Effect of long term soil fertilizer application on forms and distribution of potassium in soil under rice-cowpea cropping system

Abstract

An experiment was conducted at Zonal Agricultural Research Station, VC farm, Mandya to assess the effect of long term soil fertility management on behaviour of potassium with respect to different forms and distribution pattern in rice-cowpea cropping system. Soil of the study area belong to sandy loam texture having initial pH (6.28), EC (0.14 dSm-1), CEC (9.60 cmol (p+) kg-1), MWHC (20.70%) and bulk density (1.67 g cc-1). The organic carbon (0.34 %), available nitrogen (163 kg ha-1), available potassium (134 kg ha-1) were low and medium in available phosphorus (29.20 kg ha-1). Results indicated that the water soluble K content of soils varied from 8 to 16 mg K kg-1 in the surface layer and 5 to 14 mg K kg-1 in the sub surface layer in the plots treated with different fertilizer, manure and their combinations. Exchangeable K also ranged between 59 and 116 mg K kg-1 in the surface layer and 58 to 98 mg K kg-1 in the sub surface layer. The non-exchangeable K content ranged from 111 to 874 mg K kg-1 and from 160 to 880 mg K kg-1 , respectively in the upper and the lower layers. The total K content varied from 792 to 3017 mg K kg-1 at 0-15 cm depth and from 874 to 3318 mg K kg-1 at 15-30 cm depth.

Forms and Distribution of Potassium in Selected Maize Growing Soils of Haveri District of Karnataka, India

“…Based on degree of weathering and soil type the surface and sub-surface lattice K content might have been varied among the samples. The results corroborated with the findings of Divya et al, (2016) (Fig. 2).…”

“…The increase in non-exchangeable potassium at sub surface may be attributed to adsorption and fixation of K removed from surface through leaching. The similar findings were obtained by Kundu et al, (2014) and Divya et al, (2016). However, the nonexchangeable K content of black soil was more compared to red soils at both the depths may be because of nature and amount of clay present in black soils (Hebsur andGali, 2011 andKundu et al, 2014).…”

“…Depending on clay mineralogy, lattice K content and organic matter content, the total K content might have been varied in surface and sub-surface layers. The results were in comparison with those of research findings of Gali and Hebsur (2011), Jagmohan and Grewal (2014) and Divya et al, (2016) (Fig. 3).…”

Integrated Nutrient Management on Sustainable Production of Rice- Maize Cropping System in Bhadra Command area of Karnataka, India

“…Organic carbon in the sample was determined by Walkley and Black's rapid titration method and the available P content was computed and expressed in Kg ha -1 and Available K content was extracted using neutral N NH 4 OAC as described and outlined by Jackson [8a]. The alkaline potassium permanganate method of Subbaiah and Asija (1956) was adopted for the estimation of available N content in the soil.…”

“…Higher buildup of K fraction in soil was observed in integrated treatments, and may be due to addition of K from organic sources [14]. The relatively lower contents of K fraction observed in control treatment might be due to the depletion of K by crop removal without supplement through external inputs and partly due to leaching of K with colloidal fractions of the soil to the lower layers [25,4].…”