Nitrogen (N) fertilizer application is one of the causes of soil acidification at tea plantations. However, the effect of N fertilizer application on the soil acidification characteristics of tea plantations with different acidities remains unclear. In this study, field experiments were conducted to investigate the effects of different nitrogen fertilizer application rates on the pH, pH buffer capacity (pHBC), exchangeable total acidity (ETA), exchangeable base cations (EBCs), and cation exchange capacity (CEC) in the topsoil of non-acidified (NA), mildly acidified (MA), and heavily acidified (HA) tea plantations. The results showed that the exchangeable Al³⁺ (E-Al) and CEC were HA > MA > NA in all tea plantations, whereas the EBCs and base saturation percentage (BSP) were HA < MA < NA. In the tea plantations with pH > 4.0, the pH, EBCs, and BSP showed decreasing trends with increasing N fertilizer application, whereas E-Al showed an increasing trend. In the tea plantations with pH < 4.0, the soil pH showed a small increasing trend with the increase in N fertilizer application, whereas the soil exchangeable H⁺ (E-H), E-Al, and CEC showed decreasing trends. Meanwhile, in the pH range of 4–6, the soil acid–base buffer curve rose sharply, and an excessive application of N fertilizer (N900) significantly reduced the pHBC. In addition, a stepwise regression analysis showed that the BSP, EBCs, and exchangeable Mg²⁺ (E-Mg) had significant direct effects on the soil pH, whereas the CEC and N application had significant direct effects on the soil pHBC. In conclusion, a decrease in the BSP and an increase in E-Al were the main mechanisms of acidification at tea plantations, whereas a decrease in the BSP caused by the application of N fertilizer was the main cause of exacerbated soil acidification in non-acidified tea plantations.

A survey of the taxonomy and diversity of freshwater fungi from Karst Plateau wetlands in Guizhou Province, China, three fresh collections were collected from a freshwater river. They have cheiroid, digitate, dictyosporous conidia with one or two hyaline appendages. Phylogenetic analysis of the combined ITS, LSU and tef1-α sequence data support their placement with genera Dictyocheirospora and Dictyosporium (Dictyosporiaceae, Pleosporales). Two collections represent the same species, Dictyocheirospora rotunda. The other collection is introduced as a new species Dictyosporium duliujiangense. An updated phylogenetic backbone tree, descriptions and illustrations of the two taxa are provided for Dictyosporiaceae.

Microthyriaceae is typified by the sexual genus Microthyrium, with eight asexual genera. Three interesting isolates were collected during our investigation of freshwater fungi from the wetlands in Guizhou Province, southwest China. Three new asexual morphs are identified. Phylogenetic analyses using ITS and LSU gene regions revealed the placement of these isolates in Microthyriaceae (Microthyriales, Dothideomycetes). Based on the morphology and phylogenetic evidence, two new asexual genera, Paramirandina and Pseudocorniculariella, and three new species, Pa. aquatica, Pa. cymbiformis, and Ps. guizhouensis, are introduced. Descriptions and illustrations of the new taxa are provided, with a phylogenetic tree of Microthyriales and related taxa.

Biochar as an amendment has been widely applied to enhance crop productivity and improve soil quality. However, the effect of biochar-based fertilizer (BF) on the production capacity and economic benefits of open-field eggplant in the karst region remains unclear. A field experiment was carried out in the karst region of Southwest China from 2020 to 2021 to study the ameliorative roles of different application rates (1875, 2250, 2625, and 3000 kg ha⁻¹) of BF on the fresh yield, quality, fertilizer utilization, and economic benefits of fresh eggplant. The results show that BF increased the yield of fresh eggplant by 3.65–13.76% (2020) and 23.40–49.04% (2021) compared to the traditional fertilization practice (TFP). The application of BF reduced the nitrate content and increased the vitamin C (VC) and soluble sugar content of the fruits, which is beneficial for improving the quality of eggplant fruits. Meanwhile, the application of BF not only increased the nutrient uptake of the eggplant but also significantly improved the fertilizer utilization rates, especially the agronomic efficiency (AE) and recovery efficiency (RE). Moreover, BF could also significantly increase the output value and net income of fresh eggplant, which can help farmers increase their income. In conclusion, a BF application rate of 2544–2625 kg ha⁻¹ could be used to improve the yield, fertilizer efficiency, and economic benefits of open-field eggplant and is recommended for managing agricultural production in the karst region of Southwest China.

Biochar is frequently utilized as a helpful amendment to sustain agricultural productivity. However, it remains uncertain whether biochar can effectively replace chemical fertilizers, especially in karst regions. To investigate the effects of co-applying biochar and chemical fertilizer on the biological characteristics and fertilizer uptake of pod peppers, as well as to determine the optimal ratio of biochar to chemical fertilizers, a two-year field experiment was conducted in southwest China. The results showed that, compared to the locally typical chemical fertilizer treatment (CF), the combined application of biochar and chemical fertilizer significantly increased the yield of both fresh and dry pod pepper. Chemical fertilizer reduction and biochar application also ameliorated fruit quality, increased nutrient accumulation, and improved fertilizer utilization efficiency. What is more, although the employment of biochar made production costs higher, the reduction in chemical fertilizers and the increase in yield improved economic efficiency, especially in the CF₇₀B treatment (70%CF + biochar). In conclusion, moderate amounts of biochar instead of chemical fertilizers may be a valid nutrient management strategy for pod pepper in the karst mountain areas, which is beneficial for maintaining yield stability, improving quality, and increasing net income.

In recent years, vermicompost (V) has been widely used as an amendment for improving crop productivity and soil quality. However, the ameliorative effect of vermicompost on the continuous cropping pepper remains unclear, particularly in the karst areas of southwestern China. A field experiment was conducted to study the effect of vermicompost application on the yield, quality, nutrient accumulation, fertilizer utilization, and economic benefits of continuous cropping pepper from 2021 to 2022. The experiment included six treatments: CK (no fertilizer), FP (the fertilization practice of local farmers), and FPV (FP combined with vermicompost of 1500, 2250, 3000, and 3750 kg·ha⁻¹). The results show that vermicompost application increased the yield of fresh pod pepper by 28.34–51.36% (2021) and 47.13–68.82% (2022), whereas the yield of dry pod pepper increased by 16.97–35.14% (2021) and 34.48–62.61% (2022), respectively, compared with the FP treatment. The application of vermicompost reduced the nitrate content and increased the vitamin C (VC) and soluble sugar content of the fruits, which is beneficial for improving their quality. Vermicompost application not only increased nutrient uptake but also significantly improved agronomic efficiency (AE) and recovery efficiency (RE). In addition, although the application of vermicompost increased production costs, the increase in yield improved net incomes (16.02–31.83% in 2021 and 35.83–62.85% in 2022), especially in the FPV4 treatment. In conclusion, the use of vermicompost amendment had a positive effect on the productivity and economic benefits of continuous cropping pepper, which may be an effective nutrient management strategy for the continuous cropping pepper in the karst mountain areas of southwest China.