The Army's latest field manual on land warfare challenges its own deployment of nuclear guns on the NATO front by disclosing it would take 24 hours to get permission to fire them.

Before that time, recent NATO studies have warned, an invading Warsaw Pact force might well have penetrated beyond the current nuclear artillery positions along the East German border.

Although NATO's 8-inch guns and 155-mm. howitzers have ranges of about 16 and 11 miles respectively, they are pulled a few miles back from the front lines. An invading force from East Germany therefore would be within NATO artillery range for no more than about 10 miles before it crossed into West Germany.

In the face on a quick thrust from the East, NATO commanders would have the choice of having their nuclear guns over-run or pulling them back farther into West Germany, defense strategists have warned. Any nuclear shells fired from farther back would fall in West Germany.

U.S. Army field manual 100-5, issued last summer to set forth the latest tacties for winning the land battle, provides a chart entitled "request sequence" which shows it would take 24 hours to send the request to fire tactical nuclear weapons up and down the chain of command.

The Corps Commander in Germany, according to the chart, would have send his request through four layers of command - Central Army Group; Allied Forces Central Europe, Supreme Headquarters, Allied Powers, Europe, and the ATO Millitary Committee comprised of representatives of member nations - before it reached the President of the United States, who could then grant permission.

The order to fire the nuclear weapon would go back down the same chain, reaching Corps within 14 hours of making the request.The chart shows it would take as long as another 10 hours to reach the individual artillery unit.

The Army field manual portrays in one section a battle situation that NATO commanders could both proedict and control, stating: "In order to dampen the escalatory effects of using nuclear weapons, release will normally be approval to employ pre-planned packages of weapons to be fired within a specified time frame and within specified geagraphical areas according to the constraints established by the releasing authority.

"A package," explains the manual, which has an Orwellian tone, "is a group of nulear weapons of specific yields for employment in a specified area within a limited time frame to support a tactical contigency.

"The first use of U.S. tactical nuclear weapons," the manual continues, "would probably be in a defensive mode based on prepared defense plans. Later use could include support for offensive operations to destroy the enemy or regain lost territory."

In that guidance, the Army is assuming that using nuclear weapons on a European battlefield could be done in a controlled way - even to selecting the right number of kilo-tons for a specific target. Critics have argued that once the first nuclear weapon was fired - no matter what size - the war would be pushed across the fireback between conventional warfare and all-out nuclear war.

The manual talks further about nuclear war as a precise art by advising field commanders how many rads (a measuring of radiation to disperse to various part of the battlefield.

States the manual:

"An active soldier suddenly exposed to 3,000 rads could become incapacitated within 3 to 5 minutes. He may recover to some degree in about 45 minutes, but due to vomiting, diarrheah and other radiation sickness symptoms, he would be only partially effective until he dies within a week.

"A soldier exposed to 650 rads initially shows no symptoms, but loses some of his effectiveness in about two hours and can be expected to die in a few weeks under battlefield conditions. Exposure in the 100-rads region usually has title effect.

"Accordingly," the U.S. Army manual advises, "in conventional nuclear combat it would be prudent to subject from line enemy to 3,000-8,000 rads or more; enemy in the rear to 650-3,000 rads, and avoid subjecting friendly forces and civilians to an unacceptable dose level (100 or more rads).