Dicyandiamide (DCD) and thiosulfates are two type of nitrification inhibitors (NIs) that have been widely used in agriculture to improve nitrogen (N) fertilizer use efficiency and mitigate negative effect of N on environment. Little information is available concerning the comparison of the efficacy of DCD and thiosulfate on N transformations in soil. The aim of this study was to compare the effects of DCD and thiosulfate (K2S2O3) on changes of NH4+-N, nitrification inhibition and N recovery in a latosolic red soil. An incubation experiment was conducted with four treatments of control (CK), N, N+DCD, and N+K2S2O3. Soil samples were collected periodically over 50 d to determine concentrations of mineral N, and the amoA gene abundance of ammonia monooxygenase (AMO) for ammonia-oxidizing bacteria (AOB) was estimated by qPCR after 10 d incubation. In the N treatment, 67.8% of the applied N as NH4+-N disappeared from the mineral N pool and only 2.7% and 30.8% of the applied N was accumulated as NO2--N and NO3--N, respectively. Addition of DCD and thiosulfate to the soil prevented NH4+-N disappearance by 63.0% and 13.6%, respectively. DCD suppressed the production of NO2--N by 97.41%, whereas thiosulfate increased accumulation of NO2--N by 14.6%. Application of N along with DCD and thiosulfate inhibited nitrification, respectively, by 72.6% and 33.1%, resulting in the delay of the nitrification process for 30 days and 10 days, respectively. Apparent N recovery in N treatment was 66.2%, which increased by 55.2% and 4.8% by DCD and thiosulfate, respectively. Numbers of AOB amoA gene copy was significantly inhibited by both DCD and thiosulfate, and the stronger inhibition induced by DCD than thiosulfate was recorded. Results indicated that both DCD and thiosulfate were effective inhibitors for NH4+-N oxidation, NO3--N production, mineral N losses and AOB growth. DCD showed a more pronounced effect on nitrification inhibition than thiosulfate.
Salinity is a major factor negatively affecting plant growth and agricultural productivity. To gain a better insight into Basella alba responses to different salt stress, some physiological parameters were investigated on this species after 15-day exposure to 200 mM NaCl or 100 mM Na 2 SO 4 stress. Plant growth was significantly suppressed under salinity and a more pronounced impairment induced by NaCl instead of Na 2 SO 4 was observed. A high level of water content was maintained in salt-treated shoot. Salinity stress caused marked increase in Na ? , Ca 2? , Cl -and SO 4 2-concentrations and decrease in K ? level and K ? /Na ? , Ca 2? / Na ? and Mg 2? /Na ? ratios in plants. The absorptive abilities of K ? , Ca 2? and Mg 2? in plants were improved significantly under salinity. Plants suffered a deeper oxidative stress in the presence of NaCl than Na 2 SO 4 as evidenced by the higher increase in foliar superoxide anions (O 2 Á-) and malondialdehyde (MDA) production as well as electrolyte leakage. No salt-induced alterations were observed on foliar hydrogen peroxide (H 2 O 2 ) level. B. alba responded to the oxidative stress by enhancing antioxidant capacity involving ascorbate, reduced glutathione as well as antioxidant enzymes. Superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) were all involved in the detoxification of reactive oxygen species (ROS) in plants exposed to salt stress, whereas catalase (CAT) only functioned in the Na 2 SO 4 -treated plants. The ability of water maintenance in shoot and improvement of cation absorbability as well as enhanced foliar antioxidant capability all contribute to the salt adaptation of B. alba, whereas a more efficient cation transport system and antioxidant mechanisms may be responsible for the better acclimation of this species to Na 2 SO 4 than NaCl.
While the effects of carbon on soil nitrogen (N) cycle have been extensively studied, it is not clearly understood how co-existing macronutrients, such as phosphorus (P), affect the N cycle in agroecosystems. In this study, P amendment effects on nitrification in a fertile agricultural soil were investigated under a typical N-P amendment rate. In a laboratory incubation study, soils were amended with urea, monopotassium phosphate and a mixture of urea and monopotassium phosphate at the same rate. In soils that received no amendments (control), P only, urea only, and urea plus P amendment, nitrification occurred within the first five days, with an average net nitrification rate of 5.30, 5.77, 16.66 and 9.00 mg N kg−1d−1, respectively. Interestingly, nitrification in urea-treated soils was retarded by P addition where a N:P ratio seemed to be a key factor impeding nitrification. This was also supported by the response of ammonia-oxidizing bacteria (AOB), which was more sensitive to P addition than ammonia-oxidizing archaea (AOA). The outcome of this study showed that application of P fertilizer suppressed the nitrification process in urea amended soil, suggesting that a synergistic aspect of N and P nutrient management should be further explored to retard N losses from agricultural systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.