Farmers generally recognize the need for balancing the rate of application of nitrogen with the supply of available moisture. Soil analyses that indicate the amount of available nitrogen and moisture supplies help them establish the proper rate of fertilization. Estimates of need for fertilizers are more satisfactorily made on summer-fallowed land than on cropped land, because of the greater amounts of available nitrogen and moisture present in the fallowed land.

Fertilization with nitrogen or the use of green manure crops tends to raise the protein content of the wheat. The protein content of soft wheats usually does not exceed the desired optimum of a pastry-type flour when the fertilization rate is not in excess of that required for maximum yields. It is difficult to predict the rate of fertilization required for maximum yield for a particular year. An application of nitrogen that decreases the yield may cause soft wheat to have an excessive protein content. High-protein, soft white wheats are unsatisfactory as bread wheats, and they have little use except as feed.

Several other plant nutrients are deficient in some soils. The deficiencies are most pronounced for legume production on forest soils in the Moscow Mountain foothills and Nez Perce-Grangeville Plateau areas.

The problem also occurs, but to a lesser extent, for other crop and soil conditions in different sections of the region. Sulfur is the most generally deficient of these nutrients. The application of some of the trace elements, including boron and molybdenum, have improved the growth of legumes.

The difficulty encountered in establishing a vigorous legume crop seems to be associated with poor nodulation, but we do not know whether this problem is due to a nutrient deficiency.

The continuing decline in the content of organic matter will reduce the fertility level and impair the physical condition of the soil. The rate of decline in organic matter is greatest with the wheat-fallow cropping system. Organic matter is maintained or increased above the present level by the use of rotations that have a sod crop of sweet-clover or alfalfa at least one-fourth of the time. Continuous cropping to wheat with a high rate of nitrogen fertilization also tends to maintain adequate organic matter.

Wind erosion is worst in the low-precipitation zone. Erosion by running water occurs in other sections. Both types of erosion are most severe on intensively tilled land that has inadequate vegetative cover usually land that has been seeded or is being prepared for seeding to winter wheat.

Soil erosion by water occurs largely between November and April. It generally results from the longer, more intense rains and from snow melting on frozen ground. The high content of moisture in the soil during the winter reduces the rate of infiltration of water and leads to high runoff. Summer-fallow land enters the months of high rainfall with considerable moisture, and therefore is subject to greater runoff losses than land on which a crop has withdrawn this excess water.

Intensive tillage of summer fallow is a common practice in the annual cropping zone to eradicate such weeds as Canada thistle, bindweed, and wild oats. Land in the summer-fallow zone is given extra tillage to control cheat-grass, gromwell, and tarweed. This tillage causes greater soil pulverization, loss of the mulch cover, and a wider use of summer fallow factors that favor soil erosion.

Effective practices to control erosion include stubble mulch, cloddy tillage, crop rotations, contour stripcropping, and cover crops. Stubble mulch and cloddy tillage operations are the most effective for controlling both water and wind erosion on wheatland.

ADOPTION OF CONSERVATION practices has been inadequate in most sections of the region for effective control of erosion and maintenance of soil organic matter. Much of the land is farmed to the wheat-fallow or wheat-peas cropping systems and with tillage operations that pulverize the soil.

Stubble mulch has been used extensively in the sections that are subject to wind erosion. The practice is easier to adopt in this zone because of the low yields of straw. It has not been adopted widely in the areas of higher rainfall because of the problems en-countered as the result of the greater quantities of straw produced and more difficult weed control. Stubble mulch reduces wheat yields more in areas of high precipitation.

Rotations that include a sod crop have been adopted (at least partly) by most farmers in the higher rainfall sections of the eastern Palouse and Blue Mountain areas and in the Moscow Mountain foothills and Nez Perce-Grangeville Plateau areas. Conservation rotations have been used very little in the rest of the region.

Utilization of crop residues by various methods has been extensively adopted; many farmers used to burn their straw. The large increase in the use of nitrogen fertilizer, plus the utilization of residues, has increased crop production and strengthened the program to maintain organic matter.

Stripcropping has been adopted to a limited extent, mostly in areas that have gentle slopes.

Scientific findings and experience of farmers have indicated that more effective conservation and efficient crop production can be achieved in the Pacific Northwest wheat region.

Erosion losses can be reduced substantially, where moisture conditions permit, by substituting rotation systems of cropping for summer fallow. Less tillage also would reduce runoff and erosion.

A wider adoption of stubble mulch tillage in areas of higher precipitation would reduce erosion losses sharply. Further improvements in tillage, fertilization, and weed control are necessary in order that the stubble mulching will be more widely accepted, however.

The cropping system should be adapted to the soil and climatic conditions of the particular locality. Fertilization should provide sufficient nutrients, in addition to those furnished by sod crops, to balance the supply of available moisture. With the return of crop residues to the soil, this soil-management system would be expected to maintain an adequate level of organic matter and sustained production.