An Integrated Extension/Research Program for Replacing Herbicides with Mechanical Cultivation in New York State

Final Report for LNE93-034

Project Type: Research and Education
Funds awarded in 1993: $103,235.00
Projected End Date: 12/31/1995
Matching Non-Federal Funds: $70,246.00
Region: Northeast
State: New York
Project Leader:
Jane Mt. Pleasant
Cornell University
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Project Information


A statewide educational program to encourage the use of cultivation as a substitute for chemical weed control in corn was implemented in 1993 and continued in 1994 and 1995. Using on-farm trials at several locations in NY, the effectiveness of cultivation in a range of soil and environmental conditions has been demonstrated to farmers and extension field staff.

Research on cultivation tools and systems has found that cultivation can be used in place of herbicides to control weeds in both conventional and reduced tillage regimes with modest or no reduction in corn yields. In conventional till, little difference in effectiveness was found among several implements. However, in no-till, a cultivator equipped with multiple sweeps on heavy shanks without disk coulters was superior to the other implements tested. Cost of cultivation was comparable to or less than chemical control in these experiments.

Research has also confirmed that banded herbicide combined with a single cultivation provides equivalent weed control and yields compared to broadcast herbicides. Banding reduces herbicide use by 65% and requires less labor/time than weed control by cultivation solely. Timing of cultivation in this system is relatively unimportant thereby allowing the farmer greater flexibility.

Project Objectives:

1. To reduce herbicide use by implementing a state-wide educational program on cultivation as a substitute. The program will consist of cultivation clinics, on-farm trials, demonstration plots, a farmer-to-farmer information network and literature.

2. To research the comparative value of various cultivators and cultivation systems for replacement of herbicides in the northeastern U.S.


Research results and discussion:

A. Findings and Accomplishments

1. Objective 1. Statewide Educational Program on Cultivation
On-farm replicated trials were established at three sites in 1993 and continued in 1994 and 1995 to demonstrate the effectiveness of cultivation in corn and to provide information regarding the integration of mechanical and chemical weed control. An additional trial was established at Cornell's Hudson Valley Research Station in 1994. The trials. Located in diverse geographical regions of the state, represent varying soil and climatic conditions. Two demonstrations using cultivation to control weeds were also established on farmers' fields.
Farm field days/tours were held at three of the on-farm sites in 1993. In addition, cultivation research was featured at Cornell's Aurora Research Field Day 1993 and 1995 and at the Hudson Valley Research Field Day in 1994. Cooperative Extension field staff have received updates on the progress of cultivation research during "Agriculture Production Training Week" in November 1993, 1994 and 1995. A Cultivation Conference was held in association with the New York State Vegetable Growers Conference in February 1995. A cultivation bulletin comprised of implement comparisons, economic analyses and other research results is currently in preparation.

2. Objective 2

Experiment 1: Comparison of Cultivation Systems for Conventionally Tilled Corn

This experiment, established in 1991 and completed in 1994, compared cultivation implements for controlling annual weeds in conventionally tilled corn. Implements tested included: (1) John Deere rotary hoe Model 400; (2) Lely tine weeder Model 450; (3) John Deere Model 825 row crop cultivator equipped with Danish S-tines; (4) Lilliston rolling cultivator Series 6400/6430 equipped with either 4-spider gangs or 3-disk gang; (5) Several combinations of Bezzerides Spyders, torsion weeders, spring hoes and spinners mounted on a modified Oliver frame equipped with three Danish 5-tine. All primary cultivation treatments received four cultivations: two early with either a rotary hoe or Lely weeder before and after crop emergence and two late with the Lilliston, J. Deere or Bezzerides tooling. After five growing seasons we have found:

Tine weeders were better than or equal to rotary hoe in controlling weeds and maintaining corn yields. Both reduced corn stands by 5%.
• In 3 of 4 years corn yields in the best cultivation treatments were equal to those in herbicide alone. In one year, cultivation failed because rain prevented the last cultivation.
• Weed control was poorer in the best cultivation treatment compared to the herbicide treatment in 2 out of 4 years and was equal to the herbicide treatment in the other 2 years.
• Cultivation tools differed little in weed control or yield.
• Cost of cultivation and herbicide treatments were approximately equal and there was little variation in cost among the cultivation treatments.

