NCR-202-W
Seedbeds for corn and soybeans can be prepared in several ways--by deep tillage using a moldboard or chisel plow* by shallow tillage using a disk, field cultivator or rotary tiller; by strip tillage using sweeps or rotors; or by very narrow strip tillage (i.e., no-till planting). Tillage systems vary in the amount of soil they manipulate, required number of trips across the field, pesticide applications to be made, their soil erosion control potential, and the management skill needed for success.
By omitting some field operations or switching to ones that have lower energy requirements, substantial, readily measured fuel savings can result. However, changing tillage operations often leads to changing other practices in crop production. And in terms of energy conservation, the net effect of these changes may actually be negative, even though the original tillage change was a fuel saver.
Considerations such as the energy used in equipment manufacture and maintenance or in pesticide and fertilizer production are often overlooked in assessing the 'energy efficiency' of tillage-planting systems. But these indirect energy costs could well tip the scales in favor of one system over another, when comparing the total energy burden on society.
This publication discusses and provides a procedure for determining total energy requirements of any tillage-planting system. It looks at not only the fuel needs for each field operation in a given tillage sequence, but also the energy demands of those no-so-obvious factors involved in crop production. It then reviews the probable economic and agronomic impacts of reduced tillage and suggests under what conditions it is likely to be most successful.
From this information, both on-farm fuel use and total energy consumption for the tillage systems best-adapted to particular soil types can be estimated. A worksheet is provided to make these estimates for your farm.
The amount of fuel used for tillage and planting operations depends on tillage depth, soil type, previous crop, equipment adjustment and operator skill. Table 1 shows the average diesel fuel requirements for most field operations involved in corn and soybean production (up to harvesting). The figures are for soils of three different `draft' ratings-low draft (sands and sandy loams), moderate draft (loams and silt loams) and high draft (clay loams and clays).
If you know the sequence of field operations for a particular tillage-planting system, then by referring to Table 1 you can estimate with reasonable accuracy fuel use per acre.
Fuel requirement when
soil draft rating is-**
------------------------
Mod-
Field operation Low erate High
--------------------------------------------------------
gallons per acre
Shred cornstalks 0.75 0.75 0.75
Subsoil chisel, 14 inches 1.30 2.10 2.95
Moldboard plow, 8 inches 1.15 1.85 2.60
Chisel, 8 inches 0.75 1.25 1.75
Offset disk 0.60 0.95 1.35
Field cultivate plowed ground 0.55 0.60 0.65
Tandem disk plowed ground 0.50 0.55 0.60
Tandem disk, second trip 0.45 0.50 0.55
Tandem disk cornstalks 0.40 0.45 0.50
Form ridges, fall 0.40 0.45 0.50
Harrow, spring tooth 0.35 0.40 0.45
Harrow, spike tooth 0.35 0.35 0.35
Apply NH3, no-till ground 0.65 1.05 1.45
Apply NH3, plowed ground 0.60 0.70 0.80
Field cultivate + plant 0.95 1.05 1.15
Strip rotary till + plant 0.85 0.95 1.05
Plant, wheel-track 0.60 0.65 0.70
Plant, conventional 0.40 0.50 0.60
Plant, till 0.40 0.50 0.60
Plant, no-till 0.40 0.50 0.60
Cultivate, disk hiller 0.35 0.40 0.45
Cultivate, sweeps 0.30 0.35 0.40
Cultivate, rolling tines 0.30 0.35 0.40
Rotary hoe 0.25 0.25 0.25
Spray fertilizer 0.20 0.20 0.20
Spray pesticides 0.15 0.15 0.15
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* To convert diesel to gasoline equivalent, multiply by 1.4
**Fuel requirements given are averages of tests conducted over a
wide range of soils The actual fuel requirements for a particular
field operation in a particular soil type may vary as much as 25% or
more from the values shown here Soil types associated with the draft
ratings include Low-sands and sandy loams; Moderate--loams and silt
loams. High--clay loams and clays
Table 2 gives examples of how such estimates might be made for conventional (moldboard plow), chisel and no-till systems for corn following corn. Although the field operation sequence for conventional and chisel methods in the table are typical for the Corn Belt, the specific kinds and amounts of secondary tillage can vary from area to area and farm to farm. Therefore, use your actual or planned field operations, not necessarily the ones listed.
As Table 2 illustrates, the greatest fuel savings are usually achieved when primary tillage operations, such as plowing or chiseling, are omitted. But even if they can't be totally eliminated, cutting out even one trip in seedbed preparation with better planning before the spring season can save about 1/2 gallon of diesel fuel per acre.
