Showing 3 results for Potential Buffering Capacity
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 Ghanavati, M Malakouti, A Hossein Por,
Volume 13, Issue 49 (10-2009)
Abstract
Correlation between components of Q/I and wheat (Triticum aestivum L.) growth indices was studied in a greenhouse experiment during 2003-04 growing season. Eighty soil samples (0 – 30 cm depth) were collected randomly in farms around the Abyak region, Ghazvin province. Twenty-one samples were then selected based on soil texture and NH4OAC-K. The research included treatments of 21 soils and two potassium (K) levels (0, 100 mg/kg) and was conducted in a factorial manner in a randomized complete block design with three replications for studying correlations between Q/I and treatments. Effect of potassium application on the wheat growth was found to be significant at 5% level. The effect of soil properties on wheat growth was also found to be significant at 1% level. However, the interaction of K and soil was not significant. There were no significant differences among the different equilibrium time intervals. The soil potassium buffering capacity (PBCK) values were strongly correlated with CEC (r =0.996**), clay content (r = 0.921**) and moisture saturation percentage (r = 0.811**). Final equation derived from stepwise regression for prediction of PBCK was as follows: PBCK = 7.419 CEC –19.743 R2adj = 0.782** The equilibrium potassium activity ratios (ARke) were strongly correlated with soluble potassium (r =0.846**), NH4OAC-K (r =0.730**), SP (r = 0/794*), OC (r = -0.477ns) and clay content (r=-0.602*). Similarly, readily exchangeable potassium (ΔK0) was strongly correlated with ammonium acetate extractable potassium (r = 0.871**), soluble potassium (r = 0.778**), saturation percentage (r = 0.551*), organic carbon percentage (r=-0.045ns) and clay content (r=-0.206ns). There was no significant correlation between ΔK0 and ARKe with potassium uptake values by wheat. In contrast, there was a strong correlation between PBCK values and potassium uptake by wheat (r = 0.729**), and relative wheat yield (r = 0.735**). There was no significant correlation between Q/I parameters when KCl and K2SO4 were used, and the soil physicochemical properties. However, Q/I parameters obtained from KCl showed a higher correlation with wheat plant's growth indices.
M. Samavati, B. Eskandari,
Volume 17, Issue 63 (6-2013)
Abstract
Quantity-Intensity (Q/I) curves and their derived parameters provide general information about soil Potassium (K) availability. This investigation was conducted to obtain K different varieties and their correlations with K, Q/I parameters in 13 soils sample from Bahar area as the major potato producing area in Iran. Soil Samples were equilibrated with solution containing different potassium activity ratios (ARK), and changes in potassium concentrations in the equilibrium solution (ΔK) were ploted against activity ratio of K, and Q/I parameters were determined. The results showed that, potassium activity ratio at equilibrium (AR0) ranged from 0.007 to 0.995 with an average of 0.16 (mmol L-1)0.5, The readily exchangeable potassium (ΔK0) ranged from 0.04 to 2.199 with an average of 0.49 cmol kg-1, The potassium potential buffering capacity (PBCK) ranged from 13.21 to 75.37 with an average of 42.02 (mmol kg-1) / (mmol L-1)0.5. Highly significant linear correlations were found between PBCK and CEC (r = 0.6*), AR0 and KSO (r = 0.99**), AR0 and Kex (r = 0.85**). Among the studied soils, one soil (Chopolgh Lo soil) absorbed potassim on edge position of clay minerals and the others absorbed potassium on planar surface.
