Short-term cultivation limiting soil aggregate stability and macronutrient accumulation associated with glomalin-related soil protein in Eucalyptus urophylla ? Eucalyptus grandis plantations

The relationship between glomalin-related soil protein (GRSP) and soil aggregation has been a hot topic of research for its close link to soil stability and quality. However, the short-term cultivation of Eucalyptus poses serious threats to soil stability and nutrient stocks, and the effects of GRSP on soil aggregate stability and macronutrient accumulation re-main unclear. The aim is to clarify the potential mechanisms affecting soil aggregate stability and macronutrient accu-mulation in short-term Eucalyptus plantations. Five Eucalyptus urophylla x Eucalyptus grandis plantations with different cultivation periods (1-5 years) in this study were investigated, anda native evergreen broadleaf forest (0 year) was selected as control. The mean weight diameter index increased in the first 3 years and then significantly decreased dur -ing 5 years cultivation of Eucalyptus. Soil organic carbon (SOC) and total nitrogen also decreased after planting Euca-lyptus for 3 years, but variation in total phosphorus was not obvious. The relative abundance of Glomeraceae and Claroideoglomeraceae decreased in the 5-year-old Eucalyptus plantations and was positively correlated with GRSP con -tent. In pathway modeling, nutrient-acquisition enzyme activities positively affected GRSP and macronutrient content. Total GRSP (T-GRSP) had higher total effects than easily extractable GRSP on soil aggregate stability, and positively correlated with SOC in macroaggregates. Both T-GRSP and SOC had positive and direct effects on soil aggregate sta-bility. Variance partitioning analysis further explained the contribution of GRSP and SOC to aggregate stability, partic-ularly in >2 and 2-0.25 mm macroaggregates. Our results suggested that GRSP was directly associated with SOC content and soil aggregate stability, and was a potential key factor affecting soil aggregate stability in Eucalyptus plantations. Improving T-GRSP and SOC are efficient approaches for preventing the gradual deterioration of soil aggre-gate stability. Short-term cultivation should be carefully used in Eucalyptus plantations, and a new cultivation period is needed.

Automated summary

The relationship between glomalin-related soil protein (GRSP) and soil aggregation has been extensively studied, but the effects of GRSP on soil aggregate stability and macronutrient accumulation in short-term Eucalyptus plantations are still unclear.