Long-term rice-based cropping system effects on near-surface soil compaction

Abstract

Irrigated rice (Oryza sativa L.) production is as-sociated with frequent cycling between anaero-bic and aerobic conditions, which can lead to a greater rate of soil organic matter (SOM) de-composition, thus potentially increasing soil bulk density (BD) over time. A study was con-ducted in the Mississippi River Delta region of eastern Arkansas, USA to evaluate the long-term effects of rice-based crop rotations, tillage [conventional tillage (CT) and no-tillage (NT)], soil fertility regime (optimal and sub-optimal), and soil depth (0-10 and 10-20 cm) after 10 years of consistent management on near-surface soil compaction, as measured by BD. Soil BD was greater under NT than CT in the top 10 cm, but was similar between NT and CT in the 10- to 20-cm depth interval. Soil BD differed among common rice-based cropping systems with corn, soybean, and winter wheat, but few consistent trends were evident. It appears that, even after 10 years of continuous CT or NT rice production on a silt-loam soil, substantially increased near-surface soil BD has not occurred to the point where soil compaction would be a likely culprit responsible for a reduced early season stand establishment or crop yield differences among rice-based copping systems.