Mitigating life-cycle environmental impacts and increasing net ecosystem economic benefits via optimized fertilization combined with lime in pomelo production in Southeast China.

Excessive fertilization is acknowledged as a significant driver of heightened environmental pollution and soil acidification in agricultural production. Combining fertilizer optimization with soil acidity amendment can effectively achieve sustainable crop production in China, especially in Southeast China. However, there is a lack of long-term studies assessing the environmental and economic sustainability of combining fertilizer optimization with soil acidity amendment strategies, especially in fruit production. A four-year field experiment was conducted to explore pomelo yield, fruit quality, and environmental and economic performance in three treatments, e.g., local farmer practices (FP), optimized NPK fertilizer application (OPT), and OPT with lime (OPT+L). The results showed that the OPT+L treatment exhibited the highest pomelo yield and fruit quality among the three treatments. The OPT treatment had the lowest net greenhouse gas (GHG) emissions among the three treatments, which were 90.1 % and 42.6 % lower than those in FP and OPT+L, respectively. It is essential to note that GHG emissions associated with lime production constitute 40.7 % of the total emissions from fertilizer production. The OPT+L treatment reduced reactive nitrogen (Nr) emissions and phosphorus (P) losses, compared to FP and OPT. Moreover, the OPT+L treatment increased the net ecosystem economic benefit by 220.3 % and 20.3 % compared with the FP and OPT treatments, respectively. Overall, the OPT and OPT+L treatments underscore the potential to achieve environmentally friendly and economically sustainable pomelo production. Our study provides science-based evidence to achieve better environmental and economic performance in pomelo production through optimized NPK fertilization and alleviating soil acidification by lime.

Differential response of bacterial diversity and community composition to different tree ages of pomelo under red and paddy soils.

Rhizosphere soil microbial communities substantially impact plant growth by regulating the nutrient cycle. However, dynamic changes in soil microbiota under different tree ages have received little attention. In this study, changes in soil physicochemical properties, as well as bacterial diversity and community structures (by high-throughput Illumina MiSeq sequencing), were explored in pomelo trees of different ages (i.e., 10, 20, and 30 years) under red and paddy soils cultivated by farmers with high fertilizer input. Moreover, soil factors that shape the bacterial community, such as soil pH, AP (available phosphorous), AK (available potassium), and AN (available nitrogen), were also investigated. Results showed that pH significantly decreased, while AP, AK, and AN increased with increasing tree age under red soil. For paddy soil, pH was not changed, while AP was significantly lower under 10-year-old pomelo trees, and AK and AN contents were minimum under 30-year-old pomelo trees. Both soil types were dominated by Proteobacteria, Acidobacteria, and Actinobacteria and showed contrasting patterns of relative abundance under different tree age groups. Bacterial richness and diversity decreased with increasing tree age in both soil types. Overall, bacterial community composition was different under different tree ages. RDA analysis showed that soil pH, AP, and AN in red soil, and pH and AP in paddy soil showed the most significant effects in changing the bacterial community structure. A random forest model showed Sinomonas and Streptacidiphilus in red soil, while Actinoallomurus and Microbacterium in paddy soil were the most important genera explaining the differences among different age groups. The ternary plot further revealed that genera enrichment for Age_30 was higher than that for Age_10 and Age_20 in red soil, whereas specific genera enrichment decreased with increasing tree age under paddy soil. Co-occurrence network revealed that bacterial species formed a complex network structure with increasing tree age, indicating a more stable microbial association under 20 and 30 years than 10-year-old pomelo trees. Hence, contrasting patterns of changes in soil physicochemical properties and soil microbial communities were recorded under different tree ages, and tree ages significantly affected the bacterial community structure and richness. These findings provide valuable information regarding the importance of microbes for the sustainable management of pomelo orchards by optimizing fertilizer input for different ages of trees.