Gis for Improved Soil Management
GIS (geographic information system) is a computer-based technology which manipulates spatial data from various sources, including satellites. It might seem a long way from the world of the Asian farmer. However, GIS is now being used in many countries in Asia, to help them manage their soil resources more efficiently.
It also presents the information briefly and clearly in the form of a map or diagram. This makes it very easy for people to understand a lot of complicated data.
A GIS combines layers of information about a place to give you a better understanding of that place. For example, it can take soil maps, rainfall maps and topographic maps, together with land use data, and combine all this information to show areas where there is a high danger of soil erosion (e.g. where there are annual crops growing on steep slopes during periods of high rainfall). Or it might use the same information to show suitable areas where governments could carry out a program to promote fruit production or develop new irrigated rice fields.
GIS is a computer-based technology that requires suitable software. Also, the information it uses, such as the maps and other data, must be in digital form (i.e. it must be a computer file). Maps have to be scanned, and text has to be keyed in. A lot of the work in adopting GIS systems in soil management is in assembling and digitalizing all the records from field surveys and mapping projects made in various parts of the country over many years.
Using Gis on Small Farms
In the past, sophisticated systems such as GIS would only be used on very large farms overseas. Now, GIS is being adapted for use on small Asian farms. In Japan, Korea and Taiwan, government programs are developing the use of web-based GIS systems. The concept is that farmers use the Internet to obtain free information about the soil properties of their farms, including soil fertility and nutrient levels.
Precision farming practices, also in the past used only on very large farms, are now being used for small ones. In Japan, precision farming is being developed as a way of increasing productivity while reducing production costs. The key concept in precision farming is to describe variability, in particular, the variation within each field.
Variable-rate technology is then used to adjust the agricultural inputs according to the specific needs in different parts of the field. If machines are used, this needs variable-rate machinery. On small farms, inputs can be applied as needed by hand.
Using Gis for National Development
The old saying "Better information gives better decisions" is very true for GIS. A person using a GIS is able to select the information he needs according to what goal he is trying to achieve. This makes GIS an invaluable tool in planning and monitoring land use at a regional or national level.
For example, GIS can be used to help reach a decision about different kinds of agricultural land use. It can take into account such factors as the fertility and gradient of the land, the annual rainfall pattern, the availability of rural labor, and access to markets (whether there are good roads, and whether the area is close to a population center).
In Indonesia, GIS is being used to reevaluate appropriate agricultural land use. The results so far indicate that on some islands, substantial areas of land that are suitable for agriculture are being used for forestry. Conversely, in Java and some parts of Sulawesi, land that should be forested is being cultivated. The system can be used, not only to identify which areas are suitable for arable land, but the best crop choices for a particular region.
GIS can also allow planners to identify areas which need special protection from natural disasters such as floods. In the Philippines, the staff of the Environmental Remote Sensing and Geo-Information Laboratory, UPLB, have produced an Atlas of four key watersheds. The aim is to help promote the effective management of watersheds, and thus help safeguard the country's water resources. The Atlas assesses the susceptibility of each watershed to soil erosion, and the risks of fires and floods. Changes in susceptibility over time will indicate whether land use is appropriate or not, and where changes are needed. It is planned to develop similar Atlases for other watersheds in the Philippines.
Global warming is making environmental disasters such as floods and landslides both more common and more disastrous. GIS will not prevent global warming, but it will help give early warning of where such disasters are most likely, and how they might be avoided. GIS also represents an enormous saving of cost and labor in the efficient management of soil resources.
Index of Images
Figure 1 1. Gis Map Showing Zinc Status, Central Taiwan. Each Small Square Is a Rice Farm. Pale Brown: Possible Zinc Deficiency; Green: No Zinc Deficiency; Dark Green/Brown: Care Is Needed to Avoid Excess Zinc
Figure 2 Changes in Soil Erosion, Wuser Watershed, Taiwan, 1987-1992. One of a Series of Gis Maps Showing Changes in Land Use, and the Impact of These Changes on Soil Erosion. by 1992, Soil Erosion Is Declining in Most Areas (Green Color). Even Where It Is Increasing, the Increase Is Less Than 5% (Yellow Color). This Is Because of a Change from Vegetable Crops to Tea.
