Continuous monoculture of alfalfa and annual crops influence soil organic matter and microbial communities in the rainfed loess plateau of China

Yining Niu, Zhuzhu Luo, Liqun Cai, Jeffrey A. Coulter, Yaoquan Zhang, Marisol Berli

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Abstract

Cropping systems are structured to maximize crop yields and increase sustainability in agricultural production. A field study was conducted to investigate different long-term cropping systems on soil organic matter and microbial communities. The cropping systems studied were: (i) a 14-year continuous alfalfa (Medicago sativa L.) (CA), (ii) a 9-year alfalfa removed and rotated with 4-5 years continuous annual crops (spring wheat fTriticum aestivum L.), maize (Zea mays L.), potato (Solatium tuberosum L.), and millet (Panicum miliaceum L.)), and (iii) a 5-year field fallow after alfalfa. Results showed that continued annual crops decreased total organic C and labile organic C by 10 to 20% and 17 to 34% in the topsoil (0-30 cm), and by 15 to 35% and 20 to 46% in the subsoil (30-60 cm), respectively, compared with CA. Similar trends were found in soil total N concentration, which decreased by 7 to 20% in the topsoil. Highest microbial biomass C was found in CA. Shannon-Wiener diversity and substrate richness of soil microbes measured by Biolog EcoPlates was significantly affected by cropping system with CA exhibiting a higher degree of soil microbial functional diversity in the topsoil, while the lowest values were found in the alfalfa-potato system. The higher soil organic matter content and functional diversity of soil microbe in CA indicates that soil nutrition and microbial activity did not limit alfalfa development and growth in the dryland area. The lower microbial activity and functional diversity observed in the potato field indicates the importance of crop selection in cropping systems.

Original languageEnglish (US)
Article number10071054
JournalAgronomy
Volume10
Issue number7
DOIs
StatePublished - Jul 21 2020

Bibliographical note

Funding Information:
Funding: This research was funded by the program of Gansu Provincial Key Laboratory of Aridland Crop Science, Gansu Agricultural University (GSCS-2019-04, GSCS-2020-Z2), the National Natural Science Foundation of China (31860364, 31560379 and 41461067), and the Natural Science Foundation of Gansu Province (18JR3RA175).

Keywords

  • Biolog ecoplates
  • Continuous monoculture
  • Functional diversitv
  • Microbial biomass c and n
  • Rainfed cropping systems

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