Potassium fertilization effects on yield and longevity of established alfalfa

Abstract

Limited information is available which describes the response of established alfalfa (Medicago sativa L.) to topdressing applications of K fertilizer in the Southeastern United States. Field experiments were conducted for three years to determine alfalfa response to rates and time of K application. The experiments were established in two-year old stands of alfalfa on a Decatur silty clay loam (clayey, kaolinitic, thermic Rhodic Paleudults) and a Hartsells fine sandy loam (fine loamy, siliceous, thermic Typic Hapludults) located in northern Alabama. Potassium as KCl was broadcast in the spring prior to regrowth. For split application treatments, the K was applied in early spring and after the second cutting. Annual total K rates ranged from 56 to 596 kg/ha. Potassium fertilization maintained alfalfa stand density on both soils, but the experiment on the Decatur soil was discontinued after two years due to severe stand loss when the lowest rate of added K was used. Alfalfa yields were increased by the application of K and maximum yields occurred when K was applied according to soil test recommendations made by the Auburn University soil testing laboratory. Potassium applications increased the concentration of K, decreased the concentration of Ca and Mg and had little effect on the concentration of N in tissue from the two cuttings sampled. The split application of K did not consistently increase forage production. There was little movement of K below 25 cm in either soil when K rates of 56 to 596 kg/ha/yr were repeated yearly for up to three years. 2047

Impact of Long‐Term Phosphorus and Potassium Fertilization on Alfalfa Nutritive Value–Yield Relationships

“…The details of this yield response have been published previously (Berg et al, 2005(Berg et al, , 2007 and are consistent with previous studies (Markus and Battle, 1965;Barbarick, 1985;Lloveras et al, 2001). However, others have found no eff ect of K fertilization on forage CP concentrations (Burmester et al, 1991;Lloveras et al, 2001) or on IVDMD (Smith, 1975;Sheaff er et al, 1986). Concentrations of NDF, ADF, and ADL rose with increasing K application levels (Table 4).…”

“…Application of K fertilizer decreased both IVTDMD and CP concentration; nevertheless, both DNY and CPY increased with K application up to 200 kg K ha -1 because of the impact of K on forage yield. Although Smith (1975) showed consistent eff ects of K fertilization on herbage yield, studies by others (Sheaff er et al, 1986;Burmester et al, 1991;Lloveras et al, 2001) showed no or only a slight eff ect of K fertilizer rates on herbage yield. Previous studies found decreased N (or CP) concentrations in forage as yield increased in response to K fertilization (MacLeod, 1965;Smith, 1975;Sheaff er et al, 1986).…”

“…This decrease was believed to be caused by a reduction in leaf-to-stem ratio as K fertilization rates increased (Smith, 1975). Other studies have shown no eff ect of K fertilization on alfalfa herbage N concentrations (Burmester et al, 1991;Lloveras et al, 2001). However, nodulation increases in response to K fertilization (Collins and Duke, 1981;Grewal and Williams, 2002), which may result in greater CP.…”

Fertiliser management for higher productivity of established lucerne pasture

“…Berg et al (2005) reported higher herbage yields for lucerne with the combined application of P and K compared to applying each element alone. Adequate K nutrition has been reported to be positively associated with improved lucerne persistence (Burmester et al 1991;Simons et al 1995;Grewal and Williams 2002;Berg et al 2007). The inverse linear relationship (R 2 00.99) between lucerne herbage yield and weed biomass found in this study (Fig.…”

Sustainable Alfalfa Production on Coastal Plain Soils of the United States

“…Deep sandy soils such as this Darco usually test low and sometimes medium in plant-available K. Coastal Plain acid-sandy soils rarely test in the high K category by soil analysis. The best use of the soil test for K on these soils may be to initially estimate the plant-available soil K level and then recommend K application based on requirements for the crop to be grown plus an additional amount to compensate for plant use efficiency and potential soil fixation of applied K. Burmester et al (40) reported the highest alfalfa yields were attained at the rate of 484 kg K ha 21 on two Ultisols on the Coastal Plain, and that there was no advantage to split application of K on established stands of alfalfa. Kafkafi et al (41) concluded that K applications should be split applied, allowing for two alfalfa harvests between each application of K for sandy loam soils with low cation exchange capacity.…”