Pulsation parameters of new and used milking liners with round cross section

G. Dineva*, K. Peychev, D. Georgiev

Department of Agricultural Engineering, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

(Manuscript received 4 June 2021; accepted for publication 26 July 2021)

Abstract. Milking machines equipped with new and used milking liners with a round cross section were studied. The used milking membranes were operated for 3 months on a farm for rearing 60 cows (Holstein cattle) with double milking per day. The experiment involved recording the standard pulsation phases “a”, “b”, “c” and “d” (in absolute units) in the frequency range from 1 Hz to 2.5 Hz, in a vacuum mode of 40 kPa and 50 kPa and at a pulsation ratio of 50/50%. It was found that the transients (phase “a” and phase “c”) are faster and the established phases (phase “b” and phase “d”) are longer in milking units equipped with used milking liners. The conclusions are related to the service life of the milking liners.

Comparative study of a milking unit pulsation system in laboratory and field conditions

G. Dineva*

Department of Agricultural Engineering, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

(Manuscript received 20 May 2021; accepted for publication 12 July 2021)

Abstract. A comparative study of the pulsation phases in classic milking units was performed. The testing of the same is done in laboratory and field conditions (during milking). The pulsation settings at which the test was performed were pulsation rate 60 min-1 and 90 min-1, ratio 50/50% and vacuum mode 50 kPa. The experiments were performed in the laboratory of “Machine milking” (Department of Agricultural Engineering, Faculty of Agriculture, Trakia University) on a milking installation with a pipe line and on a farm for 60 lactating cows at the same milking installation. It was found that the transients (phases “a” and “c”) are significantly reduced during milking. Respectively, the actual phases (phases “b” and “d”) are significantly increased during the milking process. The conclusions are related to the settings and timely diagnostics of the milking machine.

Selectivity and stability of herbicides, herbicide tank mixtures and herbicide combinations on seed yield of Clearfield oilseed canola (Brassica napus L.)

G. Delchev*

Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

(Manuscript received 31 May 2021; accepted for publication 26 July 2021)

Abstract. During the period 2018-2020 a field experiment was carried out with the winter Clearfield oilseed canola hybrid Phoenix CL (Brassica napus L). Factor A included the years of investigation. Factor B included untreated control, 2 combined herbicides: Cleranda SC and Cleravo SC; 6 herbicide tank mixtures: Electron 500 SC + Maza 4 SL, Springbok + Maza 4 SL, Tanaris + Maza 4 SL, Butisan max + Maza 4 SL, Cliofar 600 SL + Maza 4 SL and Galera super + Maza 4 SL; 6 herbicide combinations: Caliph 480 ЕC + Maza 4 SL, Caliph mega + Maza 4 SL, Bismark CS + Maza 4 SL, Nero ЕC + Maza 4 SL, Brasan 540 EC + Maza 4 SL and Colsor trio ЕC + Maza 4 SL. Herbicides Cleranda, Cleravo and Maza were used in addition with adjuvant Dash HC. Foliar-applied herbicides were treated during 2-4 leaf canola stage. Soil-applied combined herbicides were treated during after sowing before emergence period of the canola. It was found that: (i) the highest seed yields are obtained by use of combined herbicide Cleranda, followed by herbicide tank mixture Electron + Maza and combined herbicide Cleravo; (ii) the high canola yields are also obtained by herbicide tank mixtures Butizan max + Maza, Springbok + Maza, Tanaris + Maza, as well as by herbicide combinations Caliph mega + Maza, Brasan + Maza, Bismarck + Maza; (iii) technologically the most valuable are combined herbicide Cleranda, followed by herbicide tank mixture Electron + Maza and combined herbicide Cleravo; (iv) in terms of technology for growing winter Clearfield oilseed canola, herbicide tank mixtures Springbok + Maza, Butisan max + Maza and Tanaris + Maza, as well as herbicide combinations Caliph mega + Maza, Bismar + Maza and, Nero + Maza get high rating; herbicide tank mixtures Cliofar + Maza and Galera super + Maza and herbicide combinations Caliph + Maza and Colsor trio + Maza get low rating.

