humicadj.n.

1844 Petzholdt Lect. Farmers Agric. Chem. 93 A substance..which has been called humic acid.

1863 C. Lyell Geol. Evid. Antiq. Man viii. 148 Mr. Staring..has attributed the general scarcity of human bones in Dutch peat..to the power of the humic and sulphuric acids to dissolve bones.

1891 Chem. News 22 May 248/2 The part played by humic matters in the fixation of nitrogen.

1918 M. C. Stopes & R. V. Wheeler Monogr. Constit. Coal 19/2 Potonié's separation of coals into two main groups, sapropelic and humic, is now widely adopted... But the use of the phrase ‘humic coals’ is much in want of elucidation, as it, too, is given different meanings by different authors. As used by Potonié and most palæontologists, it means that the coal was formed from ‘humic débris’, or the various largely undecayed accumulations of mixed organs of plants... When the word ‘humic’ is applied to coals by chemists..it may convey the implication that ‘humic acid’ exists in the substance of the coal.

1936 S. A. Waksman Humus iii. 62 One may..feel justified in abandoning without reservation the whole nomenclature of ‘humic acids’.

1954 W. Francis Coal v. 245 Humic substances are the major constituents of all normal coals.

1957 G. E. Hutchinson Treat. Limnol. I. ix. 609 The peaty sediments (dy) of brown humic lakes.

1960 N. Polunin Introd. Plant Geogr. xv. 497 Humic matter in solution may result in a browning of waters coming in from leached soils.

1966 B. Simpson Rocks & Minerals xx. 234 The first group is the Humic Coals in which woody tissue is of paramount importance in the composition... The second group, the Sapropelic Coals, have little woody tissue in their composition.

1971 Nature 19 Nov. 150/2 They are usually found in moist, humic soil, often near water.

1859 Trans. Illinois State Agric. Soc. 1857–8 3 410 The soils in this portion of Illinois not only need ‘humics’, for the successful growth of cereals, but the earth should be kept loose.