Abstract
The content of soil organic carbon (SOC) and total nitrogen (Ntot) was studied in a long-term field experiment with a three-field crop rotation (potato – spring wheat – spring barley) set up on arable sandy loam Stagnic Albeluvisol at Eerika, Tartu, Estonia. The studied factors were: (A) organic fertilizers with three treatments: (i) without organic fertilizer, (ii) farmyard manure (60 t ha−1) used in every third year, and (iii) different organic (alternative) fertilizers (beet leaves + straw; pure beet leaves; slurry + straw; cereal straw) and (B) mineral nitrogen fertilizer with the rates: N-0; N-40; N-80; N-120 and N-160 kg ha−1. The study years were 1993, 1996 and 1999. The average content of SOC (1.03%) was significantly influenced by the use of organic fertilizers. Only Ntot (mean value 0.110%) was influenced also by fertilization with mineral nitrogen. The C/N ratio (mean value 9.5) reflected changes in the content of SOC and Ntot
Acknowledgement
This research project No. 0172613AGML03 was supported by the Estonian Ministry of Education and Research.