Soil Conservation An Assessment of the National Resources Inventory, Volume 2 (1986) / Chapter Skim
Currently Skimming:
10. A Midwestern Perspective on Targeting Conservation Programs to Protect Soil Productivity
10. A Midwestern Perspective on Targeting Conservation Programs to Protect Soil Productivity
Pages 273-295
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 273... ...
to assess the potential onsite long-term productivity losses due to soil erosion in six Major Land Resource Areas (MLRAs) of the region.
|
From page 274... ...
The first scenario is a baseline estimate of the long-term effects of current erosion rates and the long-term productivity of soils in the six MLRAs if there are no changes in soil and water conservation programs or practices recorded by the 1982 NRI.
|
From page 275... ...
In this case, all land in row crops in the MLRAs under study with an erosion rate greater than the local soil loss tolerance limit (T) for the particular soil series would be put into forage.
|
From page 276... ...
The potential productivity losses of soils in each MLRA, as calculated from the vulnerability (V value) of various soil types to erosion, is used as the basis for this targeting criterion.
|
From page 277... ...
277 Us or or U]
|
From page 278... ...
In MLRA 109, on the other hand, a CP value of 0.36, indicating relatively nonintensive conservation practices, was associated with very high erosion rates of 15.2 tons/acre/year, about four times the tolerable level of 3.9. This suggests that within the NLRAs, as well as among them, more accurate targeting of conservation practices is required.
|
From page 279... ...
The productivity index is 0.84, greater than in both MLRA 109 and MLRA 113, where conservation practices are nearly half as intensive on average and where the average productivity indices are lower. The relative potential productivity of the soils in BRA 105 suggests strong reasons why it should continue to be targeted for improved conservation practices.
|
From page 280... ...
Based on the assumed continuance of the level of conservation practices reported in Table 1 above, the estimated impacts of these practices on soil productivity over 100 years are then calculated. The highest levels of soil productivity losses are observed in Group I, while the lowest levels would occur in Group II, (hence the rationale for the groupings)
|
From page 282... ...
V-Value Scenario Scenario 3 uses the information contained in the NRI and Soils-5 data files to target more accurately those soils highly vulnerable to productivity losses due to erosion. The V values listed in Table 1 were the basic criterion used to determine whether lands should be shifted out of row-crop production.
|
From page 283... ...
Overall, the implicit rate of depletion resulting from use of T values is approximately 1.0 percent over 100 years. The strictest assumption -- of only a 0.01 percent reduction in soil productivity over 100 years -- gives some indication of the magnitude of land use shifts that would be necessary to pursue essentially "steady-state" policies with respect to soil loss.
|
From page 284... ...
As the figure shows, the distribution of vulnerability differs, and the acreage taken out of production rises at an increasing rate as the requirements for maintained productivity converge to the "steady state. n In all, these results suggest that substantially fewer acres could be shifted from row crops to forage if targeting policies for soil and water conservation were based on soil vulnerability to productivity losses rather
|
From page 285... ...
When the conservative assumptions used in this study are modified, substantial improvements in soil productivity may result without major disruptions in land use, provided policies are properly targeted. Finally, it must be reiterated that corn and soybean production in 1982 nearly broke records
|
From page 286... ...
IMPLICATIONS FOR POLICY Use of more accurate targeting criteria for soil and water conservation policy can reduce onsite productivity losses and minimize the acreage affected by more restrictive land use practices. Acres taken from production can and should be targeted, and those that are most vulnerable to erosion can increasingly be isolated.
|
From page 287... ...
Finally, the preliminary nature of these findings must again be emphasized, along with the need for continued improvements in technical methods to identify onsite productivity losses due to soil erosion. These losses are, of course, only one aspect of a larger problem that includes important offsite damages (see Christensen, this It seems, however, that important beginnings can be made by estimating onsite damages, with further and more difficult estimates of offsite damages to follow.
|
From page 288... ...
1984. Soil productivity in the Corn Belt: An assessment of erosion's long-term effects.
|
From page 289... ...
S is the slope-steepness factor and is the ratio of soil erosion from the field slope gradient to that from a 9 percent slope under identical conditions. C is the cover and management factor and is the ratio of soil erosion from an area with a specified cover and management factor to that from an identical area in tilled, continuous fallow.
|
From page 290... ...
as the maximum level of soil erosion that will permit a high level of crop productivity to be sustained economically and indefinitely. When substituted for A in the USLE, it allows an estimate of the maximum CP value necessary to keep erosion rates below the tolerance level, once RKLS is considered as a constant for a given location.
|
From page 291... ...
All results were weight-averaged by acreage for each MLRA. Scenario 2: Use of Soil Loss Tolerance Limit Value Using the same basic data as in Scenario 1, each sampling location had its erosion potential (EP)
|
From page 292... ...
1983. A soil productivity index based upon predicted water depletion and root growth.
|
From page 293... ...
Miranowski Runge, Larson, and Roloff have presented a framework for policy analysis that provides an excellent beginning in a new area of conservation policy research -- using physical measures of soil productivity loss as the basis for soil conservation policy decisions. Simply targeting erosion control to the most erodible acres may not be the most efficient approach to the soil erosion problem.
|
From page 294... ...
These adjustments may create related erosion problems but of lesser magnitude on the remaining cropland acres. In cases where highly productive soils are found on highly erodible lands, it may nevertheless be appropriate from an economic perspective to continue farming these soils but to employ more intensive conservation practices.
|
From page 295... ...
Finally, the economics profession needs to be challenged to focus greater attention on the economics of the soil erosion problem. Economists have made a major contribution to measuring productivity losses because they come from a tradition that tends to look for common factors to explain systematic behavior, that has been willing to aggregate individual decisions and draw broader generalizations, and that has emphasized model development and simulation.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.