Tillage system and Fuel
field operations required
---------------------------------------------
gals./A
Conventional system
Disk stalks 0.45
Moldboard plow 1.85
Disk 0.55
Field cultivate 0.60
Apply anhydrous 0.70
Plant 0.50
Cultivate 0.35
5.00
Chisel system
Chisel plow* 1.25
Disk 0.55
Field cultivate 0.60
Apply anhydrous 0.70
Plant 0.50
Cultivate 0.35
3.95
No-till system
Shred stalks 0.75
Apply liquid N 0.20
No-till plant 0.50
1.45
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* Assumes a coulter-chisel-- i.e. chisel plow with
gang of coulters at the front to cut through trash.
Here are some practices to consider which will minimize secondary tillage:
The energy required to manufacture equipment, pesticides and fertilizers must be considered in calculating total energy used in agriculture and, more specifically, in assessing any savings that may result from reducing tillage. This section looks at the indirect energy `costs' of these three tillage system inputs.
Energy Used in Equipment Manufacture and Maintenance
When the number of field operations or the horsepower required to do them is cut, the on-farm complement of equipment may be reduced accordingly. Often, however, reduced tillage is practiced on only part of the farm's total acreage in any given year; thus, large tractors and equipment may still be necessary for the remaining acres. But even partial tillage reduction should extend the life of the equipment and delay replacement purchases, resulting in less equipment manufactured.
The energy required to manufacture and maintain the equipment used in tillage-planting systems has been estimated at roughly one-half of that required for fuel on a per-acre basis. A more precise estimation procedure based on equipment weight and class, developed by Purdue energy specialists, shows indirect machinery energy for tillage operations on a 600-acre grain farm (expressed in diesel fuel equivalents) to be:
These figures will be used in examples presented later (Tables 5 and 6).
Energy Used in Pesticide Production
Pesticide use often increases as tillage is reduced. This is especially true when deep tillage is omitted. With less tillage, fewer weeds are killed and fewer weed seeds buried. In addition, crop residue left on the soil surface may further reduce the effectiveness of standard herbicide treatments.
Achieving adequate weed control when deep tillage is omitted, therefore, may require increasing herbicide rates, or using two or more pre-emergence herbicides in combination, or adding a contact herbicide to kill growing weeds. (Currently, fields infested with perennial weeds, such as Johnsongrass, Canada thistle and milkweed, require moldboard plowing in combination with chemical treatment to realize adequate control. Hopefully, development of more effective materials and application techniques in the near future will allow for control of perennials with reduced tillage).
Use of insect and rodent control chemicals may also have to increase somewhat with certain forms of reduced tillage. For instance, corn that has been no-till planted into a chemically killed sod is more likely to need chemical protection from armyworm and field mice than conventionally planted corn. However, any increase in insecticide and rodenticide usage for reduced tillage is apt to be small compared to increased herbicide needs.
Energy used in pesticide production is difficult to estimate and varies with the materials. Some require a high-energy carrier to mix with the active ingredient, while others are mixed with water or applied dry.
A recent study in England showed that the energy used to produce several common pre-emergence herbicides averaged about 1/2 gallon of diesel fuel equivalent (DFE) per pound of actual toxicant. Paraquat production used about 2 1/2 times that amount, however. Based on the figures from this study, Table 3 gives the energy requirements of typical herbicide programs for conventional, chisel and no-till systems for corn. Note that rates per acre are higher for the non-conventional tillage systems.
Herbicide needs with reduced tillage sometimes exceed those listed in Table 3. Continuous no-plow tillage, for example, often requires the use of post-emergence herbicides for weeds that escape the pre-emergence chemicals. No-till-fields sometimes have Paraquat-resistant weeds, also making post-emergence herbicide application necessary.
Tillage system and Application Diesel fuel
herbicides used rate* equivalent**
-------------------------------------------------
lbs./A gals./A
Conventional system
Atrazine 1.50. 0.75
Lasso 2.00 1.00
1.75
Chisel system
Atrazine 1.75 0.88
Lasso 2.25 1.13
2 01
No-till system
Atrazine 2.00 1 00
Lasso 2.50 1.25
Paraquat 0.50 0.63
2.88
------------------------------------------------
* Rates are in pounds actual toxicant per acre
**Based on 18.479 kcal/lb actual toxicant for Atrazine
and Lasso. 46,198 kcal/lb actual toxicant for Paraquat, and
36.958 kcal/gal of diesel fuel.
