Soybean Response to Available Potassium in Three Silt Loam Soils

Abstract

The range in soil environments has likely contributed to variation in the determination of that level of K availability at which no further yield increase to K is expected. Potassium response of soybean [Glycine max (L.) Merr.] from three different soil environments was studied in the field to determine if a single index of K availability could be found. Relationships between grain yield, R1‐R2 leaf K concentration, ammonium acetate exchangeable K, Ca, Mg, and water soluble K, Ca, and Mg were determined. Significant (P ⩽ 0.05) yield responses to added K were found at all three sites, as were increases in R1‐R2 leaf K. Water soluble K, K/Mg, and K/(Ca + Mg)1/2 were more stongly related to plant response than extractable K, K/Mg, or K/(K + Ca + Mg). All soils provided optimal K nutrition to soybeans at soil test levels ≤100 mg K kg−1 soil, as determined by neutral, molar ammonium acetate solution. Determinations of soil solution phase composition may improve our understanding of the role(s) of soil properties on divergent patterns of response to K nutrition.

Differential Response of Two Cotton Cultivars to Fertilizer and Soil Potassium

“…Only 49 and 28% of the observed variation in seed cotton yield was accounted for with the best-fit models based on NH 4 -extractable K for SJ2 and GC51 0, respectively. The poor association between cotton yield and NH 4extractable K as reported here is in agreement with Grove et al ( 1987), who found soybean [Glycine max (L.) Merr.] yield to be more closely associated with water-soluble K levels than with NH 4 -extractable K values on silt loam soils in Kentucky.…”

Réponse du soya à la fertilisation minérale en éléments majeurs NPK sur des sols classés de riches à excessivement riches en phosphore ou en potassium des Basses Terres du Saint-Laurent

“…La fertilisation des sols classés pauvres et très pauvres en phosphore ou en potassium assimilables par la plante se traduit généralement par une augmentation des rendements du maïs-grain et du soya (DeMooy et al 1973;Grove et al 1987;Mallarino et al 1991a). Les augmentations de rendement permettent ainsi aux producteurs de dégager des profits qui sont supérieurs aux coûts additionnels de la fertilisation.…”

“…La surfertilisation en potassium a toutefois été identifiée comme un facteur important de la dégradation des sols au Québec (Tabi et al 1990). D'autre part, plusieurs études démontrent qu'il y a peu ou pas d'augmentation de rendement du maïs-grain ou du soya lorsque la richesse des sols en phosphore et en potassium assimilables par les plantes est supérieure au niveau moyen (Hanway et al 1962;Grove et al 1987). Quelques essais réalisés sur des sols riches en phosphore ou en potassium du Corn Belt révèlent que les probabilités que le soya ou le maïs-grain répondent à une fertilisation en phosphore ou en potassium sont très faibles (Hanway et al 1962;Bharati et al 1986).…”

Phosphorus and potassium management for corn and soybeans in conservation tillage

“…These are evidence that many producers could increase both the profitability and sustainability of crop production by reducing fertilization rates. Many reports show that yields of com and soybean are seldom increased by fertilizing soils testing above medium in P or K Walker et al, 1985;Bharati et al, 1986;Grove et al, 1987;. The results from Iowa for conventionally tilled fields show that (1) large net returns from fertilization are likely when available P and K in soils are deficient, (2) applications of P and BC fertilizers that increase soil-test levels from medium to high usually result in negative returns to investments in fertilizers, and (3) it is more expensive to maintain high soil-test values than medium values.…”

“…Extensive research has shown that yields of soybeans managed with conventional tillage usually are increased by application of P and K fertilizers to soils deficient in this nutrients (Bray, 1961;deMooy et zil., 1973;Thom, 1985;Rhem, 1986;Grove et al, 1987;Obreza and Rhoads, 1988;Million et al, 1989). Early studies and more recent studies (Mallarino et al, 1991, Webb et all., 1992 show that the soil-test P or K values needed to maximize yields of soybeans and com are similar.…”