Gayatri Anusthan cannot be said to be fully accomplished unless it is accompanied by Yagya .
In old affluent times Agnihotra used to be performed with number of Ahutis equal to one-tenth of the quantum of Jap , but now, in view of the prevailing circumstances, Ahutis are given in one to hundredth ratio.
Those lacking in requisite resources fulfil the requirement of Yagya by performing one-tenth additional Jap . There is a reference in the scriptures to a famous ancient dialogue between Janak and Yagya valkya.
Janak went on pointing out the difficulties in daily performance of Yagya because of non-availability of required materials whereas Yagya valkya, while emphasising the essentiality of performing Yagya , said that even if charu and other materials are not available, food grains of daily consumption can be offered in Havan.
If they are also not available, mental Yagya can be performed by offering meditation and divine sentiments in the fire of reverence and devotion.