Operational characteristics of a machine-tractor unit for direct sowing of barley using the JD LINK telematics system

G. Tihanov*, G. Hristova

Department of Agricultural Engineering, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

(Manuscript received 11 June 2021; accepted for publication 26 August 2021)

Abstract. A study has been conducted for some operational indicators of a machine-tractor unit (MTU) for direct sowing of barley. The data for this study has been collected and retrieved by using the JD Link telematics system from two different fields sown with barley: field A with irregular shape and area of 13.75 ha and field B with rectangular shape and area of 16.26 ha. It was found that for both fields the values for the most monitored parameters were very close as follows: for the engine speed of the sowing unit during working stroke – 1553.65 min-1 (A) and 1586.11 min-1 (B) (the difference is <2.08%); for the idle mode of the sowing unit – 900.08 min-1 (A) and 905.63 min-1 (B) (the difference is <0.62%); for the actual working speed – 9.97 km/h (А) and 10.16 km/h (В) (the difference is <1.9%), registered when the MTU is performing the technological operation “sowing”; those parameters of MTU are nor influenced by the field size and shape. Larger differences in values between the two fields were established in terms of the relative share of engine used – 19.98% (A) and 21.55% (B) (the difference is <7.3%) and for the consumed diesel fuel (in field А it was 7.2% liters higher than in field В, respectively, 11.7% higher referring to the average diesel fuel consumption – liters per hour). The actual hourly productivity in field A was 20% lower than in field B – 3.05 vs 3.81, which is due to the fact that in the field with irregular shape – A the sowing unit made more turns at the end of the levels than in the field with rectangular shape – B.

Optimizing the thickness of a straw outer wall of a building for sows in a view to achieving cost-effective heat insulation

V. Dimova*, D. Georgiev

Department of Agricultural Engineering, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

(Manuscript received 22 November 2020; accepted for publication 16 April 2021)

Abstract. The aim of the study is to determine the optimum thickness of the surrounding wall structure of a building for nursing sows by using heat insulation from straw and different fuel (pellets and dry wood) for heating the building. To achieve the purpose, 6 models of walls made of environmentally friendly panels with wooden skeleton, thermal insulation from pressed straw bales and double-sided clay plaster have been developed, such that the accepted thickness of the thermal insulation layer is respectively: 20, 25, 30, 35, 40 and 45 cm. The construction value of the finished wall is determined by adding the value of the construction and assembly works on the construction site to the value of the preparation of the panels (in a workshop), including the payment of labor, materials and additional costs for the implementation of clay plaster and waterproofing membrane. The annual energy losses through 1 m2 of the enclosing wall and the annual heat insulation costs (as a sum of annual energy cost and the depreciation deductions) are determined through the described methodology and verification of condensation of water vapor on the inner surface of the wall was carried out. The results of the research show that by using pellets for fuel, the optimal thickness of the thermal insulation is 45 cm, and by using dry wood it is 35, 40 and 45 cm. All studied models of enclosing straw wall meet the hygienic requirements for preventing condensation on their inner surfaces.

Effect of transport vehicles on the grain harvester idle time during harvesting

G. Tihanov*

Department of Agricultural Engineering, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

(Manuscript received 12 December 2020; accepted for publication 2 April 2021)

Abstract. The article studied the effect of transport vehicles on the grain harvester idle time during wheat, barley and rapeseed harvesting in 6 agricultural farms. In each of the farms one grain harvester and the established harvesting organization were studied without changing the unloading mode and the specific activities performed by the harvester operators and transportation vehicles. By multifactor regression analysis the effect of time for moving the transport vehicle on the grain harvester idle time was established. In addition, the value of the determination coefficient R2=0.54 reveals that 54% of the harvester idle time for unloading the grain hopper (Т1) change is due to the change of significant times and 46% to the effect of unmanageable factors. It has been established that the change in the time from opening the unloading auger to its activation depends on the position of transport vehicles on the field (t1) and the time for their movement to the harvester auger (t2). The results obtained can be used to minimize costs in the technological process of crop harvesting.

Length-weight relationship of European catfish (Silurus glanis L.) fry reared at different stocking densities under controlled conditions

V. Krasteva*, M. Yankova

Institute of Fisheries and Aquaculture, 4003 Plovdiv, Bulgaria

(Manuscript received 14 October 2020; accepted for publication 18 January 2021)

Abstract. The present paper investigates the body length and weight, and the size-weight variations of one-month-old European catfish reared at 4 variants of stocking density: Variant 1 – 5 spec/l; Variant 2 – 10 spec/l; Variant 3 – 15 spec/l and Variant 4 – 28 spec/l. The experiment is carried out at the Institute of Fisheries and Aquaculture, Plovdiv for a period of 16 days, using a production system consisting of tubs with continuous water flow (0.7 l/min). At the end of the experiment, the fish from each variant are sorted in three size-weight groups: A – large, B – medium and C – small. The number of fish in each group is established. From the group of the medium- and small-sized fish, 150 speciments are measured, while from the group of the large specimens, which are the smallest in number, all specimens are measured for the biometric parameters body weight (BW, g) and total body length (TL, cm). The results from the study show small variations in the length and weight of the fish reared at the lowest stocking density (Variant 1). As the density increase, the size-weight differences between the specimens from Group A also increased, while of those from Group B they decrease. The number of the medium-sized fish decrease (p≤0.001) while the number of large specimens (p≤0.01) and small fish increase (p≤0.001).

