Is nutrient cycling affected by tillage and rotation?
Tillage and rotation also affected the mineralization of N in the cropping system throughout the life of the study. Nitrogen uptake by wheat at maturity was increased by NT and legume crops. At seeding CT plots had 28 kg ha-1 more soil nitrate-N to 100-cm depth, and was more dependent on this stored nitrate for wheat growth, than NT plots. No-tilled wheat depended more on N mineralized during the growing season. Growing season apparent net N mineralization was 71 and 22 kg N ha-1, respectively, for the NT and CT systems. Previous crop effect on net N mineralization was red clover> field pea> wheat. Approximately 18 kg N ha-1 was net mineralized from red clover residues compared to insignificant amounts from pea and wheat residues. Microbial biomass turnover’s contribution to net N mineralization (28 to 40 kg N ha-1) was greater under NT and previous legume crop treatments. Soluble organic N decreased by 7 kg ha-1 between seeding and maturity, and was unaffected by tillage or previous c
