Under a continuous rice±wheat cropping system,
the decline in yields may either be reversed, or minimised by application of complete doses of fertiliser
NPK to both the crops. Supplementing 50% dose of N
by organic manures in rice and applying complete
doses of NPK to succeeding wheat may improve the
sustainability of crop yields. However, at locations
such as Ludhiana and Pantnagar in the present study,
where comparatively greater yields are harvested,
current fertiliser management practices may not be
adequate to sustain yields in long-term rice±wheat
cultivation. Therefore, in the high productivity zones,
there is a need to analyse causes other than fertiliser
NPK and manures for yield decline. Emergence of
de®ciencies of sulphur and micronutrients due to their
continuous removal without replenishment is one of
the probable causes. In long-term rice±wheat cropping, soil OC content declined only in soils having
high initial OC contents. Otherwise, soil OC content
tends to increase with continuous cropping and fertiliser/manure application.
Under a continuous rice±wheat cropping system,the decline in yields may either be reversed, or minimised by application of complete doses of fertiliserNPK to both the crops. Supplementing 50% dose of Nby organic manures in rice and applying completedoses of NPK to succeeding wheat may improve thesustainability of crop yields. However, at locationssuch as Ludhiana and Pantnagar in the present study,where comparatively greater yields are harvested,current fertiliser management practices may not beadequate to sustain yields in long-term rice±wheatcultivation. Therefore, in the high productivity zones,there is a need to analyse causes other than fertiliserNPK and manures for yield decline. Emergence ofde®ciencies of sulphur and micronutrients due to theircontinuous removal without replenishment is one ofthe probable causes. In long-term rice±wheat cropping, soil OC content declined only in soils havinghigh initial OC contents. Otherwise, soil OC contenttends to increase with continuous cropping and fertiliser/manure application.
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