A basic principle is that the destruction of the undesirable plants is not enough. They must be replaced with something better, or something worse may take their place.

Is there enough of an understory of desirable forage plants to take over the site? If not, seeding of adapted species should be made part of the plan. Are there undesirable species in the under-story that would also be encouraged when the dominant species is destroyed? If so, it may be better to let well enough alone.

The control treatment must be adapted to the life cycle of the plant that is being removed. For example, it is best to plow or burn sagebrush in spring or early summer. To do so in late summer or fall while seed is being produced is almost certain to result in a heavy seedling stand and more sagebrush eventually than was present before the treatment.

Always after improvement efforts have been made, careful grazing management is essential, particularly when the plant cover has been greatly disturbed, there is danger of soil erosion, and the plant community has been opened up to invasion by undesirable species. Grazing freshly burned range, for example, may weaken the desirable forage species one is trying to invigorate and encourage the reestablishment of the undesirable species.

FERTILIZATION is an important part of the grassland economy where rain is plentiful, but its place on the range in drier regions is by no means established. We have little research or experience to indicate where, when, and how fertilizers can be used profitably on ranches.

Studies at scattered places in the West suggest some possibilities of improving the range by the wise use of fertilizers.

At Sunol, Calif., for example, unfertilized annual range produced an average of 1,284 pounds of forage an acre annually for 5 years, compared to 4,166 pounds on a similar area fertilized with 200 pounds an acre of ammonium phosphate-sulfate (16-20-0) annually. The grazing date in the spring was advanced by 6 weeks, and the length of the green-feed period was doubled. Fewer fluctuations in production occurred from year to year when fertilizer was used.

At the San Joaquin Experimental Range in California, application of sulfur-bearing fertilizers stimulated native clovers and improved the forage on soils of granitic origin where sulfur is deficient. Fertilization at a rate equivalent to 60 pounds of sulfur an acre applied every 3 years gave an average annual increase of air-dry forage of about 900 pounds an acre at a cost of about 4 dollars an acre for the fertilizer and spreading.

Some species use fertilizers more efficiently than others a particularly significant point to bear in mind. For example, no amount of additional phosphorus would improve burclover growth on Placentia and San Joaquin soils in California even though the soils are deficient in phosphate. When rose, crimson, and subterranean clovers were seeded on phosphated plots, however, yields of forage increased from less than 1 thousand pounds an acre to more than 4 thousand pounds, and protein was increased more than sixfold.

Certain grasses use nitrogen more efficiently than others. In northern California, some reseeded perennial grasses, such as intermediate wheat-grass, have given outstanding responses to nitrogen. Native Idaho fescue has given little or no response, but sometimes has actually produced less with nitrogen than without.

Near Havre, Mont., yields of hay as high as 1 thousand pounds an acre annually for 6 years were obtained when barnyard manure was applied on native range. About 80 pounds an acre was obtained from untreated range. Near Mandan, N. Dak., nitrogen has increased the production of the native range and reseeded introduced species, such as crested wheatgrass, smooth bromegrass, and Russian wild-rye.

From native grass on cleared virgin brushland at the Red Plains Conservation Experiment Station, Guthrie, Okla., 133 pounds of beef an acre were produced when phosphate and nitrogen fertilizers were applied. Only 84 pounds an acre were produced without fertilizer. This represents nearly a 60-percent increase in animal gain from fertilization at an annual rate equivalent to 100 pounds of superphosphate and 33 pounds of nitrogen to the acre.

Range grasses in some parts of southern Texas do not contain enough phosphorus to provide adequate nutrition for grazing livestock. Range fertilization is employed there to increase the yield of forage and to improve its phosphorus content. An experiment was conducted on the King Ranch near Falfurrias to determine the most practical methods of supplying phosphorus to range cattle and to determine the effect of phosphate on the yield and chemical composition of forage. Phosphate applied to such rangelands prevented phosphorus deficiency in cattle. The application of about 200 pounds of 48-percent triple superphosphate to the acre increased the yield and phosphorus content of forage for a period of 4 to 5 years.

A new band-seeding method of establishing pastures has shown promise in range seeding trials. The seed is drilled over bands of fertilizer placed 1 to 2 inches below the seed. Available fertilizer is thus made accessible to seedling plants.