Soil variables for regressing Iowa corn yields on soil, management, and climatic variables

Crop Yield Interpretation for North Dakota: III. Long-Term Empirical Models

“…Many researchers have used this procedure to develop productivity models for various crops in specific agricultural regions (Sopher and McCracken, 1973; Walker, 1976; Henao, 1976; Allgood and Gray, 1978; Goyne et al, 1978 Culot, 1981 De la Rose et al, 1981; Feyerherm and Paulsen, 1981; Hammer et al, 1982; Olson and Olson, 1986). In North Dakota, seasonal production functions have been developed for wheat (Ali et al, 1981; Vasey and Leholm, 1982) and sunflower (Zubriski et al, 1979).…”

Concentrations of N, P, and K in the corn leaf as affected by weather indexes and selected soil and management factors

“…The data used in this study included the same soil, weather and management variables that were previously described by Henao (1976) Table 3.…”

Selection of management variables for regressing Iowa corn yields on management, climatic, and soil variables

“…He tested these indexes together with selected management and soil variables and found that they accounted for significant yield variation in the data from seven selected counties. Henao (1976) continued the research, modified the climatic indexes, and selected the most important soil variables for regressing Iowa corn yields on soil, management, and climatic variables. He also observed that the presence of intercorrelations among variables in the multiple regression model caused difficulties in interpreting the regression statistics.…”