4.2.3 In Situ Sensors
In agriculture, in situ sensors denote the sensors installed in the fields. The sensors
may be fixed on the top of a standing pole, laid on the ground, immersed under water,
buried in the soil, or carried by people or vehicles. The measurements are taken very
close to the targets and share the same circumstances with the crops. The data are
normally considered as ground “truth” as they have slight noises comparing to
satellites and UAVs. Such in situ way is the heritage of agricultural monitoring
technique that was adopted before aircraft and spacecraft appear. Today, it still plays
an important role thanks to the significant improvements of close-range measuring
instruments. We surveyed the currently operational sensors in agricultural fields and
the corresponding datasets available online. According to the agriculture-relevant
targets, we divided the in situ sensors into four classes: weather, soil, water, and
vegetation.
Automated network of weather data collection for agriculture has been addressed
back in 1980’s (Hubbard et al. 1983). The agricultural industry demands accurate
weather information to apply appropriate treatments on the crops or animals. A slight
error of 2 or 3 degrees of temperature has quite different consequences on crops. The
public weather map is interpolated by the measurements from weather stations
which may be located as far as 50 miles away. Affordable and readily available
weather stations perfectly solve this problem. Through decades of developments, the
methods and technologies have turned very mature and been commercialized in
weather industries. The small-sized devices as weather stations have been on sale
such as AcuRite Pro 5-in-1 weather station tagged $119.99 on Costco website. The
weather station can measure rainfall, wind speed and direction, temperature (actual
and feel like), moon phase, heat index, dew point, wind chill, and more, and stream
the data real time to the user. The information is remotely accessible from
smartphone, tablet, and laptop web browser. People can keep the data privately or
share the data with friends and weather communities like weather underground
2 to
enrich the public records. Accurate weather data of a crop field must be one of the
easiest datasets that can be achieved via relatively low cost.
Similar to weather stations, sensors for both soil and water have been in use for a
long time, but it is only recently that miniaturized and affordable sensors have
become available (Rossel and Bouma 2016). In situ and multiple-point measuring
is feasible now. A number of commercial sensors are on the market to measure the
presence of water in the surface and root-zone soil (soil moisture), soil nitrate,
salinity, soil reaction (pH), available water capacity, bulk density, soil crusts,
macropores, earthworms, particulate organic matter, soil enzymes, total organic
carbon, etc. (Mukhopadhyay 2012). Using soil sensors in agriculture can provide fundamental information about the local soil and environmental conditions in
space and time, enhancing the efficiency of crop yield and minimizing environmental side effects. The sensed information can accumulate to a site-specific database,
2 https://www.wunderground.com
4 Agro-geoinformatics Data Sources and Sourcing
53
In agriculture, in situ sensors denote the sensors installed in the fields. The sensors
may be fixed on the top of a standing pole, laid on the ground, immersed under water,
buried in the soil, or carried by people or vehicles. The measurements are taken very
close to the targets and share the same circumstances with the crops. The data are
normally considered as ground “truth” as they have slight noises comparing to
satellites and UAVs. Such in situ way is the heritage of agricultural monitoring
technique that was adopted before aircraft and spacecraft appear. Today, it still plays
an important role thanks to the significant improvements of close-range measuring
instruments. We surveyed the currently operational sensors in agricultural fields and
the corresponding datasets available online. According to the agriculture-relevant
targets, we divided the in situ sensors into four classes: weather, soil, water, and
vegetation.
Automated network of weather data collection for agriculture has been addressed
back in 1980’s (Hubbard et al. 1983). The agricultural industry demands accurate
weather information to apply appropriate treatments on the crops or animals. A slight
error of 2 or 3 degrees of temperature has quite different consequences on crops. The
public weather map is interpolated by the measurements from weather stations
which may be located as far as 50 miles away. Affordable and readily available
weather stations perfectly solve this problem. Through decades of developments, the
methods and technologies have turned very mature and been commercialized in
weather industries. The small-sized devices as weather stations have been on sale
such as AcuRite Pro 5-in-1 weather station tagged $119.99 on Costco website. The
weather station can measure rainfall, wind speed and direction, temperature (actual
and feel like), moon phase, heat index, dew point, wind chill, and more, and stream
the data real time to the user. The information is remotely accessible from
smartphone, tablet, and laptop web browser. People can keep the data privately or
share the data with friends and weather communities like weather underground
2 to
enrich the public records. Accurate weather data of a crop field must be one of the
easiest datasets that can be achieved via relatively low cost.
Similar to weather stations, sensors for both soil and water have been in use for a
long time, but it is only recently that miniaturized and affordable sensors have
become available (Rossel and Bouma 2016). In situ and multiple-point measuring
is feasible now. A number of commercial sensors are on the market to measure the
presence of water in the surface and root-zone soil (soil moisture), soil nitrate,
salinity, soil reaction (pH), available water capacity, bulk density, soil crusts,
macropores, earthworms, particulate organic matter, soil enzymes, total organic
carbon, etc. (Mukhopadhyay 2012). Using soil sensors in agriculture can provide fundamental information about the local soil and environmental conditions in
space and time, enhancing the efficiency of crop yield and minimizing environmental side effects. The sensed information can accumulate to a site-specific database,
2 https://www.wunderground.com
4 Agro-geoinformatics Data Sources and Sourcing
53