United States

Department of

Argriculture

Forest Service Research Note

Southern Forest

Experlment Station

SO-287

December, 1982

Machine Planting Costs are Influenced by

Site Characteristics and Preparation Practices

Richard W. Guldin

SUMMARY Cost Data

An analysis of 14 contracts for planting southern

pine seedlings by machine on 1,781 acres of industrial land shows that 4 factors explain 90 percent of the variation in costs.

Additional Keywords: regeneration, southern

pine, site preparation

The data collected represent costs paid contractors for planting and site preparation (table 1). They

were market-determined values, which are

preferable to accounting costs for analysis.

INTRODUCTION

Planting southern pine seedlings with a tree

planting machine pulled behind a small crawler

tractor is an alternative to planting by hand. Approximately 30 percent of the seedlings planted

southwide in 1980 were set out by machine. The effects of preparation intensity and costs on the

subsequent cost of planting southern pine seedlings by machine are reported here.

Seedling costs were excluded from total planting

costs because the land-owning firms either provided seedlings from their own nurseries or purchased

seedlings from state nurseries. Seedling costs per

1,000 vary considerably between public and private

nurseries, reflecting differences in cost accounting

practices. Seedling costs were excluded to

eliminate this variation and focus the analysis on

contract service costs.

Site preparation costs included the cost of all

treatments including prescribed burning.

Number of Seedlings

DATA

In collecting data to study influences of site

characteristics and preparation practices on contract hand planting costs, several cooperators also

provided machine planting costs. The data were

obtained from 4 forest products firms active in the

coastal plain and Piedmont of Alabama, Louisiana,

Mississippi, and South Carolina in the 1980 planting season.

The analysis used considered the number of

seedlings per acre specified in the contract rather

than the number planted. On 12 of the 14 sites, 726

seedlings per acre were specified, although 2 different spacings were used. Eight of the 12 used

6 x 10 foot spacings; 4 specified 5 x 12 spacings.

The remaining 2 sites used 8 x 8 and 7 x 10 foot

spacings. The number actually planted varied from

5 to 7 percent less than specified because the contracts provided for 10 percent leeway, and contractors planted the fewest seedlings necessary to

meet the minimum acceptable stocking level.

Southern Forest Experiment Station/l-102lO U.S. Postal Services Bldg., 701 Loyola Avenue, New Orleans, La. 70113

Forest Service, U.S. Department of Agriculture.

Serving Alabama, Arkansas, Louisiana, Mississippi, E. Oklahoma, Tennessee, E. Texas, Puerto Rico, U.S. Virgin Islands

1
Tab@ l.-Summary statistics for 14 industrial machine planting ContraM for the 1980planting

se@on. 1 ,

.,:. ):.1~

.

r

,’

Machine plantlng cost

(dollars per acre)

Site preparation cost

(dollars per acre)

Prescribed burning cost

(dollars per acre)

Number of seedlings

planted per acre

Total acreage offered _, ,’

for plantlrig

Number u)! mWhlne psres:

to complete site

preparation

20.74 4.21 21.00 38.04

85.97 31.11 27.80 135.00

1.14 1.46 0.00 3.00

718.43 38.78 622.00 786.00

127.21 loo.14 21.00 39I.w

2.07 0.47 1.00 3.00

Table 2.-Combinations of treatments used to prepare sites for

contract machine planting

Treatment comblnatlon Number of contracts Acreage

Shear

+ Bed 1 4 1

+ Burn + Bed 4 301

+ Chop + Burn 1 300

+ DISC 2 312

+ Rake 2 142

+ Rake + Bed 3 544

Chop + Burn 1 21

Total Acreage

The‘ total acreage offered for planting

represented the scale of the operation. The total

acreage actually planted may have been reduced

because of equipment breakdowns, and insufficient seedlings. Such reductions in acreages could

not be anticipated prior to bidding.

Number of Machine Passes

The intensity of mechanical site preparation was

measured by the times machines traversed the

site. Shearing and piling was counted as a single

machine pass because both steps are generally accompitshed under a single contract for a single

price. Shearing and raking were counted as 2

machine passes because the contractor usually

charges additionally for raking following shearing

because of the time involved and machinery adjustments.

Prescribed burning done by the land-owning

company was not counted as a machine pass, even

though fire lines were plowed around the perimeter

and occasionally through the site. Also, burning

slash piles or windrows foiiowing,shearing or raking was considered a part of those’treatments and

not a separate one.

Eight treatment combinations were used (table

2). Shearing was the Initial treatment on 98.8 percent of the acreage treated. Bedding was the final

treatment on 53 percent of the acreage.

Zero-One Variables

Some site characteristics and site preparation

variables were assigned code numbers: 1 if present, 0 otherwise. The terrain of the planting site

had a slope exceeding 5 percent In 7 of the 14

cases, rating a 1. Broadcast burns were used in 6 of

the 14 cases. Bedding was the flnai site preparation treatment in 9 of the 14 cases. Only 1 site was

injected with herbicides as a part of preparation.

Each of these zero-one variables was included in

the analysis to test whether they had a significant

effect on machine planting costs.

Rlchard iN. Guldln Is Research Forester, Southern Forest Experiment Station, Forest Service-USDA, New Orleans, La.

