Correlation and Calibration of Soil-Test Sulfur Concentrations from Different Soil Depths with Soybean Yield

Sulfur (S) fertilization in soybean (Glycine max (L.) Merr.) production was investigated across 50 research sites in northeastern Louisiana during the 2023 and 2024 growing seasons. The objective of the study was to assess soybean yield response to six rates of S fertilizer (0, 11, 22, 34, 45, and 67 kg S ha-1), particularly in the context of declining atmospheric sulfur dioxide (SO₂) deposition following the implementation of the U.S. Clean Air Act (US-EPA, 2024). This work represents one of the most comprehensive datasets ever compiled in the United States for developing soil-test-based S fertilizer recommendations for soybean production.Of the 50 trials, 21 were conducted at the Macon Ridge Research Station (MRRS) in Franklin Parish, which features Gigger-Gilbert silt loam soil, and 29 were conducted at the Northeast Research Station (NERS) in Tensas Parish, characterized by Commerce silt loam soils (NRCS, 2024). Trials were laid out in a randomized complete block design with 4-5 replications per treatment. In 2023, fertilizer-S treatments included Sul4r-Plus (23% Ca, 17% S) and K-Mag (22% K₂O, 11% Mg, 21% S), while in 2024, Sul4r-Plus and gypsum (23% Ca, 17% S) were used. Each plot consisted of four rows, 10.67 m in length, with row spacing of 1.02 m at MRRS and 0.97 m at NERS.Soil samples were collected before planting from untreated control plots at two depths: 0–15 cm (10–12 cores) and 0–30 cm (8–10 cores) using a 2.2 cm diameter AMS soil probe from the top of the middle two seedbeds. Samples were air-dried for five days at 45°C, ground to pass through a 2 mm sieve, and analyzed by Waters Agricultural Laboratories in Vicksburg, Mississippi. Nutrient analysis was performed using Mehlich-3 extractant (Helmke & Sparks, 1996), while soil pH and organic matter content were determined following Sikora and Kissel (2014) and Schulte and Hopkins (1996), respectively. Cation exchange capacity (CEC) was estimated using methods outlined by Maguire and Heckendorn (2015).Fertilizer treatments were applied on the seedbed surface at or before planting. Soybeans were seeded between mid- to late May at a rate of 321,000 seeds ha-1, following corn (Zea mays L.), cotton (Gossypium hirsutum L.), or soybean. All sites were conventionally tilled and furrow irrigated. Lime and additional fertilizers were applied based on LSU AgCenter soil-test-based recommendations (Parvej, 2021, 2024), with lime incorporated only at sites with soil pH below 6.0. Standard irrigation, pest, and weed management practices were followed in accordance with LSU AgCenter Extension guidelines (Padgett et al., 2024; Stephenson et al., 2024; Villegas & Towles, 2023). Soybean was harvested at physiological maturity (R8 stage, as per Fehr & Caviness, 1977), and yield was calculated based on a uniform grain moisture content of 13% (130 g H₂O kg-1).This 50-site-year dataset offers a unique and robust foundation for establishing science-based, soil-test-calibrated S fertilizer recommendations for soybean production. It serves as a valuable resource for producers, agronomists, and consultants aiming to fine-tune S fertilization strategies, enhance productivity, and reduce unnecessary input costs. This dataset is part of the article submitted to the Soil Science Society of America Journal (Moni et al., 2025).2023年与2024年生长季，研究团队在路易斯安那州东北部的50个试验站点开展了大豆（Glycine max (L.) Merr.）生产中的硫（Sulfur, S）肥施用相关研究。本研究旨在评估大豆产量对6个硫肥施用量（0、11、22、34、45与67 kg S ha⁻¹）的响应，尤其聚焦于美国《清洁空气法案》实施后大气二氧化硫（sulfur dioxide, SO₂）沉降量下降的背景（US-EPA, 2024）。本数据集是美国有史以来针对大豆生产制定基于土壤测试的硫肥推荐方案所汇编的最全面数据集之一。 50个试验中，21个设于富兰克林堂区梅肯里奇试验站（Macon Ridge Research Station, MRRS），该站点土壤类型为Gigger-Gilbert粉砂壤土；剩余29个设于滕萨斯堂区东北部试验站（Northeast Research Station, NERS），土壤类型为Commerce粉砂壤土（NRCS, 2024）。试验采用随机完全区组设计（randomized complete block design），每个处理设置4~5次重复。 2023年所用硫肥处理剂为Sul4r-Plus（含23%钙、17%硫）与K-Mag（含22%氧化钾、11%镁、21%硫）；2024年则采用Sul4r-Plus与石膏（含23%钙、17%硫）。每个试验小区包含4行作物，行长10.67 m，MRRS的行间距为1.02 m，NERS的行间距为0.97 m。 播种前，研究人员使用直径2.2 cm的AMS土壤采样器，从中部两个苗床顶部采集未处理对照小区的土壤样品，采样深度分为两层：0~15 cm（采集10~12个土芯）与0~30 cm（采集8~10个土芯）。样品于45℃下风干5天后，研磨过2 mm筛，交由密西西比州维克斯堡的沃特斯农业实验室进行分析。养分分析采用Mehlich-3浸提法（Mehlich-3 extractant）；土壤pH与有机质含量分别参照Sikora与Kissel（2014）、Schulte与Hopkins（1996）的方法测定；阳离子交换量（cation exchange capacity, CEC）则采用Maguire与Heckendorn（2015）所述方法估算。 硫肥处理于播种时或播种前施用于苗床表面。大豆于5月中下旬播种，播种密度为321000粒 ha⁻¹，前茬作物为玉米（Zea mays L.）、棉花（Gossypium hirsutum L.）或大豆。所有试验站点均采用常规耕作与沟灌模式。根据路易斯安那州立大学农业中心（LSU AgCenter）的土壤测试推荐方案施加石灰与其他肥料（Parvej, 2021, 2024），仅在土壤pH低于6.0的站点施加石灰。灌溉、病虫害与杂草管理均遵循路易斯安那州立大学农业中心推广指南（Padgett et al., 2024; Stephenson et al., 2024; Villegas & Towles, 2023）。大豆于生理成熟期（R8期，参照Fehr & Caviness, 1977）收获，产量按统一籽粒含水率13%（130 g H₂O kg⁻¹）计算。 本50个站点-年度数据集为制定基于科学、经土壤测试校准的大豆生产硫肥推荐方案提供了独特且可靠的基础，可为种植者、农学家与顾问优化硫肥施用策略、提升生产效率并降低不必要的投入成本提供宝贵参考。本数据集为投稿至《美国土壤学会学报（Soil Science Society of America Journal）》的研究文章的一部分（Moni et al., 2025）。