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<br />ono 01'4 <br /> <br />INTRODUCTION <br /> <br />The site selected for this demonstration, partially funded by the Colorado Water Conservation Board <br />(Fig. I), was the Stonewall Springs (Farm) located in Pueblo County east of the City of Pueblo and <br />divided by Highway 50 (Fig.2). The property is located immediately north of the Arkansas River and has <br />a shallow water table varying from 8 to 22 fuet as seen in static well levels. "Perched" water table areas <br />have been creat~? over-irrigation in some areas of the property causing excessive salting of the soils. <br /> <br />~ .. <br />Nine full-cir e and two half-circle center pivot systems are located on the property. Two full circle <br />pivots were t represented different soil types or salinity conditions_ The pumps being used to supply , <br />these pivots "were tested to determine pumping capacity and pump efficiency and the pivots were <br />"customized" to fit the specifications of these pumps. Crops and/or grass and legume mixtures planted <br />on these soils were determined by the soil type and salinity levels shown by the soils and salinity <br />mapping. Also, the quality of the water being pumped to each of the demonstration sites was tested for <br />irrigation suitability and different methods of water application used by LEP A system were observed to <br />determine the effect of water quality on crops. Drag hoses and low drift nozzles (LON) were used to <br />apply the water. ~..rp possiQle, higher quality water was appli~ the alfalfa and the lower quality <br />water was applied to the more salt-tolerant grass-legume and/or grass mixtures. <br /> <br />The demonstration area was re-:ped for soil type in the summer of 199.1.b.yJhelSRCS, (Fig. 3). Soil <br />types and shallow water table co ItiOnS found on the demonstration site property are Limilar to those <br />found in rjyer bottom arells in Colorado and New Mexico. Management problems of irrigated soils of <br />this type are greater due to the ~-COntent. Clayey soil is difficult to cultivate as it is cloddy and <br />cracks when dry (Fig. 4) and stiCk)' and plastic when wet. These soils also have a low water-infiltration <br />rate and the available water holding capacity is high. Also, these soils are moderateiytOStrOiiglyiiffected <br />by salts, partially due to the shallow water tables. Salts tend to accumulate m sOlis tIlatare not well <br />drained. <br />--- <br /> <br />Salinity problems start when previously non-saline soils become saline as a result of irrigation. Salts <br />begin to accumulate within the soil profile because all waters contain some dissolved salts. The <br />accumulation occurs when salts are left behind as crops take up water. With continued salt <br />accumulation, water becomes less available for plant growth, causing lower crop yields. <br /> <br />Salinity problems in fields are often difficult to spot before signjficant crop damage occ!!.rs. Typically, <br />saline SOlis are recognized by the presence of white crusting on the soil surface, spotty crop stands or by <br />irregular plant growth. <br /> <br />Historically, field salinity problems have been assessed by taking soil samples and sending them to a <br />laboratory for analysis. There are several limitations to assessing salinity using this conventional <br />technique. To effectively sample a field, several hundred soil samples may be required, particularly for <br />large fields. At 10 minutes per sample, time investment in the field is substantial. Second, it is not <br />uncommon for the cost of analysis to exceed $25 per sample. Third, it is common for laboratory results <br />to take weeks before information is received. Fourth, conventional methods aren't conducive to returning <br />to a field to check and monitor the effectiveness of any management or structural practice on the salinity <br />problem. <br /> <br />5 <br />