2.2 Estimates of cost of potential soil losses by water erosion
Potential soil losses by water erosion were estimated considering
Brazil’s land use and coverage in 2017 (Table 1). In the areas of annual
and perennial crops and planted forest the soil loss was estimated
considering a low usage of agriculture conservation practices such as
contour tillage, terracing and barriers for water contention and using
intensive tillage methods, with deep ploughing, disc harrowing and
subsoiling, in which the soil is revolved and exposed to heavy and
erosive rains, causing the increase of superficial water runoff (Landers
et al., 2006). Also, by considering monoculture for annual crops and
lack of cover crops in the perennial (Hernani et al., 2002a). The
estimative of annual economic impact of soil losses was based on the
revision presented by Eswaran et al. (2001) for crop and pasture areas.
The estimation of economic impacts of implementing conservation
agriculture (ZT/CA and iCLF-CA) principles towards soil erosion control
considered the concepts proposed by Hernani et al. (2002a; 2002b), based
on the costs of liming and nutrient replenishment by using fertilizers
(organic and mineral), as well as fuel and other inputs.
The modelling of evolution of the conservation agriculture systems
(ZT/CA and iCLF-CA) was performed using data from the agricultural
census (2017) published by the Brazilian Institute of Geography and
Statistics (IBGE). The economic impact of using ZT/CA for an area of
14.4 109 ha was projected as 1.85
109 US dollars, or 129.4 US dollars
ha-1 year-1 (Hernani et al., 2002b).
For areas with annual crops and ZT/CA, the mitigation of soil loss was
considered from an average rate of 5.6 t ha-1year-1 (313.3 million tons in 55.6 million ha) to a
value of 2.5 t ha-1 year-1 when
using ZT/CA (Hernani et al., 1999). In the case of the adoption of
iCLF-CA, it was considering cultivated pastures (not degraded and in
good conditions) with an average loss of 13 t ha-1year-1; where the integration of iCLF-CA with the
basic principles of ZT/CA reduced soil losses to 2.5 t
ha-1 year-1.