# Blockchain Applications in Agriculture: A Scoping Review
## 3 Results  
### Selection of Evidence Sources  
A total of 636 abstracts were retrieved (398 from Scopus and 238 from Google Scholar). First, we removed 118 duplicate records. After the first screening, 387 of the remaining 518 papers were excluded: 110 were not related to our research scope, 30 were not in English, 44 were introductory materials from conference proceedings, 48 were not scientific papers, 55 were review papers, 70 were discussion papers, and 35 were papers that could not be accessed. Eventually, we came up with 131 unique papers identified for the complete paper analysis. During the second screening, 22 papers were excluded as they were not relevant to blockchain applications in the agriculture sector. The remaining 104 research papers were included in the scoping review. The source selection process is shown in Figure 1. Overall, 16.35% of the retrieved papers were relevant to the study's topic and were included in this scoping review.  
Figure 2 shows the yearly distribution of the publications that were retrieved by search engines (after duplicate removal) and the final papers included in our scoping review. As we found out, there is an increasing trend in blockchain research in the agricultural sector. All the papers in our review were published from 2017 onward: 3 papers (3%) published in 2017, 7 papers (7%) published in 2018, 28 papers (27%) published in 2019, 47 papers (45%) published in 2020, and 19 papers (18%) published until April of 2021.  
Figure 1: Source selection process from bibliographic search engines.  
Figure 3 presents the number of papers per publisher that were finally included in our scoping review. The IEEE holds the highest number of papers, corresponding to the 42% (44 papers) of all the relevant papers. Other publishers that appear very often in our papers collection are Elsevier 13% (13 papers), Spring 13% (13 papers), and MDPI 11% (11 papers). In addition, few works have been published in IOP 5% (5 papers) and ACM 4% (4 papers). Finally, there are 14 papers (13%) that have been published in other publishers.  
A further analysis of 104 papers related to blockchain application in the agriculture domain shows that 63 (61%) publications are full conference papers and 41 (39%) are journal papers (Figure 4). Journal papers are scattered in 25 different journals; only 8 journal titles have published more than one paper on blockchain applications in agriculture. The journals with the most published papers are: _IEEE Access_ (6 papers), _Sustainability_ (5 papers), and _Computers and Electronics in Agriculture_ (3 papers). There are also five more journals with more than one paper in our review: _Journal of Cleaner Production_, _Future Generation Computer Systems_, _Sensors_, _Journal of Computers_, and _International Journal of Advanced Computer Science and Applications_. Conference papers are published in 59 different conference proceedings; only four conference proceedings titles published more than one paper included in this scoping review, namely IEEE ICBC, IEEE ICCCSP, ITIA, and IEEE ISPA/BDCloud/SocialCom/SustainCom (2 papers).  
Figure 3: Distribution of papers per publisher related to blockchain applications in the agriculture domain.  
Figure 2: Yearly distribution of papers retrieved (blue) and finally included (orange) in our scoping review.