Sustainability effects of introducing legumes in traditional cropping systems : an experimental case study in Swedish context

Abstract: The agricultural sector of the world faces a growing food demand because of a growing world population. To support this growing demand, it could be necessary that agricultural production increases, this increase in production must be achieved sustainably. One way to achieve more sustainable production in agricultural could be to diversify the production systems. Legumes are a crop group that holds properties that could be of importance when trying to achieve more diverse and sustainable agriculture. This study aims to examine how a diversification with legumes would affect typical Swedish cereal dominated cropping systems in terms of sustainability. More specifically, the three dimensions of the triple bottom line are investigated separately. Indicators of sustainability in each dimension are identified, and these show the effects of legumes in the cropping systems. To examine the effects legumes attributable to the sustainability in the cropping systems, two case farms are developed. Five different indicators are applied; these are profitability, nitrogen usage, phosphorus usage, energy production, and protein production. The study considers three different legumes, feed peas, yellow peas, and broad beans. From the two case farms, a mathematical optimization model is developed from which the indicators are calculated. The approach of the study is quantitative and uses secondary data from several sources. Results from the study indicate that legumes could increase the profitability of both case farms. The results show an increase in the profitability of between 0-4 %. The study indicates that nitrogen and phosphorus usage on the farm decreases. The results on phosphorus differ from previous studies, where it is found that legumes would increase the usage of phosphorus in a cropping system. The results on the indicators of energy and protein are similar to previous research and point towards an increase in protein production and a decrease in energy production. The major conclusion is that diversification with legumes could have an impact on the sustainability of the two case farms. Only one out of five indicators point towards reduced sustainability compared to a state with no legumes; this is the indicator of energy production. However, in the discussion, the implication of lower energy production is discussed, and it is found that a lower energy production might not be bad for the single farmer.