Influence of long-term cropping systems on soil physical properties related to soil erodibility

Crop rotations and manure application are thought to alter soil quality. This study was conducted to quantify the effects of over 100 yr of continuous crop management and annual manure applications on selected soil physical properties at Sanborn Field, Columbia, MO. Intact soil cores (76 non i.d. by 76 mm) were collected from continuous corn (Zea mays L.), continuous wheat (Triticum aestivum L.), continuous timothy (Phleum pratense L.), and a rotation of corn-wheat-red clover (Trifolium pratense L.). The soil was Mexico silt loam (fine, smectitic, mesic, Aeric Vertic Epiaqualfs). Soil was tested throughout a 1-yr period for aggregate stability, single-drop rainfall splash detachment, and soil shear strength. Cropping systems affected aggregate stability (P < 0.01), soil strength (P < 0.01), and splash detachment (P < 0.01), but not bulk density. Continuous cropping to timothy produced soil that had three to four times greater aggregate stability, 21 to 27% greater soil strength, and 55 to 67% less soil splash compared with continuous wheat or continuous corn. Season significantly affected all measured soil properties, but the effect was inconsistent. The highest aggregate stability was found during July for all treatments. Splash detachment was more sensitive to cropping systems than other soil measures, and thereby the best measure for evaluating changes in soil erodibility. Cropping and soil management that accumulate plant residues can improve soil quality by increasing soil aggregate stability, shear strength, and resistance to splash detachment.