解析库 > Kaplan
It is imperative that rice fields are flooded at the proper time. Rice will grow less productively if flooded before reaching 4 inches. Flooding should begin when the rice reaches a height of 4 to 6 inches. Floodwaters will then provide a favorable environment for rice growth, help control weeds and stabilize soil ammonium nitrogen. In order to aid weed control of both broadleaf and grass, and to reduce nitrogen losses, establish the first flood within 3 to 5 days after pre-flood nitrogen applications. The depth of the flood is as important as its timing. The flood should be no deeper than 6 inches; deeper water interferes with proper tillering of rice. Generally, a 2-inch flood on the upgrade side will prevent too-deep water if the levees were properly surveyed.