Fig. 5. Soil NO₃–N and NH₄–N concentrations in the top 10 cm before (15 April) and after (5, 13, 19, and 31 May) litter application, incorporation, and rice planting, but before flooding, by location for five N-equivalent litter rates and an unamended control. Significant differences in soil NO₃–N among litter rates occurred on 13 and 31 May. LSD_0.05 values are 4.05 and 4.96 for 13 May and 3.65 and 4.47 for 31 May for comparing soil NO₃–N among litter treatments and for comparing a litter treatment with the unamended control, respectively. Significant differences in soil NH₄–N among litter rates occurred on 19 and 31 May. LSD_0.05 values are 0.82 and 1.01 for 19 May and 0.69 and 0.84 for 31 May for comparing soil NH₄–N among litter treatments and for comparing a litter treatment to the unamended control, respectively. Soil NO₃–N decreased over time in the unamended control at PTBS (P = 0.001).