President Reagan and his wife last year received $18,590 in gifts, ranging from a $672 fertilizer spreader to a $7,000 oil painting of a cowboy, according to a White House financial disclosure statement released yesterday.

The statement provided further details on the $741,253 in income that the Reagans previously reported for 1982, including interest from 30-day certificates of deposit and Treasury bills, a $24,769 pension from the state of California and a $3,015 advance to Nancy Reagan for her book "To Love a Child."

The president also made $127,000 in improvements to his Santa Barbara ranch, according to the annual statement required under the 1978 Ethics in Government Act.

Some of the gifts came from the Reagans' closest friends, including a $1,112 riding lawn mower from Walter and Lee Annenberg, Betsy Bloomingdale and her late husband, Alfred, and two other couples from southern California.

Washington lobbyist Robert K. Gray gave Reagan a $400 tack box for equestrian equipment. Nancy Reynolds gave the First Lady a $180 necklace. And steel magnate Earle Jorgensen, a member of Reagan's "Kitchen Cabinet," gave the fertilizer spreader and $250 in "casual plates."

Other gifts to the Reagans included a $195 lizard belt, a $250 saddle, $414 boots, a $275 bronze sculpture, a $240 silver bracelet and a $175 garden cart.

"This is the Rolls Royce of garden carts," said Mrs. Henry J. Muller Jr. of Santa Barbara, who said she had never met the president. "We manufacture this fabulous garden cart, and we felt the Western White House should have one." She said that the Reagans sent a "gracious" thank you note and added that "we hope the president uses it when he chops wood."

The White House was put on the defensive last year after some gift-givers used their presidential thank-you notes to promote commercial products, a practice now frowned upon by the administration.

Many presidents have received generous gifts over the years. Reagan's $30,000 in gifts in 1981 were dwarfed by those presented Richard M. Nixon, who as president received 951 gifts from foreign governments worth at least $2 million and 2,632 gifts of unknown value from private foreign donors.

Congress has since made it illegal for a federal official to keep any foreign gifts after leaving office.

Reagan also received two paintings worth a total of $12,000 from Olaf Wieghorst, a California artist whose work Reagan has purchased, along with a $90 book entitled "Olaf Wieghorst." Susan Cummings and her late husband, Theodore, a former ambassador to Austria, gave their friends an antique Oriental plate valued at $1,120.

Vice President Bush received $6,729 in gifts, including a pair of Nike running shoes, two brass elephants filled with popcorn and 48 pairs of socks in a basket.

Bush also received a leather-bound Bible, a $575 silver Tiffany bowl, a three-screen Sanyo television and a carved duck from Rep. Marjorie S. Holt (R-Md.).

But Bush returned a $10,000 bronze sculpture from Oklahoma artist Don Baker because Bush "felt it was so expensive that it would be improper to keep it," a spokesman said.

Financial statements filed by the Supreme Court justices indicate that Lewis F. Powell Jr. has assets of at least $2.7 million, followed by Sandra Day O'Connor, with family assets between $876,000 and $1.65 million, and Warren Earl Burger, with between $422,000 and $1.09 million. At the bottom of the scale was Thurgood Marshall, who listed no reportable assets worth at least $1,000.