Samples of soil, mulch, and the soil/mulch interface zone were collected from commercial highbush blueberry (Vaccinium corymbosum L.) fields typical in their use of mulch under Arkansas conditions. Mulches included 1-year-old hardwood sawdust, 5-year-old hardwood sawdust, and 1-year-old pine needle mulch. Herbicide adsorption (Kd values) of the samples was determined for diuron, terbacil, and simazine. The soils, mulches, and interfaces adsorbed nearly 10 times as much diuron and more than twice as much simazine as terbacil. Adsorption of the herbicides was three to five times greater to the mulches than to the soils. Adsorption was significantly correlated with the organic matter content of the mulch. Adsorption was not related to herbicide solubility. Although no statistical differences were found among the three mulch materials, adsorption coefficients (Kd values) were numerically lower for each chemical on the 5-year-old hardwood mulch than on the 1-year-old hardwood or pine mulch. Chemical names used: 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron); 3- tert -butyl-5-chloro-6-methyluracil (terbacil); 2-chloro-4,6-bis(ethylamine)- s -triazine (simazine).
Laurie Hodges and Ronald E. Talbert
Bert M. Cregg and Robert Schutzki
unmulched plots. Similarly, Greenly and Rakow (1995) observed no difference in soil pH of soils mulched for 2 years with 0, 7.5, 15, or 25 cm of shredded hardwood chips or chipped pine bark. Iles and Dosmann (1999) found that pine mulch and hardwood
Abby B. Griffin, Amy N. Wright, Kenneth M. Tilt and D. Joseph Eakes
not indicate the need for any addition of fertilizer to the soil. A 7.6-cm layer of pine straw ( Pinus taeda L., loblolly pine) mulch was applied to the ground between plants and rows. A fresh layer of pine straw 7.6 cm was added again in Sept. 2008