Data_Sheet_1_Foliar Application of a Microbial Inoculant and Alkali-Extracted Humic Product Boosts Forage Productivity and Quality on a Central Coast California Rangeland.docx

There is increasing interest in using biostimulant products, such as microbial inoculants and alkali-extracted “humic” substances to help manage rangelands regeneratively and rebuild soil health. Understanding how plant and soil communities on rangelands respond to these products is therefore important. In this 3-year study, we examined the combined effects of a commercial inoculant and alkali-extracted “humic” product that are currently on the market (Earthfort Inc. Soil Provide and Revive®) and asked whether they influenced rangeland forage productivity and quality, soil microbial biomass and community composition, and abiotic soil parameters in Central Coastal California. Treatments were established in February 2018 and the products were applied two to three times a year during the growing season (approximately November—May). Sampling of plant and soil samples also began in February 2018 and continued in the fall and spring for three consecutive growing seasons. We found that forage productivity responded positively to the foliar application of these commercial products, with forage production on average 58% percent higher in treated compared to control sites. Some metrics of forage quality (acid detergent fiber, calcium, and fat content) also responded in a desirable way, but these benefits were not mirrored by changes belowground in the microbial community or abiotic parameters. While our study derives from one ranch and therefore requires confirmation of its ubiquity prior to broadscale adoption, our results provide new insights into the usefulness of this approach for managing rangeland productivity in California's Central Coast—and suggest biostimulants could warrant attention as a potential tool for regenerative stewardship of rangelands more broadly.

当前，利用生物刺激素（biostimulant）产品——包括微生物菌剂（microbial inoculants）与碱提取腐殖质类物质（alkali-extracted "humic" substances）——开展牧场修复性管理并重建土壤健康的研究日益受到关注。因此，明确牧场植物与土壤群落对这类产品的响应机制至关重要。本研究为期三年，针对当前市售的商业菌剂与碱提取腐殖质类产品（Earthfort Inc. Soil Provide与Revive®）的联合效应展开探究，旨在明确其对加利福尼亚中部沿海地区牧场牧草生产力与品质、土壤微生物生物量及群落组成，以及土壤非生物参数的影响。试验处理于2018年2月设立，在生长季（约11月至次年5月）每年施用2至3次受试产品。植物与土壤样品的采集工作同样始于2018年2月，在随后连续三个生长季的春秋两季持续开展。研究结果显示，叶面施用上述商业产品可正向提升牧草生产力，处理组的牧草产量较对照组平均高出58%。部分牧草品质指标（酸性洗涤纤维、钙含量与粗脂肪含量）也呈现出向好的响应趋势，但这类地上益处并未在地下微生物群落或土壤非生物参数的变化中得到体现。尽管本研究仅基于单个牧场开展，因此在大规模推广前仍需验证其普适性，但研究结果为加利福尼亚中部沿海地区牧场牧草生产力的管理策略提供了全新视角，同时表明生物刺激素有望作为更广泛范围内牧场修复性管理的潜在工具，值得进一步关注。