The technology for season-long weed control in soybeans with shallow or no-till planting is just now being developed. And it appears likely that more energy will be needed for weed control in no-till soybeans than in no-till corn.
Research in the central Corn Belt shows that rates of phosphorus and potassium fertilizer should not vary greatly among various tillage systems. However, farmers and researchers alike have noted reduced nitrogen (N) efficiency with no-till corn. N losses through leaching, volatilization, denitrification and tie-up by decaying organic matter all appear to be greater with no-till planting under certain conditions.
Tillage-planting systems often require different forms and rates of nitrogen to produce comparable yields. This can significantly affect the overall energy ratios among systems. The energy needed to produce the common forms of fertilizer N used in the Corn Belt is shown in Table 4.
Energy per
unit mass Diesel fuel
Nitrogen material of nitrogen equivalent**
-------------------------------------------------------------------
kcal/lb. gal./lb.
Urea, solid 8625 0.233
Urea, solution 8603 0.233
28% liquid
(1/2 urea, 1/2 NH4NO3) 8465 0.229
Ammonium nitrate, solid 9154 0.248
Ammonium nitrate, solution 8328 0.225
Anhydrous ammonia 6527 0.177
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* Source Hoeft and Siemens (1975)
** Based on 36.958 kcal/gal of diesel fuel
Here are alternative methods of applying nitrogen fertilizer in no-till corn to insure efficient N utilization:
Total energy used for a particular tillage-planting system is merely the sum of its direct energy requirement (i.e., fuel) and indirect energy requirements (i.e., energy for machinery, herbicide and N fertilizer production). Tables 5 and 6 are example calculations of total energy use by three common corn tillage-planting systems based on these energy requirement factors. Table 5 compares conventional, chisel and no-till systems using the field operations and herbicides listed in Tables 2 and 3 with the same rate and form of nitrogen fertilizer (from Table 4). Table 6 varies the N rate and form.
In Table 5, the DFE energy `savings' over conventional tillage is nearly 1 gallon per acre for the chisel system and over 3 1/2 gallons per acre for no-till planting. These figures represent the maximum total energy savings that can be expected compared to our conventional tillage system. Notice that the off-farm (indirect) savings in machinery is largely offset by the off-farm energy increase because of greater herbicide use. Thus, the net savings with both chisel and no-till planting is due primarily to reduced on-farm fuel use.
Diesel fuel equivalent
when tillage planting system is-
----------------------------------
Input item* Conventional Chisel No-till
--------------------------------------------------------
gals./A gals./A gals./A
On-farm fuel 5.00 3 95 1.80
Machinery* 2.57 2.48 1.05
Herbicides 1.75 2.01 2.88
Nitrogen*** 26.55 26.55 26.55
Total 35.87 34.99 32.28
Savings vs
conventional ( -- ) (+0.88) (+3.59)
---------------------------------------------------------
*Only those energy-consuming input items likely to be altered by
changing tillage practices are listed
** For manufacture and maintenance
*** Application rate of 150 lbs/A as anhydrous ammonia for all three
systems.
Diesel fuel equivalent
when tillage-planting system is-
---------------------------------
Input item* Conventional Chisel No-till
---------------------------------------------------------------
gals./A gals./A gals./A
On-farm fuel 5.00 3.95 1.45
Machinery** 2.57 2.48 1.00
Herbicides 1.75 2.01 2.88
Nitrogen 26.55 26.55 41.22
Total 35.87 34.99 46.55
Savings vs.
conventional (---) (+0 88) (-10.88)
----------------------------------------------------------------
*Only those energy-consuming input items likely to be
altered by changing tillage practices are listed
**For manufacture and maintenance
*** Application rate of 150 lbs/A as anhydrous ammonia for
conventional and chisel systems. 180 lbs/A surface-applied as 28%
liquid for no-till system
In Table 6, both form and rate of nitrogen fertilizer were changed for the no-till system, substituting 28% liquid N and increasing the amount applied by 20 percent. Notice the drastic energy balance shift that results from the change in N fertilizer. While on-farm fuel savings for no-till compared with conventional tillage is about 3 1/2 gallons per acre, the total energy cost to society is increased more than 10 gallons per acre.
These two examples do indicate an opportunity to reduce on-farm energy use through reduced-tillage systems where they are adapted. However, total energy use will be less for such systems only if N form and rate can be kept comparable to the systems being replaced.
Determining Energy Use by Alternative Tillage-Planting Systems
At the end of this publication is a worksheet for estimating both field operation fuel requirements and total energy usage for any tillage-planting method. The results provide a basis for evaluating the energy efficiency of current tillage practices as well as determining the energy savings potential of alternative systems.
