Carbon indices to assess quality of management systems in a Subtropical Acrisol

Abstract

Management systems to improve soil quality are essential for agricultural and environmental sustainability. We assessed the quality of soil management systems applied to a subtropical Acrisol in terms of the carbon management index (CMI), the stratification ratio for total organic carbon (SR-TOC) and light fraction of organic matter (SR-LF). In addition, we examined their relationship to chemical, physical and biological soil quality indicators, as well as to maize yield. The study was conducted on a long-term experiment (18 years) in southern Brazil involving two different systems [no tillage (NT) and conventional tillage (CT)], two cropping systems [black oat/maize (O/M) and black oat + vetch/maize + cowpea (OV/MC)] and two nitrogen fertilizer rates for maize (0 and 180 kg ha-1). Based on the three indices, the best managements for soil quality comprised NT (50-212 % better than CT), legume cover crops (10-47 % better than O/M) and N fertilization (8-33 % better than no fertilizer). All three indices proved accurate to assess the impact of soil management systems, especially SR-LF, which showed increased sensitivity and close relationships with chemical, physical and biological soil quality indicators. On the other hand, a poor relationship was observed between soil C indices and maize yield, which was improved only by legume cover crops and N fertilization. The results showed that the association of no-till system to an abundant supply of crop residues is key to ensure high soil quality and crop yields in humid subtropical regions.

Soil quality and fertility dynamics under a continuous cassava-maize rotation in the semi-deciduous forest agro-ecological zone of Ghana

“…These results are in line with the findings of Zanatta et al (2019) who indicated that N fertilization was able to contribute about 8-33% improvement in soil quality better than no fertilizer under similar soil condition in Brazil. Furthermore, these results also corroborate with the findings of Adjei-Nsiah et al (2007) who identified N and K as playing major roles in sustaining crops yield under cassava-maize rotation in Ghana.…”

Physical Fractionation and Carbon and Nitrogen Stocks in Soil After Poultry Waste Applications

“…Higher CMI values mean higher soil quality, whereas lower values indicate lower soil quality (ASSMANN et al, 2014). CMI also indicates increased lability of organic matter, as it is highly correlated with the C-MOP stock (SILVA et al, 2016) and positively correlated with several chemical, physical and biological attributes of the soil (ZANATTA et al, 2019). In this study, all treatments with the use of turkey litter indicated improvement in soil organic matter quality, especially at the highest dose evaluated (69.24 Mg ha -1 ) and in all layers evaluated, reaching increments of 156% compared to the control treatment, in the 0.1-0.2 m layer.…”

“…For this, other attributes have been used, such as the C and N stocks in particulate organic matter (POC and N-POM) and the C management index (CMI) (ASSMANN et al, 2014;SOUZA et al, 2016). CMI is considered a sensitive attribute because it is correlated with other physical, chemical and biological indicators of soil quality (ZANATTA et al, 2019).…”