Effect of previous crop roots on soil compaction in 2 yr rotations under a no-tillage system

Authors: Jabro, Jalal - Jay; Allen, Brett; Rand, Tatyana; Rana Dangi, Sadikshya; Campbell, Joshua

Submitted to: Land
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2021
Publication Date: 2/17/2021
Citation: Jabro, J.D., Allen, B.L., Rand, T.A., Rana Dangi, S., Campbell, J.W. 2021. Effect of previous crop roots on soil compaction in 2 yr rotations under a no-tillage system. Land. 10(2):202. https://doi.org/10.3390/land10020202.
DOI: https://doi.org/10.3390/land10020202

Interpretive Summary: Compaction is a form of soil degradation affecting future global food security. Previous research has shown that compacted soils can reduce crop yield by 40-50% due to reduced air, water and nutrient movement, and increased resistance to root growth and penetration. Several approaches have been used to alleviate soil compaction in agricultural lands including mechanical, natural and biological. Biological methods such as deep-rooted cover crops can be a potential solution to ameliorate the negative effects of soil compaction, particularly in no-tillage farming production. Cover crops (i.e., rye grass, radish, safflower, turnip, etc) with vigorous taproots can reduce soil compaction by penetrating and loosening the compacted layer. Over time, these roots eventually decompose and form root channels and large bio-spaces that enable air, water, nutrient and roots of successive crops to move more deeply through the soil profile. This method may potentially free farmers from the need to use costly mechanical measures such as sub-soiling and deep tillage to combat soil compaction in no-tillage farming.

Technical Abstract: Compacted soils affect global crop productivity and environmental quality. A field study was initiated in 2014 to evaluate the effect of various rooting systems on soil compaction in 2-yr rotations of camelina, carinata and a cover crop mix planted in place of fallow with durum. The study was designed as a randomized complete block with three replications in a no-tillage system. Three measurements of soil penetration resistance (PR) were taken with a penetrometer to a 30-cm depth within each plot. Soil moisture contents were determined using a TDR sensor at the time of PR measurements. Both measurements were monitored prior to planting in spring and after harvest. Initial PR results from spring 2014 showed that all plots had an average of 2.244 MPa between the 8 - 20 cm depth, due to a history of tillage and wheel traffic caused by various field activities. Covariance analysis indicated that soil PR was not significantly affected by crop type and moisture content. After one cycle of the 2-yr rotation, the 2016 measurements indicated that the compacted layer existed at the same initial depths. However, after two and three cycles, soil PR values were reduced to 1.480, 1.812, 1.775, 1.645 MPa in spring 2018 and 1.568. 1.581, 1.476, 1.458 MPa in 2020 under camelina, carinata, cover crop mix, and durum treatments, respectively. These findings indicate that previous cover crop roots could effectively improve soil compaction by penetrating the compacted layer, decompose over time and form voids and root channels. This biological approach could offer a less expensive solution to combat soil compaction and provide better soil quality benefits than deep tillage and subsoiling. More research is needed on different soils and under cover crops with different root systems to support our findings prior to making any conclusion.