Nutrient Cycling in Agroecosystems 60: 209–218, 2001. © 2001 Kluwer Academic Publishers. Printed in the Netherlands. 209 Biogenic versus abiogenic emissions from agriculture in the Netherlands and options for emission control in tomato cultivation Jacomijn Pluimers 1 , Carolien Kroeze 1 , Evert Jan Bakker 2 , Hugo Challa 3 & Leen Hordijk 1 1 Environmental Systems Analysis Group, Department of Environmental Sciences, Wageningen University, P.O. Box 9101, 6700 HB Wageningen, The Netherlands 2 Sub-Department of Mathematics, Wageningen University, Wageningen, The Netherlands 3 Farm Technology Group, Wageningen University, Wageningen, The Netherlands Key words: acidifying compounds, agriculture, emission reduction, greenhouse gas, greenhouse horticulture Abstract In this paper, present-day emissions of greenhouse gases and acidifying compounds from agriculture are analysed at the farm level. Quantitative estimates are given for these emissions from three nested systems in the Nether- lands: the agricultural sector, greenhouse horticulture, and tomato cultivation under glass. Total emissions are subdivided into emissions from biogenic sources and abiogenic sources. We conclude that, although most of the emissions from the agricultural sector have biogenic sources, those from abiogenic sources should not be neg- lected. Abiogenic emissions are mainly from greenhouse horticulture. The cost-effectiveness of options to reduce carbon dioxide (CO 2 ) and nitrogen oxides (NO x ) emissions from on-farm combustion of natural gas in tomato cultivation under glass is analysed. An inventory is given of technical reduction options that are presently available in practice. Based on information about the costs and the reduction potential of each option, cost-efficiency curves are derived for both types of emissions. Relative to a situation where none of the described options were applied (early nineties), CO 2 and NO x emissions from tomato cultivation can be reduced at most by about 70% and 75%, respectively, by combinations of technical options. Introduction It is well known that agricultural activities contribute to greenhouse gas emissions and other environmental problems such as acidification and eutrophication. In Dutch agriculture specific sectors have specific envi- ronmental problems (Poppe et al., 1995; RIVM, 1996; CBS, 1997). For example, the breeding of cattle is a major source of acidification due to the emissions of ammonia (NH 3 ) from animal waste. Greenhouse hor- ticulture, on the other hand, contributes to the problem of global warming, particularly through emission of the greenhouse gas carbon dioxide (CO 2 ) as a result of the combustion of natural gas for greenhouse heating and for increasing CO 2 concentration in the green- house to stimulate crop growth (CO 2 fertilisation). Both sectors also contribute to emissions of other atmospheric pollutants, such as methane (CH 4 ), ni- trous oxide (N 2 O), nitrogen oxides (NO x ) and sulphur dioxide (SO 2 ). In the Netherlands greenhouse horticulture has a special position within the agricultural sector as a whole as compared to other countries. Dutch green- house horticulture (about 10,000 hectares) is leading in global greenhouse production and is an economi- cally important part of Dutch agriculture (CBS, 1996a). The consequence of the intensive production is that relatively large amounts of natural gas and other inputs are used resulting in high emissions of greenhouse gases and acidifying compounds. As a res- ult, emissions from greenhouse horticulture contribute considerably to agricultural emissions in the Nether- lands (Spakman et al., 1997). This situation is specific for the Netherlands. Emissions of air pollutants can be biogenic or abiogenic. Biogenic emissions are here defined as those resulting directly from biological processes (thus caused by living organisms) and those released from manure. Other emissions are called abiogenic and result, for instance, from the use of fossil fuels. Emis-