The personal income of Americans rose sharply in March after posting more moderate increases in February and and January, the government reported yesterday--indicating the economy is still growing at a relatively rapid rate.

Commerce Department figures showed personal income up 1 percent, or $19.2 billion, following increases of 0.7 percent in February, and 0.4 percent in January, reaching a new annual rate of $1.832 trillion.

The rebound in March appeared to bolster arguments by some analysts that the economy still has more strength than is desirable-a factor they say is heightening excess demand and adding to inflationary pressures.

However, William A. Cox, the department's deputy chief economist, said most of last month's gain probably was eroded by inflation and so may not spur still further increases in demand, as otherwise would be the case.

Analysts said at least a portion of the increase may represent a bounce back from the previous months' figures, when some workers were forced to stay home because of bad weather.

Nevertheless, the increase followed a pattern of relatively strong economic statistics for March and early April. Economists are divided over whether-and how much-the economy may be slowing.

By far, the bulk of the March increase was concentrated among private wages and salaries, which jumped a sharp 1.2 percent over the month, following jumps of 0.9 percent in February and 1 percent in January.

The only major sector to decline was the income of farm owners, which fell 0.7 percent last month following drops of 1.6 percent in February and 1.2 percent in January. CAPTION: Graph; no caption, The Washington Post