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Fluid Journal : Fluid Journal 2002-2004
2 Fluid Journal Winter 2003 Methodology Sites. The SDI study was conducted at the South Research Facility 30 miles south of the Agricultural Science Center at Clovis, New Mexico. The CP study was conducted at Chandler's Farm 20 miles south of the SDI site. Soil at both sites was Amarillo loamy fine sand with an annual average rainfall of 18 inches. Plots were 100 feet long and 3.3 feet wide under SDI and 1200 feet long and 3.3 feet wide under the CP irrigation system. Scheduling under SDI was based on estimated daily evapotranspiration (ET) values multiplied by crop coefficient value. The CP was irrigated at the farmers' discretion. Design of the experiment under the SDI system was a split plot with compost application as main plots and chelated calcium as subplots. The design under the CP system was a randomized complete block system with four different calcium rates. No compost was applied under the CP system. Variety used was Valencia-C in both studies. Planting. Plots were planted in rows at a spacing of 40 inches between rows and 2 inches within the row (about 6 plants per foot of row or 78,408 plants per acre). Calcium source was Librel calcium chelate with 9 percent readily soluble form of chelated calcium. SDI vs CP Yield. Under the SDI system, application of compost resulted in a 10 percent higher yield compared with no compost treatment (Figure 1). High rates of Ca (6 lbs/A) in combination with compost resulted in a 16 percent higher yield, compared to no compost application. Figure 2 shows that pod yields with the SDI system averaged 2,381 lbs/A while the CP system averaged 2,025 lbs/A. The yield advantage of SDI over CP may be due to constant soil water content under SDI, or higher canopy cover under SDI when compared to CP. With CP there tends to be a period of drying between irrigations that would not occur under SDI. In addition, the constant water content observed in the SDI treatment resulted in increased leaf area or leaf mass covering the soil surface. This helped prevent the soil surface from drying out as fast as with the CP treatment. Among the four Ca rates tested, an application rate of chelated Ca of 1.5 lbs/A under SDI resulted in a significant yield increase of 37 percent higher compared with the CP system. Water efficiency. SDI averaged 0.18 inch per irrigation while CP averaged 0.5 inch per irrigation. SDI received about 21 inches of water compared with 25 inches of water applied through the CP system, or about 19 percent less water. Dollar return SDI peanuts had an average monetary return of $722/A while the CP system Figure 3. Monetary return of SDI vs CP systems. 560 600 640 680 720 760 800 0 1.5 3.0 6.0 Calcium rate-lbs/A Yield/lbs/A SDI CP had an average monetary return of $650/ A. Among the four rates of calcium tested, an application rate of 1.5 lbs/A of Ca resulted in 31 percent higher monetary returns with SDI when compared to the CP system. The next best monetary return was with an application rate of 3.0 lbs/A as shown in Figure 3. Mr. Puppala is college assistant professor, Dr. Baker is superintendent, Agricultural Science Center, New Mexico State University and Dr. Sorensen is Agronomist with National Peanut Research Lab. at Dawson, Georgia.
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