Exclusions:
5 USC 5102(c)(19)

"emergency or seasonal employees whose employment is of uncertain or purely temporary duration, or who are employed for brief periods at intervals;"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`

TITLE 7 > CHAPTER 55 > § 2225
§ 2225. Employment of temporary personnel

The Department of Agriculture may employ persons or organizations, on a temporary basis, by contract or otherwise: Provided, That no expenditures for such temporary employment shall be made unless provision is made therefore in the applicable appropriation and the cost thereof is not in excess of limitations prescribed therein.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

TITLE 7 > CHAPTER 55 > § 2225

NOTES: (Ab note, the page has links to many other acts, etc. Only the text is copied and pasted below.)
Source
(Sept. 21, 1944, ch. 412, title VII, § 706(a), 58 Stat. 742 ; Ex. Ord. No. 9577, June 29, 1945, 10 F.R. 4253 .)
Codification

This section was enacted as a part of the Department of Agriculture Organic Act of 1944.

First sentence of section which related to the authority of the War Food Administrator to employ personnel was omitted on the authority of Ex. Ord. No. 9577, which terminated the War Food Administration .

The exception from "the Classification Act of 1923, as amended" was omitted as obsolete. Sections 1202 and 1204 of the Classification Act of 1949 ( 63 Stat. 972, 973) repealed the 1923 Act and all laws or parts of laws inconsistent with the 1949 Act. While section 1106(a) of the 1949 Act provided that references in other laws to the 1923 Act should be held and considered to mean the 1949 Act, it did not have the effect of continuing the exception contained in this section because of section 1106 (b) that provided that the application of the 1949 Act to any position, officer, or employee shall not be affected by section 1106 (a). The Classification Act of 1949 was repealed by Pub. L. 89-544, § 8(a), Sept. 6, 1966, 80 Stat. 632 (section 1 of which revised and enacted Title 5, Government Organization and Employees, into law). Section 5102 of Title 5 now contains the applicability provisions of the 1949 Act. Section was formerly classified to section 574 of Title 5 prior to the general revision and enactment of Title 5, Government Organization and Employees, by Pub. L. 89-554 , § 1, Sept. 6, 1966, 80 Stat. 378 .
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

TITLE 7 > CHAPTER 55 > § 2226
§ 2226. Employment of persons for forest fire fighting, pest control, and handling of animals

Notwithstanding any other provisions of law , the Department is authorized on and after August 31, 1951, to employ or otherwise contract with persons at regular rates of pay for necessary hours of work for emergency forest fire fighting and pest control and for handling of animals, including dairy cattle, without regard to Sundays, Federal holidays, and the regular workweek.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

TITLE 16 > CHAPTER 3 > SUBCHAPTER I > § 554e
§ 554e. Employment of workers for emergencies

Notwithstanding any other provision of law , on and after October 21, 1998, the Forest Service is authorized to employ or otherwise contract with persons at regular rates of pay, as determined by the Service, to perform work occasioned by emergencies such as fires, storms, floods, earthquakes or any other unavoidable cause without regard to Sundays, Federal holidays, and the regular workweek.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

TITLE 43 > CHAPTER 31 > § 1469
§ 1469. Employment and compensation of personnel to perform work occasioned by emergencies

Notwithstanding any other provision of law , persons may be employed or otherwise contracted with by the Secretary of the Interior to perform work occasioned by emergencies such as fire, flood, storm, or any other unavoidable cause and may be compensated at regular rates of pay without regard to Sundays, Federal holidays, and the regular workweek.