Search

BACKGROUND: Efficient utilization of phosphorus (P) has been a major challenge for sustainable agriculture. However, the responses of fertilizer rate, region, soil properties, cropping systems and genotypes to P have not been investigated comprehensively and systematically. RESULTS: A comprehensive analysis of 9863 fertilizer‐P experiments on rice cultivation in China showed that rice yield increased first and then fell down with the addition of P fertilizer, and the highest yield of 7963 kg ha−1 was observed under 100% P treatment. Under 100% P treatment, the yield response of applied P (YRP) and agronomic efficiency of applied P (AEP) were 12.8% and 30.1 kg ha−1, respectively. Lower soil pH (< 5.5) and organic matter (< 30.0 g kg−1) were associated with lower YRP and AEP. By contrast, soil available P < 25.0 mg kg−1 resulted in decreased YRP (15.3 to 11.4%) and AEP (32.3 kg kg−1 to 26.2 kg kg−1), whereas soil available P > 25.0 mg kg−1 maintained the relatively stable YRP and AEP. Also, the YRP and AEP were significantly higher for single‐cropping rice compared to other cropping systems. Moreover, the rice genotypes such as 'Longdun', 'Kendao' and 'Jigeng' had higher YRP and AEP than the average value. Overall, the fertilizer‐P rate was the primary factor affecting YRP and AEP, and the recommended P fertilizer rate can be reduced by 9–21 kg P ha−1 compared to existing expert recommendations. CONCLUSION: The present study highlights the role of fertilizer‐P rate in maximizing the YRP and AEP, thereby providing a strong basis for future fertilizer management in rice cultivation systems. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The riparian zone is an important ecological corridor connecting the upstream and downstream rivers. Its highly complex biological and physical environments significantly affect the biogeographical pattern of species and various ecosystem functions. However, in alpine riparian ecosystems, the distribution patterns and drivers of arbuscular mycorrhizal (AM) fungi, a group of functionally important root-associated microorganisms, remain poorly understood. In this study, we investigated the AM fungal diversity and community composition in near-bank (wetland) and far-bank (alpine meadows) soils along the Niaqu River in the Nam Co watershed, and assessed the relative importance of abiotic and biotic filtering in shaping these distributions. Overall, 184 OTUs were identified in the riparian ecosystem, predominantly belonging to the genus Glomus, especially in the downstream soils, and Claroideoglomus in near-bank soils. AM fungal colonization, spore density, and a diversity showed an overall increasing trend along the river, while the extraradical hyphae declined dramatically from the middle of the river. AM fungal communities significantly varied between the wetland and alpine meadows in the riparian zone, mainly driven by the geographic distance, soil water content, soil pH, and plant communities. Specifically, soil pH was the principal predictor of AM fungal community in near-bank wetland soils, while soil water content had a most substantial direct effect in alpine Frontiers in Microbiology 01 frontiersin.org meadows. These findings indicate that abiotic factors are the most important divers in shaping AM fungal communities at the watershed scale, which could be helpful in alpine riparian biodiversity conservation and management. [ABSTRACT FROM AUTHOR]

Background: Soil microbes exist throughout the soil profile and those inhabiting topsoil (0–20 cm) are believed to play a key role in nutrients cycling. However, the majority of the soil microbiology studies have exclusively focused on the distribution of soil microbial communities in the topsoil, and it remains poorly understood through the subsurface soil profile (i.e., 20–40 and 40–60 cm). Here, we examined how the bacterial community composition and functional diversity changes under intensive fertilization across vertical soil profiles [(0–20 cm (RS1), 20–40 cm (RS2), and 40–60 cm (RS3)] in the red soil of pomelo orchard, Pinghe County, Fujian, China. Results: Bacterial community composition was determined by 16S rRNA gene sequencing and interlinked with edaphic factors, including soil pH, available phosphorous (AP), available nitrogen (AN), and available potassium (AK) to investigate the key edaphic factors that shape the soil bacterial community along with different soil profiles. The most dominant bacterial taxa were Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Crenarchaeota, and Bacteriodetes. Bacterial richness and diversity was highest in RS1 and declined with increasing soil depth. The distinct distribution patterns of the bacterial community were found across the different soil profiles. Besides, soil pH exhibited a strong influence (pH ˃AP ˃AN) on the bacterial communities under all soil depths. The relative abundance of Proteobacteria, Actinobacteria, Crenarchaeota, and Firmicutes was negatively correlated with soil pH, while Acidobacteria, Chloroflexi, Bacteriodetes, Planctomycetes, and Gemmatimonadetes were positively correlated with soil pH. Co-occurrence network analysis revealed that network topological features were weakened with increasing soil depth, indicating a more stable bacterial community in the RS1. Bacterial functions were estimated using FAPROTAX and the relative abundance of functional bacterial community related to metabolic processes, including C-cycle, N-cycle, and energy production was significantly higher in RS1 compared to RS2 and RS3, and soil pH had a significant effect on these functional microbes. Conclusions: This study provided the valuable findings regarding the structure and functions of bacterial communities in red soil of pomelo orchards, and highlighted the importance of soil depth and pH in shaping the soil bacterial population, their spatial distribution and ecological functioning. These results suggest the alleviation of soil acidification by adopting integrated management practices to preserve the soil microbial communities for better ecological functioning. [ABSTRACT FROM AUTHOR]

