Soil Infiltration Rate and Its Dynamics in Six Land Management Systems of Western Kentucky.

The evaluation of infiltration rates is vital to estimate surface runoff in order to reduce the risk of pollutant contamination and to efficiently apply water and fertilizers for a crop’s benefit. The objectives of this study were (1) to assess the impacts of six agroecosystems on infiltration rates; (2) to observe the temporal variability of soil infiltration rates under various seasons (fall-spring-summer-fall); and (3) to quantify the relationships between soil infiltration rates with other properties including soil organic carbon (SOC), macroaggregates, and bulk density. The study was conducted in Calloway County of western Kentucky using six agroecosystems.  They were no-till corn, conventional tillage soybeans, conventional tillage tobacco, organically grown vegetables, woodland, and prairie. All of the soils used in this study have a silt loam texture. The infiltration rates were measured using a single ring infiltrometer. Soil organic carbon (SOC) was measured using the loss on ignition (LOI) method. Macroaggregates and bulk density were determined using wet sieving and ring methods, respectively. The data was statistically analyzed using ANOVA followed by the least significant difference (LSD) test at α 5%.The results show that organic farming and the wooded system have the highest infiltration rates(35.2 cm/hr and 37.7 cm/hr) and the lowest bulk densities (1.0 g/cm³ and 1.1 g/cm³), respectively. The relationship between infiltration rate and organic carbon, bulk density, macroporosity, and total porosity was r²=.99, r²=.60, r²=.69, and r²=.66. The no-till corn field had a higher bulk density than the conventionally tilled systems (1.7 g/cm³) and lower total porosity of 37%, but had a higher infiltration rate than the conventionally tilled systems at approximately 12.9 cm/hr. The organic system had a 60% lower bulk density than the no-till corn, which were the highest and lowest bulk densities, respectively. The most dramatic differences amongst infiltration rate occurred in the wooded system which increased from 36.3 cm/hr in the fall of 2013 to 39.3 cm/hr in the summer of 2014. Amongst the averages, however, which range from 4.3 cm/hr to 37.7 cm/hr, the seasonal changes were not significant.