Effect of Polymeric Soil Conditioners on Emergence of Tomato Seedlings

We conducted laboratory-glasshouse experiments with three different California soils known for severe crusting problems that hinder seed emergence. Some new polymers gave very effective control of the crusting problem, especially during the period of seedling emergence. One reason they are effective is that they are of higher molecular weight than polymers used in the past. Dry polymers were put into solution, and the solution was applied to soils as an anticrusting agent. Amounts needed are in the cost-effective range. Products tested included a natural polysaccharide (galactomannan)of molecular weight about 200 K daltons, a cationic polymer with molecular weight of about 5000 K daltons, and an anionic polymer with molecular weight of about 5000 to 12000 K daltons. Without polymers for the soils tested, there was very little seed emergence. In general, the most favorable results for seed emergence and water infiltration came from the anionic polymer, followed by the cationic polymer.