**3.1 Saving resources through precision farming**

Precision farming (PF) is considered the best practicable approach to achieve sustainable agriculture. Precision farming is an integrated, information- and production- based farming system that aims to raise efficiency, productivity and profitability of long term, site-specific and whole farm production while avoiding the undesirable effects of excessive chemical loading to the environment or insufficient input application.

The role of PF in crop production technology is recognized worldwide, but so far, it is applied mostly on large farms. Implementation of PF should be followed in three main steps of information gathering in terms of variability, data processing to evaluate the significance of variation and employ new management strategy to apply farming inputs. Fig. 9 demonstrates some equipment and technologies in a typical precision farming crop growing cycle. Some describe precision farming as applying the right inputs, at the right place, at the right time, right amount, and in the right manner.

Fig. 9. Precision Farming Cycle (Grisso, 2009)

Implementation of management strategy based on precision farming concept is the vital factor to achieve a desired outcome for the farm. Managers should make out their own strategies that allow them to manage variability precisely. Blackmore (1999) stated the three types of variability that have been identified are spatial variability, which can be found through changes across the field, temporal variability which means changes over time and predictive variability, that identifies the difference between predicted and what actually happen in the field.

One of the precision farming approaches to manage spatial variability is site specific crop management (SSM). In order to match application of farm practices with soil and crop requirements, zone management was suggested. Zone management represents sub-fields with similar characteristics including soil properties, topography, slope, nutrient levels and so on.