Experiment 2: Timing of Cultivation in Corn

A field experiment was established in 1992 to determine the effects of timing of a single cultivation. Three weed control treatments were used: (1) broadcast herbicide + cultivation; (2) band herbicide + cultivation; and (3) cultivation only. Within each of these weed control treatments a single cultivation was performed at the 2-, 4-, 6- or 8-leaf corn stage. After four years we have found:

• Weed levels are higher and corn yields lower when weed control relies on a single cultivation compared to treatments that combine cultivation and herbicide.
• Band herbicide + a single cultivation is equivalent in weed control and corn yields to broadcast herbicide + cultivation.
• Timing of cultivation has little impact on corn yields or weed control, but there is a tendency for reductions in both when cultivation is delayed until the 8-leaf corn stage. Cultivation at the 2-, 4-, or 6-leaf stage may provide better control of in-row weeds than an 8-leaf cultivation.

Experiment 3: Comparisons of cultivations systems for reduced tillage corn

This experiment, established in 1993, compared cultivation equipment under no-till and chisel/disk. Within each tillage treatment, three cultivation systems were compared: (1) 3 sweeps on heavy shanks without disk coulters (Brillion Rocrop); (2) a single sweep with disk coulters (Taylorway); and (3) disk gangs + a single sweep (Lilliston). Each treatment was further divided for rotary hoe (2 passes) and no rotary hoe. After 3 years we have found:
• Rotary hoeing had little effect on weed levels in 1993 (a dry year), but resulted in large reductions in 1994 and 1995 when rain induced weed germination early in the season.
• In no-till conditions, the rotary hoe was only effective in planter and fertilizer furrows; little action was observed in more compacted areas.
• In minimum till (chisel/disk), the Brillion was equal to the Taylorway and both were superior to the Lilliston.
• In 1993 and 1994 in no-till the Brillion performed best, the Taylorway was intermediate and the Lilliston the poorest. In 1995 the Brillion and Taylorway were equal, but again superior to the Lilliston. Performance was related to differences in ability to penetrate and maintain depth in hard soil.
• Rotary hoeing did not reduce residue cover, but row cultivators did. Since corn canopy was well established at time of residue reduction, erosion risks were minimized. No-till with and without cultivation had similar water infiltration rates.

The three experiments above are all located on the Musgrave Research Farm in Aurora, NY. Soil is Lima-Honeoye silt loam (high-lime) with variable drainage and slopes of 1-3%. Cumulative Growing Degree Days average 2200-2400 on this site. The on-farm trials represent Bath, Howard, Hudson, Ontario and Palmyra series with textures from silt loam to gravelly loam. Cumulative Growing Degree Days range from 1700-2500.

Participation Summary


Educational approach:

Research results from this project have been presented at field days at on-farm sites, as well as Cornell Research Field Days, Cornell Coop. Ext. In-service events and at professional research meetings (see Table 1). In addition, a Cultivation Conference was held in February 1995 in Syracuse as part of the NYS Vegetable Growers' Conference. Approximately 180 growers and extension staff attended. A cultivation bulletin comprised of implement comparisons, economic analyses and other research results is currently in preparation.

No milestones

Project Outcomes

Impacts of Results/Outcomes

A. Our research indicates that substituting cultivation for herbicides will have a neutral to slight decrease on corn production levels and that cultivation can be an effective weed control practice in both conventional and reduced tillage situations. Using cultivation to replace herbicides may result in improved water quality if less herbicides are leached to ground water or less herbicide exposure to surface water occurs. Shifting to reduced tillage systems can significantly decrease soil erosion.

We have also confirmed that banded application of herbicide combined with cultivation provides weed control and corn yields equivalent to those from broadcast herbicide treatments. Banded herbicide reduces herbicide use by 65% while requiring only one pass with a cultivator. Since time and labor constraints have forced NY dairy farmers to rely on herbicides in corn, this practice may be particularly attractive to dairy farmers.

Our research also suggests that timing of the cultivation operation may not be as critical as commonly thought. Banding herbicides combined with cultivation offers farmers considerable flexibility in choosing when to cultivate. Farmers may time cultivation operations according to field moisture conditions and/or labor availability without fear of reducing weed control or corn yields.

B. Atrazine (Atrex), pendimethalin (Prowl) and metachlor (Dual) were the herbicides used for comparison in these studies. They are commonly used to control a broad spectrum of weeds by growers in NY State at rates of 1.25, 1.5 and 2.0 lbs/acre, respectively. Atrazine is a restricted use pesticide and allowable rates of application have declined greatly in the past 5-8 yrs because of water quality concerns. The use of atrazine and metachlor will probably be further restricted in the future. Our project has shown that these herbicides can be reduced by 65% with no impact on corn production and that complete substitution by cultivation results in modest or no reductions.

