Fellow: Anthony Walekhwa Wamono
Advisors: Dean D. Steele and Zhulu Lin

The installation of tile drainage to remove excess moisture in the fall and spring poses a risk of transforming saline-sodic soils to sodic soils in the Northern Great Plains. Yet, leaching of sodic soils with low EC water results in the swelling of the soil, dispersion of clay particles and consequently the breakdown of soil structure. Changes in soil hydraulic and physical properties ensue, such as reduced hydraulic conductivity and increased soil hardness when the soil is dry. In this study, the cone index (CI), a measure of penetration resistance, will be determined for the plots at Wyndmere and Grand Forks sites in North Dakota using a hand held penetrometer. Soil water content measurements will augment the CI data. Statistical analyses of CI relationships with depth, moisture content, drainage state, and surface treatments will be determined. A Cornell sprinkler infiltrometer will be used to measure the changes in hydraulic conductivity of the plots. The effectiveness of calcium based surface amendments and cover crops under drainage and non-drainage options on improving the hydraulic and mechanical properties soil will be evaluated.

Project Objectives:

The main objective of this study is to evaluate effectiveness of calcium based surface amendments and cover crops under drainage and non-drainage options on improving the hydraulic and mechanical properties of the soil.

Progress:

Infiltration Measurements
A total of 54 mini-disc tension infiltrometer and 18 Cornell sprinkler infiltrometer tests were successfully completed in the summer of 2014 at the Wyndmere, ND, field site. The Cornell sprinkler infiltrometer tests were limited due time constraints to one sample per plot as opposed to three samples as was the case in mini disc tension infiltrometer. Further analysis of infiltration tests is being done using analysis of variance techniques.

Penetration Resistance Measurements
To investigate the effects of drainage and surface amendments on the hard setting of sodic soils in Wyndmere, the penetration resistance (PR) data was collected in August when the soil was fairly dry. However, extremely hard spots with PR readings greater 7000 kPa, the upper limit of the penetrometer, were encountered in the soil profile during data collection. Preliminary analysis of results shows weak relationships between the penetration resistance and surface treatments. This could be attributed to the limitation of the hand held penetrometer in extremely hard soil. Further analysis of results is ongoing. The manuscript "Effects of calcium based surface amendments on the penetration resistance of subsurface drained saline-sodic soils" is still in preparation for submission in the Transactions of the ASABE.

Significance:

Maintaining productive and sustainable agriculture on poorly drained soils depends on understanding the risk of hard setting posed by draining saline-sodic soils. The results of this study will help develop guidelines and recommendations for removing excess water, thereby improving the trafficability and workability of sodic-saline soils.

Conference/Seminar Presentations:

     Wamono A.W., D.D. Steele, Z. Lin, T. DeSutter, and X. Jia. 2015. Effects of calcium amendments on infiltration rates of subsurface drained sodic soils. Presented to the North Central American Society of Agricultural and Biological Engineers Conference, 10-11 April 2015, Fargo, North Dakota. Presentation No. RRV15-031.

     Steele, D.D., A.W. Wamono, T. DeSutter, Z. Lin, and X. Jia. 2015. Measuring Chisel Plow Draft on a Sodium-Affected Soil. Written for presentation at the North Central American Society of Agricultural and Biological Engineers Conference, 10-11 April 2015, Fargo, North Dakota. Presentation No. RRV15-046.

     Wamono, A.W., D.D. Steele Z. Lin, T.M. DeSutter, X. Jia and D. Clay. 2014. Effects of calcium based surface amendments and cover crops on the penetration resistance of subsurface drained sodic-saline soils. Presented at the 2014 ASABE and CSBE/SCGAB International Meeting, July 13-16, Montreal

     Wamono, A.W., D.D. Steele Z. Lin, T.M. DeSutter, X. Jia and D. Clay. 2014. Penetration Resistance Measurements to Evaluate the Effects of Calcium Amendments and Water Management Strategies in Sodic-Saline Soils. Presented at the 2014 ASABE Intersectional Meeting, 28-29 March, Brookings, South Dakota