ARS | Publication request: AN INEXPENSIVE AND SIMPLE METHOD TO DEMONSTRATE WATER INFILTRATION AND WATER-HOLDING CAPACITY IN THE FIELD AND CLASSROOM

Submitted to: Meeting Abstract
Publication Type: Abstract
Publication Acceptance Date: February 15, 2006
Publication Date: July 9, 2006
Citation: Nichols, K.A., Liebig, M.A., Samson-Liebig, S.E. 2006. An inexpensive and simple method to demonstrate water infiltration and water-holding capacity in the field and classroom. Meeting Abstract. World Congress of Soil Science, Philadalphia, PA, July 9-15, 2006.

Technical Abstract: In semiarid regions, such as the Northern Great Plains, water is usually the limiting resource in plant production, but demonstrating the link between soil quality and water infiltration and water-holding capacity is challenging. The Soil Quality Test Kit provides for measurement of seven soil quality indicators: bulk density, infiltration rate, water-holding capacity, electrical conductivity, soil pH, soil nitrate, and soil respiration. This kit is sold commercially for approximately 500 U.S. dollars. Soil samples at surface depths (0-5, 0-10, and 0-15 cm) were collected from four studies in North and South Dakota: 1. a cropping systems study at the Northern Great Plains Research Laboratory (NGPRL) near Mandan, ND; 2. a rangeland restoration study at NGPRL; 3. a combination cropping and rangeland management study near Huron, SD; and 4. a rangeland management study near Streeter, ND. All samples were air-dried, except for the NGPRL cropping systems study which had both field moist and air-dried samples. Soil was placed into a 5 ounce (147.83 ml) paper cup with holes in the bottom (50 holes made with an 18 gauge needle) to a height were the internal diameter was 4.74 cm giving the soil would have an area of 17.6 cm. This paper cup was placed into a 3 ounce (88.7 ml) paper cup. Milli-Q water equivalent to 2.54 cm (1 in) was added and the infiltration rate was measured. For the air-dried samples, another 2.54 cm of water was added. Water collected in the bottom cup was measured using a graduated cylinder. This water will be further analyzed for soil nitrate colorimetrically using AquaChek Nitrate/Nitrite water quality test strips and anions and cations will be measured in the laboratory using an ion chromatograph. Soil in the bottom cup was incubated in the laboratory to measure the rate at which the soil returned to an air dry state. Preliminary results show that the infiltration rate in the rangeland studies was faster than in the cropland studies for both the first and second 2.54 cm. In the field moist samples from the cropland study at NGPRL, the no till treatment had an infiltration rate of 12 min 3 s while the minimum till treatment had a rate of 41 min, 22 s. There was no difference in the amounts of water collected in the bottom paper cup between rangeland and cropland air-dried soils or the field moist cropland soils. However, incubation studies in the laboratory are demonstrating that there difference in the time required for the soils to return to an air-dried state, and on-going trials in the field have shown a difference in the amounts of water collected in paired cropland and rangeland studies with the rangeland treatments retaining more water in the soil. This method provides an inexpensive and simple procedure to demonstrate water infiltration and soil water-holding capacity in the field or classroom setting.