Responses of mass loss and nutrient release in litter decomposition to ultraviolet radiation

Journal of Soils and Sediments - Ultraviolet (UV) radiation plays an important role in litter decomposition, but the direction and magnitude of its effect remain inconsistent. To determine the...     

Evaluation of physiological traits of summer maize under drought stress

A study was conducted to investigate the sensitivity of physiological traits under different soil water availability in summer maize (Zea mays L.). Plant growth (plant height and stem), water relations (relative water content), gas exchange (net photosynthesis rate, stomatal conductance and transpiration rate) and nutrient levels were measured after 5, 10, 15 and 20 days of drought with different soil water availability. We found that all these physiological traits were inhibited by drought stress, but they showed differing levels of sensitivity with different soil water availability. Our results show that stomatal conductance was the most sensitive in mild drought conditions, that carbon accumulation was more sensitive than the other parameters in moderate drought, and that height and stem showed the largest response ratio in severe drought conditions. Different traits performed differently under drought conditions; thus, choosing an adequate index for evaluating soil water availability is necessary for maize cultivation.     

Sodium hydrosulfide modifies the nutrient ratios of soybean (Glycine max) under iron deficiency

Iron (Fe) deficiency in calcareous soils is a major limiting factor which influences production and yield of field crops. The present study investigated the effect of NaHS, a donor of H₂S, which is emerging as a potential signaling molecule, on the nutrient ratios of soybean (Glycine max L.) under Fe deficiency. Soybean seedlings with and without NaHS were subjected to Fe deficiency and Fe sufficiency for 18 d. Subsequently, we determined the biomass of seedlings, chlorophyll concentration, Fe concentration, as well as the ratios of carbon (C), nitrogen (N), phosphorus (P), and potassium (K). The growth of soybean seedlings was inhibited by Fe deficiency. However, under Fe deficiency the application of NaHS increased the biomass as well as the Fe, N, P, and K concentrations compared to the controls. Furthermore, our results also show that the application of NaHS affected the ratios of C : N, C : P, C : K, N : P, N : K, and P : K in soybean seedlings under Fe deficiency and sufficiency. H₂S played an important role in promoting the growth of soybean seedlings by enhancing the accumulation of nutrients under Fe deficiency.     

Differential responses of litter decomposition to nutrient addition and soil water availability with long-term vegetation recovery

The litter decomposition, nutrient patterns, as well as nutrient release and soil nutrient contents were determined in response to nitrogen (N) and phosphorus (P) addition and drought treatments following long-term vegetation recovery. The litter decomposition rate decreased with vegetation recovery, due to changes in litter quality, soil nutrient availability, and soil enzyme activity. Nitrogen addition promoted litter decomposition in the early recovery stages but inhibited decomposition in the later stages, indicating a shift in the nutrient limitations to litter decomposition with succession. Neither N nor P addition had any effect on the release of litter carbon (C), whereas N addition inhibited litter N release. In addition, drought decreased litter decomposition and nutrient release during the vegetation recovery process. Our findings suggest that litter quality, soil nutrient availability, and moisture at different vegetation recovery stages should be considered when modeling the C cycle and nutrient dynamics in these ecosystems.     

Nutrient limitation of litter decomposition with long-term secondary succession: evidence from controlled laboratory experiments

Purpose

Understanding ecosystem processes such as litter decomposition in response to dramatic land-use change is critical for modeling and predicting carbon (C) cycles. However, the patterns of litter decomposition along with long-term secondary succession (over 100 years) are not well reported, especially concerning nutrient limitations on litter decomposition.

Materials and methods

To clarify the response of litter decomposition to changes in soil nutrient availability, we conducted four incubation experiments involving soil and litter and nutrient addition from different successional stages and investigated the changes in microbial respiration and litter mass loss.

Results and discussion

Our results revealed that microbial respiration increased with succession without any litter addition (1.19~1.73 mg C g^?1 soil), and litter addition significantly promoted microbial respiration (16.5~72.9%), especially in the early successional stage (grassland and shrubland). The decomposition rate of the same litter decreased with succession. In addition, nitrogen (N) and phosphorus (P) addition showed significant effects on litter decomposition and microbial respiration; P addition promoted litter decomposition (2.4~15.3%) and microbial respiration (10.1~34.5%) in all successional stages, while N addition promoted litter decomposition (4.0~10.3%) and microbial respiration (5.4~27.2%) in all except the last stage of succession, which showed a negative effect on litter decomposition (??7.5%) and microbial respiration (??6.1%), indicating possible N saturation of litter decomposition and microbial respiration.

Conclusions

This work highlights that soil nutrient availability and successional stages need to be taken into account to predict the changes to litter decomposition in response to global changes.