Although applications (apps) for mobile devices show increasing popularity in the agricultural sector, studies regarding their availability are still incipient. In the present study, a survey was conducted to assess global trends of app availability for agriculture. This survey was conducted in 2015 and 2018 in two app stores with free access (Google Play and Windows Phone); searches for the following keywords were included in the survey: agriculture, agri, and farming. In 2015 and 2018, these searches foun d 244 and 599 apps from 33 and 61 countries, respectively. Countries with the largest number of apps (i.e., USA, Brazil, and India) accounted for ~64% of all surveyed apps. However, diversity and availability of paid apps was greater in USA and Brazil compared to India. Although many apps were related to magazines and market information, numerous other apps were available on farm management, pests and diseases, precision agriculture, and technical assistance. Related apps that used photographic input and ci tizen science data were also found. Our study indicates that the global development of apps for agriculture is growing rapidly, with most serving informative purposes at no cost to users.
The objective of this study was to evaluate the long-term effects of piling secondary forest residue (after 3 decades) on soil chemical properties, growth, and nutrition of Pinus taeda and weeds at three locations. After secondary forest removal and residue piling, areas were cultivated with P. taeda (22 years), followed by eucalyptus (7 years), and returned to P. taeda. At 2 years of age, tree height and needle-nutrient levels of ongoing P. taeda from areas influenced by residue piling and areas outside the piling zone were evaluated. Biomass and nutrient levels of herbaceous and shrub weeds, NDVI indices (via a drone), and soil chemistry were also evaluated. Residue-piled areas displayed a decrease in soil pH and an increase in available soil P and K. Although herbaceous and shrub-weed biomass increased 2.5 to 10 times in residue-piling areas, this did not compromise pine growth. While residue piling had little impact on the nutritional status of pine and weeds, NDVI values indicated greater plant growth in piling areas. In general, the long-term effect of residue piling was an important factor associated with the large variation in tree growth and weed incidence after 3 decades.
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