Such information would be quite valuable if local fuel shortages develop in the future, resulting from seasonal shortages or reduced allocations. Farmers need to know where and how to cut field operations without lowering yields, and what kinds of fuel savings they can expect by reducing tillage.
Value from an Energy Savings Standpoint
Although energy savings from reduced tillage can be important at the farm level, it should be kept in perspective with national energy use.
The energy used by agriculture has been estimated at 2.8 percent of the total energy consumed in the U.S. Of total agricultural energy consumption, crop production uses only 31 percent; and of that figure, tillage expends only about 15 percent. This means that energy used for tillage is about 0.1 percent of the total energy consumed in the U.S. as a whole. Thus, any energy savings through reduced tillage will have little effect nationally, although it may be important on the individual farm.
Value from an Agronomic Standpoint
On the average, the dollar value of fuel saved through reduced tillage is small-equaling less than 2 bushels of corn per acre in going from conventional to no-till methods; and even this savings may be offset by added chemical costs. However, there are other reasons for considering reduced tillage systems on soils where adapted. Let's look at them briefly.
Where Reduced Tillage Is Adapted
Tillage research in the Corn Belt has identified four factors that greatly influence the success of no-plow tillage systems.
1. Soil drainage. As drainage improves, less tillage is needed.
2. Latitude. As length of growing season increases, no-plow tillage is more likely to succeed.
3. Previous crop. No-plow tillage works better for corn following soybeans or sod than for corn following corn.
4.Hard-to-control pests. Serious pests that cannot be controlled with chemicals may make moldboard plowing a necessity.
Research and farmer experience with tillage systems for corn and soybeans in many states have led to evaluation of these systems based on soil drainage and texture characteristics. Check with your state's Cooperative Extension Service for information on the adaptability of specific tillage-planting methods under your particular soil conditions.
Energy savings of up to 1 gallon per acre diesel fuel equivalent for chisel tillage systems and 3 1/2 gallons per acre DFE for no-till planting, compared with conventional tillage, are possible where these systems are adapted. Most of the savings comes from reduced fuel use for field operations.
Remember, though, that if reduced tillage necessitates increased rates and use of less energy-efficient forms of nitrogen, the energy cost to society at large will be greater than with conventional tillage. Careful evaluation of possible tillage alternatives is necessary to determine which system provides the most benefits in terms of energy savings, yield potential and maintenance of soil productivity.
* Deep tillage in this instance does not refer to subsoiling or the use of giant plows.
Alternative #1: _________________________________ Alternative #2: ____________________________________
Direct Energy Use-Diesel Fuel
Field operations [from Table 1) Gals./A Field operations [from Table 1) Gals./A
a.___________________________________ __________ a.__________________________________ ___________
b.___________________________________ __________ b.__________________________________ ___________
c.___________________________________ __________ c.__________________________________ ___________
d.___________________________________ __________ d.__________________________________ ___________
e.___________________________________ __________ e.__________________________________ ___________
f.___________________________________ __________ f.__________________________________ ___________
g.___________________________________ __________ g.__________________________________ ___________
h.___________________________________ __________ h.__________________________________ ___________
i. Total gals/A (sum a thru h) = __________ i. Total gals./A (sum a thru h) = ___________
j. Total acres = __________ j. Total acres = ___________
k. Total gals, diesel fuel used directly k. Total gals, diesel fuel used directly
at farm (i x j) = __________ at farm (i x j) = ___________
Indirect Energy Use - Diesel Fuel Equivalents (DFE)
Gals./A Gals./A
m. Machinery manufacture and m. Machinery manufacture and
maintenance (x 0.50) = __________ maintenance (x 0.50) = __________
Herbicide @ lbs. actual x Herbicide @ lbs. actual x
used toxicant/A DFE/lb used toxicant/A DFE/lb
n. _________ @ ____________ x 0.50 = __________ n. _________ @ ____________ x 0.50 = __________
o. _________ @ ____________ x 0.50 = __________ o. _________ @ ____________ x 0.50 = __________
p. _________ @ ____________ x 0.50 = __________ p. _________ @ ____________ x 0.50 = __________
