Effects of fertilizer salt concentration on viability of seed and Rhizobium used for hydroseeding

For testing salt effects on seed and Rhizobium, 10–30–10 fertilizer and KCl solutions were used; the solutions had an osmotic potential of − 2.5 MPa, equivalent to 90 kg of the fertilizer per cubic metre of water. Solution contact for 1 h slightly affected the viability of Rhizobium trifolii Dangeard but the effects were not of practical significance. Reduced viability was exhibited by Festuca arundinacea Schreb., F. rubra L. var. commutata Gaud., and Trifolium repens L. seed which had been rinsed after 1 h of fertilizer solution contact. Agrostis alba L., Dactylis glomerata L., F. rubra L., Lolium perenne L., L. multiflorum L., Phleum pratense L., T. hybridum L., and T. pratense L. were not significantly affected. In tests of seed unrinsed after solution contact for 1 h, viability of F. rubra, F. arundinacea, and T. repens was significantly reduced; that of L. multiflorum was not. Trifolium repens was more affected than in the test of rinsed seed.As T. repens viability was reduced as much as 30%, seed of this species might be applied separately from hydroseeder slurries having high fertilizer concentrations. Significant effects on other species tested are too small to influence hydroseeding methods, but amount and proportion of the seed mix may be altered where high fertilizer concentrations are used.