Rapid recovery of nitrogen retention capacity in a subtropical acidic soil following afforestation. (May 2018)

• Record Type: Journal Article
• Authors: Xie, Yu; Yang, Lin; Zhu, Tongbin; Yang, Hui; Zhang, Jianbing; Yang, Jinling; Cao, Jianhua; Bai, Bing; Jiang, Zhongcheng; Liang, Yueming; Lan, Funing; Meng, Lei; Müller, Christoph
• Is Part Of: Soil biology and biochemistry. Volume 120(2018)
• Page Start: 171
• Page End: 180
• Publication Date: 2018-05
• Subjects: Afforestation -- 15N tracing -- Gross N transformation -- Autotrophic nitrification -- N retention; Soil biochemistry -- Periodicals; Soil biology -- Periodicals; Sols -- Biochimie -- Périodiques; Sols -- Biologie -- Périodiques; Sols -- Microbiologie -- Périodiques; Bodembiologie; Biochemie; 631.46
• DOI: 10.1016/j.soilbio.2018.02.008
• Languages: English
• ISSNs: 0038-0717

Abstract

Abstract: Understanding soil nitrogen (N) dynamic and availability during afforestation (the conversion of cropland to forest plantations) is critical to maintain forest growth and long-term productivity, especially in rainfall-rich, subtropical region. However, only few studies have investigated the inherent N transformation processes involved in N availability in subtropical acidic soils. In a 15 N tracing study, nine soils from croplands, 10-y and 50-y afforested woodlands were sampled to investigate the changes in soil gross N transformation rates in humid subtropical China. Gross N transformation rates were not significantly different in soils under 10- and 50-y after afforestation. Compared to cropland, however, afforestation stimulated the rates of mineralization, microbial NH4 + immobilization and adsorption of NH4 +, leading to a faster turnover of NH4 + pool in afforested soils. Moreover, afforestation inhibited autotrophic nitrification and resulted in NO3 − production dominated by heterotrophic nitrification. Furthermore, afforestation significantly enhanced NO3 − consumption mainly through the increase in microbial NO3 − immobilization rather than dissimilatory NO3 − reduction to NH4 + in soil. These differences in gross N transformation rates resulted in low net NO3 − production and strong NO3 − retention capacity in afforested soils, similar to that found in undisturbed natural forest. Our results suggest a rapid recovery (several years) of soil N retention following afforestation. Soil NO3 − retention capacity was correlated positively with TOC, TN, WHC, CEC, Al, free Al oxide and exchangeable Al 3+, but negatively with pH, Ca and exchangeable Ca 2+, indicating that the absence of agricultural management (e.g., N fertilizer and liming) and alteration in soil environment by tree establishment are responsible for the recovery of N retention capacity in subtropical acidic soils during afforestation. Highlights: Afforestation alters soil inorganic N forms and gross N transformation rates. Afforestation induces the faster turnover of soil NH4 + than NO3 − . Afforestation significantly decreases autotrophic nitrification but increases microbial NO3 − immobilization. Rapid recovery of N retention capacity following afforestation was found in acidic soil.