Philosophical differences exist in the interpretation and recommendations made from soil test values acquired by different organizations that provide advice to farmers on fertilizer use. It was the objective of this study to evaluate the economic and agronomic impacts of these varied philosophies with particular reference to concepts of cation ratio, nutrient maintenance, and nutrient sufficiency level. Field experiments were conducted during 1973–1980 on four major soils of Nebraska comparing yields of corn (Zea mays L.) grown with fertilizer treatments as recommended by five soil testing laboratories operating in the state. The 29 field comparisons revealed no real yield differences despite wide variation in number, rate, and cost of nutrients applied. Since soil test levels are increasing or at least holding steady with the “nutrient sufficiency” approach to soil testing, we find no economic or agronomic basis for the “balance” or “maintenance” concepts on these representative soils of the western Corn Belt. Not to be overlooked are environmental implications nor the waste of energy and resources from any approach responsible for excessive fertilizer use. It is recognized that reserves of available nutrients in the deep subsoils and underlying soil‐forming materials in this region have a substantial bearing on soil test calibration and that different calibrations may exist with less favorable subsoil rooting conditions.

Genes that increase the grain protein potential of wheat (Triticum aestivum L.) are known. The interaction of such genes with factors of the production environment, particularly soil nitrogen availability, determines their probable value and contribution to higher protein content in wheat. Two hard winter wheat varieties differing inherently in the protein content of their grain were grown in replicated plots at selected sites in Nebraska over a 3‐year period. Nitrogen fertilizer was applied at five rates in the 1st year and at seven rates in the 2nd and 3rd years. Data were recorded for yield, test weight, and protein content of the grain. Significant protein responses to nitrogen fertilizer occurred in all trials. Responses of both varieties were linear and positive. C.I.14016 maintained a protein advantage of 2 percentage points over ‘Lancer’ at all levels of fertilizer. The protein advantage of C.I.14016 over Lancer was independent of the relative yields of the two varieties. The feasibility of effectively increasing the grain protein content of wheat by breeding is indicated by the data. Statistically significant yield responses to fertilizer were recorded in 6 of 10 trials. Yield responses of both varieties were nonlinear with the second‐degree polynomial providing a good fit of the data. Less nitrogen fertilizer was required for maximum yield of Lancer, the lower protein variety, than for C.I.14016. Test weight responses of the varieties to fertilizer were negative and linear. The test weight of Lancer was higher than C.I.14016 at all fertilizer rates.

Phosphate fertilizer recommendations for winter wheat have traditionally been in terms of doubling the row applied P rate if broadcast application is to be used. A literature search failed to locate a significant amount of supportive data for this practice. The experiments reported here were conducted to determine if there is a consistent relationship between broadcast and row applied P rates for winter wheat and if so, what that relationship is. Six field experiments were conducted over a 2 year period on soils of, the Typic Argiustoll subgroup. Treatments were five rates of 0‐46‐0 (0, 11, 22, 34, 45 kg P/ha) applied as either preplant broadcast or drilled with the seed. All experiments were on soils that responded positively to P fertilization. Results contradicted the concept of a 2:1 ratio of broadcast to row P application as standard practice. The relative effectiveness of row and broadcast methods changed with changing soil tat P levels. Low soil test locations exhibited an effective ratio of about 3:1 while medium soils tests had ratios of 1:1.

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