Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/24/2014
Publication Date: 3/15/2015
Publication URL: http://handle.nal.usda.gov/10113/60746
Citation: Jabro, J.D., Stevens, W.B., Iversen, W.M., Evans, R.G. 2015. Spatial and temporal variability of soil penetration resistance transecting sugarbeet rows and inter-rows in tillage systems. Agronomy Journal. 31(2):237-246. DOI: 10.13031/aea.31.10722.
Interpretive Summary: Tillage is one of the most influential agricultural management practices that alters soil physical properties. A study was conducted to evaluate spatial and temporal variations of soil PR across the rows and inter-rows of sugarbeet on a clay loam under both CT and ST systems. Soil PR was significantly greater in CT than in ST when averaged across positions in rows and inter-rows of sugarbeet at the 0 to 30 cm depth for all sampling dates. Averaged across all depths and positions along a 61 cm transect, soil PR measurements were significantly influenced by tillage and they were greater in CT than that in ST on all four sampling dates. Soil PR was significantly greater in CT plots (1.5794 MPa) than in ST plots (1.1425 MPa) when averaged across all positions in sugarbeet rows and inter-rows, all depths, all replications, and all sampling dates. Statistical results indicated that significant temporal and spatial variations in soil PR under each tillage system were observed across the rows and inter-rows of sugarbeet on each sampling date throughout the growing season. Soil PR varied significantly among sampling dates in each tillage system and PR values increased as the growing season progressed and were the highest prior to crop harvest, approaching values greater than 3.5 MPa below the soil surface in inter-rows under CT. Spatial variation results showed that less compaction was observed in the planted crop rows than in inter-rows under CT and ST tillage systems because crop inter-rows were more affected by traffic passes thus contain less pore spaces than that in rows area and due to roots expanding action in the crop row area under both CT and ST.
Technical Abstract: Soil compaction has detrimental consequences on soil quality and plant root growth. Soil compaction is a variable property due to tillage in both space and time. A field study was conducted near Sidney, MT, USA, in 2007 to evaluate spatial and temporal variations of soil penetration resistance (PR) on a 61 cm transect across the rows and inter-rows of sugarbeet on a clay loam in both conventional (CT) and strip tillage (ST) systems. A cone penetrometer was used to measure PR as an indicator of compaction on a grid sampling scheme (5 cm horizontal x 2.5 cm vertical). The penetrometer was pressed into the soil every 5 cm along a 61 cm transect using a steel template bisecting the rows and inter-rows of sugarbeet. At each transect point, measurements were recorded at 2.5 cm depth increment to a depth of 30 cm. Soil PR measurements were recorded prior to planting (26 April), after the first cultivation (13 June), before harvest (03 October) and after harvest (04 October). Soil water contents were gravimetrically determined at the time of PR measurements. Soil PR was significantly greater in CT than in ST across the rows and inter-rows at the 0 to 30 cm depth for all sampling dates. Generally, soil PR increased with depth at every position on transect for all sampling dates under both tillage systems. Significant temporal variations in soil PR within each tillage system were observed throughout the growing season. Spatial variation data showed that less compaction was observed in crop rows compared to inter-rows under both tillage systems. Soil PR values increased as the growing season progressed and were highest prior to crop harvest, approaching values greater than 3.5 MPa below the soil surface. Interpolative kriged maps of soil PR were also produced to visualize spatial soil compaction distribution induced over time by each tillage system.