamental ones used in bouquets.

Also nearby are soybeans, which could also be used for biodiesel.

Nakahata said a big problem with the birds was when plantings were going on for the oil seed crops, and the birds knew when seeds were being planted.

“The birds were literally lined up on the field waiting to go,” she said.

Also, another test crop is the purple bana grasses, Volner said. The grasses from afar look like sugar cane, and they could be used for biofuel, he said.

While most of the test crops are being grown on flat parcels on the plantation near the mill, the grass-fed beef production project is ongoing at the higher and cooler elevations of the plantation on 30 acres of irrigated land in Hamakuapoko.

Work began about a year ago to get a variety of plants to grow in fields for cattle grazing. The crops included a variety of tropical grasses and legumes, which are high in protein and good for the cattle to eat, said Jacob Tavares, who does double duty as the livestock project manager and works in human resources at HC&S.

Another 150 acres is dedicated to grazing. But those lands consist of naturally grown vegetation, Tavares said.

Now, there are 104 head of adult cattle on the properties, with 24 steer on the 30 acres of irrigated fields; along with 50 steer, 30 cows and two calves on the 150 acres, HC&S said.

HC&S is working on the beef production project with Maui Cattle Co., which is made up of a partnership of Maui ranches. Cattle company officials have said the ranches produce 1,000 head of cattle annually, most of which stays on Maui. Some cattle are sent to Oahu.

Normally, it would take about a year for the cattle to get to an optimum weight of 1,200 pounds, Tavares said. The cattle now on the experimental HC&S properties were placed there in February. But so far they are gaining weight quick enough that it may take less than year for them to reach the optimum weight, he said.

The project is going “very, very well . . . exceeding our expectations,” said Tavares, who has his own small ranch in Huelo.

The Hamakuapoko site is a good area for cattle-grazing crops because they grow best in areas that receive about 55 to 60 inches of rain a year.

Company officials estimated that perhaps 10,000 acres on the plantation could be used for cattle grazing.

* Melissa Tanji can be reached at mtanji@mauinews.com.