During the past decade, reduced, or conservation, tillage has appealed to growers seeking lower fuel and equipment costs, preservation of soil quality, water savings, and fewer weed management inputs. Reduction of dust due to tillage is another goal.
At the recent California Alfalfa and Forage Symposium at Monterey, Jeff Mitchell, University of California Cooperative Extension vegetable crops specialist at the Kearney Agricultural Center, Parlier, and Carol Frate, Tulare County farm advisor, reported on case studies with growers using reduced tillage.
"If there is a cropping context where these systems might work best, the dairy forage crop rotation sequence seems to lend itself quite well," said Mitchell.
Mitchell cited the experiences of Stanislaus County dairyman Mike Nutcher with strip-tilled, forage corn. Nutcher has 1,200 cows and farms about 350 acres of forage land adjacent to his dairy.
He decided to experiment with the strip-till method in 2002 after reading of trials in Oregon and attending the University of California’s conservation tillage workshops.
Coming off a winter, small-grain forage crop such as triticale, Nutcher had customarily followed conventional methods in preparing for planting forage corn in the spring.
Those steps included disking, ripping, a second disking, pre-irrigation, a finish tool pass, and planting, at a combined cost of up to $80 per acre.
Eliminate land prep
"What Mike attempted to do," Mitchell said, "was eliminate the land preparation altogether and replace it with a single strip-till pass and a planting pass."
The two operations, performed on a 17-acre trial in early April, cost a total of $30 per acre, a $50 savings in contrast to the conventional practice.
Nutcher also saved the two weeks time the conventional preparation required, and that meant a gain of five tons, or $60, per acre with sudan for silage in his double-crop program.
The strip-till method, Mitchell explained, used a six-row, Unverferth Ripper-Stripper to till six 8-inch strips in the flat soil where the winter forage had grown. The implement was fitted with coulters to cut through the crop residue, sub-soil shanks to loosen the soil profile, and finally "clod-buster" roller tools to form the seedbed for planting.
A Roundup Ready, silage corn variety was planted immediately after the strip-tillage operation. The grower envisions potential for additional savings by mounting the planter behind the tillage equipment for a single-pass operation.
"Our first try at strip-tilling turned out pretty well," Nutcher said, noting that yields averaged 29.5 tons to the acre on the strip-till field, compared with his ranch average of 31.5 tons.
Room to improve
But he also said he saw room for improvement. First, he could have had higher plant populations by keeping the corn planter closer in line with the strip-tiller and having more downward pressure on the planter.
Second, more fertilizer could have been available at planting. Another improvement would be a more level field, since the one used required cross levies for flood irrigation.
In summarizing his first go at strip-till, Nutcher said, "It takes some forethought and planning to make sure you have enough moisture in the soil. We irrigated 12 days prior to chopping off the winter forage and had no problems with moisture when we were ready to plant the corn."
In detailing her 2003 trials during the symposium, Carol Frate said interest in reduced tillage and no-till corn has increased in Tulare County. She reported savings with fewer field operations of reduced tillage, although yield differences favored conventional practices.
She observed various treatments using five to seven steps fewer than the nine used conventionally after winter forage was harvested. She also monitored results of trials on sandy loam soil and clay loam soil.
Forage yields from Asgrow RX897 RR on the sandy loam field ranged from 35.9 tons per field acre by conventional to 30.4 tons by no-till (spread manure, pre-irrigate, plant).
On the clay loam field the range was 34.6 tons per field acre by conventional to 29.3 tons by strip-till post (spread manure, pre-irrigate, strip till, plant). With either soil texture, the differences in reduced till treatment yields were not significantly different.
Frate said the borders used in the fields were about 10 feet wide. "Calculating the reduced and no-till yields, including the area of the borders not planted, and comparing those yields to the yields of the conventional planting in which borders are not needed, there is significant yield advantage for the conventional."
She said not all growers using reduced or no-till methods in corn are using borders so wide. "Some are using alfalfa-style borders and believe they are losing just one row of corn for each border."
Growers, she added, need to experiment to learn what works best for their fields. "The width between borders and the size of borders will be dependent on soil type, the volume of water applied, slope (both down and across the field), and whether there is a return system."
GPS guidance systems can be a big help, since their precision allows for accurate placement of borders for minimal loss of planted area.
"These trials are just one year’s results," Frate said. "Repeated no-till and strip-till within a field could bring other issues to the forefront. Certainly the amount of residue from the previous crop can be an issue as well as compaction from one year or field to the next. Winter forage harvest occurs in the spring when weather can be unpredictable."