Field experiments were carried out to quantify the effects of cover cropping on soil physical properties. Field capacity (FC), permanent wilting point (PWP), soil-water holding capacity (SWHC), bulk density (pb), saturated and unsaturated hydraulic conductivity (Ks and Kus, respectively), and infiltration rates were measured and compared for four land cover treatments [cover crop without seed maize (CC), seed maize followed by cover crop (SCCC), bare soil, and seed maize without cover crop (SC)] in three large-scale production fields (~64 ha each) with silt loam soil in the 2012-2013, 2013-2014, 2014-2015, and 2015-2016 cover crop growing seasons. All production fields had been in a maize or soybean and cover crop rotation since 2002 and were farmed with row crops for decades before 2002. Field-measured soil properties in the SCCC treatment were also compared with historical values measured by the USDA-NRCS in 1974. In general, soil physical properties were unaffected by incorporating rotational cover crops into row crop cultivation. No significant differences (p > 0.05) in SWHC were observed between the treatments at any of the periods (seasons). When compared to the 1974 NRCS-measured values for the research fields, overall, the FC, PWP, and as a result the SWHC did not exhibit change at the end of the research in 2016 after cultivating cover crops since 2002. Ks values at the topsoil exhibited interannual variation for the same treatments, but there were no significant differences (p > 0.05) in Ks between land cover treatments neither in any year nor for the same treatment between years. Kus values were not significantly different (p > 0.05) between treatments neither for a given year nor between years. On average, the infiltration rate in the SCCC treatment was about 64% lower than in the SC treatment, indicating that incorporating cover crops into a maize-soybean rotation decreased the infiltration rate. While cover crops could be beneficial for grazing due to their nutritional value, and perhaps other benefits, which depend on numerous factors, in this research there was no sufficient evidence that cover crops can significantly alter the soil physical properties that were investigated in these experimental conditions.
Bibliographical noteFunding Information:
This project was funded and supported by the USDA-NRCS National Conservation Innovation Grants Program under Project No. 69-3A75-12-207. As the project Principal Investigator, Dr. Suat Irmak expresses his appreciation to the USDA-NRCS for collaboration and for providing financial support for this project. Dr. Irmak also expresses his appreciation to Roy Cast, David Cast, and Doug Cast in Beaver Crossing, Nebraska, for allowing us to conduct these extensive projects in their production fields and for their excellent collaboration. We also thank Kari E. Skaggs and all other current and former Irmak Research Laboratory members for their contributions in field data collection. This study is based on work that is supported by the USDA National Institute of Food and Agriculture under Dr. Irmak’s Hatch Project (Project No. NEB-21-155).
© 2018 American Society of Agricultural and Biological Engineers.
- Cover crops
- Maize-cover crop rotation
- Soil properties