Chris Lamb says he gets good, low-cost replacement heifer gains with a silage mixture of corn and soybean forage. After the heifers are bred, in fact, corn-soybean silage is the only feed they get.
Lamb grows the two crops together on 220 acres of his Darien, NY, farm. He says growing and ensiling the crop combination cuts protein purchases, improves soil tilth, and nitrogen fixed by the soybean crop gives the corn a late-season boost.
Silage yield is enhanced, too, he says. He aims for the same corn population (30,000 plants/acre) as when he grew silage corn alone, but now adds 99,000 plants/acre of soybeans. His Ontario silt loam soils are deep chisel-plowed before planting.
“In a very good corn year, we used to get 20 tons/acre,” says Lamb, who farms with Christie Ludwig and Curtis Lamb, his daughter and son. “Now we easily get 25 tons/acre.”
Other farmers have tried growing corn and soybeans together, usually with limited success. That's probably because corn germinates at cooler soil temperatures than soybeans, so it typically gets a head start. The interplanted soybeans don't do well, and the silage ends up being mostly corn.
Lamb avoids that problem by planting the corn 3½” deep and the soybeans only 1½” deep.
“They germinate at the same time,” he says.
Planting more soybeans than corn also benefits the shorter crop, says Lamb. He doesn't always get the ratio just right, but wants corn plants to be 6.5-7" apart, with three soybean plants in between. Both crops do well with heifer manure as the only fertilizer. Corn still dominates the resulting silage, with soybean forage accounting for about a third of it, Lamb estimates.
His forage-testing lab hasn't been able to analyze the silage for protein content, but based on heifer gains and body condition scores, he figures it's around 14-15%.
He first planted the crop combination seven years ago, after reading about three tall-growing forage soybean varieties that had just been developed by USDA. He tried one USDA variety the first year and another the second, but neither matched the maturity of his 110-day corn. When the corn was ready to chop, the soybeans had pods but the grain wasn't fully developed.
Lamb switched to grain-type soybeans the third year, and in recent years has been planting the same variety — a late Group I variety popular in his area. The corn and soybeans are both Roundup Ready.
Shaded by corn plants, he says the beans grow taller than in neighbors' soybeans-only fields, which results in more pods.
To plant both crops in the same rows at the same time, he needed a planter with two frames. So he bought a Kinze 2000, moved the six existing planter units to the front frame and mounted six new units on the rear frame directly behind them. Mounting the front units was the most difficult part, requiring some modifications to the frame. The total planter cost came to $15,000, including $5,000 for labor.
Rigging up a planter may be a challenge for anyone who wants to plant two crops in one pass, says Lamb.
“It's tricky, but the soil benefits, the heifers benefit and dairy farmers and everyone else would benefit if they would make it work,” he says.
He buys 225 baby calves per year from area dairy farmers and sells them as springing heifers. They start getting corn-soybean silage at four months of age, and increasing amounts as they get older. They're bred to Jersey bulls when they weigh about 750 lbs at 14-15 months. After that they get silage only — no protein supplement — until they're sold as springing heifers weighing about 1,250 lbs.
Ninety percent of them are sold back to their original owners.
“They do very well,” Lamb claims.