Corn silage producers can use a ‘more crop per drop’ strategy in a water deficit year if they are willing to accept a little less productivity, according to Mark Lundy, area agronomy advisor with the University of California Cooperative Extension for Colusa, Sutter, and Yuba counties.
Lundy, on a panel of experts speaking at a 2015 World Ag Expo forage seminar in Tulare, Calif., said while corn doesn’t do well with water stress, there are points beyond which application of higher amounts of water do not bring a proportionate return in boosting yield.
Lundy also emphasized there are times - when tassels and silk are forming when corn is most susceptible to stress.
“There is never a good time to water-stress corn, but some times are worse than others,” he said.
Planted dates and maturity
Lundy recommends choosing planting dates and varieties that might offer better times for maximizing efficiency of irrigation.
“Look at what you choose to grow and perhaps plant later with a short variety or drought tolerant variety,” he said. “And get weeds under control. They take up water.”
Many growers use furrow irrigation to water corn silage, because “other options are not economic for corn alone,” Lundy said.
Drip irrigation, while it is more efficient, may become economically viable to corn growers if they have other higher value crops, including processing tomatoes and melons in the rotation.
Growers can reduce water loss through evaporation with reduced tillage and retention of vegetative residue.
Soil moisture monitoring
Soil moisture monitoring is another key to optimizing water use, said Craig Hornung, solution specialist with the agriculture and turf division of John Deere. Growers should try to understand the differences in water retention and permeability of soil types that include clay, silt, fine sand, coarse sand, gravel, loam, and sandy loam.
There is an optimum mixture of soil components, according to Hornung — 25percent each of air and water, 45 percent minerals, and 5 percent organic matter. Tipping the balance in various ways can have significant impacts.
Hornung said these questions should be answered before planting a crop:
1 - Do you have ample water for the crop?
2 - How is the infiltration of water into the soil profile?
3 - Are you dialed in to the frequency and duration of your irrigation cycles?
4 - How much does the chemistry of your well water differ from that of your district water?
5 - How does your soil-water chemistry affect your irrigations?
6 - Is your salt load increasing in your soil profile?
7 - What is your target area for fertilizer applications?
Hornung urged growers to carefully monitor and document the actions they take, along with rainfall events.
Doing everything right
To get the most out of applied water “everything else has to be done right,” said Dennis Craig, produce development agronomist with Mycogen Seeds. This includes ground preparation, hybrid selection, seeding depth, plant population, nutrition, and weed and insect control.
Under optimal conditions, longer season crops give the best yield in terms of tonnage produced. But in a water deficit year, growers may want to look at shorter season hybrids, Craig said.
It’s crucial to not delay the first corn irrigation. He says doing so does not condition the plant for later stress, improve root development or promote deep water uptake. It does delay leaf emergence, silking and maturity by a few days and decreased biomass (dry matter) up to the milk stage.
Craig said planting early could have an impact on the corn silage crop because the plant can take advantage of cooler temperatures at critical times.