2.3 Estimates of the increase in the area of ZT/CA
The evolution of ZT/CA as a major land management system in Brazil (Figure 1), from 1972/73 to 2017/2018, was calculated from statistics in FEBRAPDP (2020). Data from IBGE’s agricultural census, obtained in 2017 (adapted from Fuentes-Llanillo, 2018), shows an area of 32.88 million ha in the agricultural year of 2017/2018, distributed all over Brazilian territory and including cash crops such as soybean, corn, cotton, common beans and wheat, in addition to mixed systems where annual crops are integrated with pasture and forestry.
The ZT/CA time series presented a gap of five years without values measured; therefore, data imputation was performed. Here, we used an annual average between the last and the first data observed, respectively, before and after the missing values (i.e., 2013 to 2017). This type of data imputation is plausible for exponential data (Beretta & Santaniello, 2016) when considering that the values between the missing period, are the important values for filling the gaps (Figure 1).