Different mulches have variable effects on soil physical properties and plant growth. This study aimed to compare the effects of mulching with inorganic (round gravel, RG), organic (wood chips, WC), and living (manila turf grass, MG) materials on soil properties at 0–5-cm and 5–10-cm depths, as well as on the growth and physiological features of Osmanthus fragrans L. ‘Rixianggui’ plants. Soil samples were collected at three different time points from field plots of O. fragrans plants treated with the different mulching treatments. Moisture at both soil depths was significantly higher after mulching with RG and WC than that in the unmulched control (CK) treatment. Mulching did not affect soil bulk density, pH, or total nitrogen content, but consistently improved soil organic matter. The available nitrogen in the soil increased after RG and WC treatments, but decreased after MG treatment during the experimental period. Mulching improved plant growth by increasing root activity, soluble sugar, and chlorophyll a content, as well as by providing suitable moisture conditions and nutrients in the root zone. Plant height and trunk diameter were remarkably increased after mulching, especially with RG and WC. However, while MG improved plant growth at the beginning of the treatment, the ‘Rixianggui’ plants later showed no improvement in growth. This was probably because MG competed with the plants for water and available nitrogen in the soil. Thus, our findings suggest that RG and WC, but not MG, improved the soil environment and the growth of ‘Rixianggui’ plants. Considering the effect of mulching on soil properties and plant growth and physiology, round gravel and wood chips appear to be a better choice than manila turf grass in ‘Rixianggui’ nurseries. Further studies are required to determine the effects of mulch quality and mulch-layer thickness on shoot and root growths.

Plasmon-assisted visible light photocatalysis presents a possible solution for direct solar-to-fuel production. Here we investigate the plasmon-enhanced photocatalytic water splitting using different TiO2/Au electrode structures. Experimental data demonstrates that the Au embedded in TiO2 (Au-in-TiO2) electrode greatly outperforms the Au sitting on TiO2 (Au-on-TiO2) electrode. Numerical simulation shows that the local electric field is very intense in the semiconductor near Au nanoparticles, which causes the enhancement of electron-hole pair generation. A 3D Au-embedded TiO2 structure is thus proposed to further improve the light absorption and photocatalytic performance.

Biochar can potentially increase crop production in saline soils. However, the appropriate amount of biochar that should be applied to benefit from resource preservation and increase both grain yield (GY) and quality is not clear. A pot experiment was conducted to evaluate the effects of biochar applied at various rates (i.e., 0, 5, 10, 20, 30, 40 and 50 t/ha) on the nitrogen use efficiency (NUE), GY and amino acid (AA) contents of wheat plants in saline soils. The results showed that the application of 5–20 t/ha biochar increased wheat NUE by 5.2–37.9% and thus increased wheat GY by 2.9–19.4%. However, excessive biochar applications (more than 30 t/ha) had negative effects on both the NUE and GY of wheat. Biochar had little influence on leaf soil and plant analyzer development (SPAD) values, the harvest index or yield components. The AAs were significantly affected by biochar, depending on the application rate. Among the application rates, 5–30 t/ha biochar resulted in relatively higher (by 5.2–19.1%) total AA contents. Similar trends were observed for each of the 17 essential AAs. In conclusion, the positive effects of biochar occurred when it was applied at appropriate rates, but the effects were negative when biochar was overused.

Understanding mulching influences on nitrogen (N) availability is important for developing N management strategies in plantations at the upland sites of the southwestern China. Dynamics of biomass loss and nutrient release of mulching material, N availability in the soil and N mineralization in situ were evaluated for the treatments with different mulch quantity in degraded agricultural soil. The time taken for 95% decomposition of the initial biomass of Cogon grass (Imperata cylindrical L. Beauv. var. major) was 17 months with a half-life (t 1/2 ) of about 4.8 months. During the first 4 months about 55.2% of N was released, and after 1-year decomposition about 71.6% of N was released from the mulch material. The fresh grass mulch increased the available N in the soil as they decomposed. Compared to no mulch treatment, mulch treatments with 2.5, 5.0 and 7.5 kg m −2 mulching grass increased available N by about 13.1, 40.8 and 56.4% in the top soil (0-5 cm), and about 23.6, 78.0 and 139.3% in the middle layer (5-20 cm), respectively. The mean annual net N mineralization in the mulched plots had 9.0-40.9% higher cumulative rate than that in no-mulch plots, and the majority of the accumulated N in the incubated soils existed as NO 3 -N. There was a positive relationship between the rate of N mineralization and the available N in both the top soil and the middle layer. Mulch improves soil nutrients and this improvement increased with increasing mulching quantity. The increment of net N mineralization was approximately 69, 161 and 322 kg N ha −1 year −1 in the soil of 0-20 cm depth for the 2.5, 5.0 and 7.5 kg m −2 grass mulch treatments, respectively. The results from this study will provide a basis to optimize mulching techniques for poplar plantations in degraded agricultural soils of southwestern China.

Arbuscular mycorrhizal fungi (AMF) provide essential nutrients to crops and are critically impacted by fertilization in agricultural ecosystems. Understanding shifts in AMF communities in and around crop roots under different fertilization regimes can provide important lessons for improving agricultural production and sustainability. Here, we compared the responses of AMF communities in the rhizosphere (RS) and root endosphere (ES) of wheat ( Triticum aestivum ) to different fertilization treatments: Non-fertilization (Control), mineral fertilization only (NPK), mineral fertilization plus wheat straw (NPKS), and mineral fertilization plus cow manure (NPKM). We employed high-throughput amplicon sequencing and investigated the diversity, community composition, and network structure of AMF communities to assess their responses to fertilization. Our results elucidated that AMF communities in the RS and ES respond differently to fertilization schemes. Long-term NPK application decreased the RS AMF alpha diversity significantly, whereas additional organic amendments (straw or manure) had no effect. Contrastingly, NPK fertilization increased the ES AMF alpha diversity significantly, while additional organic amendments decreased it significantly. The effect of different fertilization schemes on AMF network complexity in the RS and ES were similar to their effects on alpha diversity. Changes to AMF communities in the RS and ES correlated mainly with the pH and phosphorus level of the rhizosphere soil under long-term inorganic and organic fertilization regimes. We suggest that the AMF community in the roots should be given more consideration when studying the effects of fertilization regimes on AMF in agroecosystems. Importance Arbuscular mycorrhizal fungi are an integral component of rhizospheres, bridging the soil and plant systems and are highly sensitive to fertilization. However, surprisingly little is known about how the response differs between the roots and the surrounding soil. Decreasing arbuscular mycorrhizal fungal diversity under fertilization has been reported, implying a potential reduction in the mutualism between plants and arbuscular mycorrhizal fungi. However, we found opposing responses to long-term fertilization managements of arbuscular mycorrhizal fungi in the wheat roots and rhizosphere soil. These results suggested that changes in the arbuscular mycorrhizal fungal community in soils do not reflect those in the roots, highlighting that the root arbuscular mycorrhizal fungal community is pertinent to understand arbuscular mycorrhizal fungi and their crop hosts’ responses to anthropogenic influences.