Possibilities of Using White Sweetclover Grown in Mixture with Maize for Biomethane Production

Abstract

Methods of growing plant biomass for the production of biogas in anaerobic digestion plants have a decisive influence on arable land and on the evaluation of biogas plant technologies from the environmental point of view. The main benefit of anaerobic digestion is the possibility to use various agricultural crops for energy production. Some of these plant species, e.g., legumes, are generally considered to be beneficial for arable soil quality, as compared with maize monocultures with frequently manifested soil degradation and adverse environmental impact on arable land. A possible change is offered by cultivation systems composed of two and more crops and defined as mixed cropping (MC) systems. The systems are characterized by a more efficient utilization of natural resources of the site as well as by a greater potential for arable soil protection. A question remains as to whether the MC system of growing maize and white sweetclover can be used for biogas yield. In the presented research study, a mixed cropping system was tested with maize (Zea mays L.) and white sweetclover (Melilotus albus MED.). The goal of our research was to determine an optimum ratio of maize and white sweetclover (s.c.) shreddings in silage for a biogas plant. For this purpose, model micro-silages of monocultures were prepared: maize (100%), white s.c. (100%), as well as variants with different weight shares of these two crops (maize:white s.c.; 3:7, 1:1, 7:3, 8:2, 8.5:1.5, 9:1). The silages were subjected to biomethanation tests, in order to determine the influence of the increased addition of white s.c. biomass on methane yield and methane concentration in biogas. The highest values of biogas yield were recorded in the maize monoculture and in the MC variant of maize and white s.c. at 9:1 (>0.26 m3/kgVS). The lowest methane yield values were recorded in the white s.c. monoculture (0.16 m3/kgVS). It was found out that the yield of methane decreased with an increasing share of white sweetclover in the maize silage, due to the increased content of poorly degradable organic substances and the presence of fermentation inhibitors (e.g., coumarin).

EFFECT of digestates derived from the fermentation of maize-legume intercropped culture and maize monoculture application on soil properties and plant biomass production

“…Different plant species used to produce silage affected its quality. This is confirmed in the experiment by Kintl et al [35], who focused on the effect of legume addition into maize silage on biogas production and silage quality. The authors noticed that the biomass of legumes increased the content of N substances in silage.…”

“…The Zea mays L. plant has been bred into various silage hybrids, which have top properties supporting its high biogas production [69]. It was confirmed also in the experiment by Kintl et al [35], where the silage of maize monoculture showed lower contents of CF, ADF, ADL and a higher NDF content compared to silage made of legume monoculture. This suggests that using legumes can lead to the enhancement of CF, ADF and ADL contents in the fermenter and subsequently in the digestate.…”

“…This is crucial, because the C/N ratio is a significant indicator of digestate quality [68,69]. According to some studies [18,35,59], the addition of silage prepared from legumes may lead to changes in digestate properties, i.e., to the reduced C/N ratio, because the biomass of legumes contains a larger amount of N substances than maize. This was not confirmed in our experiment, which data suggest that the organic N in legumes was partially lost during anaerobic fermentation.…”

Effect of Seed Coating and PEG-Induced Drought on the Germination Capacity of Five Clover Crops

“…Apart from the process of after-harvest treatment (purification and calibration), very important are also special pre-sowing treatments focused on enhanced seed uniformity, uniform germination and emergence, or on facilitating the subsequent seed handling, which would allow a better distribution of seeds at sowing so that a uniform and precisely established, evenly developing stand is achieved [ 2 ]. All seed treatments leading to a precisely established stand can support the use of legumes within a mixed culture system [ 3 , 4 ].…”

The use of biological fabaceae resources of the cretaceous south of Russia in breeding on the example of the species Melilotus albus medik

“…The breeding for the duration of flowering and increasing the plant leaf coverage is carried out [19]. Due to the intensive growth of biomass during the growing season, M. albus has the prospect of being used as biofuel [20].…”