Premium
Responses of soil gross nitrogen transformations to three vegetation restoration strategies in a subtropical karst region
Author(s) -
Li Dejun,
Wen Li,
Xiao Kongcao,
Song Tongqing,
Wang Kelin
Publication year - 2021
Publication title -
land degradation and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.403
H-Index - 81
eISSN - 1099-145X
pISSN - 1085-3278
DOI - 10.1002/ldr.3907
Subject(s) - nitrogen , mineralization (soil science) , nitrification , restoration ecology , pennisetum purpureum , nitrogen cycle , chemistry , agronomy , vegetation (pathology) , environmental science , zoology , botany , biology , ecology , dry matter , medicine , organic chemistry , pathology
Abstract Investigation of soil internal nitrogen cycles is useful for unravelling the mechanisms responsible for soil nitrogen availability change. Here, gross nitrogen transformations were investigated in a subtropical karst area after 16 years of vegetation restoration. The experiment included four treatments with one control and three restoration strategies, that is: (i) maize‐soybean rotation field (CR, control); (ii) restoration with Toona sinensis (TS); (iii) restoration with Guimu‐1 hybrid elephant grass (GG, Pennisetum americanum (L.) Leeke × Pennisetum purpureum Schumach); and (iv) restoration with Guimu‐1 hybrid elephant grass and Zenia insignis as a mixture (ZG). Soil NH 4 + and NO 3 − responded differentially to three restoration strategies, resulting in no significant change of total inorganic N content following vegetation restoration. Gross nitrogen mineralization (GNM) rate increased by 124.0%, 96.8%, and 60.3% in TS, GG, and ZG, respectively, relative to CR (2.88 ± 0.05 mg N kg −1 d −1 ). The strongest explanatory variable was microbial biomass carbon for both GNM ( R 2 = 0.82) and gross nitrification ( R 2 = 0.66). Dissimilatory NO 3 − reduction to NH 4 + (DNRA) rate in TS or ZG, which was significantly greater than that in CR, was significantly correlated with SOC: NO 3 − ratio ( R 2 = 0.61), implying that DNRA was limited by SOC availability. Gross NH 4 + immobilization rate, which was highest in GG, and lowest in CR, was best predicted by carbon to nitrogen ratio ( R 2 = 0.65). However, gross NO 3 − immobilization rate could not be well predicted by the measured soil properties. Our results suggest that vegetation restoration especially TS significantly enhanced soil N availability as reflected by gross N mineralization rate.