CROP RESPONSES TO POTASSIUM APPLICATION IN VERTISOL UNDER RICE-WHEAT CROPPING SYSTEM
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Date
2004
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Indira Gandhi Krishi Vishwavidyalaya, Raipur (C.G.)
Abstract
Crop responses to potassium application in Vertisol were studied in ricewheat
cropping system, at Instructional Farm in the Department of soil Science,
IGAU, Raipur (C.G.). The objectives of the experiment were (i) to study the crop
responses to fertilizer K application in rice-wheat cropping system (ii) to estimate
the content and uptake of potassium by rice and wheat. (iii) to evaluate the
different K fractions in Vertisol as influenced by rice-wheat cropping system. (iv)
to monitor the potassium balance after two successive cropping season. (v) to
study the fixation of potassium in Vertisol as influenced by K fertilization at
surface and subsurface soil layer. The treatments consisted of five graded levels
of fertilizer K application (0, 50, 100, 150 and 200 kg K2O ha-1) in four
replication using RBD.
The amount of all fractions was higher in surface layer (0-15 cm) than
that in sub surface layer (15-30 cm). The order of dominance of different forms
of potassium in the soil were non-exchangeable K >exchangeable
K>available>water soluble K. The over all changes in different forms of K due to
cropping indicates a decreasing trends in available and exchangeable K fractions
but water soluble and non-exchangeable K did not show such trends. The initial
value for total K (water-soluble + exchangeable + non-exchangeable K) was 1944
kg/ha that increased after rice season up to 2026 kg/ha then decreased to 1927
kg/ha after wheat crop season.
No crop responses were observed to K fertilization in terms of yield and
K uptake of rice and wheat crops. This indicates that soil under study is sufficient
to meet the K requirement of the crops. The potassium balance indicates that
application of 100-150 kg K2O/ha can sustain the K fertility status of the soil.
Potassium fixation study reveals that the rate of fixation is enhanced in
the treatment, which did not received any fertilizer K as compared to that
receiving fertilizer K (@ 200 kg K2O ha-1). While comparing K fixation in twosoil
depth, indicate that subsurface soil layer had slightly higher fixation as
compared to that in surface layer.