On May 6, Pecos Valley, N.M., farmer Jerry Calvani looked up in the sky and saw something he hadn’t seen in months — a cloud.
By his count, his trees had gone without rain more than 190 days. Three days later he baled some hay.
“At 7:00 in the morning, the humidity was just 9 percent,” he recalls. “It’s bone dry here.”
Jerry and his son, Dean, who own Calvani Farms, grow 500 acres of pecans near Carlsbad. Their orchards are in an area of prolonged drought that has farmers in much of the Southwest facing damages and losses that range from moderate to exceptional.
The Calvanis get water for their flood-irrigated orchards from wells and from the local irrigation district.
“The water situation doesn’t look good at all this year,” Jerry says. “The district has reduced our allotment to 1.4 acre feet. Our yearly entitlement is 3.25 acre feet.”
Water keeps the trees productive, but it also produces weeds. The main problems are barnyardgrass, bermudagrass, kochia and wild mustard.
At one time, they used Roundup to suppress the weeds, making four to five applications per season. But four years ago, after watching the herbicide’s price double in just one year, the Calvanis decided to reduce their chemical costs by changing weed control tactics.
Disking row middles to keep weeds down would bring numerous small rocks to the surface, where they would be picked up with nuts during harvesting operations. Also, using tillage to control weeds would require the time, trouble and expense of re-leveling the orchard floor prior to harvest so harvesters could pick up the nuts.
“Before planting an orchard, we laser level the ground twice, after which we don’t ever intend to go back and disturb the soil,” Jerry says.
To maintain a no-till approach, the Calvanis bought two flail mowers. Now, they spray Roundup in a 3-foot wide strip on either side of thes tree rows, which are spaced 30 feet apart. The mowers, with their 12-foot cutting width, can clip weeds in the untreated 24 foot-wide row middles in two passes.
Before taking this step, they had been concerned that weeds would rob their trees of some water. But, a presentation by a New Mexico State University researcher at a Western Pecan Growers Association conference convinced them that any water used by the weeds wouldn’t hurt their pecan production.
Uptake of nutrients by weeds in older orchards where they broadcast fertilizer isn’t a problem either, they say, because the shading of larger trees helps minimize any weed growth. In the the case of smaller trees, however, they minimize the threat to profits by spoon-feeding fertilizers around each tree.
They cut the weeds to a height of one inch or lower. Mowing frequency varies with tree size. Because older, larger trees shade over the row middles, they may only need to mow these orchards three times a season. The smaller trees — those under 10 years old — require more frequent mowing. They’ve already mowed some of these orchards twice this year.
They make more trips through the fields with their mowers, but at a faster ground speed than when spraying the herbicide.
The Calvanis are pleased with the results of combining mowing with herbicide strips.
“It’s a better deal for us,” Jerry says. “We’ve cut our herbicide costs by about 80 percent and the mowers do a good job of knocking down the weeds. We don’t get the misses that we did every once in awhile with the sprayer.
“Also, at harvest, the nuts fall on the weed stubble instead of bare ground, and that helps to control dust when the harvester goes through to pick up nuts.”