Over the years soil fertility declined due to several factors. It can be attributed to over application of inorganic fertilizer; soil erosion, depletion of soil nutrients due to continuous tillage and lack of information on soil characteristics.
Aware of this problem on soil fertility, the Department of Agriculture in Bicol, conducted test on the capacity and limitations of Bicol soils. The study focused on rice production areas particularly the rice cluster farms covered by the GMA Rice production program. In the past, soil test kits (STKs) were provided free to LGU technicians, NGOs and farmers to determine the fertilizer requirement of these cluster areas. The data gathered were turned over to the Regional Soils Laboratory (RSL) initially as reference for fertilizer recommendation.
Today, the RSL together with the LGUs has come up with site characterization or profiling. Soil characterization is one method to determine soil fertility. Hence, farmers can now practice judicious use of fertilizer in a particular soil by referring to the soil maps.
In order to carry out soil characterization the DA used the Geographical Information System (GIS) technology in site mapping. The technology on GIS particularly the Global Positioning System (GPS) instrument and the data gathered from STK results were used to characterize and map rice farms in the region indicating the fertility level. Acidity or alkalinity, macro and micro nutrient status, fertilizer utilization status, important land features and other relevant land-base information necessary in understanding the capacity and limitation of these areas.

How GPS works –
The GPS is a fully-functional satellite navigational system. It is a vital global utility for modern navigation on land, sea and air around the world and an important tool for map-making and land surveying. It provides an extremely precise time reference, required for telecommunications and some scientific research, including the study of earthquakes. On the ground any GPS receiver contains a computer that calculates its own position by getting time signals from three of the four satellites, using a process called trilateration (similar to triangulation). The result is provided in the form of a geographic position – longitude and latitude – to, for most receivers, within 100 meters. Some specialized GPS receivers can also store data for use in Geographic Information System (GIS) and map making.

Methodology of the project
The initial activity of the project was to identify/profile rice production areas. Physical and biological aspects were quickly determined using existing reports and maps. Information like coordinates, elevation and other satellite data were collected using GPS instrument. Soil properties using the STK and laboratory results were determined and presented in graphs and maps. Meanwhile, soil samples were collected in different rice production farms in coordination with the LGUs and farmer association. A briefing was also conducted to discuss the details of the activity and the protocol including the use/operation of the GPS instrument. The areas for profiling were identified and masterlisted in the GMA Rice Program. Important characteristics of these areas taken by the BSWM and the Regional Soils Laboratory (RSL) were gathered for use in mapping soil characteristics.
The project specifically collects information on the location of the farm, sampling sites, name of farmers, soil pH, NPK levels and other relevant data. The GIS map developed using the GIS software contains result on soil pH, available N, P and exchangeable K, micro nutrients such as Iron (Fe), Copper (Cu), Zinc (Zn) and Manganese (Mn) levels and the NPK levels were developed using the GIS software.
Meanwhile, the fertility maps produced were practical and user-friendly emphasizing the STK results indicating low, deficient and high instead of numerical values like 1.0%N, 5% etc. where farmers seldom understand. The fertilizer recommendations for different rice production farms were also mapped based on soil characteristics. In order to validate the effectiveness of the recommended fertilizers a calibration or correlation with existing yield results will be conducted in selected areas through techno demo research.

Who will benefit from the maps
The different maps generated will serve as guide for technicians and farmers on the effective management of their farms by using the right kind and amount of fertilizers. To come up with a more complete and reliable result massive soil sampling is being done in all the six provinces of the region. Information campaign on how to collect soil samples are being done to create awareness among farmers and technicians. Furthermore, the STK results are also validated in the laboratory in order to come up with an accurate recommendation.
Assistant Regional Director for Operations and Regulatory, Jose V. Dayao said that with the available maps, and corresponding fertilizer recommendations, the farmers would save much from fertilizer as they would be applying the right amount thereby minimizing excesses or over usage. He also added that the results are important for policy makers and the DA in particular in order to effectively implement the rice program in the cluster areas. He also suggested that same study be conducted for other commodities and come up with maps up to the farm level.

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Source:
UMAsenso
Official publication of the Department of Agriculture RFU 5
October - December 2006
Vol. 15 No. 4