A comparison of fertilizer recommendations by soil testing program and alfalfa yield response in soils of two associations
Titel:
A comparison of fertilizer recommendations by soil testing program and alfalfa yield response in soils of two associations
Auteur:
Alva, A. K.
Verschenen in:
Communications in soil science and plant analysis
Paginering:
Jaargang 16 (1985) nr. 2 pagina's 213-228
Jaar:
1985-02
Inhoud:
Soils of an association may vary in productivity and fertility response because of differences in landscape positions, hydrologic properties, and capacity to retain and release nutrients. These differences may in turn affect the validity of fertilizer recommendations based on soil testing programs. The yield pattern of alfalfa was studied over three years in Gilpin, Ernest, Brinkerton soils of an association developed in residium and colluvium from sandstone and shale parent material (from Brookville, Jefferson County, Pennsylvania), and in the Cambridge - Venango — Frenchtown soils of an association developed in sandstone and shale glacial till (from Meadville, Crawford county, Pennsylvania). Soil test recommendations for F and ? were compared with yield response of alfalfa to increasing application of the respective nutrients (0, 45 and 90 kg P.ha-1, and 0, 175, 350 and 525 kg K.ha-1) in each of the six soils. The better drained soils of either association (Gilpin, Ernest, Cambridge, Venango) in general, failed over 3 years to show significant yield responses to ? and ? applications above 45 and 175 kg per ha, respectively, although some exceptions were apparent especially during the second harvest year. However, soil test program recommendations for ? (64 to 85 kg.ha-1) and ? (187 to 277 kg.ha-1) applications were in excess of the quantities of respective nutrients required for optimum yield. Furthermore, the soil testing program recommendation was for the application of 56 to 64 kg P.ha-1 and 213 to 283 kg K.ha-1 for the wet soils (Brinkerton and Frenchtown soils). Apparently, these soils had severe limitations for alfalfa production and failed to respond to ? and ? applications at any quantities as compared to the control treatments. The tissue concentrations of ? or K, in most of these soils, increased significantly at applications of respective nutrients in quantities higher than those at which the yield response ceased to increase significantly. In treatments receiving no ? or K, the tissue ? concentrations were above the sufficiency level (0.25 percent) in all the soils, however, the tissue ? concentrations were lower than the sufficiency level (2.0 percent) in all the soils except the Brinkerton soil. The soil testing program overestimated the ? and ? requirements for optimum alfalfa yields in the soils chosen in this study, which apparently had varying degree of drainage limitations to alfalfa production. Thus, soil testing alone is not adequate to predict the nutrient requirement for optimum crop yield in soils with known limitations to crop production. Therefore, while considering soils with known limitations to crop production, the fertilizer recommendations based on soil tests should be adjusted to account for the soil limitations.
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