Conservation Tillage Effects on the Potassium Status of Some Kentucky Soils

Abstract

Changes in the soil K status occurring as a result of shifting from conventional to no‐tillage management in selected fields were evaluated in this study. The fields were on loess‐ and limestone‐derived soils in western and central Kentucky and have been under no‐tillage management for the last 6 to 16 yr. Two‐ to three‐fold increases in exchangeable and soluble K were evident in most upper surface horizons (Ap1) of soils receiving no‐tillage management, and these increases correlated well with organic matter (OM) accumulations. Adsorption of exchangeable K appeared to be favored over that of Ca and Mg with increases in OM up to a maximum value, beyond which additional OM accumulations had a negative or no effect. Notillage management resulted in a lower overall affinity for K of the exchange sites in all soils (especially the Memphis soil) apparently due to OM accumulations. Quantity/intensity plots reflecting the tillage‐shift effect on K relationships suggested that the loessial soils could reach K‐availability equilibria sooner than the limestone soils due to mineralogical and textural differences. This could mean less fertilizer‐K use on loess‐ than on limestone‐derived soils to attain maximum crop yields under no‐till management.

Nitrogen and Potassium Fertility Impacts on Aggregate Sheath Spot Disease and Yields of Rice

“…1). Available soil K was higher in the straw incorporated field as has been observed elsewhere (Hoagland and Martin, 1950;Karanthansis and Wells, 1990;Dobermann et al, 1996;Prasad et al, 1999;Singh et al, 2004). It is unusual that soil K declined at similar rates in both fields; certainly, one would expect that it to decline more rapidly in the field where straw was removed.…”

Soil chemical quality changes and implications for fertilizer management after 11 years of no‐tillage wheat production systems in semiarid Morocco

“…The need for K is less likely because of the inherent reserve in Moroccan soils (except sandy soils) (Azzaoui et al, 1993). Karathanasis and Wells (1990) found higher exchangeable K under NT due to increased levels of soil organic matter. They recommended reduced application of K fertilizer under NT.…”

“…This soil preference will result in more loss of nitrogen under NT and the authors recommended subsurface N fertilizer application and at lower rate. Karathanasis and Wells (1990) found that the changes were prominent in surface horizons, while subsurface or upper subsoil horizons remained unaffected. In our experiment, no K de®ciency was observed even with low K levels below the seed zone under NT (lower than 150 ppm, the critical level).…”

Phosphorus and potassium placement for corn and soybean managed with two conservation tillage systems

“…Both nutrients accumulate near the soil surface due to the cycling of nutrients by plant roots from subsurface to surface soil depths, minimal mixing of organic matter and applied fertilizers with the soil, and the limited vertical mobility ofP and K in the soil profile (Shear and Moschler, 1969;Griffith et aI., 1977;Ketchenson, 1980;Moncrief and Schulte, 1982;Timmons, 1982;Cruse et aI., 1983;Rehm et aI., 1995;Mackay et aI., 1987;Karathanasis and Wells, 1990;Karlen et aI., 1991). The results reported by Shear and Moschler (1969) after 6 years of no-till cropping found P in the upper 5 cm of soil was 3.8 times greater than under conventional tillage, while at greater depths (5-20 cm) conventionally tilled soils possessed twice as much P. Similar results were reported by Karlen et al (1991), Randall (1980), Griffith et al (1977), and Ketchenson (1980) after 12, 10, 6, and 3 years ofno-till cropping.…”

“…The results reported by Shear and Moschler (1969) after 6 years of no-till cropping found P in the upper 5 cm of soil was 3.8 times greater than under conventional tillage, while at greater depths (5-20 cm) conventionally tilled soils possessed twice as much P. Similar results were reported by Karlen et al (1991), Randall (1980), Griffith et al (1977), and Ketchenson (1980) after 12, 10, 6, and 3 years ofno-till cropping. In Kentucky, five different soils under no-till from 6 to 16 years produced up to three times as much soil exchangeable K and five times as much soluble K in the 5 cm depth of soil compared with the 5-17 cm depth (Karathanasis and Wells, 1990). Nutrient stratification can be a significant problem in drier areas of the Midwest.…”