The effects of agronomy on the carbon and nitrogen contained in the soil biomass

Abstract

Summary Soils of various agronomic histories were fumigated with chloroform, and the resultant increased production of CO 2 and mineral-N measured and expressed as biomass C and the flush of mineral-N production ( F N ), respectively. Biomass C and F N contents of grassland soils were greater than those of arable soils, and significant correlations with macro organic-matter content were found. Biomass C contents varied from 7 to mg C/100 g soil in arable soil and from 31 to 222 mg C/100 g soil in grassland or woodland. The proportion of soil organic C that was contained within the biomass ranged from 0·3 to 4·0%, whilst F N comprised from 1·0 to 11·7% of total soil N. F N contents ranged from 1·1 to 13·2mg N/1OOg soil for arable soils, and from 2·5 to 31·7 mg N/100 g soil for grassland and woodland. Application of organic manures increased biomass C and F N contents in grassland soil.