Here is what Ferdinand Hahn wrote as recorded in Introduction to the Kols Mission Field, by Ferdinand Hahn.Part 3 - The Religion of the Kols. Chap. 15. The Understanding of the Kols about the Highest Nature. as translated by Theodore C. Feierabend (unpublished 2019)
It is the Oraon, however, who worship the most ardently, that the earth may be fruitful. At the Khaddi festival, also called Sarhul, in the spring, when the sal-tree begins to bloom, they celebrate the marriage of Dharme with the earth. The former is personified by the village priest, the latter is identified by the elder of the holy grove. The Korwa hold the Mother Earth, the Dharti-Mata, as the supreme deity, who dwells in the sacred grove under a sal-tree. They perform sacrifices for the grain to flourish. Thus, too, the Oraon imagines the earth as one with the spirit under the sal-tree, the Jhakra borhi. The meal between her and Dharme takes place in the following manner: The village priest, together with his wife, fasts at the beginning of the festival, on the eve of the same. Then, accompanied by his assistant, he goes from house to house through the whole village. Each housewife gives them some hands full of rice. The priest keeps about half of it, and the other half the priest returns. Through this symbolic action the main food is blessed. Of the returned rice, the women hide some grains in their house, and when it grows, it is a good sign of a rich harvest. On the evening of the first feast, the priest, with the help of his assistant, takes a new large earthen vessel, filling it with water, and carrying it to the holy grove, where he places it at the seat of the god, the certain ancient sal-tree. Such vessels are porous, and therefore lose content, even if they remain only one night in the open. It is now very important that very little water is lost during the festive season, as this is a sure sign of a good rainy season, which is so important for the prosperity of the crop. Thereupon the priest takes a sacrifice in the presence of the villagers on that tree, consisting of two white hens, some vegetables, rice, oil and brandy, and, last but not least, cinnabar, with which he bites a twig of the sal tree with a piece of zeng or a cotton thread, then brushing his chest, his forehead and his ears, and thus marrying himself with the tree; the representative of the sun god being the tree and the representative of the mother earth residing in him. Thereupon the priest prays: “O Old One, bring forth the fruit of this year. May the rain fall, so that the corn may grow and flourish." As the bridegroom and bride are carried to the village or dwelling-house, the priest is now carried into his house. Then he visits all the houses again, and distributes sal-blossoms, which the women use to decorate their houses. Then they wash his feet and give him rice and money. His assistants sprinkle the roof of every house with water to indicate that now rain and fertility will follow, and finally dining, drinking, and dancing, as is customary at weddings, with all shame and good manners being laid aside.
In the case of the Ho, this feast is celebrated in a particularly exuberant manner, although they lack the idea of combining Singbonga with the earth. The Santal and Munda also have their seed sacrifice and feast, which they call Kadlo-Sa.