Soil nutrient concentrations and stoichiometry under different tree-cropping systems in a purple hillslope in southwestern China

ABSTRACT

Agroforestry systems strongly impact soil properties, yet their effects on the stoichiometry of soil nutrients remain unclear. This study aimed to determine the tree-cropping systems effects on soil C, N, P and K concentrations and their stoichiometry in 0–10 and 10–20 cm soil depths in a purple hillslope of southwestern China. Five typical agroforestry systems, including Citrus sinensis (L.) Osbeck system (CO), CO and Ipomoea batatas (L.) system (CI), CO and Arachis hypogaea (L.) system (CA), CO and Zea mays (L.) system (CZ), and CO and Solanum melongena (L.) system (CS), were investigated. Tree-cropping systems (i.e. CI, CA, CZ and CS) showed significantly higher soil C, N, P and K concentrations and clay percentage, and lower bulk density than CO system. Nutrient ratios altered inconsistently among five agroforestry systems. Soil depth differed N concentration, N:K ratio, bulk density and total porosity. Soil nutrient concentrations and stoichiometry showed significant correlations with physical properties. N:P ratio was 69.78 and 78.55% lower than the Chinese and World averages in the 0–10 cm soil depth, indicating that severe N limitation occurred in the agroforestry systems. Rational N fertilization and allocation of tree-cropping systems are urgently needed for sustainable development of agroforestry.

KEYWORDS:

• Agroforestry systems
• nutrient limitation
• soil stoichiometry
• fertilization
• purple soil

Acknowledgments

Funding from the National Key Research and Developmental Program of China is duly acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Key Research and Developmental Program of China [2016YFC0502303].