Journal of Agricultural Studies
EISSN : 2166-0379
Current Publisher: Macrothink Institute, Inc. (10.5296)
Total articles ≅ 524
Latest articles in this journal
Journal of Agricultural Studies, Volume 9, pp 272-282; doi:10.5296/jas.v9i2.18328
World market is increasingly expanding in food production. Coffee has been underscored within the new scenario and positively impacts the economy of the country, together with other crop types. Current analysis assesses the insertion index of new technological resources and the fastness of the production process of coffee culture on small coffee plantations in the south of the state of Minas Gerais, Brazil. Field study comprised the analysis of 225 farms by an open and closed questionnaire. Data, analyzed by cluster analysis, revealed that small farms have invested in technologies and data access technology for harvest and production processing. Corroborating other scientific investigations, the above activity decreased the labor force and consequently triggered an increase in profits for small producers.
Journal of Agricultural Studies, Volume 9, pp 151-170; doi:10.5296/jas.v9i2.18389
We present a computational procedure to maximize the production of a given agricultural crop with limited inputs (water-nitrogen), and where a fixed cost (or expense) of the inputs (general problem of agricultural production) is imposed. Theoretically the procedure is based on the Karush-Kuhn-Tucker optimality conditions and numerically was tested with three different scenarios defined in the literature, for the cultures: Lettuce, Oats, Onions and Melons. In each agricultural scenario considered, it was possible to verify that the procedure is a reliable alternative in making agribusiness economic decisions.
Journal of Agricultural Studies, Volume 9, pp 171-187; doi:10.5296/jas.v9i2.18046
The present work aims to evaluate the possibility of anticipating the wheat harvest by the application of non-selective herbicides in the pre-harvest conditions, thereby providing productive and economic viability. In total, 13 treatments were executed, which includes the spraying of different herbicide combinations (glufosinate-ammonium, glyphosate, and paraquat) in the phenological stages (Z-83, Z-85, Z-87, Z-92), and treatments without application of herbicides. Further, the treatment step was followed by providing different harvest conditions such as (i) glufosinate-ammonium: 9.5 and 8.8 days, (ii) glyphosate: 11.2 and 10.9 days, and (iii) paraquat: 7.9 and 8.5, where the first numerical value corresponds to number of days for the year 2016 followed by 2017. A mean reduction in seed yield of 4.6 % (BRS Parrudo) and 25.4 % (TBIO Sinuelo) was observed upon application of herbicides in the first two phenological stages. Additionally, an economic loss reaching up to R$ 2512 ha-1, was demonstrated. Therefore, the application of the non-selective herbicides glufosinate-ammonium and paraquat in the pre-harvest results in wheat phytointoxication, however, promoting harvest anticipation in 4.8 and 5.3 days, respectively.
Journal of Agricultural Studies, Volume 9, pp 188-204; doi:10.5296/jas.v9i2.18032
The economic viability of a commercial oral anthelmintic suspension containing 10% fenbendazole was evaluated in Angus x Nelore cattle in a feedlot. Two groups of 37 animals (treated and non-treated) were formed. A random-block design was used based on initial weight, egg count per gram of feces (EPG) and carcass grade. EPG counts and the determination of weight were performed on Days 0, 42 and 122. Carcass grade and yield were determined on the day of slaughter. Economic viability was evaluated using cost-effectiveness, sensitivity and financial analyses, considering three economic scenarios: most likely (M), optimistic (O) and pessimistic (P). The anthelmintic achieved 99.89% efficacy regarding EPG reduction. The animals exhibited an increase of 20.7 kg in live weight, 20.2 kg in live weight gain and 0.166 kg in daily weight gain (p < 0.05). No effects were found on yield or carcass grade (p > 0.05). The genus Haemonchus predominated at the onset of the study, whereas only the genus Cooperia was found after treatment. A net return of 14.60 USD per animal was found in the treated group, which remained viable under O, M and P scenarios, with respective differences of 18.92%, 12.86% and 91.15% in gross profit. The treatment was financially superior under all scenarios (real, M, O and P), with reductions of 1.89, 1.04, 0.48 and 16.39 years for the recovery of the initial investment. These results demonstrate the importance of economic analysis methods in the evaluation and selection of anthelmintics.
Journal of Agricultural Studies, Volume 9, pp 32-56; doi:10.5296/jas.v9i2.18156
The inclusion of natural extracts and solution of synthetic astaxanthin in the Macrobrachium amazonicum diet were tested to verify their effect on performance, body indexes and total accumulation of astaxanthin in the reproductive tissues and gametes of this crustacean in comparison with newly captured wild animals. The experiment was randomized in blocks (five treatments with three replicates). Four groups were submitted, during 20 days, to diets in recirculation tanks: control diet (CONT); diet containing natural extract of “buriti” (CAR); diet with inclusion of natural “urucum” extract (BIXN), diet with synthetic astaxanthin (ASTX) and NATURAL group (not fed with ration). 180 prawns were used, with 60 males (6.08±1.96 g) and 120 females (4.55±1.03 g) distributed in five groups containing four males and eight females each. There were no significant differences in performance and body indexes. The number of released spermatozoids, live spermatozoids, body and egg pigmentation was higher in BIXN and ASTX treatments. The ASTX treatment was superior to the NATURAL group in the body pigmentation of females and eggs and release of spermatophores by males. These results demonstrate that the use of natural and artificial carotenoid pigments in the diet are beneficial for reproduction of M. amazonicum.
