ISSN:
1435-0645
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Zea mays L.). Long-term P and K trials were established in 1994 at five Iowa research centers and were evaluated for 3 yr. Eleven short-term P–K trials were established in farmers' fields during the same period. Treatments were various P (0 to 56 kg P ha-1) and K (0 to 132 kg K ha-1) rates broadcast, banded with the planter 5 cm beside and below the seeds, and deep-banded at the 15- to 20-cm depth before planting. Soil samples were collected from the 0- to 7.5-cm and 7.5- to 15-cm depths prior to planting. Soil-test P (PST) at the 0- to 15-cm depth ranged from very low to very high across sites; soil-test K (KST) ranged from optimum to very high. There were grain yield responses to fertilization at several sites, but no significant differences between the P or K rates and no interactions between rates and placements. Phosphorus increased yields only in soils testing very low or low, and there was no response to P placement at any site. Potassium increased yields in several soils that tested optimum or higher in KST, and yields were higher when K was deep-banded. High rates of broadcast or planter-banded K did not offset the advantage of deep-banded K. Responses were better related with deficient rainfall in late spring and early summer than with KST. Current soil-test P interpretation and P fertilizer recommendations based on chisel-plow tillage are appropriate for most Iowa soils managed with no-tillage. Further work is needed to better characterize and predict responses to deep-banded K. Because yield response was small, the cost-effectiveness of deep-band K will be determined largely by application costs.
Type of Medium:
Electronic Resource
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