| 01 Jul 2025
Soil health approaches to assess the impacts of no-tillage with agricultural terraces in southern Brazil
Abstract. Soil health assessment depends on the appropriate selection of indicators and robust, sensitive methods for its determination. In this study, four integrative approaches were evaluated to assess the impacts of no-till with and without agricultural terraces on soil health in Southern Brazil. The different methods used were: (1) Principal Component Analysis (PCA); (2) expert opinion (EO); (2) FERTBIO; and (4) Soil Management Assessment Framework (SMAF). All approaches followed four steps: (i) selection of indicators; (ii) interpretation of indicators; (iii) integration of indicators; and (iv) calculation of soil health indices. The methods varied in the steps of indicator selection, interpretation, and the method of indicator integration. The indicators used included physical (bulk density, total porosity, soil penetration resistance, and water retention capacity), chemical (pH, calcium, phosphorus, potassium, organic matter, CEC, and base saturation), and biological indicators (microbial biomass carbon, β-glucosidase, and arylsulfatase). Crop yield was evaluated for maize (2019/20 and 2021/22 harvests), wheat (2021 harvest), and soybean (2020/21 harvest). Descriptive statistics, median comparisons, principal component analysis and spearman correlation analysis were applied for the analysis of results. The results showed that only the EO and FERTBIO approaches were sensitive enough to detect differences in soil health between management systems, indicating that no-till with terraces had better soil health. Biological indicators were more sensitive in differentiating treatments, showing a rapid response in the short term. Maize (2019/20 harvest) and wheat (2021 harvest) yields were higher under the no-till with terraces treatment. Over time, yield showed a stronger relationship with soil health. The results highlight the importance of selecting appropriate indicators for soil health assessment and reinforce the benefits of agricultural terracing for the sustainability of production systems.
General Comments
This manuscript presents a well-designed and executed study comparing four different integrative approaches (PCA, Expert Opinion, FERTBIO, and SMAF) for assessing soil health in no-till systems with and without agricultural terraces in Southern Brazil. The research addresses a highly relevant topic in sustainable soil management, particularly in the context of tropical agriculture and the need for effective conservation practices beyond no-till alone. The experimental design is robust, with a high number of replicates and multi-year monitoring, which strengthens the findings. The primary strength of the paper is its practical, comparative analysis of established methodologies, providing valuable insights into their sensitivity and applicability for detecting short-term management effects. The finding that biological indicators are the most sensitive and that the Expert Opinion and FERTBIO approaches were most effective in this context is a significant and useful contribution. The manuscript is generally well-written and the data support the conclusions. However, the novelty of the study is more in the comparative application of these methods in a specific, important agro-ecosystem rather than in the introduction of a fundamentally new concept. Some aspects, particularly the framing of the study's novelty and the discussion of limitations, could be strengthened to enhance the manuscript's impact.
Specific Comments
Novelty: The introduction should more clearly state the specific knowledge gap: a direct, comparative evaluation of the sensitivity of these established methods for detecting short-term impacts of conservation practices like terracing.
Methods Clarification: The description of the Expert Opinion (EO) method requires clarification. Specify if the initial indicator selection was purely based on expertise, while only the weighting was data-derived, to avoid a circular argument.
Conclusions: The conclusion that SMAF and PCA were "not sensitive" is too strong. A more nuanced statement is warranted, reflecting that EO and FERTBIO were the most sensitive in this specific context.
Technical Corrections
Line 65: "its effects on soil health" to "their effects on soil health" (referring to terracing combined with no-till).
Line 325: " A) Maize - 2019/20 Haverst, " to “harvest" (typo).