2/19/2016. Objectives. The Basis of Life. Previous Studies. Physical Properties DYNAMICS OF SOIL INFILTRATION RATES IN VARIOUS AGRO-ECOSYSTEMS

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1 DYNAMICS OF SOIL INFILTRATION RATES IN VARIOUS AGRO-ECOSYSTEMS Landon Gibbs and I.P. Handayani Murray State University Hutson School of Agriculture The Basis of Life Soil provides the medium for plant growth- and soil health directly impacts the production of crops in agriculture. Soil physical properties such as soil texture, structure, density, and water holding capacity are important in regards to erosion, crop health, land management and use, and conservation practices. Soil fertility also greatly influences crop health and production. Objectives To measure infiltration rates in six agro-ecosystems To illustrate infiltration rate in relation to temporal variability. To determine the contribution of soil organic carbon, aggregation, bulk density, and porosity in relation to infiltration rates. Physical Properties Maroaggregates are clusters or clumps of soil particles (sand, silt, or clay) in a particular structure such as a prism, or block. Macroaggregates are held together by organic matter. Porosity is the amount of pore space in a soil profile or sample. Bulk density is the mass of the soil divided by the volume of the sample. Highly compacted soils have higher bulk densities. Previous Studies Previous studies indicate that soil infiltration rates are affected by soil physical properties, such as distribution of particle size, bulk density, total porosity and soil structure (Boyle et. al., 2014). 1

2 Soil Infiltration Rate What is the Impact? Soil infiltration rate is the entry of water into the soil surface (Lang & Wang, 2013) The rate at which water enters the soil is directly relatable to the amount of runoff coming from the land management system. Intensive cultivation and farming practices can alter soil structure and limit infiltration, which results in inefficient water use and can expedite runoff and erosion (Boyle et. al., 2014). Poor infiltration rates increase runoff creating more erosion problems and loss of nutrients from the topsoil (Burri et al., 2009). The study sites (6) are located in Murray State University Farms in Calloway County, Kentucky (36.61 o N, o W and o N, o W). Six management systems ( Organic farming, corn, woods, soybean, tobacco, prairie). A single ring infiltrometer was used with three replications at each site, and each replication was repeated three times in randomized locations. Readings were taken in the Spring of 2013 and the Summer and Fall of Infiltrometer Soil samples were harvested to determine organic carbon, macroaggregates, and water content at air dry. These samples were composite samples, made up of four samplings to form the composite; three samples were taken from each site. 2

3 The organic carbon was determined using a muffle furnace at 500 C for five hours, and was measured in duplicate from the soil samples, resulting in 36 organic carbon samples. Macroaggregates were determined using air dry samples and the wet sieve method. Bulk density was measured by taking core samples and allowing the cores to dry at 105 C and then utilizing the cores net dry weight (Stockfisch et. al., 1999). Core samples were also allowed for the evaluation of porosity of the six land management systems that were assessed, using the method of of Chevallier et al. (2011)

4 Soil Properties Soil Infiltration Rates (cm/hr) Soil Organic Carbon (g/kg) Macroaggregate Content (g/kg) Porosity % (Macro) Bulk Density (g/cm^3) Soil Organic Carbon Organic carbon content is an indicator of the amount of organic matter in a soil. Organic matter is composed of various dead plant and animal parts in differing stages of decomposition. Organic matter improves the binding of soil particles into aggregates which can increase infiltration rates (Liu et al., 2012). 4

5 Conclusions Conclusions Organic farming and the wooded system have the highest infiltration rates(35.7 and 37.7 cm/hr), each also having the lowest bulk densities of 1.0 and 1.1 g/cm³ and highest percentages of organic carbon at 65 and 32 g/kg, respectively. Infiltration rates of the organic farming system were nearly 54% higher than that of the conventional tillage tobacco which was the lowest. r²= 0.99 for SOC and r²= 0.88 for macroaggregates. Infiltration rates were higher during the summer for five out of the six systems( cm/hr), although the results were not statistically significant. Conclusions Further Studies This study signifies the importance of maintaining SOC and macroaggregates to reduce runoff and compaction in agricultural fields. With better management and monitoring of SOC and soil structure (macroaggregation, porosity), infiltration can be improved and runoff can be reduced. For future implications, I would like to replicate this study once more, utilizing a larger sample base and perhaps a double ring infiltrometer. 5

6 References Ayu, IW, S. Priyono & Soemarno Assessment of Infiltration Rate Under Different Drylands Types in Unter-Iwes Subdistrict Sumbawa Besar, Indonesia. Journal of Natural Sciences Research 3(10): Boyle, M., W.T. Frankenberger & L.H. Stolzy The Influence of Organic Matter on Soil Aggregation and Water Infiltration. Journal of Production Agriculture. 2 (4): Burri, K., F. Graf & A. Boll Revegetation Measures Improve Soil Aggregate Stability: a case study of a landslide area in Central Switzerland. Swiss Federal Institute for Forest, Snow, and Landscape Research. Liu, Z., N. Lang & K. Wang Infiltration Characteristics Under Different Land Uses in Yuanmou Dry-Hot Valley Area. Proceedings of the 2nd International Conference on Green Communications and Networks. DOI: / Springer-Verlag Berlin Heidelberg. Acknowledgements I would like the thank The Hutson School of Agriculture, The Office of Research and Scholarly Activity on MSU s campus, and the Murray State Honors College for helping to fund my travel. Questions? 6