• Lime+Mg application increased the availability of N, P, Ca, Mg in acidic soils. • Lime+Mg increased edible rate, soluble solids, and reduced titratable acidity. • Pomelo yield increased by 30.5% under Lime+Mg application. • Lime+Mg application increased annual net income by 37.4%. Magnesium (Mg) is an essential mineral nutrient for plant growth, and its deficiency in citrus orchards has been widely observed in the acidic soils of southern China. Lime amendments have been proposed as potential solution to mitigate the soil pH and improve the soil quality. Therefore, we evaluated the effects of lime and Mg fertilizer on soil physicochemical properties, nutrients uptake, pomelo quality and yield, and economic benefits in the pomelo production area. For this, a field experiment was conducted during 2017–2019 using three treatment combinations; (i) control with no lime and Mg fertilizer (CK), (ii) Mg fertilizer with no lime (+Mg), and (iii) lime combined with Mg fertilizer (Lime+Mg). We found that Lime+Mg treatment significantly increased pomelo yield by 34.2% and 26.8% in 2018 and 2019, respectively over CK. Economically, Lime+Mg application increased the annual net income by 37.4%. Under Lime+Mg treatment, the concentration of N, K, Ca, and Mg was increased, while Fe and Mn decreased in leaf, peel, and pulp. Lime+Mg application significantly increased the edible rate, and total soluble solids (TSS) by 7.2% and 4.2%, respectively, while decreased the titratable acid (TA) by 11.7% in pomelo. Lime+Mg treatment also raised the soil pH, available N, P, Ca, and Mg concentrations significantly. Our results demonstrate that Lime+Mg incorporation to acidic soils of pomelo orchard alleviates the soil acidification, improves the nutrients availability, yield and fruit quality, and results in more economic benefits. [Display omitted] [ABSTRACT FROM AUTHOR]

Soil amendments, including lime, biochar, industrial by-products, manure, and straw are used to alleviate soil acidification and improve crop productivity. Quantitative insight in the effect of these amendments on soil pH is limited, hampering their appropriate use. Until now, there is no comprehensive evaluation of the effects of soil amendments on soil acidity and yield, accounting for differences in soil properties. We synthesized 832 observations from 142 papers to explore the impact of these amendments on crop yield, soil pH and soil properties, focusing on acidic soils with a pH value below 6.5. Application of lime, biochar, by-products, manure, straw and combinations of them significantly increased soil pH by 15%, 12%, 15%, 13%, 5% and 17%, and increased crop yield by 29%, 57%, 50%, 55%, 9%, and 52%, respectively. The increase of soil pH was positively correlated with the increase in crop yield, but the relationship varied among crop types. The most substantial increases in soil pH and yield in response to soil amendments were found under long-term applications (>6 year) in strongly acidic (pH < 5.0) sandy soils with a low cation exchange capacity (CEC, <100 mmol c kg−1) and low soil organic matter content (SOM, <12 g kg−1). Most amendments increased soil CEC, SOM and base saturation (BS) and decreased soil bulk density (BD), but lime application increased soil BD (1%) induced by soil compaction. Soil pH and yield were positively correlated with CEC, SOM and BS, while yield declined when soils became compacted. Considering the impact of the amendments on soil pH, soil properties and crop yield as well as their costs, the addition of lime, manure and straw seem most appropriate in acidic soils with an initial pH range from <5.0, 5.0–6.0 and 6.0–6.5, respectively. [Display omitted] • Soil amendments increased soil pH and crop yield by ca. 13% and 36%, respectively. • Amendments increased soil CEC, OM and base saturation and decreased bulk density. • Lime is the most economical while biochar is the most expensive for raising pH. • Lime, manure and straw are recommended at pH < 5.0, 5.0–6.0 and 6.0–6.5, respectively. [ABSTRACT FROM AUTHOR]

Extensive fertilization is a major factor of soil acidification worldwide and especially in China, where farmland soil pH has been declined significantly and resulted in soil deterioration. However, the status of fruit orchard systems is currently unclear. Therefore, we choose pomelo as a case study to analyze the current status, characteristics and improvement of soil acidification in orchards according to element and charge balances. The survey results showed that the soil pH in pomelo orchards continued to decrease from 2010 to 2018 and caused yields to decrease when the soil pH was lower than 4.5. In this period, the total soil acidification rate of pomelo orchards increased significantly from 29.6 to 39.6 keq H+ ha−1 yr−1. In addition, 67.0, 21.8 and 25.3% of soil acidification was caused by chemical fertilization, fruit harvest and pruning, respectively, and 19.8% of that was buffered by manure application. Reducing the inputs of nitrogen and phosphorus and increasing their nutrient use efficiencies can significantly reduce the soil acidification rate and product acid footprint (soil acidification rate per unit product) and increase the economic income/cost ratio. By using a structural equation model, the effects of nutrient use efficiency and the acid footprint on the income/cost ratio were 0.111–0.136 and −0.341 to −0.354, respectively. Scenario analysis further showed that the trade-off between soil acidification and economic benefits can be best circumvented in orchards while reducing greenhouse gas emissions based on the 'balanced fertilization +50% nitrogen substituted by manure +100% return of pruned parts' strategy. [Display omitted] • Severe soil acidification occurs in typical Chinese pomelo production systems. • 65.1–68.9% of the soil acidification is caused by chemical fertilization. • Manure application can buffer 11.4–28.1% of the soil acidification rate. • Improved nitrogen and phosphorus use efficiencies can reduce the acid footprint. • The trade-off between soil acidification and economic benefits can be circumvented. [ABSTRACT FROM AUTHOR]