Economic Analysis

Under conventional tillage, costs among the treatments with both broadcast and row cultivation varied by less than $5/acre ($155 157 in 1993; $171 176 in 1994), and were all less than herbicide only ($160 in 1993; $176 in 1994). Costs of row cultivation only ($145 in 1993; $163 in 1994) was somewhat cheaper than the other treatments while herbicide plus row cultivation was more expensive ($173 in 1993; $183 in 1994).

Since cost differences among treatments were small, net returns largely reflected corn yields. Herbicide plus row cultivation gave the best return in 1993 ($118/a) but the worst return in 1994 ($115), due to a high rate of lodging. In 1993 net return for treatments with Bezzerides tooling ($59 79) were somewhat less to somewhat more than for the herbicide only treatment ($74), depending on the tools used. Returns in 1993 for the Deere row crop cultivator were poor whether the plots were rotary hoed ( $19) or not ($1), and returns of the Lilliston spiders ($35) and Lilliston disks ($35) were intermediate. In contrast, 1994 net returns for all Bezzerides treatments ($197 199) and Lilliston treatments ($195 197) exceeded the return for herbicide alone ($184). Returns for the Deere row crop cultivator with rotary hoe or tine weeder ($178 177) were less than for herbicide alone, but returns were greater than herbicide alone when used without broadcast cultivation ($189).

Brief summarization of results from the reduced tillage experiment is difficult due to interactions between tillage, rotary hoeing, cultivation treatment and year. On average, hoeing had little effect on net return because decreased weed pressure was offset by stand reduction and the added expense of the hoeing.

However, this analysis does not consider the potential costs of carry over of weed populations to future years, or the possibility of compensating for stand loss by increasing planting density. Total costs of the three cultivator treatments averaged over tillage and hoeing were similar in each year (1993 1995: Taylorway $166, 169, 153; Brillion $163, 163, 149; Lilliston $166, 165, 150). The average cost for the herbicide treatments ($183, 177, 155) was greater than for any of the cultivation treatments in each of the three years. Net returns from cultivation treatments tended to be lower than from the corresponding herbicide treatments in 1993 ($36 40 vs. $71) and 1994 ($119 156 vs. $211), but higher in 1995 ($202 205 vs. $193). A late cultivation due to wet weather and poor soil drainage created heavy weed pressure and resulted in poor returns for 1994.

Farmer Adoption

A. Changes in Practice
Extension agents indicate increased requests for information on cultivation. Additionally, federal initiatives and policy aimed at significantly reducing pesticide use by the year 2000 have greatly increased interest in cultivation. Results from this project can be used to provide growers with specific recommendations for reducing herbicide use in corn.

B. Operational Recommendations
Relying completely on mechanical weed control is likely to require planning for additional time and/or labor. In-row weed control will usually require additional equipment (rotary hoe or tine weeder). Specialized tools (e.g, Bezzerides) can be effective in controlling n-row weeds, but require significant set-up and adjustment time, thus greatly limiting their utility in field corn. In addition, they should not be used with a rear-mounted cultivator unless a guidance system is in use. In conservation tillage systems, growers should use cultivation equipment designed for high-residue conditions. Growers who have not used cultivation before should consider banded herbicide + cultivation as a first step toward eliminating herbicides completely.

Areas needing additional study

New Hypotheses

Both the tine weeder and rotary hoe consistently reduced corn stands and the row machines frequently reduced populations further. Other research indicates that high crop densities increase weed control and yields in weedy conditions. We hypothesize that increasing corn populations in cultivation treatments by 5-10% should improve weed control and increase yields.

Machines that work shallowly to destroy weeds in the crop row (i.e., rotary hoes, tine weeders, spinners, torsion weeders and spring hoes) probably work significantly better in a finely prepared seedbed. Light penetrating 2" or more through gaps between clods promotes establishment of seedlings that are too deeply rooted to be removed by the machines. When the machines move clods they expose seedlings that would not be able to reach the surface otherwise. Finally, some seedlings which establish in clods may be knocked about without suffering much damage. Many of these probably desiccate before they grow large, but if the clods later disintegrate into the general soil matrix, some of these weeds may continue to grow. With the advent of zone tillage equipment, a fine seedbed is not necessarily incompatible with soil conservation through retention of residue, and may allow better mechanical control of weeds in the crop row.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.