4.2 Environmental and economic impact of ZT/CA and iCLF-CA management systems adoption
It is recognized the impacts of ZT/CA in the increase of soil organic carbon (SOC) sequestration, reduction of the emission of greenhouse gases (GHGs) and improving economic and agriculture sustainability. The emissions of GHG are reduced in the ZT/CA by decreasing the use of fossil fuels in the crop production, the efficient application of fertilizers and reduction of N2O emissions, as well as decreasing soil erosion. Pointed as an evolution of ZT/CA, iCLF-CA also affects positively soil biological, physical and chemical attributes, for example by increasing C and N stocks in the short- and long-term, and water retention, and reducing erosion soil losses. The build-up of SOM improves biological, physical, and chemical soil properties, leading to an increase in crop yields, with reduction of costs with irrigation, fertilizers, soil conditioners and other agricultural inputs (Conceição et al., 2017). The adoption of iCLF-CA also improves environmental, social and economic services and it is a promising alternative to recover degraded areas ( Lima et al., 2018; Landers et al., 2020) .
Other impacts of the adoption of ZT/CA and iCLF-CA includes the off-farm effects related by Landers et al. (2001a) considering both direct and environmental benefits, including yield and support capacity decline and land value depreciation in croplands and rangelands due to water erosion, especially due to the intensive soil preparation, monoculture practice and overgrazing. There are also off-farm benefits that implies in the reduction in public spending such as: the maintenance cost of rural earth roads – an annual economy of 3.5 US Dollars in a million ha of crop areas; which implies in a public economy of 280 million US Dollars; the reduction of turbidity and lower cost for water treatment for human consumption, estimated to be of US Dollars 5.80 for each 10 thousand m3 (based on Carroll, 1997); and, the reduction in reservoir volume storage by silting in dams for hydroelectric power plants and for irrigation projects estimated as being of more than 700 million US Dollars per year (Carvalho et al., 2000).
The adoption of ZT/CA principles in irrigated areas with central pivot, micro-irrigation, drip irrigation or localised irrigation, which comprises 4.84 million ha in 2017, implies in an economy of 10% in water volume and in pumping costs. Landers et al (2001a), considering 10% less in consumptive use of water in annual crop irrigated areas, an annual economy of US$ 20.00 per hectare in need of pumping energy and 800 m3 ha-1 in water volume, valued to be US$ 8.00 per ha. This means that, if ZT/CA adoption occurs in the irrigated area, an annual economy of 38.7 million US Dollars, considering prices of 2001. This implies in less demand of electrical energy and in water.