An automatic irrigation and drainage system for seedlings of direct-drilled rice

【Objective】 Crops are vulnerable to drought and waterlogging at their seedling stages. Experience-based irrigation and drainage is not effective to alleviate water stresses that seedlings could face. This paper presents an automatic drainage and irrigation system we developed for seedlings of direct-seeded rice. 【Method】 The system includes a micro-sprinkler irrigation system and an automatic drainage device. They are controlled by a LoRa wireless communication network; the irrigation - drainage scheduling was calculated by the fuzzy control algorithm, based on the dynamics of soil moisture and growth of the seedlings measured in the field. The applicability of the system in the fields was evaluated using performance indicators and drainage device performance indicators. 【Result】 ① In the terms of performance, the delay in the response of the system was 0.398 s, the decision-making time was 1.348 s, and the errors of the information monitoring was ±1.48%. ② The automatic drainage device took 4-6 s to close or open, and the standby electric current was 21.7 mA. ③ Experimental results showed that the systems can control soil moisture at 85% of the field capacity 15 days after the seed-drilling; the survival rate of the seedlings was 83.9%. 【Conclusion】 The automatic irrigation and drainage system for seedlings of direct-drilled rice is energy-efficient. It can maintain soil moisture in the proximity of the soil surface around the designed value, alleviating water stress and improving the survival of the seedlings of the directly drilled rice.