|Bjorneberg, David - Dave|
Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2009
Publication Date: 7/15/2009
Citation: Busscher, W.J., Bjorneberg, D.L., Sojka, R.E. 2009. Field application of PAM as an amendment in deep-tilled US southeastern Coastal Plain soils. Soil & Tillage Research. 104(2):215-220.
Interpretive Summary: Southeastern US Coastal Plain soils have low water holding capacities and firm layers that prevent root penetration. Soils have to be deeply tilled annually to soften them and permit roots to grow to water. With the increasing cost of fuel, this practice is becoming prohibitively expensive. In an attempt to eliminate the need for annual deep tillage, we added environmentally friendly versions of polyacrylamide (PAM) to these soils to improve physical properties and yields. This technique was tried in the 1950’s but abandoned because it was too expensive. Today we have incentive to try it again because of higher costs of production and newer/purer formulations of PAM. We sprayed liquid or dropped solid formulations of PAM to soils behind a modified deep tillage shank and monitored soil strength and yield for three years. Although the PAM reduced soil strength when compared to the controls, its effect was not great enough to increase yield and its effect did not last over time. Future studies will need to concentrate on different formulations, more thorough mixing, and higher but cost-effective concentrations.
Technical Abstract: Polyacrylamide (PAM) was added to sandy coastal plain soils to improve physical properties and yield. Soils were amended with 8 treatments of linear and cross-linked PAMs or controls. Treatments and controls included the following: 1. spraying a 600 mg/kg solution of linear PAM behind a subsoil shank, 2. spraying a 100 mg/kg solution, 3. spraying water, 4. dropping a dry PAM powder (formulation 3005kb) behind a subsoil shank, 5. dropping another dry PAM powder (formulation 3005k2), 6. dropping a dry PAM powder (formulation 3005k2) at half the rate of treatments 4 and 5, 7. applying nothing behind a subsoil shank, 8. not subsoiling. In each of the three years of the experiment, new sets of treatments were set up while the old ones were maintained to look at longevity of the PAM effect. Though treatment effects were dominated by the tillage, PAM reduced soil cone indices with dry cross-linked PAM reducing it more than liquid linear PAM probably because more PAM could be added in dry form than in a spray. The effect diminished with time similar to the results seen in tillage only. Though the PAM applications may have reduced cone indices, yields were not affected.