q. _________ @ ____________ x 0.50 = __________ q. _________ @ ____________ x 0.50 = __________
r. Paraquat @ ____________ x 1.25 = __________ r. Paraquat @ ____________ x 1.25 = __________
Nitrogen @ lbs actual x DFE/lb Nitrogen @ lbs actual x DFE/lb
fertilizer nitrogen/A (Table 4) fertilizer nitrogen/A (Table 4)
s. _________ @ ____________ x ____ = __________ s. _________ @ ____________ x ____ = __________
t. _________ @ ____________ x ____ = __________ t. _________ @ ____________ x ____ = __________
u. Total gals/A (sum m thru t) = __________ u. Total gals./A (sum m thru t) = __________
v. Total gal. DFE used v. Total gal. DFE used
indirectly (u x j) = __________ indirectly (u x j) = __________
Total Energy Requirement of System
Gals/A
w. Direct energy use + indirect w. Direct energy use + indirect
energy use (k + v) = __________ energy use (k + v) = _________
Alternative #3: _________________________________ Alternative #4: ____________________________________
Direct Energy Use-Diesel Fuel
Field operations [from Table 1) Gals./A Field operations [from Table 1) Gals./A
a.___________________________________ __________ a.__________________________________ ___________
b.___________________________________ __________ b.__________________________________ ___________
c.___________________________________ __________ c.__________________________________ ___________
d.___________________________________ __________ d.__________________________________ ___________
e.___________________________________ __________ e.__________________________________ ___________
f.___________________________________ __________ f.__________________________________ ___________
g.___________________________________ __________ g.__________________________________ ___________
h.___________________________________ __________ h.__________________________________ ___________
i. Total gals/A (sum a thru h) = __________ i. Total gals./A (sum a thru h) = ___________
j. Total acres = __________ j. Total acres = ___________
k. Total gals, diesel fuel used directly k. Total gals, diesel fuel used directly
at farm (i x j) = __________ at farm (i x j) = ___________
Indirect Energy Use - Diesel Fuel Equivalents (DFE)
Gals./A Gals./A
m. Machinery manufacture and m. Machinery manufacture and
maintenance (x 0.50) = __________ maintenance (x 0.50) = __________
Herbicide @ lbs. actual x Herbicide @ lbs. actual x
used toxicant/A DFE/lb used toxicant/A DFE/lb
n. _________ @ ____________ x 0.50 = __________ n. _________ @ ____________ x 0.50 = __________
o. _________ @ ____________ x 0.50 = __________ o. _________ @ ____________ x 0.50 = __________
p. _________ @ ____________ x 0.50 = __________ p. _________ @ ____________ x 0.50 = __________
q. _________ @ ____________ x 0.50 = __________ q. _________ @ ____________ x 0.50 = __________
r. Paraquat @ ____________ x 1.25 = __________ r. Paraquat @ ____________ x 1.25 = __________
Nitrogen @ lbs actual x DFE/lb Nitrogen @ lbs actual x DFE/lb
fertilizer nitrogen/A (Table 4) fertilizer nitrogen/A (Table 4)
s. _________ @ ____________ x ____ = __________ s. _________ @ ____________ x ____ = __________
t. _________ @ ____________ x ____ = __________ t. _________ @ ____________ x ____ = __________
u. Total gals/A (sum m thru t) = __________ u. Total gals./A (sum m thru t) = __________
v. Total gal. DFE used v. Total gal. DFE used
indirectly (u x j) = __________ indirectly (u x j) = __________
Total Energy Requirement of System
Gals/A
w. Direct energy use + indirect w. Direct energy use + indirect
energy use (k + v) = __________ energy use (k + v) = _________
North Central Regional Extension Publications are prepared as a part of the Cooperative Extension activities of the 13 land-grant universities from the 12 North Central states, in cooperation with the Extension Service-USDA. The following states have cooperated in making this publication available:
*Purdue University MDC, 301 S. 2nd St. Lafayette, IN 47905 *Kansas State University Umberger Hall Manhattan, KS 66506 *Michigan State University P.O. Box 231 East Lansing, MI 48824 *University of Minnesota 3 Coffey Hall, 1420 Eckles Ave. St. Paul, MN 55108 *University of Missouri 222 S. Fifth Street Columbia, MO 65211 *University of Nebraska Dept. of Ag. Communications Lincoln, NE 68583 * South Dakota State University Extension Building Brookings, SD 57007
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New 7/83
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In cooperation with the North Central Regional Educational Materials Project.
Issued in furtherance of Cooperative Extension work, Acts of Congress of May 8 and June 30, 1914, in cooperation with the U.S. Department of Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri Nebraska, North Dakota, Ohio, South Dakota and Wisconsin. H. A. Wadsworth, Director, Cooperative Extension Service, Purdue University, West Lafayette, Indiana 47907.