Soil moisure, vol. % Precipitation, in. BSEN 4210 Irrigation HW 2 Daily Rainfall and Soil Moisture Ann Nunnelley 4 Sept. 2015

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1 BSEN 4210 Irrigation HW 2 Daily Rainfall and Ann Nunnelley 4 Sept The following graphs and tables represent the precipitation and soil properties from the Princeton#1 SCAN site (site# 2005) located in Caldwell County, KY 30 miles northwest of Hopkinsville. Latitude: 37 6 N Longitude: W. Elevation: 615- ft Precipitation, in Soil moisure, vol. % Precip. SM - 2" SM - 8" SM - 20" Figure 1: Princeton#1 rainfall and soil moisture at 2, 8 and 20 depth, Aug. Sept. 2015

2 Date 30- day and Precipitation Data Precipitation Increment(in) Percent - 2in Percent - 8in Percent - 20in 8/6/ /7/ /8/ /9/ /10/ /11/ /12/ /13/ /14/ /15/ /16/ /17/ /18/ /19/ /20/ /21/ /22/ /23/ /24/ /25/ /26/ /27/ /28/ /29/ /30/ /31/ /1/ /2/ /3/ /4/ Figure 2: Table of Princeton#1 precipitation and soil moisture data for depths of 2, 8 and 20 from the most recent 30- days.

3 Soil Pedon Information Depth (cm) Horizon Texture MC %(vol) at FC 15- Jan Ap SIL Bw SIL Bt1 SIL Bt2 SIL Btx SIL Btx SIL Bx SIL 17.4 Figure 2: Princeton#1 soil texture and field capacity moisture content by horizon FC at 33kPa Figure 3: Princeton#1 soil water retention curve for horizon Ap.

4 Questions: 1. Approximately how far is your SCAN station from Auburn in miles? a. The Princeton#1 SCAN station is 400 miles from Auburn driving and about 325 miles as the bird flies. I estimated these distances using Google Maps and the scale on the NRCS map respectively 2. What is the dominant soil texture in the crop root zone (upper mm) for your SCAN site? a. The only soil texture found in the crop root zone for this soil is silt loam 3. How does the soil moisture retention curve for topsoil at you SCAN site compare to the table values in your text (Table 15-2) for the corresponding texture? Provide comparative values from text and reference the soil moisture retention curve as part of your answer. a. The soil moisture retention curve for the silt loam topsoil from the SCAN data matches up relatively well with the values in Table 15-2 of the text. The table lists the average volumetric moisture content at field capacity to be 29% with a general range from 16-36%, whereas in the soil moisture retention curve, the moisture content at field capacity is as high as 47%. However, the permanent wilting point is much more similar. The table lists the silt loam permanent wilting point to be at 11% moisture content, or a range from 3-16%. The slope of the curve becomes less steep around 14% moisture content and levels off at 9% meaning the permanent wilting point is in a similar range as that presented in the table. 4. What is the web link for the NRCS Soil Data Mart to determine texture and other water holding properties for selected Alabama soil series at other sites? a.

5 Discussion: The relationship between precipitation and soil moisture at different depths is clear from the graph in Figure 1. Although the small amount of rainfall on August 6 th and 10 th didn t seem to affect the soil moisture at 8 or 20, small fluctuations can be seen in the graph in Figure 1 at a depth of 2. This is probably because the water accumulated in the top few inches was absorbed by surrounding plants or evaporated from the topsoil. However, the larger rainfalls of 0.81 and 1.49 on August 19 th and 30 th respectively caused an increase in soil moisture at all depths. The soil moisture at a depth of 8 is most likely the highest because the soil profile contains a slightly higher percentage of clay at this depth, so the soil has a greater water holding capacity that the horizons above it and may prevent moisture from small rainstorms from penetrating to the deeper levels. As can be seen from the table in Figure 2, the soil moisture for this site is typically above field capacity. This tells us that the site receives enough precipitation to support health crops and vegetation. However it also means that since gravitational water is dripping through the profile, it is most likely leaching nutrients from the soil. This needs to be taken into consideration when irrigating or fertilizing The total rainfall depth for the most recent 30- days is If this were the average rainfall per month, the site would receive slightly less than two- thirds of the mm average annual precipitation in Alabama, and slightly more than half of the average annual precipitation in Kentucky.