Morphology and Ecology of Lithic-Mulch Agriculture

Lithic-mulch agriculture is a strategy that employs materials such as volcanic ash and cinder, pebbles, gravel, or stones as a mulch to improve crop growth. The field form has been identified at only a few prehistoric and historic sites. The form is marked by accumulation of lithic materials in solid layers, ridges, terraces, pits, or mounds. These features have been sited in natural grav- elly or stony soil on relatively level ground. The mulch has been used only at locales with a growing-season moisture deficit. Mulching increases crop yields on a sustained basis, attenuates declining yields during drought, and extends the growing season on cool semiarid uplands. food supply. This article examines lithic mulch as a taxonomically discrete agricultural form, a unique and calculated adaptation to very specific macro- and microenvironments, which both exhibits morphological variation and displays conformity in site selection, application, and purpose. The article introduces the character and distribution of pre-twentieth- century lithic-mulch agriculture and discusses the cultural-ecological essence of this unique field form. Known examples are classified according to the type of lithic material used as mulch, the morphology and engineering features of lithic-mulched plots, the climatic regimes under which it has been used, and the prehistorical and historical adoption and function of the form. The classification allows assessment of the variation or uniformity in design and application of the form, which highlights independent yet common courses of action to diversify agriculture in similar environmental parameters