Identifying and defining main changes in soil attributes to enhance environmental health and poverty alleviation in the Amazonian periphery

Abstract In the humid tropics, ensuring food security through sustainable food production relies heavily on addressing infertile soil. Identifying and enhancing key soil attributes crucial for plant growth poses significant challenges for poverty alleviation. We identify the main soil attributes that can boost crop performance and serve as predictors of sustainability, offering practical and economic recommendations for immediate improvement. The experiment was carried out in five areas of alley cropping systems where the leguminous tree Clitoria fairchildiana and annual legumes including Cajanus cajan, Crotalaria juncea, or Stylosanthes and Tithonia diversifolia were planted to increase soil organic matter, all consociated with maize. Nine soil samples were collected at each of the 10 sampling points. P, pH (H + Al3+), exchangeable K+, Ca2 + and Mg2 + were analyzed. We found that increased stabilised soil organic matter fraction, rather than P and K availability, is responsible for enhanced maize grain yield. This factor must be considered when assessing land and the environment, as well as implementing appropriate land management systems to avoid misallocation of limited resources. Input recommendations should align with the threshold values of 32 mmolc.dm-3 for Ca and 8 mmolc.dm-3 of Mg, aiming to achieve a combined level of 40 mmolc.dm-3 of Ca + Mg (Ca:Mg ratio of 4:1) and MAOC content around 14 g.kg-1. Soil researchers should further explore the interactions between Ca + Mg and MAOC and biomass-derived compounds as innovative soil quality management tools.