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Aims This study looks whether the response of soil management (liming and nitrogen fertilization) on the incidence of Fusarium wilt (Foc Race 1) in Gros Michel banana ( Musa AAA) varies with different soil properties. Methods The effect of inoculation with Foc Race 1 was studied in a factorial greenhouse trial with soil samples from eight representative soil types from the Costa Rican banana region, two pH levels; and three levels of N-fertilization. After an 8-week period, plant biomass and a disease index were measured. Results There were significant effects of soil pH and N, and their interactions on disease expression. Low pH levels and high N-fertilization increased the disease expression. The response to changes in soil pH and N-fertilization differed considerably between the different soils. Conclusions Although soil pH and N influence Fusarium wilt in banana, each soil differs in its response to these soil properties. This complicates the development of standard soil management strategies in terms of e.g., N-fertilization and liming to mitigate or fight the disease.

Background and aims If and how eutrophication influences the persistent soil seed bank is poorly understood. Here, we hypothesized that eutrophication alters the composition of the persistent seed bank indirectly through changes in the soil characteristics and aboveground plant community and productivity. We also hypothesized that changes in the persistent seed bank will consequently impact the aboveground vegetative composition. Methods We tested these hypotheses using data from a 9-year nitrogen and phosphorus fertilization experiment in an alpine meadow ecosystem on the eastern Qinghai-Tibet plateau. Results We found that long-term nitrogen and phosphorus fertilization indirectly impacted the composition of the persistent seed bank through changes in soil pH, aboveground vegetation composition and annual net primary productivity (ANPP). Changes in the composition of the persistent seed bank, however, were relatively minor in comparison to changes in aboveground vegetation composition. Finally, changes in the persistent seed bank did not feedback on aboveground vegetation composition. Conclusion Our findings demonstrate the importance of soil pH, ANPP and vegetation composition in regulating the persistent seed bank under eutrophication. Our results also highlight the relative stability of the persistent seed bank to long-term eutrophication and their important contribution to the sustainability of grassland ecosystems.

A greenhouse pot experiment was conducted to study the effects of conventional nitrogen fertilization on soil acidity and salinity. Three N rates (urea; N0, 0 kg N ha −1 ; N1, 600 kg N ha −1 ; and N2, 1,200 kg N ha −1 ) were applied in five soils with different greenhouse cultivation years to evaluate soil acidification and salinization rate induced by nitrogen fertilizer in lettuce production. Both soil acidity and salinity increased significantly as N input increased after one season, with pH decrease ranging from 0.45 to 1.06 units and electrolytic conductivity increase from 0.24 to 0.68 mS cm −1 . An estimated 0.92 mol H + was produced for 1 mol (NO 2 − + NO 3 − )-N accumulation in soil. The proton loading from nitrification was 14.3–27.3 and 12.1–58.2 kmol H +  ha −1 in the center of Shandong Province under N1 and N2 rate, respectively. However, the proton loading from the uptake of excess bases by lettuces was only 0.3–4.5 % of that from nitrification. Moreover, the release of protons induced the direct release of base cations and accelerated soil salinization. The increase of soil acidity and salinity was attributed to the nitrification of excess N fertilizer. Compared to the proton loading by lettuce, nitrification contributed more to soil acidification in greenhouse soils.

Low soil pH (acidic soil) is one of the most severe environmental constraints that severely inhibits crop production. Here, we screened 134 lines of the Cheongcheong/Nagdong Double Haploid (CNDH) rice population under low pH conditions to uncover candidate QTLs and identify low pH-resistant lines. A total of 17 QTLs against shoot length, root length and standard evaluation score in response to low pH were identified on 8 chromosomes (1, 2, 6, 7, 8, 9, 10, and 12). A QTL related to shoot length, qSL-6b , on chromosome 6 with an LOD of 5 and a QTL related to the standard evaluation score, qSES-9 , on chromosome 6 with an LOD of 3 were further investigated for candidate genes. A total of 24 genes were predicted, i.e., 17 genes on qSL-6b and 7 genes on qSES-9 on the basis of closely related functional annotations via the NCBI and RiceXPro databases. Through qRT‒PCR of the resistant and susceptible lines, we identified four genes ( Os06g0211200 , Os09g0448200 , Os09g0456200 , and Os09g0472100 ) that were significantly expressed in the resistant lines but expressed at lower levels in the susceptible lines under low-pH soil stress. During early germination, ABA levels decreased in all the resistant lines but increased in all the susceptible lines. However, the ABA level at the seedling stage significantly increased in the resistant lines but decreased in all the susceptible lines. Our results suggest that the genes responsible for K + ion homeostasis and ABA regulation play key roles in resistance to low pH in rice.

