Soil potassium—crop response calibration relationships and criteria for field crops grown in Australia

Abstract

The Better Fertiliser Decision for Crops (BFDC) National Database holds historic data for 356 potassium (K) fertiliser rate experiments (431 treatment series) for different rain-fed grain crops and soil types across Australia. Bicarbonate-extractable K (Colwell soil-test K) is the most extensively used soil test reported in the database. Data are available for several crop species grown on a range of soil types from all states except Tasmania. Species represented and number of treatment series in the database are: wheat (Triticum aestivum L.), 254; barley (Hordeum vulgare L.), 5; canola (Brassica napus L.), 130; lupin (Lupinus angustifolius L.), 32; sunflower (Helianthus annuus L.), 10; sorghum (Sorghum bicolor L.), 5; and faba bean (Vicia faba L.), 2. About 77% of the available soil-test K (STK) data on wheat, canola, and lupin are from Western Australia. The usual sampling depth of 0–10 cm is recorded for all treatment series within the database, while 68% of experiments have STK information from other soil horizons down the profile, usually in 10-cm increments. The BFDC Interrogator, a comprehensive data search and calibration support tool developed for use with the BFDC National Database, was used to examine STK–yield relationships for each crop across Australia, with more detailed analysis by state/region and then by soil type if data were available. The BFDC Interrogator was used to determine a critical STK concentration to achieve 90% of the maximum relative yield (90%RY) for each crop species, with a critical range (determined by the 70% confidence limit for the 90%RY) also reported. The STK for 90%RY for wheat was 40–41 mg/kg on Tenosols and Chromosols, ~49 mg/kg on Kandosols, and ~64 mg/kg on Brown Ferrosols. There was some evidence of critical values increasing with increasing crop yield and on soils with no acidity constraints to root growth, with effects presumably driven by increased crop K demand. The STK for 90%RY for canola, grown mainly on Tenosols, was similar to that for wheat, ranging from 43 to 46 mg K/kg, but for lupin, also grown mainly on Tenosols, the STK for 90%RY was a relatively low ~25 mg K/kg. Data for sunflower were limited and the STK for 90%RY was poorly defined. A comparison of critical STK concentrations for different crops grown on Tenosols suggested that critical ranges for 90%RY of lupin (22–27 mg K/kg) were significantly lower than that for wheat (32–52 mg K/kg) and canola (44–49 mg K/kg). Critical STK values were not determined for sorghum and faba bean.

Comparison of soil analytical methods for estimating wheat potassium fertilizer requirements in response to contrasting plant K demand in the glasshouse

“…The critical value (90% relative dry matter) for the NH 4 OAc K method was 91 mg kg −1 at low root density (large pots) in all soils. While there are few reported studies developing critical soil test K values using the NH 4 OAc K method in the literature, Brennan and Bell reported a critical Colwell K critical value of 40–64 mg kg −1 for grain yield of wheat in field condition, with the range related to contrasting soil types 55 . This value was much lower than the 114 mg K kg −1 value we derived in this study, with the difference attributed to differences in plant growth stage, root density, water content and access to greater soil volumes (e.g.…”

Effect of nitrogen fertiliser management on soil mineral nitrogen, nitrous oxide losses, yield and nitrogen uptake of wheat growing in waterlogging-prone soils of south-eastern Australia

“…The benchmark of 20 kg grain/mm plant-available water suggested by French and Schultz (1984) was reached only in 2014. We cautiously rule out other potential nutritional constraints, with S and K concentrations above levels considered to limit yield (Anderson et al 2013;Brennan and Bell 2013), although K appeared marginal in the lower layers of the topsoil (Table 1). Research elsewhere has shown that applications of K to waterlogged wheat can significantly increase yield (Belford et al 1992).…”

Spatial variability of potassium in agricultural soils of the canton of Fribourg, Switzerland

“…Therefore, distribution of soil K forms is influenced by many agroenvironmental factors, such as soil parent materials (Askegaard et al, 2004;McLean and Watson, 1985;Öborn et al, 2005), degree of soil weathering (Andrist-Rangel et al, 2006;Barré et al, 2008;Johnston and Goulding, 1990), topography (Kozar et al, 2002;Winzeler et al, 2008) and nutrient balance (Bertsch and Thomas, 1985;Simonsson Geoderma 290 (2017) , 2007). Despite the natural abundance of K in soils (Askegaard et al, 2004;Schroeder, 1978), certain regions of the world, such as Australia, China and Iran, present crop K deficiencies over large areas due to particular pedoclimatic conditions or long-term underfertilization of K (Brennan and Bell, 2013;Hseung, 1980;Ji-yun, 1997;Malakouti, 1999;Römheld and Kirkby, 2010). In Europe, soil K deficiencies are not widespread (Tóth et al, 2013), but deficiencies or reduction of soil K are reported at the regional scale, especially in countries around the Baltic Sea and in the United Kingdom (Andrist-Rangel et al, 2010;Tóth et al, 2013).…”