Impact of lime application on plants and soils in flooded rice systems.

摘要

A three year study was conducted to evaluate the impact of lime application in flooded rice (Oryza sativa) systems. In particular, rice yield, nutrient uptake, soil tilth, disease incidence, and weed pressure were monitored to determine the agronomic effects of liming. Extensive pre-application soil sampling was carried out at two grower-managed sites and multiple liming rates ranging from 0 to 27 Mg ha-1 beet lime were evaluated. Lime application had no significant effect on straw or grain yields, N uptake, or N partitioning within the plant. Using isotope dilution techniques and 15N-labeled fertilizer, fertilizer recovery ranged from 35 to 51 %, with crop recovery (grain + straw) accounting for 12 to 23% of the fertilizer applied. Liming reduced fertilizer N recovery in the crop, but increased below ground recovery (roots + soil); pool substitution resulted in the appearance of an added nitrogen interaction (ANI). Measurements of soil physical properties indicated that significant changes in soil structure occurred following the application of lime, and that the amount of force required for primary tillage operations increased. Interestingly, increased Mg availability associated with liming inhibited ricefield bulrush (Schoenoplectus mucronatus) germination and provided up to 80% control of this weed in the field. Overall, lime application does not appear to be a cost effective management practice; however, further study of the underlying mechanisms responsible for ricefield bulrush reduction are warranted and could prove useful in developing better weed management strategies.