Energy efficiency of the lettuce open filed and greenhouse production

Abstract

Greenhouse production is still among the most energy-consuming branches of agriculture. Producers are faced with high cost of the operations involved in greenhouse production processes (climate control, fertilizing, irrigation). This is the reason why an optimal combination of energy inputs that will make this production more energy efficient, needs to be found. In this paper the influence of the production technology and greenhouse construction on energy efficiency in winter lettuce production was estimated for different double plastic covered greenhouses in Serbia region. In order to see whether the greenhouse structure influences energy consumption, energy inputs were estimated for lettuce production in the open filed and in four different greenhouse structures (a tunnel and gutter connected structure and two multi-span greenhouses). On the basis of lettuce production output and the energy input, specific energy input, energy output-input ratio and energy productivity were estimated. Results show that the lowest energy consumption was obtained for gutter connected greenhouse with two bays, 3.11 MJ/m2. The highest energy consumption was measured for the open filed lettuce production, 7.99 MJ/m2. The lowest lettuce yield was measured in the open filed production (1.89 kg/m2) and the highest in the multi-span greenhouse, GH4, (6.08 kg/m2). The highest value for output-input ratio was calculated for the multi-span greenhouse with thirteen bays, 0.85 and the lowest for the open filed production, 0.11. Regression equations show the nature of the greenhouse structure influence on these parameters.

Biljna proizvodnja u zaštićenom prostoru predstavlja granu poljoprivrede sa najvećom potrošnjom energije. Proizvođači su suočeni sa visokim troškovima pojedinih proizvodnih procesa, što predstavlja jedan od razloga potrebe pronalaženja optimalne kombinacije energetskih inputa koja bi ovu proizvodnju učinila energetski efikasnijom. U ovom radu analiziran je energetski bilans proizvodnje salate na otvorenom polju i u objektima zaštićenog prostora različite konstrukcije. Utrošak energije praćen je u proizvodnji na otvorenom i u četiri tipa objekata zaštićenog prostora. Na bazi direktnih i indirektnih energetskih inputa i energetskog outputa određeni su specifični energetski input, energetski odnos i energetska produktivnost. Rezultati pokazuju da je najniža potrošnja energije po jedinici površine ostvarena u blok objektu sa dva bloka, 3,11 MJ/m2, dok je najviša vrednost utrošene energije zabeležena u proizvodnji na otvorenom polju, 7,99 MJ/m2. Najniži prinos ostvaren je u proizvodnji salate na otvorenom polju, 1,89 kg/m2, dok je najviši prinos ostvaren u blok objektu GH4, od 6,08 kg/m2. Najviši energetski odnos ostvaren je u blok objektu sa trinaest blokova, 0,85 a najniži u proizvodnji na otvorenom polju, 0,11. Jednačine regresije su ukazale na prirodu zavisnosti energetskog bilansa sistema od izabrane konstrukcije objekta zaštićenog prostora.