Ca Saturation Determines Crop Growth in Acidic Ultisols Derived from Different Parent Materials

Abstract

Soil acidity has become a major yield-limiting factor, but it is unclear which acidity indicator is the best to use for estimating crop yield changes. In this study, four pH-adjusted Ultisols derived from different parent materials were used for Chinese cabbage and wheat pot experiments. Structural equation modeling (SEM), Gompertz and linear-plateau models were used to examine main contribution of soil acidity indices and to determine their critical values. The results showed that Ca saturation had the strongest direct effect on crop biomass and thus acted as the most important factor. The critical values of Ca saturation varied slightly with crops and soils, where it was 84.6, 93.5, 95.2 and 82.9% for Ultisols derived from plate shale, Quaternary red clay, red sandstone and granite, respectively. The critical values of exchangeable Ca and Al, and Al saturation and exchangeable Al : Ca ratio (or Ca : Al ratio) were also determined as 8.21 and 0.44 cmol c kg -1 , 6.37%, and 0.069 (or 14.5), respectively. In summary, our findings evidenced that critical Ca saturation has the potential to evaluate the implementation of quality improvement of acidic soils for good crop production.

Ability of Nutrient Management and Molecular Physiology Advancements to Overcome Abiotic Stress: A Study on Sub-Saharan African Crops

“…These include the suboptimal nodulation of legumes, the proliferation of acid-tolerant weeds, stunted root growth, and a reduction in the yields of various crops, such as millet, sorghum, tomato (Solanum lycopersicum), sweet potato (Ipomoea batatas), and tea [50,51]. Soil acidity also reduces enzymatic activity, interrupts microbially mediated nutrient cycling, and hampers microbial activity [52,53]. These constraints vary depending on the degree of acidity [54].…”