Describe water management practices during crop growth period
When available water is not limited, continuous ponding of water generally provides the best growth environment for rice and will result in the highest yields. Flooding also helps suppress weed growth, improves the efficiency of use of nitrogen and, in some environments, helps protect the crop from fluctuations in temperatures. Below is the different water management practice during crop growth stages.
Early vegetative stage: After transplanting, water levels should be around 3 cm initially, and gradually increase to 5-10 cm with increasing plant height. With direct wet seeding, the soil should be kept just at saturation from sowing to some 10 days after emergence, and then the depth of ponded water should gradually increase with increasing plant height. With direct dry seeding, the soil should be moist but not saturated from sowing till emergence, else the seeds may rot in the soil. After sowing, apply a flush irrigation if there is no rainfall to wet the soil. Saturate the soil when plants have developed 3 leaves, and gradually increase the depth of ponded water with increasing plant height.
Under certain conditions, allowing the soil to dry out for a few days before reflooding can be beneficial to crop growth. In certain soils high in organic matter, toxic substances can be formed during flooding that can be removed through intermittent soil drying.
Reproductive stage: Keep the water level in the fields at 5 cm at all times during this stage. Lowland rice is extremely sensitive to water shortage at the flowering stage, and drought effects occur when soil water contents drop below saturation. Drought at flowering results in increase spikelet sterility, decreased percentage filled spikelets, and, therefore, decreased number of grains per panicle and decreased yields.
Ripening stage: During ripening stage the field does not necessarily require flooding. Soil that is 80–90% saturated is sufficient. However, for easy operations, keeping the fields flooded may still be the simplest management approach. Draining the fields some 10-15 days before the expected harvest date hastens maturity and grain ripening, prevents excessive nitrogen uptake, and makes the land better accessible (because it is dryer) for harvest operations.
Now that you know the different water management practices during crop growth period you can now proceed on how we can use aerobic rice to cope water scarcity.