Addressing Soil Chloride Variability and Its Management
Addressing Soil Chloride Variability and Its Management, 1998 In the northern Great Plains, grid sampling is not used by many wheat producers because of its expense. To be profitable, responsive areas within fields (less than 30 lb Cl/A 2 ft) need to be characterized by a minimum number of soil samples. Five sites (Mandan, Valley City, Colfax, Gardner, and Hunter) in North Dakota were selected in order to study Cl variability. Each of these sites was sampled at small grid spacings.
IPNI-1996-USA-ND8
01 Mar 1999
1998 Annual Interpretive Summary
Addressing Soil Chloride Variability and Its Management, 1998
In the northern Great Plains, grid sampling is not used by many wheat producers because of its expense. To be profitable, responsive areas within fields (less than 30 lb Cl/A 2 ft) need to be characterized by a minimum number of soil samples.
Five sites (Mandan, Valley City, Colfax, Gardner, and Hunter) in North Dakota were selected in order to study Cl variability. Each of these sites was sampled at small grid spacings (0.28 acre). Soil samples composed of 5-8 cores were taken to a 2 ft. depth. Chloride variability (lb Cl/A 2 ft.) at each site was as follows: Mandan (6 to 90), Valley City (19 to 701), Colfax (9 to 733), Gardner (9 to 351), and Hunter (3 to 167). At Valley City and Mandan, large areas within the fields tested less than 30 lb Cl/A 2 ft, classifying them as possibly responsive to Cl fertilization. However, the mean soil Cl levels at Valley City and Mandan were 200 and 29 lb Cl/A 2 ft., respectively. Thus, incomplete characterization of soil Cl variability led to missed opportunities for increased yields and Cl fertilization. To determine the best sampling scheme for Cl, this study evaluated spatial characterizations of soil Cl levels generated from topography-based sampling and grid sampling at various densities (0.28, 1.11, 2.5, and 5 acre grids). Data from the 0.28 acre grids was used as the basis for mathematically constructing the other sampling approaches. Topography was characterized by measuring relative elevation with a laser-survey device. Results indicate that soil Cl patterns could often be well defied by either a 1.11 A grid (220 ft.) or by topography sampling. Higher Cl levels were usually associated with depressional areas, while lower Cl levels appeared most frequently in upland positions. Topography sampling may be appealing to many producers because in many cases it adequately characterized Cl variability using fewer soil samples. ND-08F