Productivity and quality of experimental sunflower hybrids in climatically different years

M. Drumeva*

Department of Plant Production, Faculty of Manufacturing Engineering and Technologies, Technical University of Varna, 1 Studentska str., 9010 Varna, Bulgaria

(Manuscript received 5 September 2020; accepted for publication 16 January 2021)

Abstract. The main purpose of sunflower breeding requires the developing of high-yielding hybrid varieties with broad ecological plasticity that would guarantee the stability of the yield and the quality of the production from them. This investigation involved 10 experimental F1 hybrid combinations developed with the participation of double haploid fertility restorer lines (DHR) obtained through the method of gamma-induced parthenogenesis in combination with embryo culture. The aim of the investigation was to study the productivity and quality of the seeds from the new experimental sunflower hybrid varieties with a view of their future use in practice. The experimental work included years 2014 and 2015, which were significantly different with regard to the climatic conditions. The experiments were carried out in the experimental field and the laboratory of the Technical University in Varna. The hybrid combinations were assessed according to the main parameters of sunflower productivity, namely seed yield (kg/ha) and oil yield (kg/ha), as well as according to the main quality parameter of sunflower seeds – oil percent in seed. Under the conditions of this investigation, the analysis of the results showed that the genotype potential of the hybrids was determining for the seed and oil yield; a relatively high effect of the year conditions was also established for the parameter oil yield. The percent of oil in seeds was determined on the basis of the genotype, and the effect of the year was considerably lower. Summing up the results from the testing of the experimental hybrids, it can be pointed out that three of the studied hybrid combinations (3607A х 112DHR, 3607A х 123DHR and 3607A х 167DHR) realized good production potential under variable agro-meteorological conditions and can find future realization in practice.

Fuel consumption of a machine-tractor unit in direct sowing of wheat

G. Tihanov1*, N. Ivanov2

1Department of Agricultural Engineering, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
2Department of Plant production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

(Manuscript received 7 September 2020; accepted for publication 8 January 2020)

Abstract. A study has been conducted on the fuel consumption in direct sowing of wheat with a Horsch Avatar 6.16 SD direct seeder aggregated to a John Deere 7250 R tractor. The experimental field (29.53 ha) was sown with winter soft wheat (Silverio variety) at a sowing rate of 195 kg/ha. The data from the sowing unit were collected using the JD Link telematics system, downloaded from the system and imported and compiled in a database. Fuel consumption was analyzed in accordance with the operation mode, the idle mode and the transportion mode of the machine-tractor unit. It was found that the average fuel consumption in work mode (when the seeder was sowing) was 23.08 l/h, while in transportion mode the seeding unit consumed 16.55 l/h and while the unit was idling it consumed 4.30 l/h. The results also show that the seeding unit has travelled 63 km and consumed 185 L of diesel fuel at an average diesel consumption of 23.08 l/h.

Evapotranspiration in Sudan grass second culture grown under non – irrigated and optimal irrigated conditions

R. Bazitov*

Agricultural institute, 6000 Stara Zagora, Bulgaria

(Manuscript received 24 August 2020; accepted for publication 19 October 2020)

Abstract: The aim of the present study was to establish the evapotranspiration of Sudan grass variety Engje-1, grown as a second crop for silage on meadow-cinnamon soil for the region of Southern Bulgaria under irrigation conditions and without irrigation. For this purpose, an experiment with Sudan variety Endje-1 was conducted in the experimental field of the Agricultural Institute – Stara Zagora on soil type meadow-cinnamon soil, after its predecessor barley. The Sudan grass is harvested in the brooming stage. Two variants were explored: Variant 1 – without irrigation (control) and Variant 2 – with optimal irrigation, 70-75% of field capacity (FC). Evapotranspiration of Sudan grass grown as a second crop under non-irrigated conditions, depending on the nature of the year, ranges from 168.7 mm to 183.7 mm. Under conditions of irrigation, the largest share in the formation of the water consumption is occupied by the irrigation norm – 87.1% on average (from 86.3 to 90.8%). Under irrigated conditions, the relative participation of the initial water reserve in the formation of evapotranspiration significantly decreases.