Marginality Principle - Principles of Sustainable Soil Management in Agroecosystems - page 39

Agricultural policy and on-farm management are public concerns since tax dol-
lars are invested and external environmental benefits and liabilities derived from
agriculture affect whole populations. There have been increasing levels of conflict
and differences of opinions over the extent to which natural resource degradation
is a problem among government, environmental groups, a variety of publics, and
agricultural sectors (Morton and Brown 2007). In the United States, one trend is a
growing expectation that government will pay for the external benefits of protecting
the soil resource, and individual farmer confidence that they are doing a good job in
conservation but others are not (Lasley 1993; Morton and Brown 2007; Comito and
Helmers 2011). A 1993 Iowa survey found that farmers were most likely to believe
that soil quality was declining worldwide (58%) but not on their own farm (9%);
inversely, 56% reported that soil quality on their own farm was improving and only
8% reported that it was improving worldwide (Table 2.3) (Lasley 1993).
In regions with high portions of land in cultivated row crops, differences of view-
points and the extent of soil degradation are centered on water quality concerns as
the negative impacts of soil loss, sedimentation, and excessive P and N compounds
on natural balances are widespread (USEPA 2009; Ribaudo 2011). A US national
soil erosion service and system of funding farmers to help pay for soil manage-
ment practices was established in the 1930s as a result of the Dust Bowl, which was
caused by drought and cultivation of sensitive lands. More recently, water quality has
emerged as a primary environmental concern with scientists finding that silt, nutri-
ents, and chemicals delivered to water bodies by soil erosion are a principal cause of
agricultural nonpoint source pollution (Morton and Brown 2011; USEPA 2009). In
the Mississippi River Basin alone, US Geological Survey scientists have estimated
that agricultural sources contribute more than 70% of the N and P delivered to the
Gulf of Mexico via the Mississippi River and its tributaries (Alexander et al. 2008).
A 2011 environmental NGO report claims that the rich, dark soil of the Midwest
corn belt, which made the region the nation's breadbasket, “is being swept away at
rates many times higher than official estimates” (Cox et al. 2011). Further, they claim
that although the average soil erosion in Iowa is officially estimated at 5.2 tons per
acre, recent storms have resulted in significantly greater soil loss, estimating up to

TABLE 2.3
Results from the 1993 IFRLP on Views About Soil Quality

In general, would you say soil quality is

Declining Remaining the Same Improving

Worldwide 58 34 8

In United States 31 41 28

In Iowa 21 35 44

In my county 17 35 48

On my farm 9 35 56

Source: Lasley, P., Iowa Farm and Rural Life Poll 1993 Summary Report ,
Department of Sociology, Iowa State University, Ames, IA. 1993.