Miscanthus has good tolerance to multi-metal(loid)s and has received increasing attention in remediated studies of metal(loid)s-contaminated soil. In this study, we conducted phytoextraction techniques to investigate the synergic effects of remediation of multi-metal(loid)s-contaminated soil by Miscanthus floridulus (Lab.) and two plant growth–promoting bacteria (PGPB), TS8 and MR2, affiliated to Enterobacteriaceae. The results exhibited a decrease of arsenic (15.27–21.50%), cadmium (8.64–15.52%), plumbum (5.92–12.76%), and zinc (12.84–24.20%) except for copper contents in the soil in bacterial inoculation groups, indicating that MR2 and TS8 could enhance the remediation of metal(loid)s. Moreover, increased fresh/dry weight and height indicated that inoculated bacteria could promote Miscanthus growth. Although the activities of antioxidant enzymes and the content of chlorophyll in the overground tissues showed no significant increase or even decrease, the activities of antioxidant enzymes in the underground tissues and soil were elevated by 48.95–354.17%, available P by 19.07–23.02%, and available K by 15.34–17.79% ( p  < 0.05). Bacterial inoculants could also decrease the soil pH. High-throughput sequencing analysis showed that the bacterial inoculant affected the rhizosphere bacterial community and reduced community diversity, but the relative abundance of some PGPB was found to increase. Phylogenetic molecular ecological networks indicated that bacterial inoculants reduced interactions between rhizosphere bacteria and thereby led to a simpler network structure but increased the proportion of positive-correlation links and enhanced the metabiosis and symbiosis of those bacteria. Spearman’s test showed that OTUs affiliated with Enterobacteriaceae and soil nutrients were critical for metal(loid) remediation and Miscanthus growth. The results of this study provide a basis for the synergic remediation of multi-metal(loid)s-contaminated soils by Miscanthus and PGPB and provide a reference for the subsequent regulation of Miscanthus remediation efficiency by the other PGPB or critical bacteria.

Comprehensive and accurate acquisition of surface soil pH spatial distribution information is essential for monitoring soil degradation and providing scientific guidance for agricultural practices. This study focused on Heilongjiang Province in China, utilizing data from 125 soil survey sampling points. Key environmental covariates were identified as modeling inputs through Pearson correlation analysis and recursive feature elimination (RFE). Three machine learning models—support vector machine (SVM), random forest (RF), and extreme gradient boosting (XGBoost)—were employed to predict surface soil pH in the study area. The modeling outcomes and distinctions among these models were then thoroughly compared. The results showed that the mean monthly temperature maximum (MMTmax), mean monthly precipitation minimum (MMPmin), mean annual precipitation (MAP), drought index (DI), and mean monthly wind speed maximum (MMWSmax) were the most important environmental covariates for modeling. Climate variables are better suited to reflect the nonlinear relationships between soil properties and the environment in large and flat areas during mapping. Among the mapping models, XGBoost exhibited the highest prediction performance (R 2 =0.705, RMSE=0.633, MAE=0.484), followed by RF (R 2 =0.688, RMSE=0.656, MAE=0.497), while SVM was considered unstable in this study. For uncertainty maps, XGBoost demonstrated lower uncertainty primarily in high-altitude mountainous forest regions, whereas RF achieved higher prediction consistency mainly in low-altitude plain areas. Each prediction model had its advantages in different terrain regions, yet XGBoost was regarded as the optimal model. According to the optimal model, the typical black soil in Heilongjiang Province generally exhibited weak acidity, with an average pH of 6.42, showing a gradual increasing trend from east to west and from north to south. Soil acidification mainly occurred in the meadow black soil and albic black soil regions of Heilongjiang Province’s eastern and northeastern parts. It is imperative to rigorously control the application of nitrogen fertilizers and to focus on improving the soil’s acid–base buffering capacity.

Soil pH is a crucial indicator which greatly reflects the cultivated land fertility. Exploring its spatial distribution characteristics and influencing factors is essential for the sustainable utilization of cultivated land. This study characterizes the spatial distribution and influencing factors of pH value of cultivated land in Sichuan Province, China. In particular, spatial autocorrelation, cold hot spot analysis, and geographic detectors were applied in this study. Results revealed that: (1) the pH values of cultivated land soil in Sichuan Province ranged from 3.53 to 8.88, with a mean value of 6.78. Alkaline and slightly acidic soils accounted for the majority, representing 59.5% of the total samples. The overall variability of soil pH in the study area was moderate, with both structural and random factors contributing to its spatial variation. (2) The spatial distribution of soil pH in Sichuan Province exhibited a decreasing trend from northwest to southeast. Neutral soil predominated in the plain and basin regions, while alkaline soil was primarily found in the southeastern part. (3) The spatial variation of soil pH in Sichuan Province demonstrated significant positive spatial clustering. High-value aggregation areas were mainly located in the Chengdu Plain and northern regions, whereas low-value aggregation areas were concentrated in the southern part of the Chengdu Plain and eastern areas. (4) The relative contributions of different factors to soil pH in arable land of Sichuan Province ranked as follows: precipitation > available phosphorus > available potassium > elevation > temperature > organic matter > NDVI > topsoil thickness > total nitrogen.

