IONIC ACTIVITY IN SOIL SOLUTION AS AFFECTED BY APPLICATION OF NEWSPRINT AND NITROGEN-SOURCES

The influence of noncomposted ground newsprint (GNP) and nitrogen (N) source on corn (Zea Mays L.) dry matter production, grain yield, and s oil chemical properties has been previously reported (Lu el al. 1995). The effects of GNP and N source on soil solution ionic activities at 40 days after planting in a field study; seed germination and extracta ble aluminum (Al) in GNP in laboratory studies were evaluated to deter mine their effects on corn seedling stunting and nutrient imbalances d uring early growth stages. Ammonium nitrate (NH4NO3), urea, anhydrous ammonia (NH3), or poultry litter (PL) were the N sources used in the f ield study to adjust the C:N ratio of the GNP to less than or equal to 30:1. In laboratory experiments, cotton, soybean, and corn germinatio n at seven days was not affected by N source or GNP applied at a rate of 2.44 kg C/m(2) soil; but N source did influence the dry weight of c orn root/shoot ratio at 21 days. The Al extracted from GNP increased a s the NH4OH concentration in the extracting solution increased and fol lowed a quadratic relationship with an r(2) of 0.90. The Sigma alpha(c a)/Sigma alpha(cation) ratio in soil solution for all N sources was gr eater than the 0.15 reported by Bennett and Adams (1970a), where incip ient NH3 phytotoxicity can occur. At 40 days after planting, a two-fol d increase in soil monomeric Al (Sigma Al alpha(mon)) ionic activity a nd a five-fold increase in soil P (Sigma P-alpha) ionic activity were measured in GNP treatments as compared to no N GNP treatments. When NH 3 was the N source used to adjust the C:N ratio of GNP, the Sigma Al a lpha(mon) ionic activities were increased by a factor of five as compa red to NH3 applied alone. When PL was the N source, the Al, (Sigma Al alpha(species)) ionic activity was 119 mmol L-1 compared to the Sigma Al alpha(mon) ionic activity of 0.53 mmol L-1. It appears that Sigma A l alpha(mon) ionic activity induced nutrient disorder and caused sever e stunting of corn seedlings during early season growth. The relativel y high water-soluble organic carbon in PL (18 percent) may have acted as a chelating agent to reduce the Sigma Al alpha(mon) ionic activitie s in the GNP, or as a soluble carbon source for increasing microbial u tilization of all the N, thus slowing the formation and accumulation o f phytotoxic levels of by-products.