Automatic variable rate fertilisation system for improved fertilisation uniformity in paddy fields

China currently relies on manual labour to fertilise paddy fields, hindering the improve-ment of fertilisation uniformity, management efficiency, and fertiliser use efficiency. Following a drastic decrease in the availability of agricultural labour, fertilisation opera-tions are facing increasing labour costs and low reliability rates and this is threatening food security. This study developed an automatic fertilisation system suitable for pipe and canal irrigation systems in paddy fields, which measures the irrigation flowrate every second and adjusts the variation of the fertiliser flowrate to maintain a steady water-fertiliser ratio (WFR). An inexpensive single-chip microcomputer was used as the core of the system for precise control and tests were conducted to check its performance in concentration con-trol. Results show that the fertilisation system developed in this study steadily controlled fertiliser concentration with a normalised mean absolute error (NMAE) ranging from 0.15% to 0.58% and from 0.22% to 0.63% for the tested pipe and canal irrigation systems, respectively. The fertiliser flowrate was adjusted to the irrigation flowrate instantly and accurately, with a maximum deviation of 0.56% in the WFR. This system drastically improved fertilisation uniformity compared to manual fertilisation, and had a Christiansen uniformity coefficient of 96.30%; a distribution uniformity of 0.93, and a coefficient of variation of 0.05. It also decreases labour costs, reduces potential pollutions and increases management efficiency. Thus, it can improve fertiliser use efficiency and contribute to the development of precision agriculture. (c) 2022 IAgrE. Published by Elsevier Ltd. All rights reserved.

Automated summary

China currently relies on manual labour for fertilising paddy fields, which hinders the improvement of fertilisation uniformity and efficiency. This study developed an automatic fertilisation system that accurately controls the flowrate of fertiliser based on the irrigation flowrate, resulting in improved uniformity and precision of fertilisation. The system reduces labour costs, enhances management efficiency, decreases potential pollution, and contributes to the development of precision agriculture.