Marcelo Trybek a b , Carlos Alcides Villalba Algarin a c , Luiz Henrique Quecine Grande a , João Paulo Marin Sebim a , Lucas Pecci Canisares a b , Cristine L.S. Morgan d , Carlos Eduardo Pellegrino Cerri a b , Maurício Roberto Cherubin a b
- a“Luiz de Queiroz” College of Agriculture, University of São Paulo, Pádua Dias Avenue, 11, Piracicaba, SP 13.418-900, Brazil
- bCenter for Carbon Research in Tropical Agriculture (CCARBON) – University of São Paulo, 11 Pádua Dias Avenue, Piracicaba, SP 13418-900, Brazil
- cDepartment of Soils, Paraguayan Institute of Agrarian Technology, Capitán Miranda, Route VI, Itapúa, Paraguay
- dSoil Health Institute, 2803 Slater Road, Suite 115, Morrisville, NC 27560, USA
Highlights
- Soil aggregate stability was assessed using wet sieve method and Slakes smartphone app.
- No-tillage and cover crops increased aggregate stability in tropical soils.
- Slakes is highly responsive to cover crops, particularly in the topsoil.
- Slakes is more sensitive than the wet sieving method in the topsoil.
- Slakes is a valid alternative for measuring aggregate stability in tropical soils.
Abstract
Aggregate stability is one of the most sensitive indicators of soil health, yet traditional measurement methods (e.g., wet sieving) is time-consuming and requires specialized equipment. Consequently, new methodologies have been developed and tested around the world. Here, we evaluated the effect of conservation agriculture on aggregate stability in two long-term experiments on tropical soils via image analyses using the Slakes smartphone app (metric: slaking index, SI) and wet sieving method after slow wetting of air-dry soil (metric: weighted mean diameter, MWD). We also compared the performance of both methods in detecting management effects. For this, samples from 0–10, 10–20, and 20–30 cm depths were subjected to the Scott-Knott test (p < 0.05), power analysis, and Pearson correlations with physical and chemical indicators. The adoption of cover crops and no-tillage systems substantially improved topsoil (0–10 cm) aggregate stability compared to no adoption of these conservation practices. The aggregates stability metrics were correlated in the topsoil (r = 0.52–0.71, p < 0.05), but were not correlated at depth. The power analysis indicates that SI was more sensitive than MWD to management practices, particularly the use of cover crops. Additionally, organic carbon and bivalent cations were positively associated with aggregate stability when measured by SI, primarily at 0–10 cm. We conclude that Slakes app is a valid alternative for measuring aggregate stability in tropical soil due to changes caused by adoption of conservation agriculture, potentially serving as an accessible and reliable tool to guide management decisions toward healthier soils.
Keywords
Soil health, Soil aggregation, Digital tools, Cover crops, Regenerative agriculture, Soil organic carbon
