President Reagan, speaking to applauding bureaucrats and a noncommittal Hereford heifer, said yesterday that American farmers can expect "a beautiful spring" because economic recovery "is popping up all over the country."

Although he did not mention that U.S. farm income in 1981 and 1982 was at its lowest point in 50 years, Reagan said that his economic policies and tax-reduction program were bringing agriculture "long-lasting benefits."

High interest rates and inflation, he said, had made "surviving . . . a job in itself, but I think it is fair to say that although the winter's been harsh, it is going to be a beautiful spring. We've planted the right seeds and now economic recovery is popping up all over the country--and America's farmers aren't going to be left out."

The president defended the administration's nutrition programs, contending that "emotional and often politically motivated attacks notwithstanding, overall nutrition assistance provided to the unemployed and the needy . . . is at a higher level now than ever before."

Reagan provided no details on that point, but he said that in addition to cheese and butter giveaways the Agriculture Department is about to distribute milled rice and cornmeal from federal stocks. The administration, however, opposes legislation requiring that such surpluses be distributed regularly to the needy.

Reagan's remarks were delivered at a National Agriculture Day ceremony at the Agriculture Department, where the main patio was filled with friendly government workers and a year-old, prize-winning 670 pound purebred cow owned by Duncan and Raymond McHenry, 11 and 10, respectively, from Philomont, Va.

At one point, as audience attention shifted to the cow and White House press photographers rustling near its red-and-white pen, Reagan ad-libbed that he "learned a long time ago to never get in a scene with a kid or an animal."

Reagan touched briefly on two major issues of concern to farmers--export trade and the reduction of crop surpluses--but he provided no new information. He said that U.S. missions are seeking new overseas markets for farm products, but he did not mention renewal of a long-term grain agreement with the Soviet Union.

Reagan also said that the administration's payment-in-kind program, through which farmers will receive surplus grain in return for not planting this year, has been "received with open arms," although he gave no details. Agriculture Secretary John R. Block is to announce participation data today.