TY - JOUR
T1 - A simple soil moisture index to forecast crop yields
AU - Isard, Scott A.
AU - Welford, Mark R.
AU - Hollinger, Steven E.
N1 - Funding Information:
Acknowledgments: We are grateful to P. Lamb and W. Wendland for providing advice and support throughout this research; to B. Reinke for providing precipitation data and soil water computations; and to D. Jones, R. Reitz, K. Davie, C. Benson, and R. Allgire for taking soil moisture measurements. This work was partially supported by Illinois State Water Survey Division of the Illinois Department of Natural Resources.
PY - 1995
Y1 - 1995
N2 - Neutron probe soil moisture measurements obtained biweekly during the growing season between 1982 and 1991 from multiple depths under grass-covered plots at 17 Illinois Climate Network sites are used to forecast crop yields. A Soil Moisture Index (SMIX) that combines the effect of intensity, duration, and timing of drought or excessively wet conditions was computed by integrating the quantity of available soil moisture throughout the rooting zone over the growing season. Relationships between the SMIX values and crop yields are evaluated at county, regional, and statewide scales. Coefficients of determination (r 2) for relationships between the SMIX values and maize, soybeans, and hay yields at the statewide level are 0.88, 0.74, and 0.81, respectively, when the period of integration is terminated at the end of the growing season. This new soil index can be employed to forecast yields as early as 12 weeks before harvest for the state of Illinois. However, predictions with RMSE ≤ 10% of the mean yield can be achieved only for SMIX integration periods ending 5, 9, and 6 weeks before harvest for maize, soybeans, and hay, respectively. Nomograms are presented for using the relationships between the SMIX values and crop yields to forecast Illinois's major crops well before harvest.
AB - Neutron probe soil moisture measurements obtained biweekly during the growing season between 1982 and 1991 from multiple depths under grass-covered plots at 17 Illinois Climate Network sites are used to forecast crop yields. A Soil Moisture Index (SMIX) that combines the effect of intensity, duration, and timing of drought or excessively wet conditions was computed by integrating the quantity of available soil moisture throughout the rooting zone over the growing season. Relationships between the SMIX values and crop yields are evaluated at county, regional, and statewide scales. Coefficients of determination (r 2) for relationships between the SMIX values and maize, soybeans, and hay yields at the statewide level are 0.88, 0.74, and 0.81, respectively, when the period of integration is terminated at the end of the growing season. This new soil index can be employed to forecast yields as early as 12 weeks before harvest for the state of Illinois. However, predictions with RMSE ≤ 10% of the mean yield can be achieved only for SMIX integration periods ending 5, 9, and 6 weeks before harvest for maize, soybeans, and hay, respectively. Nomograms are presented for using the relationships between the SMIX values and crop yields to forecast Illinois's major crops well before harvest.
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U2 - 10.1080/02723646.1995.10642569
DO - 10.1080/02723646.1995.10642569
M3 - Article
AN - SCOPUS:0344810391
SN - 0272-3646
VL - 16
SP - 524
EP - 538
JO - Physical Geography
JF - Physical Geography
IS - 6
ER -