Sign up for email alerts of new Fluid Journal issues!
Fluid Journal : Fluid Journal 1999-2001
2 Fluid Journal Fall 2000 K in soil profile K in soil profile i l rofie Kinsoipr l K in soil profile Soil K content decreased with depth in both soils. In K-treated plots, K applied to the soil surface moved downward in the soil profile, resulting in significantly higher soil K content than in control plots (Figures 3 and 4). As K input increased, more K moved to deeper soil depths. Soil K content was significantly higher in the surface soil than in the subsoil, suggesting that the majority of applied K was held in the surface soil and that downward movement was slow. Slow downward movement of applied K may be partially attributed to net upward flux of soil water in the soil profile as a result of high evapotranspiration in summer. Buffer ng ap i ri c acity Buffering capacity Buffering capacity Buffering capacity The magnitude of soil K increases and movement of surface-applied K fertilizers were greater in the Madera than in the Yolo soil. The differences can be explained by the differential potential buffering capacity for soil K (PBCk, data not shown). The Yolo soil, which has abundant vermiculite and montmorillonite clays, had a higher BCk PB PBCk PBCk PBCk value than the Madera soil, which has primarily kaolinite clay. Soil K balance Soil K balance Soil K balance Soil K balance Soil K balance Potassium fertilization significantly influenced soil K balance. Without it, exchangeable K in the 0 to 30-inch depth decreased by 0.37 and 0.34 lb/ tree in the Madera and Yolo soils, respectively, resulting in depletion of soil available K. In contrast, after three years of K fertilization, there was a net increase of exchangeable K from 0.38 to 1.56 lbs/ tree in the Madera soil (Table 1) and 0.21 to 1.19 lbs/tree in the Yolo soil (Table 2), leading to soil K accumulation. Pistachio trees accumulated significantly more K in K-treated plots than in control plots (Tables 1 and 2). K accumulated in the fruit and leaves of the control trees at Madera was 2.05 lbs/ tree and 1.65 lbs/tree at Yolo. K accumulated in the fruit and leaves of the K-treated trees was 2.85 to 4.16 lbs/ tree at Medera and 2.40 to 3.07 lbs/tree at Yolo. Higher K accumulation in fruit and leaves is a result of increased K concentration and increased crop yield in K-treated plots (data not shown). Dr Zeng is a former graduate research assistant, Dr Brown is professor, Department of Pomology, University of California, and Dr. Holtz is a pomology farm adviser, Madera County, CA. Table 1. Soil K balance (lb/tree) in 0 to 30-inch profile after three years of K fertilization, Madera orchard, Zeng, et al. , University of California. Change K accumulation in 3-year K input inK fruit and leaves Soil K balance lb/tree lb/tree lb/tree lb/tree 0.0 -0.37 2.05 -1.68 3.3 0.38 2.85 0.07 6.6 1.08 4.16 1.36 9.9 1.56 4.13 4.21 Table 2. Soil K balance (lb/tree) in 0 to 30-inch profile after three years of K fertilization, Yolo orchard, Zeng, et al. , University of California. Change K accumulation in 3-year K input inK fruit and leaves Soil K balance lb/tree lb/tree lb/tree lb/tree 0.0 -0.34 1.65 -1.32 3.3 0.21 2.40 0.69 6.6 0.70 2.90 3.01 9.9 1.19 3.07 5.64 Figure 3. Changes of soil exchangeable K in soil profile with (A) and without K fertilization (B) Madera orhard, Zeng, et al., University of California. Figure 4. Changes of soil exchangeable K in soil profile with (A) and without K fertilization (B) Yolo orhard, Zeng, et al., University of California.
Fluid Journal 1996-1998
Fluid Journal 2002-2004