Q3: Spatial variability analysis is mostly use in precision agriculture. Discuss how spatial variability can use to enhance the modern agriculture practice compare to conventional.

Precision Agriculture is a collection of agricultural practices that focus on specific areas of the field at a particular moment in time. This is opposed to more traditional practices where the various crop treatments, such as irrigation, application of fertilizers, pesticides and herbicides were evenly applied to the entire field, ignoring any variability within the field. Having information on potential crop yield at an early stage, is very beneficial for the farmer, but also for countries that heavily rely on agricultural production, to satisfy the national needs for the crops and also for income through exports. There is lot of factor can affect the yield of the crop such as soil type, chlorophyll content, watering and irrigation, fertilizer application and agriculture practice itself. Some data, such as soil moisture, vegetation cover, and chlorophyll content can be measured through remote sensing (RS). Other soil properties however, require sampling of soil cores and analysis of those samples in a lab such as phosphorus (P) contamination, Potassium (K) and soil acidity (pH).  As long as the location of the samples is recorded through a GPS, it is possible to create a soil map of the field in GIS system. Then the soil map will show the distribution for each characteristic of the soil. Once we have collect all the necessary data (variable)from remote sensing, soil data from lab, we can now compile the data in GIS platform to study the relationship between those data.

There is a strong correlation between data such as soil type and watering system, and watering system and chlorophyll content. Based on the data, we can create the spatial variability model and study the correlation between each variable (data). Base on this model, we can adjust the variable (data) in according to the crop status. For example, we already know soil (variable) characteristic in the crop field, so we can adjust the fertilizer application based on the suitability of soil characteristic to supply the nutrient to the crop base on their need. So, the fertilizer apply is only on the curtain area needed compare to conventional practice that apply the same fertilizer for entire field area.