Journal of Agricultural Studies, Volume 9, pp 73-95; doi:10.5296/jas.v9i2.18139
Soy production in Brazil is an important factor for the agro-industrial, economic, and social development of the country. The expansion of soy in the Brazilian territory is mainly due to the incorporation of new genetic characteristics into cultivars that granted resistance to the Cerrado conditions and to herbicides. Currently, Brazilian soy production is the result of genetically modified cultivars. Studies regarding the chemical composition of soybeans show that qualitative and quantitative variations can occur, depending on the region of production. This work aimed to investigate the chemical composition of soybeans produced in different cities of the Triângulo Mineiro region/MG, Brazil (Harvest 2017/2018) and stored in three warehouses located in the city of Uberaba/MG. The grain analysis was made by liquid chromatography coupled to electrospray ionization mass spectrometry (LC-MS-ESI). The classes of metabolites identified from methanolic extraction were organic acids, phenolic compounds, flavonoids, sugars, amino acids, dipeptides, nitrogenous bases, nucleosides, sphingolipids, and fatty acids. The isoflavones genistein, daidzein, glycitein, genistin, acetyldaidzin, and acetylgenistin were identified in soybeans from the three warehouses. The flavonoid eriodictyol-O-hexoside was also found. The Principal Component Analysis (PCA) from the mass spectrum data obtained by direct injection in the negative and positive modes evidenced the well-defined separation of three groups, indicating that there was variance among the soy samples from each warehouse. The samples from warehouses 1 and 3 showed greater similarity in the Hierarchical Cluster Analysis (HCA) in negative mode, while in positive mode, the samples from warehouses 2 and 3 presented greater similarity.
Journal of Agricultural Studies, Volume 9, pp 57-72; doi:10.5296/jas.v9i2.18159
The color is an important factor to distinguish the commercialized Amazon river prawns. The accumulation of pigments in the body can vary according to the prawn’s diet. In this work, ethanolic extracts of “buriti” and annatto rich in pigments were obtained and tested comparatively with synthetic astaxanthin in the feeding of adults of Macrobrachium amazonicum, together with a control group without pigments and a newly captured wild group. Levels of body pigments were measured using UV reflective spectroscopy and external staining by colorimetry. Differences were observed in the accumulation of astaxanthin in body tissues, differences in saturation between genders and that annatto extract has greater stability in the feed after water immersion (P˂0.05). Further studies are recommended to verify the ideal dosage of natural pigments in relation to synthetic astaxanthin that benefits the productive development of prawns.
Journal of Agricultural Studies, Volume 9, pp 283-303; doi:10.5296/jas.v9i2.18494
To have information about the soybean productivity over the crop years is essential to define strategies to increase profits and reduce costs and most important to reduce environmental impacts. One form of monitoring is the use of Geostatistical methods, which allow us to obtain maps with more accurate predictions. In this paper, an area of 127.16 ha was studied during six crop years between 2012/2013 and 2017/2018. We found that productivity values vary between crop years, mainly due to uncontrollable climatic factors. The removal of influential points caused changes in the predicted values showed in the maps, and the use of scaled semivariograms allowed us to obtain similar maps to those obtained considering the model without influential points, then there was no need to exclude observations. The use of a model with replicates helped to identify regions where productivity was lower. The use of explanatory variables allowed us to elaborate a more accurate thematic map in the 2017/2018 crop year, which was well evidenced by the prediction standard error map.
Journal of Agricultural Studies, Volume 9, pp 323-334; doi:10.5296/jas.v9i2.18385
The fine root component, although it represents the lowest proportional biomass in a tree, has an important function in obtaining water and nutrients. In addition, it is an indicator of the physiological quality and growth of a tree. Thus, the objective of the study was to evaluate the spatial distribution of biomass and the density of fine roots in five different fertilizer treatments. The five treatments received increasing amounts of fertilizers. The collections were made between trees in the planting line and between the planting lines. Soil layers of 25 cm x 25 cm x 20 cm (length x width x depth) were collected until reaching a depth of 1 meter. Treatments that had less nutrient input via fertilization showed higher production of fine roots. In general, the line position in the superficial layers showed a higher density of fine roots. There was significant difference between the positions of the land monoliths and between the different layers. Strategically, the lower supply of nutrients via fertilization provided greater investment in the production of fine roots by trees in order to increase the area of absorption and exploration of the soil.
Journal of Agricultural Studies, Volume 9, pp 96-112; doi:10.5296/jas.v9i2.18230
Farmers' local knowledge about soil quality and management practices should be considered to assess the impact of agricultural technology packages on the environmental performance of agro-ecosystems. This study aimed to evaluate the soil quality under agroecological production in southern Brazil, which was considered of good quality by the farmers' perception. From August to November 2017, ten farms from Liberdade settlement were visited, and semi-structured interviews were conducted to collect information about soil and agricultural knowledge. “What does good quality soil mean? What cares for preserve soil quality? Does the soil location in landscape influence conservation practices?” were the questions asked. In May 2018, soil samples were collected from each area, and chemical, physical, and biological attributes were determined. All farmers mentioned the organic matter indicated good soil quality; however, the study showed that most soils have low content, a consequence of the annual tillage adopted by all farmers for the implantation of seeds crops; Farmers indicated that a good quality soil has "life" with the presence of organisms. In our study, a low population of mites and springtails in most areas was observed. Positive farmers’ perception about the organic matter content and soil organism’s presence in their agroecological production areas come from the degradation history of the areas, at the same time that they attribute improvements in soil quality due to the actions adopted over the 10 years of agroecological production.