Studies in Denitrification.

Abstract

Nore than that, the baneful efiects do not stop here, for the nitrates as they are gradually formed from the organic matter of the soil are also attacked by the denitrifying bacteria, and their nitrogen is set free. In a word, then, the animal manure applied is not only useless of itself, but is harmful because of its destructive effects on the oxidized nitrogen derived from other sources. I t is quite apparent that the interests involved are of great moment, that 'Cl'agner's theory if it be borne out by practical experience vitally concerns the man of science, the practical farmer, and the world at large. It was in the hope of contributing something to the knowledge of the subject that these experiments were planned. The scope of the work included the study o f : I. The composition of the solid and liquid portions of con. manure, fresh. 11. The composition of the solid and of the solid and liquid portions of cow manure, leached. 111. The availability of the nitrogen in the solid and in the solid and liquid portions of cow manure, fresh. 11'. The availability of the nitrogen in the solid and in the solid and liquid portions of cow manure, leached. 1-. The relative availability of the nitrogen in the form of nitrate, of ammonia and of organic matter in dried blood. IT1. The effect of the use of the solid and of the solid and liquid portions of cow manure, fresh and leached, with nitrogen in the form of nitrate, of ammonia, and of organic matt e r. DESCRIPTIOK OF THE EXPERIMENTAL PI,.\KT. In order that the conditions of the experiment might conform as nearly as possible to those in actual practice, what is known as the "cylinder method" was adopted. The cylinders were made of galvanized iron, 23.5 inches i n diameter and 4 feet long, and were painted inside and out, to retard corrosion. The area of soil surface thus exposed was, therefore, 3 square feet, and its depth was such that the roots of the crop would be practically prevented from obtaining f,Jotl other than that contained within the cylinders. In order that the conditions for each cylinder might be uniform, the surface soil was first removed entirely, and the subsoil, a mixture of clay and ~2 n d. STUDIES IN DENITRIFICATION. 787 which was taken from the holes, was thoroughly mixed. The same weight of subsoil was then placed in each one, and thoroughly packed and brought to a uniform height, so as to permit of the addition of 8 inches of surface soil; 120 cylinders were used, divided into two groups of 60 each. Thus in each group there were 20 series of three each, A, B and C, enabling a triplication of crops in each case. DIAGRAM OF EXPERIMENT.

Applying MICP by denitrification in soils: a process analysis

“…Denitrification is one of the main biological processes in the global nitrogen cycle, in which a genetically diverse group of microorganisms is able to reduce nitrate through the intermediate products of nitrite (NO 2 − ), nitric oxide (NO) and nitrous oxide (N 2 O) to nitrogen (N 2 ) gas (Robertson and Groffman, 2015). Denitrification has been intensively studied since the late nineteenth century, both in natural systems and for industrial applications (Archna et al, 2012;Ferguson, 1994;Knowles, 1982;Kuenen and Robertson, 1988;Payne, 1981;Soares, 2000;Voorhees, 1902;Wang et al, 1995).…”

Spatially tripartite interactions of denitrifiers in arctic ecosystems: activities, functional groups and soil resources

“…Denitrifier communities regulate N 2 O production and consumption and as such, the abundance of denitrifier functional groups can serve as an essential basis for understanding N 2 O dynamics in soils (Morales et al ., 2010). Denitrification has been well‐recognized for more than a century (Voorhees, 1902) and the denitrifier abundance and potential denitrification have been measured in various soil ecosystems including agricultural (Miller et al ., 2008; Hallin et al. , 2009; Philippot et al ., 2009; Enwall et al ., 2010; Morales et al ., 2010), grassland (Miller et al ., 2009; Keil et al ., 2011), riparian (Rich and Myrold, 2004; Dandie et al ., 2011) and forest (Bohlen et al ., 2001; Levy‐Booth and Winder, 2010) soils.…”