Emergy synthesis of conventional fodder maize (Zea mays L.) production in Denmark

With the demand for animal protein on the rise, there is need for phenomenal increase in production of animal feed to meet the increasing demand. Among the feed production systems, conventional fodder maize acreage is increasing due to high yields and nutritional value of maize silage over other feeds. However, conventional fodder maize production systems are input intensive and there is a need to assess resource use in fodder maize production in Danish agriculture and in Europe in general. Hence, the objective of the study was to carry out emergy synthesis to evaluate the resource use in conventional fodder maize production. Among the renewables, rain input (3.08E + 14 seJ/ha) was the largest renewable component input and considered as the total renewable input into the production system. The purchased resources was the significant input constituting 80.5% (1.54E + 15 seJ/ha) of the total emergy. Among the purchased inputs, nitrogen consisted of the bulk of the input of 37.6% (7.18E + 14 seJ/ha), followed by phosphorus (19.5%) and diesel input (16.4%). The fodder maize yield was 3.12E + 7 kg ha(-1) equivalent to output (Y) of 4.60E + 11 J/ha. The solar transformity was 4.15E + 03 seJ/J and the fraction of local renewables was 16%. Emergy yield ratio was 1.24 and environmental loading ratio was 5.2 whereas emergy sustainability index was 0.24. The study quantified the different inputs of renewables, local non-renewables and purchased inputs and used a range of emergy indicators to identify the gaps in resource use in fodder maize production. It was evident that purchased resources were the bulk of the input and management measures to improve the use efficiency of these inputs will enhance the emergy use efficiency. Hence, the study outputs are a useful resource for informed decision making to devise management measures by farmers, agricultural advisors and policy makers to optimize the inputs for sustainable production of fodder maize.