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ANAtYSlS

Machine planting cost per acre is the dependent

variable. Regression analysis of the data yielded

the following equation:

MACHINE$ =

+

$38.08 -(!;§;(TOTLACRE)

$22.24(BURNED)

(8.34)

where:

MACHINE$ =

TOTLACRE =

BURNED =

BURNCOST =

TWOPASS =

$7.22(BURNCOST)

(5.88)

$7,35(TWOPASS)

(3.93)

machine planting cost, dollars

per acre

total acreage offered for planting

1 if a broadcast burn is prescribed, 0 otherwise

cost of a broadcast burn, dollars

per acre

1 if two or more machine passes

were used to mechanically prepare the site for planting, 0

otherwise

The F-statistic for the equatlon is 19.72, having a

probability value of 0.001. The coefficient of multiple determination (R*) is 0.90, and the standard error of the estimate is 1.82. The t-statistics, shown in

parentheses beneath the coefficients, are all

significant and have probability values less than

0.003.

DISCUSSION

Smith (1982) noted that the 3 major goals of site

preparation are: (1) to control competing vegetation; (2) to provlde a more hospitable growing location; and (3) to simplify planting. Every site preparation treatment is directed at one or more of these

goals. Dollar benefits from the first 2 goals normally accrue from increases in future harvest value.

Expected future harvest value can be discounted to

present worth benefits. Present worth benefits

from simplified planting, the third goal, are

measured by reduction in planting cost. The sum of

the present worth benefits obtained from all 3

goals must exceed the cost of the treatments to

justify them.

Even though changes in independent variable

values induce changes in benefits from all 3 goals,

the equation estimates benefits only from the

simplified planting goal. ‘Only the effect on

MACHINE$ of.,changes Jn the values of the in*

dependent variables will be dlscussed.Competition control andstteamelioratlon benefits require a

separate analysig.

The negative sign for the coefficient, of

TOTLACRE indkates .that aconomleseof-scale

result from adding more ac.raage to the planting

contracat. MACHINE$drops sio.03 for each acre,add*

ed to the.planting contrast.

The combined effect of the 2 variables, BURNf-D

and BURNCOST, ,is to increase MACHiNE$,when

BURNCOST is .less than 83.08 .per ‘acre,~ For each

$0.0.1, below 83.08, -MACHtN.E$ rises, &f&07, tn no

case was BURNCOST greaterthan $3,OQ,. Benefits

from competltion control and site amelioration

must exceed both the cost of burning and the increase in planting cost for burning to be

economically justified.

The variable TWOPASS relates to the number of

machine passes. Preliminary analysis of the data

revealed a significant reduction in MACHINE$

when a second mechanical treatment was added to

the first treatment. But addlng a third mechanical

treatment did not result in further MACHINE$

reductions. Therefore, machine pass data were expressed as a zero-one variable to better reflect the

effect of increased machlne passes on MACHINE$.

If 2 or more mechanical site preparation treatments

are used, MACHINE$ Is reduced by $7.35 per acre.

Comparlson wlth Hand Plantlng Cost

The comparable equation for hand planting cost

per acre, HANDPLT$, is (Guldin 1982):

HANDPLT$ = $2.00 - $O.O4(TOTLACRE)

+ $17.2O(LOGACRE)

- $3.75(#MACHPAS)

+ $7.91(BURNED)

- $0.49(BURNCOST)

+ $20.43(OWNER)

The equation differs from the one for MACHINE$

in 3 ways. First, it includes variable LOGACRE (the

logarithm, base 10, of TOTLACRE). The machine

planting cost data showed no curvilinear trend

because variables for acreage squared and log of

acreage were both insignificant in the analysis.

Second, the variable #MACHPAS is the total

number of machine passes during site preparation,

and not a zero-one variable as in the MACHINE$

equation. Third, the HANDPLT$ equatlon is based

on data from both national forest and industry. The

OWNER variable equals 1 If the case is a national

forest contract, and 0 if It is an industrial contract.

Site characteristics and preparation data for the

machine planting contracts were inserted into the

HANDPLT$ equation to calculate predicted HAND3
PLT$. When predicted HANDPLT$ was subtracted

from observed MACHIN,E$ and the,dlfference plotted’ovsr the $lTe of the pekrdel@ planted, the results

indicated that the machine planting was always

moreBxpen&e than hatrdplanting for parcels less

than 100 acre&Other considerimtions undoubtedly

Ied forest managers to plant theoei&mall parcels by

machine. Machine*plantlRg’ is.justlfted when total

benefit to the operation beilanoesthe added cost of

planting by machine.

Land managers can use the results of this

analysis as guid#~nee for evaluating the efficiency

of thelr r&jener&i~n~,‘pr~giams, where. machine

planting is used, ,ancf !as a b@nchmark for future

regeneration invcjstment decisions.

LITEWATURE CITED

Guldin, R. W.

1982. She characteristics ,and: preparation practices influence hand plantlng~costs, Forest Scl;

(in process)

Smith, D. M.

1962. The practice of sjlviculture. 7th ed. John

Wiley & Sons, Inc. New York, N.Y. 552~.

4

irU.S. GOVERNMENT PRINTING OFFICC: 1982-669-085/11