REGULAR ARTICLE Effects of alternate partial root-zone irrigation on soil microorganism and maize growth Jinfeng Wang & Shaozhong Kang & Fusheng Li & Fucang Zhang & Zhijun Li & Jianhua Zhang Received: 22 May 2007 / Accepted: 17 October 2007 / Published online: 14 November 2007 # Springer Science + Business Media B.V. 2007 Abstract Partial root-zone irrigation creates a dy- namic heterogeneous distribution of soil moisture that may affect the numbers and activities of soil micro- organisms. In this study, three irrigation methods, i.e. conventional irrigation (CI), alternate partial root- zone irrigation (APRI, alternate watering on both sides of the pot) and fixed partial root-zone irrigation (FPRI, fixed watering on one side of the pot), and three watering levels, i.e. well-watered, mild and severe water deficit, were applied on pot-grown maize. Numbers of soil microorganisms, plant height, stalk diameter, leaf area and biomass accumulation were monitored over the treatment period. A quadratic parabola relationship between the number of soil microorganisms and soil water content was found, indicating the number of soil microorganisms reached a peak at the mild soil water deficit condition, possibly due to better soil aeration. The peak number of soil microorganism was obtained when soil water content was 66, 79 and 75% of field capacity for CI, FPRI and APRI, respectively. Soil microorganisms were evenly distributed in both sides of APRI and their total numbers were always higher than those under other two irrigation methods for the same soil water content. The count of soil microorganisms in the dry root zone of FPRI was reduced by a lack of water. Maximum biomass accumulation was obtained under well watered condition but severe water deficit led to a 50% reduction in the CI treatment. Such reduction was much smaller under APRI and therefore the highest water use efficiency was obtained. Our results suggest that APRI maintained the best aeration and moisture condition in the soil and enhanced the activities of soil microorganisms, which might also have benefited the plant growth. Keywords Irrigation method . Partial root-zone drying/irrigation . Soil microorganism . Soil water deficit . Plant growth . Maize (Zea mays) Plant Soil (2008) 302:45–52 DOI 10.1007/s11104-007-9453-8 DO09453; No of Pages Responsible Editor: Rana E. Munns J. Wang : S. Kang : F. Zhang : Z. Li Key Lab of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China, 712100 S. Kang (*) Center for Agricultural Water Research in China, China Agricultural University, Beijing, China, 100083 e-mail: kangshaozhong@tom.com F. Li Agricultural College, Guangxi University, Nanning, Guangxi, China, 530005 J. Zhang Department of Biology, Hong Kong Baptist University, Hong Kong, China e-mail: jzhang@hkbu.edu.hk (*)