Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/19/2000
Publication Date: N/A
Interpretive Summary: For producers, merely identifying yield variation with yield monitoring systems provides little information about what caused the observed variability or what management alternatives should be applied to improve yields or profitability. Producers want to know what, if anything, can be done to profitably increase yields where soil conditions warrant additional lmanagement. Inexpensive and accurate methods for measuring and mapping soil properties that affect yield within fields are needed and would greatly help those interpreting yield maps. The objective of this research was to evaluate the relationship of soil electrical conductivity (EC)to a soil productivity index developed in the 1980s for Missouri soils. The investigation was conducted on claypan soils of the historic Sanborn Field, located on campus at the University of Missouri, Columbia. We found that differences in soil EC were related to the calculated soil productivity index of claypan soils. Estimated plant-available water content and bulk density were the two soil properties that most affected soil EC. This individual study is part of a larger project designed to develop efficient ways for cost-effectively measuring soil and field characteristics. Results will benefit farmers and crop consultants by helping them understand variations in within-field crop production. From this they will be able to develop improved site-specific management plans that are more efficient and environmentally friendly.
Technical Abstract: Efficient methods and sensors are needed to explain crop yield variability associated with soil physical properties. Physical properties of claypan soils that affect crop production have been shown to correlate to soil apparent electrical conductivity (ECa). This analysis investigated the potential that ECa measurements could be used on claypan soils to estimate a soil productivity index previously developed for Missouri soils. An electromagnetic induction meter was used to measure the soil ECa at core sample sites on historic Sanborn Field, located at the University of Missouri, Columbia. Soils closely relate to and include the Mexico series (Fine, smectitic, mesic Aeric Vertic Epiaqualfs). Soil ECa measurements were taken in the horizontal mode at 0- and 75-cm heights and in the vertical mode at 0- and 50-cm heights. The soil productivity index was calculated for each core based on the soil properties of bulk density, plant available water-holding capacity, and salt pH. Variations in soil EC measurements were significantly related to the soil productivity index. Elevated measurements of ECa (horizontal, 75-cm height; vertical, 50-cm height) best explained soil productivity index variation. A regression found a combination of meter positions best explained the soil productivity index (horizontal, 0- and 75-cm heights, vertical, 50-cm height; R2=0.59). These results indicate that soil ECa may be useful in estimating a claypan soil's productivity and explaining what properties of claypan soils are prominent in inducing yield variation.