Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/19/2000
Publication Date: N/A
Interpretive Summary: As agricultural tractors and field equipment get larger, the concern about soil compaction increases. Larger land areas being farmed by the same set of machinery increases the possibility that field operation will occur when soil is easily compacted. Instrumentation is needed to measure when soil is compacted to a level that, without additional tillage, will restrict crop root growth. Furthermore, instrumentation is needed that can acquire data across a range of soil types and soil moisture contents and provide a measure of compaction that is independent of soil moisture content. This paper reports on laboratory testing of a novel instrument consisting of a USDA-Agric. Research Service designed and patented soil moisture sensor integrated into a soil cone penetrometer. The instrument uses a fiber optic bundle to transmit light down the penetrometer shaft and through a specially designed penetrometer cone onto the soil surface. Light reflected dfrom the soil is transmitted back up the shaft to the soil surface for analysis and moisture prediction. Soil cone index, measured in the same manner as with a conventional penetrometer, can then be adjusted to a standard soil moisture level. This laboratory study reports on the development of a force/ moisture relationship for 3 surface agricultural soils in IL and indicates that adjusting soil cone index to compensate for variations in soil moisture may be possible. Commercialization of this concept could significantly increase the usefulness of soil penetration resistance data and lead to reduced primary tillage when used to measure soil compaction. Reduced tillage will impact producers through savings in labor, fuel, and machinery costs and will benefit consumers through reduced erosion and sedimentation.
Technical Abstract: Soil penetration resistance continues to be an important research topic in site-specific applications. Soil compaction can restrict root growth and water infiltration, resulting in yield reduction. Maps of yield monitor data aid in visualization of variations in yield, without identifying underlying factors for these variations. Soil penetration resistance can help identify areas where soil physical characteristics are negatively impacting yield. There is a wide array of penetration devices available to measure penetration resistance. But penetration resistance is a function of moisture content and soil type as well as compaction. This paper discusses the development and testing of a penetrometer equipped with a near-infrared (NIR)reflectance sensor to also measure moisture content and organic matter. The combined instrument was tested on a selection of soil types with varying moisture contents in stationary and traverse modes.