Volume 3, Issue 4 (winter 2000)                   2000, 3(4): 57-70 | Back to browse issues page

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Kavossi M, Kalbasi M. Comparison of Soil Potassium Extracting Methods to Determine Suitable Extractants for Sepeedrood Rice Variety in some Guilan Rice Paddy Fields. Journal of Crop Production and Processing 2000; 3 (4) :57-70
URL: http://jcpp.iut.ac.ir/article-1-208-en.html
Abstract:   (17479 Views)

High-yielding rice varieties are prevailing in Guilan Province which is one of the most important rice producing regions in Iran. However, little is known about K status in this region and no suitable extraction method can yet be introduced to the farmers. This experiment was carried out to determine the available K by 15 chemical extractants and also to examine the critical K levels in paddy soils of the region. The treatments included 23 soils and 2 K levels (0 and 300 mg/kg as KCl) in a factorial experiment in a randomized complete block design with three replications.

 Results indicated that K application increased grain and straw yields, K concentration in straw as well as K uptake by rice. High correlation coefficients were observed between MgOAc, H2SO4, Morgan and 0.01 M CaCl2 methods with K concentration in straw (0, 0.83, 0.78, 0.8 and 0.78, respectively) and with K concentration in plant tops (0.79, 0.76, 0.75 and 0.73, respectively). Similarly, high correlation coefficients were observed between the same extraction methods with K absorbed by straw (0.83, 0.82, 0.78 and 0.76, respectively) and with total plant K uptake (0.79, 0.83, 0.74 and 0.71, respectively). Potassium critical levels by different extracting solutions were determined by Cate-Nelson procedure and were 38, 74, 160, 111, 36, 112 and 100 mg kg-1 for MgOAc, Morgan and Kelowana methods, Texas method H2SO4 0.01 M CaCl2 and NH4OAc without and with submergence of soil samples, respectively. In this study, available K was below the critical level in almost 75% of the soils.

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