Soil Survey Interpretation-Theory and Purpose

A two‐stage Delphi survey was used to evaluate soil productivity indexes currently used for Hard Red Spring (HRS) wheat (Triticum aestivum L.) in North Dakota. Experienced field soil scientists estimated the relative productivity of several soils having a wide range of properties. Mean productivity index for most soils changed little between the first and second questionnaires, but coefficient of variation (CV) decreased an average of 20 and 17% for wheat and sunflower, respectively. Soils with the highest yield variability for both wheat and sunflower were Entic Haploborolls and Typic Ustorthents on upper slopes, Natriborolls, and coarse‐textured or loamy soils with sand and gravel substrata. Results were compared to current productivity indexes and effects of slope, paralithic beds, and argillic horizons evaluated. The Delphi technique proved useful for accessing a source of information based on years of field observation. Relative yield estimates from field soil scientists were particularly useful in evaluating the yield potential of soils for which research data were not available. Delphi surveys should be viewed as a subjective method of investigating soil‐crop yield relationships and used only to supplement quantitative data.

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confidence: 99%

Crop Yield Interpretation for North Dakota: II. Field Questionnaires—A Delphi Approach

Ulmer¹,

Patterson²

1988

“…Statistical models were calibrated against the properties of the soils and yields were estimated for three crops representing 25 soils and 5 great groups. Aandahl (1958) and Kellogg (1961) emphasized the need for reliable crop yield estimates by soil series. Kellogg (1961) suggested that yield tables are the most important part of the soil interpretation process.…”

mentioning

confidence: 99%

Corn and Soybean Responses to Exchangeable Sodium in South-Central Illinois Soils

Olson

Endres

1996

A 4‐yr study was conducted to determine corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] yield and plant population differences between three south central Illinois soils with varying levels of exchangeable Na in subsoils. The 2‐yr corn yield average was highest (190 bu/acre) for Cisne soils, which had low exchangeable Na in the subsoil, and lowest (118 bu/acre) for the Huey soils, which had the highest level of Na in the subsoil. The 2‐yr corn plant populations at harvest were not significantly reduced by exchangeable Na in the subsoil. The 2‐yr average soybean yields were less affected by Na; however, the 1991 soybean yield was significantly reduced by 20 bu/acre. The Cisne soils averaged 43 bu/acre while the Huey soils, with higher exchangeable Na levels, had lower yields (35 bu/acre). The 2‐yr soybean plant populations at harvest were not significantly reduced by exchangeable Na in the subsoil. The corn yield (160 bu/acre) was reduced for Cisne tax‐adjunct soils, which had a medium level of exchangeable Na but there was no corresponding reduction in the soybean yield (44 bu/acre). Productivity index ratings for soils with varying levels of exchangeable Na should reflect this adverse crop yield response.

“…Selected soil properties and management practices must be determined to make maximum use of the data (Krantz, 1958). Aandahl (1958) recommended using benchmark soils in all productivity studies.…”

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confidence: 99%

“…The need for accurate and reliable yield estimates by soil taxonomic unit has been emphasized by many researchers (Aandahl, 1958; Kellogg, 1961). Yield data are used to develop productivity indexes that are useful in technology transfer, farm enterprise budgeting, erosion research, soil correlation, and other soil interpretations.…”

mentioning

confidence: 99%

Crop Yield Interpretation for North Dakota: I. Sequential Sampling

Ulmer

Patterson

1988

Sequential sampling techniques were used to collect crop yield data to develop soil‐productivity indexes for soil interpretation in North Dakota. Hard Red Spring (HRS) wheat (Triticum aestivum L.) data from four extensive agricultural soils in three northeastern counties are presented to illustrate the procedure and application of results. Soils on concave landscape positions that received runon surface water had the highest average yield and greatest range in yield. Soils on convex upper slopes had significantly lower yield than soils on other landscape positions. Results were generally comparable to current productivity estimates. Data relating A‐horizon thickness to yield indicated an average increase in yield of 1.79 bu/acre for each inch of A horizon. Sequential sampling proved to be an efficient means of collecting data for soil‐crop yield interpretation.