T HE past few years of below average precipitation have emphasized the importance of a mulch layer on annual ranges in California. It has been apparent that where sufficient mulch was found germination was better, and early growth and total production of forage was greater than on ranges lacking enough mulch cover. It was observed also that where grazing animals had old forage in fall and early winter to eat along with the new, they scoured less and made better gains than where only new growth was available. ,4 mulch layer also helps to maintain the percolating capacity of soils and prevent erosion. In studying the mulch layer near Berkeley it was found that terminology applied to it varies among different workers (1, 4, 6, 7, 8, IO, 11, 12). In an attempt to standardize terms and classification of the mulch layer on annual ranges in accordance with present usage, the writer proposes adoption of the termsmulch, forage residue, and humic mulch. Applied in this way, mulch is a collective term which refers to the whole protective blanket of vegetation after the forage has dried. Forage residue includes all dried herbage of the past year’s growth that might be used for grazing. Humic mulch is used only in referring to semi-decomposed materials which constitute but a thin layer on the surface of the soil. Considerable work has already been done in determining the amount of forage residue which should be left on annual ranges to keep them in productive condition (6, IO, 13). This varies from about 400 to 1000 pounds per acre. However, few, if any, measurements of the humic mulch layer are available even though it has been used as an important factor in determining range condition (6, 7, 10, 12). Since humic mulch on annual ranges is so thoroughly mixed with mineral soil, separation of it is difficult and time consuming. Accordingly, some method other than those used in other forage types (4,9) had to be devised for measuring the effect of intensity of grazing on the humic mulch layer of annual ranges. Several workers have noted the increase in volume weight of soils brought about by grazing and cultural practices (2, 5). In view of these results it seemed reasonable to assume that measures of volume weight of thin layers of surface soil might give usable measurements of the amount of humic mulch. If so, the effect of intensity of grazing on humic mulch could be determined indirectly by sampling the top layer of soil. This was accomplished by using a loinch length of l+-inch water pipe sharpened on one end. After first clearing away green plants and residue, the sampling tube was sunk into the surface layer of soil to a depth of about 1 inch. Rotating the tube while sampling helped to avoid compaction and shear off the sample near the end of the cylinder. Volume of the sample collected was then determined by filling the hole with sand as described by Daubenmire (3). After drying in an oven for 24 hours at 105 degrees Centigrade, the samples were weighed and volume weights determined by the ratio of dry weight of soil and humic mulch in grams/volume in cubic
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Oct 1, 1956
Harold F Heady 
