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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #173979


item Sudduth, Kenneth - Ken

Submitted to: Biosystems Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2005
Publication Date: 3/16/2005
Citation: Chung, S., Sudduth, K.A., Chang, Y. 2005. Path analysis of factors limiting crop yield in rice paddy and upland corn fields. Journal of Biosystems Engineering. 30(1):45-55.

Interpretive Summary: Site specific management, or precision farming, is a strategy in which cropping inputs such as fertilizers are applied at varying rates across a field in response to variations in crop needs. To understand what these crop needs are from point to point, it is necessary to understand the relationship between crop yield and both controllable (such as fertilizer nutrients) and uncontrollable (such as topography) factors. The effect of these factors on yield is complex, and often changes from point to point within a field. In this research, we applied a statistical technique called path analysis to investigate the relationship between yield and other factors, using data from a rice field in Korea and a corn field in Missouri. Path analysis provided more detailed information about these relationships than did other statistical techniques, and results were consistent with published crop nutrient needs for corn and rice. Scientists may benefit from this description of an additional technique they can apply for investigating crop response to limiting factors. Eventually, producers and agribusiness may also benefit through improved recommendations and management strategies.

Technical Abstract: Knowledge of the relationship between crop yield and yield limiting factors is essential for precision farming. However, developing this knowledge is not easy because these yield limiting factors are interrelated and affect crop yield in different ways. Data for grain yield and yield limiting factors, including crop chlorophyll content, soil chemical properties, and topography were collected for a small (0.3 ha) rice paddy field in Korea and a large (36 ha) upland corn field in the USA, and relationships were investigated with path analysis. Using this approach, the effects of limiting factors on crop yield could be separated into direct effects and indirect effects acting through other factors. Path analysis provided more insight into these complex relationships than did simple correlation or multiple linear regression analysis. Results of correlation analysis for the rice paddy field showed that EC, Ca, and SiO2 had significant correlations with rice yield, while Ca, Mg, Na, SiO2, and P2O5 had significant correlations with the SPAD chlorophyll reading. Path analysis provided additional information about the importance and contribution paths of soil variables to rice yield and growth. Ca had the highest direct effect (0.52) and indirect effect via Mg ( 0.37) on rice yield. The indirect effect of Mg through Ca (0.51) was higher than the direct effect ( 0.38). Path analysis also enabled more appropriate selection of important factors limiting crop yield by considering cause and effect relationships among predictor and response variables. For example, although pH showed a positive correlation (r=0.35) with SPAD readings, the correlation was mainly due to the indirect positive effects acting through Mg and SiO2, while pH not only showed negative direct effects, but also negatively impacted indirect effects of other variables on SPAD readings. For the large upland Missouri corn field, two topographic factors, elevation and slope, had significant direct effects (P<0.1) on yield and highly significant correlations (P<0.01) with other limiting factors. Based on the correlation analysis alone, P and K were determined to be nutrients that would increase corn yield for this field. With the help of path analysis, however, increases in Mg could also be expected to increase corn yield in this case. In general, path analysis results were consistent with published optimum ranges of nutrients for rice and corn production. We conclude that path analysis can be a useful tool to investigate interrelationships between crop yield and yield limiting factors on a site specific basis.