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ore desirable spoil with less desirable,
<br />gher- clay - content material below the
<br />al-spoil interface. Also, seedbed prepara-
<br />on undoubtedly resulted in some mixing
<br />F soil and spoil at the shallow topsoil
<br />epth. Data showed significant yearly dif-
<br />:rences in stored soil water, averaging
<br />55, 240, 226, and 196 mm per 0.9 -m pro-
<br />ile in 1978, 1979, 1980, and 1981, respec-
<br />ively.
<br />Water infiltration increased between
<br />,979 and 1982 for both mulch treatments
<br />ind all topsoil depths (Figure 2). Differ -
<br />;nces were significant for the 400- and
<br />300 -mm topsoil depths. Infiltration related
<br />iirectly to topsoil thickness and can be ex-
<br />plained by differences in water retention
<br />characteristics between topsoil and spoil.
<br />With 600 mm of topsoil, infiltration was
<br />greater in the stubble - mulched plots than
<br />in the crimped - straw - mulched plots in
<br />both 1979 and 1982. We have no explana-
<br />tion for the lower infiltration in the
<br />crimped- straw-mulch treatment at the
<br />600-mm topsoil depth. This reduction in
<br />infiltration occurred both years and may
<br />account for the lower forage production
<br />that occurred with 600 mm of topsoil dur-
<br />ing the last 2 years for the crimped- straw-
<br />mulch treatment.
<br />Summary
<br />Forage production by the native grass
<br />seeding mixture indicated that 400 mm of
<br />topsoil is adequate for revegetation of dis-
<br />turbed areas similar to those reported here.
<br />Increasing topsoil depth to 600 mm did not
<br />result in a significant increase in forage
<br />production. Use of grain stubble instead of
<br />crimped straw as a mulch resulted in sig-
<br />nificantly greater forage production by
<br />seeded species and significantly lower for-
<br />and S. D. Merrill. 1981. Effects of topsoil
<br />and subsoil thickness on soil water content
<br />and crop production on a disturbed soil. Soil
<br />Sci. Soc. Am. J. 45: 124 -129.
<br />5. Schuman, G. E., and E. M. Taylor, Jr. 1978.
<br />Use of mine spoil material to improve the
<br />topsoil. Res. J. No. 130. Wyo. Agr. Exp.
<br />Sta., Laramie. 11 pp.
<br />A GRICULTURAL land conservation
<br />has been addressed in 48 states, begin-
<br />ning with Maryland in 1956 (5), and on a
<br />national level with passage of the Farm-
<br />land Protection Act in 1981. This attention
<br />has stemmed from concern about future
<br />agricultural production and the costs of ur-
<br />ban sprawl on what was agricultural land.
<br />Jurisdictions have used two basic meth-
<br />ods to conserve agricultural land: the
<br />granting of incentives, typically preferen-
<br />d contro1lin¢ al-
<br />age production by nonseeded species, par - tial property taxation, an
<br />ticularly at the 400- and 600 -mm topsoil lowable land use with such planning in-
<br />depths. Mulch type, nonseeded species' struments as zoning and urban growth
<br />production, stored soil water, water infil- boundaries (18). These methods most often
<br />tration, and precipitation influenced seed- are applied independently, but when corn-
<br />ed species' production. Profile soil water bined, landowner participation commonly
<br />storage was greater with less topsoil be- is voluntary (5).
<br />cause of the greater water - holding capac- Reviews of preferential taxation pro -
<br />ity of the spoil. Infiltration rate increased grams emphasize the inability of incentives
<br />as topsoil depth increased up to 400 mm. to significantly control use conversion be-
<br />REFERENCES CITED cause of the small tax savings in relation to
<br />1. Barth, R. C., and B. K. Martin. 1982. Soil - conversion profits (5, 7, 9, 14, 20). Plan -
<br />depth requirements to reclaim surface -mined ning approaches have not been applied as
<br />areas in the Northern Great Plains. Colo.
<br />School Mines Res. Inst., Golden. 182 pp. frequently as incentives, although there
<br />2. Haise, H. R., W. C. Dorman, J. T. Phelan, have been some successes (3, 5, 11). Legal
<br />L. F. Lawhon, and D. G. Shocldey. 1956• questions, such as the "taking without just
<br />The use of cylinder infiltrometers to deter- q
<br />mine the intake characteristics of irrigated
<br />soils. ARS 41 -7. Agr. Res. Serv., U.S. Dept. Mitchel P. McClaran is a graduate research
<br />assistant, Leff Romm is an acting associate pro -
<br />Agr., Washington, D.C. 10 pp.
<br />3. Ef fects o f t ps )•, and P• )• Nic ae 1980. fessor, and James W. Bartolome is an associate
<br />E tizer of t rev thickness and nitrogen spoils. oils- Professor in the Department of Forestry and
<br />J. En vi r the on. Qual. mine spoils. Resource Management, University of Califor-
<br />J. El. 9 9: : 6 6 81 1 -685. of min
<br />4. Power, J. F., F. M. Sandoval, R. E. Ries, nia, Berkeley, 94720.
<br />252 Journal of Soil and Water Conservation
<br />6. Schuman, G. E., E. M. Taylor, Jr., F.
<br />Rauzi, and G. S. Howard. 1980. Standing
<br />stubble versus crimped straw mulch for
<br />establishing grass cover on mined lands. J.
<br />Soil and Water Cons. 35(1): 25-27.
<br />7. Young, J. F., and P. C. Singleton. 1977. Wy-
<br />oming general soils map. Res. J. No. 417.
<br />Wyo. Agr. Exp. Sta., Laramie. 40 pp. ❑
<br />Differential farmland
<br />assessment and land use
<br />planning relationships in
<br />Tulare County, California
<br />Mitchel P. McClaran, Jeff Romm, and James W. Bartolome
<br />ABSTRACT: Research has shown that participation in California's differential assess-
<br />ment program, the California Land Conservation Act (CLCA), at the rural -urban fringe
<br />is limited by landowners' "unreasonable expectations about development." Integration of
<br />land use planning and the CLCA has been proposed to increase participation by present-
<br />ing reasonable expectations. In Tulare County these two programs have been integrated
<br />since 1972 and rural -urban fringe participation in CLCA is comparable to participation
<br />in rural areas.
<br />compensation" issue, and the difficulties
<br />associated with landowner acceptance of
<br />zoning and growth boundaries have been
<br />cited as major weaknesses of the planning
<br />approach (17, 18). Integration of the in-
<br />centive and the planning approaches often
<br />has been suggested to overcome the inher-
<br />ent weaknesses of each approach used
<br />singularly. As proposed, tax reductions
<br />would provide the financial rewards
<br />necessary for the acceptance of use restric-
<br />tions while planning would create the
<br />necessary boundary to direct development
<br />away from designated agricultural areas
<br />(3, 4, 5, 7, 14, 20).
<br />Tulare County, California, has used an
<br />integrated incentive /planning approach
<br />since 1972. Here, we review, in particular,
<br />the rate of enlistment and the maintenance
<br />of participation in the incentive program
<br />in relation to the establishment and loca-
<br />tion of the planning program.
<br />Background
<br />Tulare County, in the southeastern por-
<br />tion of California's fertile San Joaquin Val-
<br />ley, consistently ranks among the top five
<br />counties nationally in value of agricultural
<br />products. In 1978 more than 51% of the
<br />county's 3.1 million acres were privately
<br />owned; 42% were in agricultural uses; and
<br />20% were irrigated (24). The gross value
<br />of agricultural products in 1978 was nearly
<br />
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