The conversion of murundu fields into agricultural areas impacts soil attributes after several years of cultivation

Abstract

The effect of Murundus Field conversion into agricultural areas on the physical, chemical and biological attributes of soil have been evaluated in 3 no-till chronosequences. The study was conducted at reminiscent Murundus Fields, at 3 other adjacent areas that were converted into agricultural fields in the state of Goiás-Brazil, over 11 (PD11), 15 (PD15) and 18 (PD18) years under a no-till system, and at a control area that suffered no anthropic interference. For this study, the native area was subdivided into mound bases (BM) and tops (TM) of murundus, due to environmental contrast among these environments. The physico-chemical and biochemical soil attributes evaluated were: fertility, texture, organic carbon, microbial biomass carbon, basal respiration, metabolic and microbial quotients, urease activity and fluorescein diacetate hydrolysis. In addition to these, microbial group densities were determined, that will vary between: total heterotrophic bacteria (2.36 × 10⁶ and 5.93 × 10⁶), total fungi (2.90 × 10³ and 9.30 × 10³), total actinobacteria (2.26 × 10⁴ and 8.92 × 10⁴) phosphate solubilizers (2.80 × 10³ and 4.20 × 10³), cellulolytic organisms (7.99 × 10⁴ and 1.18 × 10⁴), associative nitrogen-fixing bacteria (1.25 × 10⁴ and 4.24 × 10⁴), nitrifiers (0.00 and 9.37 × 10⁵) and ammonifiers (1.17 × 10⁵ and 5.20 × 10⁴). The conversion of native areas into no-till systems presented tall in areas with PD15 (184.2 μg g⁻¹) and PD18 (316.0 μg g⁻¹) microbial biomass carbon in relation to the control area, however, there was a reduction of actinobacteria density when comparing murundus mound bases to their tops, as well as reduced phosphate solubilizers, cellulolytic organisms and associative nitrogen-fixing bacteria. Murundus Fields conversions into agricultural areas alter soil microbiota, which may affect important functional processes, possibly aggravating the frailty of this phytophysiognomy.