PurposeThe purpose of this study is to determine the critical soil pH, exchangeable aluminum (Al), and Al saturation of the soils derived from different parent materials for maize.Materials and methodsAn Alfisol derived from loess deposit and three Ultisols derived from Quaternary red earth, granite, and Tertiary red sandstone were used for pot experiment in greenhouse. Ca(OH)2 and Al2(SO4)3 were used to adjust soil pH to target values. The critical soil pH was obtained by two intersected linear lines of maize height, chlorophyll content, and yield of shoot and root dry matter changing with soil pH.Results and discussionIn low soil pH, Al toxicity significantly decreased plant height, chlorophyll content, and shoot and root dry matter yields of maize crops. The critical values of soil pH, exchangeable Al, and Al saturation varied with soil types. Critical soil pH was 4.46, 4.73, 4.77, and 5.07 for the Alfisol derived from loess deposit and the Ultisol derived from Quaternary red earth, granite, and Tertiary red sandstone, respectively. Critical soil exchangeable Al was 2.74, 1.99, 1.93, and 1.04 cmolckg−1 for the corresponding soils, respectively. Critical Al saturation was 5.63, 12.51, 14.84, and 15.16% for the corresponding soils.ConclusionsGreater soil cation exchange capacity and exchangeable base cations led to lower critical soil pH and higher critical soil exchangeable Al and Al saturation for maize.

Cadmium (Cd) contamination in agricultural soils threatens crop productivity and food safety. This study examined the use of dolomite and calcite amendments in reducing Cd toxicity in pak choi grown in Cd-contaminated soil. Treatments included: control (CK), Calcite 1 (Cal1, 10 g/kg soil), Calcite 2 (Cal2, 20 g/kg soil), Dolomite 1 (Dol1, 10 g/kg soil), and Dolomite 2 (Dol2, 20 g/kg soil). Amendments significantly increased soil pH (P ≤ 0.05), with Cal2 (6.5) and Dol2 (6.2) achieving the highest values at harvest. Cd availability declined (P ≤ 0.05), with Dol2 being the most effective, reducing the toxicity characteristic leaching procedure-extractable Cd from 0.03 to 0.01 mg/kg, NH4NO3-extractable Cd from 0.05 to 0.02 mg/kg, and CaCl2-extractable Cd from 0.40 to 0.01 mg/kg. Dol2 improved biomass and chlorophyll content, while reducing Cd accumulation in shoots by 73.3% and in roots by 70% relative to the control. Antioxidant enzymes were regulated, with decreased peroxidase and superoxide dismutase indicating reduced oxidative stress, while Dol2 maximised urease, catalase, invertase, phosphatase, and phenol oxidase activities. Dissolved organic carbon and microbial biomass carbon also increased, thereby enhancing microbial activity. Dolomite and calcite significantly reduced biological concentration factors, biological accumulation coefficients, and translocation factors, thereby restricting Cd uptake. Overall, dolomite, especially at higher levels, effectively mitigated Cd toxicity, improved plant resilience, and enhanced soil health in contaminated systems.

Soil acidity threatens food production in the tropics. The effect of increasing ammonium-based fertilizer (INF) on soil pH was assessed in sub-Saharan Africa (SSA). A total of 9043 soil data from Africa soil information services, past INF use, and two future scenarios of INF use (business as usual (BAU) and equitable diet (EqD)) were used to determine soil pH variations from 1980 to 2022 and to predict soil PH variations from 2022 to 2050. Random forest and extreme gradient boosting algorithms and soil-forming factor covariates were used for the spatio-temporal soil pH predictions. Topsoil acidification was shown to be significant, with mean annual decrements of 0.014, 0.024, and 0.048 from 1980 to 2022, 2022 to 2050 (BAU), and 2022 to 2050 (EqD), respectively. Over the past 42 years, croplands with soil pH < 6.5 have declined significantly, and soil acidification is predicted to become severe by 2050 in the BAU and EqD scenarios. This was indicated by a predicted 3% increase in croplands at risk of aluminum toxicity (soil pH < 5.5) from 66 × 106 ha in 2022 to 78.5 × 106 ha in 2050. The drivers of the spatial variations in the soil pH between 1980 and 2050 were the MAP, basic cation, clay content, SOC, and nitrogen fertilizers. The evaluation metrics of the 10-fold cross-validation showed that the root mean squared errors (RMSEs) of the soil pH from 1980 to 2022, as well as the predicted soil PH from 2022 to 2050 (BAU) and 2022 to 2050 (EqD), were 0.53 pH units, 0.54 pH units, and 0.56 pH units, respectively, with coefficients of determination (R2) of 0.63, 0.64, and 0.66. The findings of this study can be used for the establishment of management strategies for increasing INF use in acidic soils.