Showing 2 results for Potassium.
B Dolati, Sh Oustan, A Samadi,
Volume 12, Issue 46 (1-2009)
Abstract
Successive cropping of potassium-demanding crops like sunflower leads to depletion of soil potassium (K). This study was conducted to investigate the different forms of K and quantity–intensity (Q/I) relationship for sunflower growing soils in Khoy region, West Azarbaijan province. Twenty composite soil samples were collected from different soil series. Different forms of K, including solution K (Kso), exchangeable K (Kex) and non-exchangeable K (Knex) were determined. The results showed that Kso values varied from 0.061 to 0.54 (mmol L-1), with an average of 0.28 (mmol L-1), Kav values ranged from 55 to 699 (mg kg-1), 265 mg Kg-1 on average, and Kex values ranged from 54 to 694 (mg Kg-1) with an average of 261 (mg kg-1). Furthermore, Knex values varied from 160 to 612 (mg kg-1), 261 (mg kg-1) on average. Available K (NH4OAc- extraction) was less than 250 mg Kg-1 in half of the soils indicating the depletion of potassium from these soils. The Q/I curves were predominantly located in the adsorption regions. The Q/I curves were linear and lacked the curvature part relating to loss and gain of potassium present in the specific sites. The PBCK values varied from 11 to 108 (cmolc kg-1)/ (mol L-1) 0.5 and an average of 38 (cmolc kg-1)/(mol L-1)0.5. There was a linear significant relationship between PBCK and CEC (r2=0.82***). The AReK values ranged from 0.0014 to 0.027 (mol L-1) 0.5 and 0.0076 (mol L-1)0.5 on average. There was a significant relationship between the values of AReK and those of the soil solution K (r=0.68**). The Ko values varied from 0.0050 to 0.49 cmolc kg-1and an average of 0.21cmolc kg-1. Additionally, there was a high significant relationship between the values of Ko and ARoK (r= 0.95***) in the soils under study.
N Barahimi, M Afyuni, M Karami, Y Rezaee Nejad,
Volume 12, Issue 46 (1-2009)
Abstract
Compost and sewage sludge contain high concentration of plant nutrients and, thus, have been used extensively as an inexpensive fertilizer. The objective of this study was to evaluate cumulative and residual effects of compost, sewage sludge and cow manure on nitrogen, phosphorus and potassium in soil and wheat. The experiment included compost, sewage sludge and cow manure, each applied at 3 rates (25, 50 and 100 Mg ha-1), a chemical fertilizer (250 kg ha-1 amonium phosphate + urea) and a control plot with 3 replications. The experimental design consisted in completely randomized blocks with treatments arranged in split plots. To study the cumulative and residual effects of the organic amendments, application was repeated on four fifths of each plot in the second year. Wheat was grown in the plots. The results showed that one application (residual effect) of organic amendments had not significant effect on total N in soil and wheat leaves and stem, but it led to significant increase of available phosphorus and potassium in soil and wheat leaves and stem. Cumulative effects of organic amendments significantly (P≤ 0.05) increased the total N (in 50 and 100 Mg ha-1 Cow manure and 100 Mg ha-1 Compost treatments), available P in all organic treatments and K (in all Compost and Cow manure treatments) in soil. Also, cumulative effects of organic amendments significantly (P≤ 0.05) increased the N (in 100 Mg ha-1 sewage sludge), P (in 100 Mg ha-1 compost) and K (in all organic treatments with the exception of 25 Mg ha-1 Compost) concentrations in leaves and stem.
