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<br />~' .... <br /> <br />,'-'" <br />~, <br /> <br />vi'\ <br />~ <br /> <br />...-'1 <br /> <br />Procedure 2 - Soil water content will be determined for each soil moisture <br /> <br />'.:.) monitoring site within the irrigation evaluation site. It is estimated that a <br /> <br />minimum of three (3) soil moisture monitoring sites are needed per irrigation <br /> <br />evaluation site with 8 soil samples per site. <br /> <br />This level of sampling will be <br /> <br />done once at the beginning of the evaluation period for each irrigation site. <br /> <br />If a neutron probe is used to determine soil moisture, it will be calibrated at <br /> <br />each sampling site. Sampling at this level will provide a high degree of <br /> <br />accuracy. <br /> <br />Gypsum percentage, calcium carbonate, and electrical conductivity determinations <br /> <br />will also be made from subsamples of the original sample as well as the physical <br /> <br />determinations. In this manner, a benchmark of soil salinity can be established <br /> <br />and monitored over the period of evaluation. <br /> <br />Soil Moisture Monitoring <br /> <br />The available soil water content will be measured prior to the first irrigation, <br /> <br />before the crop is planted or starts growing if a perenniaL If daily crop <br /> <br />evapotranspiration (ET) is calculated and used to determine the net irrigation <br /> <br />requirement, several soil moisture measurements will be made during the <br /> <br />irrigation season to verify the soil water status as a check on ET bookkeeping <br /> <br />calculations. In the case where ET is not calculated, soil moisture <br /> <br />measurements will be made prior to each irrigation to determine the net <br /> <br />irrigation requirement. A final soil moisture measurement will be made just <br /> <br />af ter the crop is harves ted or end of growing season if a pE!rennia1. <br /> <br />Methods of Soil Moisture Monitoring <br /> <br />The methods used to monitor soil moisture will depend on thE! type of equipment <br /> <br />available. Three commonly accepted methods for monitoring soil moisture have <br /> <br />been considered for this proposal: feel and appearance, gravimetric, and neutron <br /> <br />moisture logging. Each method has its advantages and disadvantages. <br /> <br />24 <br />