Effect of nutrient inter-relations on productivity of rice in lateritic soils
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Date
2002
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Department of Agronomy, College of Horticulture, Vellanikkara
Abstract
The effect of nutrient inter-relations on productivity of rice in latritic soils
was investigated during the first crop season (Virippu) Or 1999-2000 at the
Agricultural Research station, Mannuthy. The objective of the study was to arrive at
the minimum level combination of applied elements for maximum productivity
based on the interaction pattern between applied and native elements so as to
develop a sustainable management system. Jyothi was used as the Fest variety to
analyse the pattern of interacting influences of P, K, Ca and S at two levels each,
among themselves as well as on the native elements.
The results showed that treatments had significant beneficial influence on
yield expression, causing 90 and 10% increases in yield over absolute control and
the presently recommended package of practices. This indicated the necessity of
including Ca and S in the nutrient management system. Decline in chlorophyll
content and high levels of cell sap pH, together with excess contents of Fe and Zn
appear to act as the supressors of yield expression. The latter influences are inherent
in soil and are actually the net product of the balance between positive and negative
effects of nutrients. A significant finding was that application of any element by
itself was not a guarantee for its uptake, and was subject to the effect of other
elements, and similarly, had direct or indirect influences on other elements. The
positive influence of K and Ca at the maximum tillering and S at the panicle
initiation stage, and negative influence of Fe and Mn at the panicle initiation stage
pointed out to the need for phasic management of nutrients. The only element
inhibiting Fe uptake had been Si, suggesting that the reversal of the process of
laterisation holds the key to higher yields. Discriminatory transfer of individual
elements between leaf blade and leaf sheath appeared to be an important regulatory
factor in deciding yield expression. Highest yield resulted when blade-sheath ratio
was maximum tillering and panicle initiation declined in respect of Ca, Fe and Mn
and increased in respect of K and S. the study resulted in development of the broad
base of a management technology for high productivity and sustainability. The
components included keeping N at the present reconunended level, reducing P by
50%, increasing K by 100% and top dressing N using s containing fertilizers as well
as moderate basal dressing with Ca.
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171935