INTRODUCTION

1. LSD0.05 = 57 LSD0.05 = 9.95 Magnesium (ppm) Phosphorus (ppm) Fig. 5. Influence of liming materials on soil test magnesium at 0-15 cm, twenty-four months after application. Fig. 3. Influence of liming materials on soil test phosphorus at 0-15 cm, twenty-four months after application. Soil pH and available nutrient changes two years after application of liming materials in Mississippi William B. Evans*, Mississippi State University, 2024 Experiment Station Rd., P.O. Box 231, Crystal Springs, MS 39059-0231, and J. Larry Oldham, Mississippi State University, Mississippi State, MS 39762. INTRODUCTION  Selection of liming material and rate can greatly influence crop productivity. Haby and Leonard (2002) reported significant effects of lime rate, fineness, and depth of application on subterranean clover (Trifolium subterraneum L.) dry matter production in the greenhouse. The two also showed that fineness greatly influenced soil pH up to 156 weeks after application to a loamy fine sand. Huang, et al (2007) found significant difference in greenhouse media pH responses to various liming sources with equal mesh sizes. In Mississippi, Bufogle, et al. (2000) have shown significant differences in soil pH changes from various liming materials in the first fifty days after application to a sandy soil under laboratory conditions. In that report, some liming materials produced pH changes of over 1.0 units in the first fifty days after application, while others did not alter pH at all. Under field conditions at Beaumont and Crystal Springs Mississippi, materials tested over 235 days also had varied influence on pH but the changes in pH were smaller in general than those found in the laboratory study. Over ten different liming materials are available to producers in central Mississippi, and many questions still remain as to the appropriate use of each material in Mississippi agriculture. In the work presented here, ten locally-available liming materials and one untreated control are being compared in a long-term study of liming material chemical and physical qualities, and their influences on pH and other soil parameters. Materials being tested include slags, pelleted limes, dolomitic lime, and a hydrated lime. ABSTRACT Locally available liming materials were applied to replicated plots in Mississippi. Treated plots received a surface application of 4.5 Mg ha-1 of their assigned material in April 2005. The material was then tilled into the surface 15 cm on the day of application. Plots were sampled at 0, 30, 60, and 90 days after treatment (DAT), then approximately every 90 days through summer, 2007. Pre-application soil pH ranged from 6.4 to 6.6 among the four replicates. Soil pH remained significantly elevated in each treatment 24 months after application (MAA), ranging from 6.8 to 7.5 (untreated pH = 6.4 at 24 MAA). Differences in soil test P, Ca and Mg levels were also present. Neither liming nor lime source significantly altered soil test S, Zn, Na, or soil organic matter levels. Soil pH changes in response to treatment have differed indicating significant differences in the influence of the materials on soil pH under the Crystal Springs conditions to date. The study will follow soil pH in the plots for one more year or until there is significant decrease in pH down to or near the initial pH levels. Table 1. Summary of the recently-revised Mississippi lime regulations (Mississippi Bureau of Plant Industry, 2005). MATERIALS AND METHODS The field study (Fig. 1) is being run at the Truck Crops Branch Experiment Station in Crystal Springs, Mississippi on a Providence silt loam (fine-silty, mixed thermic Typic Hapludalf). Treated area of each plot is 1.5 m. X 3.0 m, and is maintained with no crop and minimal weed vegetation. Grass sod is maintained in 1.5 m borders around each plot to reduce erosion and movement of soil among plots. The equivalent of 4.5 Mg ha-1 of each material was applied by hand to the 4.5 m2 area of bare ground. The materials were tilled in with a rotary tiller to a depth of 15 cm on April 18, 2005. Plots were sampled monthly for the first three months. They were and will be sampled quarterly thereafter through year 3 (36 months) and possibly beyond.  Soil samples consist of five 2.5 cm diameter cores, 15 cm deep taken from the center axis of each plot. These are blended, air dried, and sent to the MSU Soil Testing Laboratory at Mississippi State, Mississippi for the lab’s standard soil physical and chemical analysis package, including pH. The study is a single-factor experiment, with eleven treatments arranged using a randomized complete block design, with four replications. Data are being analyzed by SAS 9.0 using the ANOVA and GLM procedures. RESULTS AND DISCUSSION Pre-application soil pH ranged from 6.4 to 6.6 among the four replicates (data not shown), somewhat closer to neutral than our team anticipated. All products tested appear to meet the recently revised State of Mississippi lime regulation standards (Table 1), having an RNV of 63 or greater (Table 2). Soil pH changes have differed among treatments and sampling dates, indicating significant differences in the influence of the materials on soil pH under the Crystal Springs conditions to date. Most products significantly raised soil pH by 30 DAT (Fig. 2). Incorporation of the “Lime - Hydrated” or “Slag product” lead to the largest degree of change in soil pH. The remaining treatments produced intermediate changes in soil pH compared to the other treatments. By two years after application, plots receiving either the “Lime – Hydrated” or the “Water Treatment By-Product” showed declining soil pH. The other materials do not seem to have lead to this type of response. No material applications resulted in an increase in soil pH at two years after application over those seen at the one month sample. At two years after application, “Lime – Hydrated” had increased soil test phosphorus values, four materials had significantly elevated soil test calcium values, and five had significantly elevated soil test magnesium values (Figs. 3-5). Soil organic matter concentration, potassium, zinc and sulfur test values were not altered by material applications at two years after application (data not shown). Figure 1. Liming study plot area at Crystal Springs, Mississippi, October, 2007. LSD0.05 = 414 Calcium (ppm) Table 2. Characteristics of locally-available liming materials being tested. Fig. 4. Influence of liming materials on soil test calcium at 0-15 cm, twenty-four months after application. Soil pH LITERATURE CITED  Bufogle Jr., A., M.S. Cox, P.D. Gerard, and P.M. Hudson. 2000. Speed and effectiveness of various liming materials. 1999 Progress Report Central Mississippi Research and Extension Center. Info. Bull. 366. pp. 172-177. Bureau of Plant Industry. 2005. Regulations under the Mississippi Agricultural Liming Act of 1993. Mississippi Department of Agriculture and Commerce. (http://www.mdac.state.ms.us/ n_library/agency_info/reg_laws/pdf/reg_feedfert_lime.pdf) Haby, V.A. and A.T. Leonard. 2002. Limestone quality and effectiveness for neutralizing soil acitidy. Comm. Soil Sci. Plant Anal. 33(15-18):2935-2948. Huang, J., PR. Fisher, and W.R. Argo. 2007. Container substrate-pH response to differing limestone type and particle size. HortSci. 42(5)1268-73. Sampling Date *By wet sieving; **Lab reported too much iron in product for proper CCE determination. Fig. 2. Soil pH at 0-15 cm after application of locally-available liming materials on April 18, 2005. Sampling dates shown: May 18, 2005; April 18, 2006; and April 18, 2007 (1, 12, and 24 months after application). Thank you to: the Truck Crops Branch Experiment Station crew; Operations Coordinator Peter Hudson; Research Associate Keri Paridon; Keith Crouse and the MSU Soil Testing Laboratory; and Reba Ingram and the Mississippi State Chemical Laboratory.